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FORS2 FIMS Manual

1. Button Explanation FORS Save mos 2 e start the target acquisition saving sequence OK e in the reference target verification window or 2 4 in case those targets are not accepted OK e acknowledge verification message after op tional delete of rejected reference targets OK e Save the set up file to the default directory AP ptl e if more than one local catalog is active select one e Look in the status panel if the last saved file name is updated FORS Reset Mode e reset the mask FORS Reference Targets reset e delete all reference targets FORS Load SetUp e load the target set up file again Table 9 Session 7 MOS target acquisition save MOS set up FIMS Manual VLT MAN ESO 13100 2308 38 Button Explanation FORS Reset Mode FORS Reference Targets reset FORS Load SetUp Data Servers Catalogs USNO at ESO In the Catalog Window Set from Image CW MinRadius O MaxRadius 5 CW Brightest CW Equinox J2000 MaxObjects 1000 Faintest CW Search CW File Save as CW File Close Graphics Clear Data Servers Local Catalogs Load from file e reset the mask e delete all reference t
2. Session 4 Button Explanation File Open e load your FITS image FORS Enter Mode IMG e enter imaging mode FORS Status Demos Status Panel e open the FIMS status panel if it is not open from the previous session FORS Config Layout Labels e show labels FORS Config Layout collimator e select high resolution collimator COLL_HR 7 FORS Reset Mode B1 on the green circle e move the mask by dragging the green circle B2 and Shift B2 on the green circle e rotate the mask by clicking on the green circle B1 B2 e move optionally MOS slit blades inside the CCD field to obscure presumably saturated ob jects B1 e on the slit number label at the rim of the focal field to deselect both blades B1 e on the slit width label to edit free space be tween both blades FORS Config Layout Transparency e highlight the user defined slit blades e Continue with Reference Target set up before saving Table 11 Session 9 IMG occult acquisition FIMS Manual VLT MAN ESO 13100 2308 40 Button Explanation FORS Config Layout ProjectName e select project name this name will appear in the set up file Enter Close e for the p
3. Config Layout Transparency flag is to highlight selected MOS slits only FIMS Manual VLT MAN ESO 13100 2308 16 4 1 4 Slitless spectroscopy Slitless spectroscopy imaging with a grism is handled either as a special sub mode of MOS open option in the slit width menu or through the imaging mode with occulting bars see section 4 3 For this purpose all MOS slit blades are out of the focal field by default but may be individually set as in IMG to occult selected light sources in the sky field 4 2 PMOS mode 4 2 1 PMOS mode As in imaging polarimetry IPOL the odd numbered MOS slits are closed while only the even numbered slits can be moved via mouse button B1 The mask preparation steps as well as the target acquisition on the sky is done with the same sequences and procedures as for MOS mode Basic mouse bindings associated with the green circle are retained see section 3 1 The collimator check button in the layout menu is disabled in order to avoid PMOS in high resolution collimator mode No PMOS mode with the high resolution collimator Spectro polarimetry using MOS slitlets and the high resolution collimator is not supported with FORS since the mode would require MOS slitlets of 11 arcsec length to be used with the given Wollaston prism 4 3 IMG mode imaging with occulting bars For the imaging mode it is possib
4. Status Demo Status Config Layout Labels Config Layout Grism GRIS_600z 23 Config Layout OS Filter GG435 81 Config Layout MXU slit type STRAIGHT Config Layout Slit Width 1 4 Config Layout Slit Length 8 Bi B1 B1 Enter Close B1 Config Layout Center slit B1 Config Layout MXU slit type CIRCLE B1 Config Layout MXU slit type CURVED B1 B1 B1 Session 4 Save 0K FIMS Manual VLT MAN ESO 13100 2308 41 Button Explanation FORS Enter Mode MXU e Enter Mask eXchange Unit mode of FORS2 We assume that there is already an underlying image e pop up status window e Switch labels on e select grism select order separation filter e select aperture type straight slit e select common slit width e select common slit length e on the green circle move and rotate the mask as in all other modes e on a target to create a slit on the target e on the slit width label 1 4 to edit length width and position angle of slit e on the slit number label 1 at the rim of the focal field to purge the slit again e switch on the center slit option and wait until the pick object window appears e press and drag as usual and release B1 to carry out the center gauss If the object is inside the current focal field a new slit will be created and centered to match the target position e select apertu
5. Table 2 Default target set up file names and keywords ec exposure counter PN project name Note The saved set up files for IMG use different keywords for the slit blades with respect to MOS and PMOS Therefore setup files of different modes are not exchangeable therefore do not load e g the file img1 13 NGC_0815 fims when the current mode is mos MOS and PMOS slit positions are defined by WCS IMG slit blade positions are defined by mm in the focal plane One exception is slitless spectroscopy FORS Config Layout Slit Width open where the MOS slit blades are out of the focal field by default They can however be used as in IMG to occult bright foreground sources and their spectra Default target set up file names and used keywords are summarized in table 2 6 5 Quit Mode This menu item deletes the mask of the current mode and de activates all FIMS features 6 6 Auto Slit The automatic positioning of P MOS MXU and HIT MS slits on catalog positions requires target lists For large user defined target lists the slit blades can be positioned automatically under several constraints In any case the slits will be positioned to the catalog targets which might not fully coincide with the optical positions in the FITS frame When P MOS MXU HIT MS slits are positioned by the Auto Slit routine the reference target positions must be specified from the same catalog and not fro
6. e purge to purge individual reference targets from the list e g enter 1 4 to purge targets 1 and 4 e verify to check that all reference targets can be handled by FORS e reset to delete the complete list of reference targets e MOS10 to switch the MOSI0ALI flag When MOSI0ALI is ON the MOS slit 10 will be in the focal field in the MOS acquisition image for high precision alignments Reference targets under this slit cannot be used to align the telescope position hence this sky region should be omitted when selecting reference targets 6 9 Status Demo Status creates a new toplevel window showing the current status of the FIMS session The contents of the three fields e Instrument e Session e FORS MXU are self explaining Demo A brief demonstration of the capabilities and functions of FIMS 6 10 Config Layout This cascaded menu contains instrumental configuration options and options for the graphical layout of the mask Depending on the selected instrument mode certain parameters can be selected from the FIMS configuration menu Only some configuration parameters like the collimator and the slit geometry are written in the FIMS output files Other parameters selected within FIMS e g wave length range grisms and filters are only used within the FIMS session to display the location of the spectra and other user supporting features Accordin
7. FIMS the FORS Instrumental Mask Simulator is the FORS Observer Support Software It is a graphical user interface to show the FORS sky field which allows the precise positioning of the 19 FORS MOS slits and the slits of MXU masks by moving an instrumental mask over a sky image FIMS is a plug in for the ESO Skycat Tool a browser for astronomical images and catalogs It can be installed and used at the user s home institute It is also available at ESO headquarters and at the Paranal Observatory Figure 1 shows FIMS in the context of the ESO Skycat FIMS the auxiliary software and installation instructions can be downloaded from the following WEB page http www eso org observing p2pp 0SS FIMS FIMS tool html 2 2 Some technical details in advance 2 2 1 The fsmosaic plug in Functionality of fsmosaic With the instrument now using mosaic detectors the CCDs are read from two ports one port per CCD The raw data product to be delivered to the users will be two files with the images read from the upper master and lower slave detector respectively The mask preparation with fims will require a combined mosaic image of the full field of view The merging will be done with a plug in function fsmosaic which is called by fims for any FORS2 mosaic images to be loaded into fims fsmosaic will classify the input files automatically as either old FORS pre images or contributed images or as images taken with the new MIT E2V detec
8. Save as button in the catalog pop up window with the same name the initially loaded full target list gets saved for security reasons to lt targetlist gt BAK Therefore it is recommended to load a copy of your full target list to Skycat FIMS Manual VLT MAN ESO 13100 2308 28 6 8 Reference Targets MOS PMOS HIT MS and MXU target acquisitions have to be aligned using reference stars For P MOS HIT MS and MXU mode select up to 10 bright reference targets ideally close to the slit positions Reference targets can be specified at any time during a FIMS session but no longer during the save sequence Press FORS Reference Targets add to add reference targets Purge reference targets by a comma separated list e g 7 3 in the purge menu The reset button finally erases all entries in the reference target list Selected reference targets will be highlighted via a cyan circle The parameters of the chosen reference targets will be shown in the PickObject window If less than 10 reference objects are required Enter an empty string in the entry form and ignore the error message The sub menus are e plot to plot the reference targets on the screen e show to list the reference targets and their positions e add to add further reference targets The forbidden area for reference target selection is obscured by a cyan strip
9. 5 at the rim of the focal field to de select MOS 5 Bi e click on the slit width label of MOS 7 to specify new slit width for MOS 7 FORS Config Layout Center Slit e switch the center slit option ON Wait a mo ment for the PickObject pop up window B1 on the object e a click on the target in the main window b hold B1 and shift the cursor and watch the target in the zoom window of the PickObject window c release B1 The source will be fitted by a 2D Gaussian and the slit will move from the cursor position to the source center If the fit failed use the z in the PickObject window and try again If fit failed the slit will move to the last B1 press position Table 7 Session 5 MOS target acquisition position MOS slit manually and Center Gauss slit positioning Button Explanation Data Servers Catalogs GSC 2 at ESO In the GSC2 Catalog window a 6 min Radius 4 0 max Radius 7 4 Brightest 11 0 Faintest 14 0 Search e create a local set of guide stars e type the mask center telescope pointing e specify TCS guide star search field Use only these values e specify TCS guide star limiting magnitude Use only these values e If more than 3 5 guide stars are found it will be ok Table 8 Session 6 TCS guide star search FIMS Manual VLT MAN ESO 13100 2308 37
10. 56 35 674 i 72 27 12 34 2000 FIMS Manual VLT MAN ESO 13100 2308 24 6 FORS Menu Reference This section gives a comprehensive description of all pull down menu items in the FIMS FORS menu and its sub menus FORS Enter Mode gt section 6 1 Reset Mode section 6 2 Refresh Mask section 6 3 Load SetUp section 6 4 Quit Mode section 6 5 Auto Slit gt section 6 6 Save lt mode gt lt number gt section 6 7 Reference Targets gt section 6 8 Status Demo gt section 6 9 Config Layout gt section 6 10 6 1 Enter Mode Selecting one of the items in this menu IMG Direct Imaging MOS Multi Object Spectroscopy PMOS Polarimetric Multi Object Spectroscopy MXU Mask Exchange Unit HIT MS HIgh Time resolution Multi Shift plots the focal field blue square and the current instrumental mask over the sky image The mask is initialized and oriented according to the FORS2 reference system definition The rotator angle 1 x position angle on the sky is zero The orientation means MOS slit blade pair 1 is on the Northsxy side MOS slit blade pair 19 is a the Southsxy side MOS drive unit A is on the Westsxy side and MOS drive unit B is on the Eastsky side The correct orientation of the mask with respect to the underlying sky image can be verified using the FORS Config Layout Lab
11. MXU slit size Sizes of all individual slit apertures are restricted to 40 arcsec for mechanical reasons since the long metal pieces can get stuck in the punching machine It is however not excluded to produce larger multi slits or unusual slit geometries by punching several individual MXU slits next to each other with some space in between However such large multi slits may cause mask plate bending and are thus to be discussed with the observatory staff More than one curved slit It is possible to specify more than one curved slit in one setup If a second curved slit is created the previously created cannot be edited any longer It is not possible to modify previously defined curved slits one has to delete the previous slit and define a new one Slow shape modification Curved slits change their shape on line but not real time while moving a cyan Bezier polynomial grid point The on line low resolution shape of the curve is determined in Tcl Tk and is hence very slow It is recommended to use a large slit width and hence a large Bezier circle to avoid loosing the anchor when modifying the slit shape When the desired slit shape is achieved the fake large slit width can be set back to the originally intended slit width FIMS Manual VLT MAN ESO 13100 2308 19 4 5 HIT MS mode Visitor Mode only 4 5 1 Basic information The HIT MS mode is based on the MXU mode with the difference that the dispersion direction is orthogonal to th
12. Setting The settings are complete and can be saved to a target set up file 7 Create Finder Chart The finder chart should show the overlay of the mask on the pre image and attached to Service Mode OBs The target set up file just created should be verified by loading the fims set up file again The mask should adjust according to the entries in the target set up file A full description of the Finding Chart plug in can be found at These instructions should be followed for all OBs submitted as part of the Phasell package The following tables are a summary of button sequences executed for several tasks The FITS im age used in the following example sessions is a 10 second test exposure taken by FORS1 This frame is available via the FIMS web page http uww eso org observing p2pp OSS FIMS FIMS tool html FIMS Manual VLT MAN ESO 13100 2308 33 Button Explanation File Open click on FORS1 fits Scale 1 4x Low 450 High 800 Data Servers Catalogs GSC 2 at ESO In the Catalog Window Set from Image CW MinRadius 0 MaxRadius 5 CW Brightest CW Equinox J2000 MaxObjects 1000 CW Search CW File Save as Faintest CW File Close Graphics Clear Data Servers Local Catalogs Load from file
13. a ae orn een aem awe OG ERE a dn A A a 16 20 PMOS made sses ars a ane dee ee he dea aa a os 16 4 3 IMG mode imaging with occulting bars e e ae 16 Ba MXU made nne a a hes ee Ge E De ee es NEE Ee ede a 16 AEN MMO IO 16 AAD Creating ste EE ann ae REE a Ea EER Bean ee AR A aed 17 AAS MXU reference slits or o e one na oe ee a ee EEN A Be 17 444 Fils and rmmbers EE aas eea Rohe ae a Be ew OU AAS MAU constraints gt es nnen a EO A SEA RE a 45 HIT MS mode Visitor Mode okt EEN nwe a ddd Yas Ahl Basie MONO 50 vam wa mn Baw BR OR Swe Da Bk HE A die EE Ste E EE Et ee ee BB EE B ae a a 4 5 3 HIT MS reference slits ANNER d emor e a ee A E a el a 404 Kies and TUNDES na An eck ae ee A de as kOe eS 5 Target Lists 5 1 How to generate target lists ooo cock ta amad kaasa nasai D2 Example target USE sucias ane a a ee AN e a A ec DS paving target Scquisition Ales ENEE de a ee de ha we eS 5 4 More about fims preparation with target Datz 6 FORS Menu Reference Ol Ener Modo sa Bad ee ae A ae de We enh a ld aa 0 2 Reset Modo a emt a Bb ba oe aa BE BR e aa ee a dE A e et emi ISS oon ee a E et AN em ep Breet ae BT Bete ln OE ER B B oe er 64 Load SetUp c an aman AeA RE AE AAA 05 Komt Modes cos pe Boe ee Ee en be Ad oe aces Pe GG AWOSE oia er a EBR HARE SAR ERT Rea es 6 1 Reguirements e 2 2 4 5 EN doe Pe Re ewe as we Wd O SA A ge E ai G aaa h A a Coa STATIG oor ar poa So he RS a Od ae EB Meee BS AL Re
14. as the slits into the invar mask sheet at a position outside the focal field When saving a MXU set up FIMS creates a file with the gbr extension This file contains the slit set ups the default mask id and the mask size in the extended Gerber format GerberX format or RS274X format This file will have to be included in the OBs for the MXU via P2PP At Paranal this file will be used by the Paranal mask preparation software to produce the mask with the Mask Manufacturing Unit MMU Finally the mask will be inserted into FORS2 before the observations are scheduled Mask name Mask id Mask NAID When saving a setup for the MXU the keyword INS MASK NAID will be created and included to the setup files The value is Middcccccccc dddddd or M lt INS MASK NA gt lt INS MASK ID gt where ddd is the FIMS internal counter as a three digit number Its the same number that appears in the name of the well known p_focf file The cccccccc is a 8 char long string Its the user defined project name which also appears in the name of the p_focf file By default the first 8 chars of the fits file name is taken The dddddd is a six digit random number between 900101 and 999999 When a mask is manufactured the six digit INS MASK ID is the only identification Postscript file of the slit mask when saving a setup for the MXU a postscript file is saved to fims LOG for printing an image of the mask with slit positions 4 4 5 MXU constraints Maximum
15. e select and load a FITS image e choose a suitable image scale e select cuts in the main panel e Create a target list from the online ESO archive The following steps are optional for ob servation preparation e Take initial search starting point from the FITS image e specify the circle to search in the archive e using empty fields to take all targets available e default e 22 objects are found and plotted e copy this catalog to disk Here we use the name A ptl e close the Guide Star catalog e clear catalog drawings on the screen e load A ptl now as local working catalog Table 3 Session 1 Loading an image and a catalog CW Catalog Window FIMS Manual VLT MAN ESO 13100 2308 34 Button Explanation FORS Enter Mode MOS e Enter MOS mode draw MOS mask FORS Config Layout Labels e Show the Labels Regard the correct mask ori entation FORS Status Demo Status e pop up the FIMS status panel FORS Config Layout Grism e select grism GRIS_600z 23 Help Grism info e read the appropriate order sorting filter FORS Config Layout 0S Filter e select OS filter 0G_590 32 ei FORS Conf ig Layout Wavelength Range enter 700 and 850 Enter Close FO
16. pop up window appears Each time a slitlet is moved by a simple cursor click the slitlet is re centered from the current cursor position to the resulting position of the center gauss method If center gauss fails indicated by the red message in the PickObject window the cursor position is used as if this option is off This option is suitable when FIMS Manual VLT MAN ESO 13100 2308 31 using MOS MXU HIT MS in connection with point source targets while for extended and spatially asymmetric targets like galaxies the direct cursor position might be a better solution to position the MOS MXU HIT MS slits Center Slit option The center slit option selectable from the configuration menu will sig nificantly improve the slit positions for point sources and other relatively compact targets A Skycat feature with the centroid algorithm a single click on the target and the centroid might fail Click somewhere with the left mouse button B1 hold the button while moving the mouse wait until you see the target in the center of the pick object window and release the mouse button now Slits behind the green circle The left mouse button while used on the location of the green circle is defined to move the mask It is only possible to put a slit behind the green circle with the Center Slit functionality as described above click somewhere keep the left mouse button pressed while moving the mouse behind the green circle wai
17. run please contact the FORS Science Operations Team at Paranal fors2 eso org 1 2 Recent Changes The changes listed in the P84 version of the manual are the following e Major revision due to FORS merger only FORS2 available R ed and B lue CCD options available and polarimetry on FORS2 e FORS1 E2V mosaic images are now handled by fsmosaic e column names for the input catalogues have been revised following reports of erratic behaviour In P85 the changes are the following e FIMS version 3 released e Section 4 5 added with description of HIT MS mask creation e Table 14 added with Example Session of HIT MS mask acquisition e Revisions in many places to reflect changes introduced by FIMS 3 1 3 Acknowledgments The first edition of this FIMS manual was delivered as part of the FORS User Manual by the FORS Consortium Landessternwarte Heidelberg and University Observatories of G ttingen and Munich Germany in the scope of the FORS contract It was then edited by Gero Rupprecht Hermann Bohn hardt Thomas Szeifert and Emmanuel Jehin ESO The FIMS software releases up to September 2000 were prepared by Wolfgang Hummel University Observatory Munich now at ESO and since then by Ana Maria Aguayo Pedro Baksai and Mario Kiekebusch ESO Paranal In recent years and until P91 Ivo Saviane ESO was the editor of the manual FIMS Manual VLT MAN ESO 13100 2308 2 2 Introduction and Requirements 2 1 The FIMS Concept
18. the spectrum is about 155nm long covering a range of 467 pixels or corresponding to 61mm in the focal plane For the absolute wavelength position on the CCD Note that the central A 590nm appears on the CCD where the through slit image would appear The sixth line gives the total user defined USD wavelength range blue and red part together The seventh line gives the total wavelength range as permitted by the grism filter combination This is the wavelength range not contaminated by the second order of the grism In our example the total available uncontaminated range is 435nm The CCD can cover 679nm last line 3 4 Finding guide stars for the VLT FIMS or Skycat can be optionally used to verify if there are appropriate guide stars in the field of view of the unit telescope The search is confined to an annular sky region around the telescope pointing coordinates where the guide probe can be positioned without vignetting the relevant FORS field of view The standard limiting radii of the search are 40 lt R lt 7A 1 when using the standard resolution collimator and 22 LR TA 2 when using the high resolution collimator A further seeing dependent constraint for guide star selection is the brightness range of 10 0 lt my lt 13 0 for the median seeing of 0 8 arcsecs If the telescope control system cannot find a suitable guide star within this region the pointing cannot be achieved hence the observations cannot be carried out To
19. 05 P77 update no change 78 June 08 2006 P78 update no change 79 Sept 01 2006 P79 update no change 79 Jan 04 2007 Included section on finding charts 80 Jul 16 2007 all P80 update minor changes due to E2V mosaic 81 Dec 19 2007 few General overhaul Update on format of catalogues 82 Jun 24 2008 none P82 update no change 82 Jul 24 2008 5 Update to target lists 83 Nov 10 2008 all P83 update for merged FORS includ ing CCD choice 83 Dec 8 2008 minor changes 84 Jul 15 2009 P84 release 85 Dec 15 2008 added 4 5 and some P85 with HIT MS added Table 14 cleaning of a few more added 86 Jun 22 2010 none P86 update no change 87 Dec 27 2010 none P87 no change 88 Jun 28 2011 none P88 no change 89 Feb 29 2012 none P89 no change 90 June 08 2012 none P90 no change 91 Jan 04 2013 none P91 no change 92 Jul 04 2013 none P92 no change Editor H Boffin hboffin eso org ESO Paranal Contents 1 About this manual 1 bel MOO En ee Be Se so Renee rdt ete alt EO GE en an SL e a 1 L2 Recent CHAMBER gt a aas aon de be kG ae aie A ba ee on ee A 1 13 ia ao re nona le eee HE B Wa er Bl el Ae 1 2 Introduction and Requirements 2 21 The FIMS Concept ann an an en en a A ae e ein a rie ee ei nar 2 2 2 Some technical details in advance 2 221 The tsmosaic plug in oc corsa an eee ee 2 2 22 Environment variables o soan ae E ae a ER B Ee Ce es 4 2 2 0 Startup of FIMS
20. EA EENHEETEN 60 ROTATE osos d E da e nee Gwe Rae doe Pak A bee A A Gor MB in EN E hie ere CA eee AC BAS oe aos Gee Be 6 8 Reference Targets ee 09 Sm DS A te eb ae eke etek ket Eh rd er PRE RO O10 Conte Lay seise aha me Wat kre har ea a AR Bd AAS 6 10 1 Instrumental configuration options 6 102 Graphical layout OPUODS si aa an ea B ee eh ee a E 6103 Special options s saa an aerden de a en ae Mie A ere 7 FIMS Cook Book and Example Sessions A PSO Internal information B List of Acronyms C World Coordinate System Information List of Figures 1 Concept Ol PING a a dunt a os arend Perik ar ee He B BOR latr a BS 2 FIMS DE Sireen Snapshot o ete eaten senen he Hdd 21 21 22 22 22 24 24 24 24 24 25 25 25 26 26 26 27 27 28 28 28 29 30 30 32 43 45 46 3 FIMS 3 x screen snapshot FIMS Manual VLT MAN ESO 13100 2308 1 1 About this manual 1 1 Scope This manual describes the FORS Instrument Mask Simulator FIMS It should be used together with the FORS2 User s Manual ESO document VLT MAN ESO 13100 1543 and the FORS2 Template Manual ESO document VLT MAN ESO 13100 2309 both are available via the FORS web page http www eso org instruments fors In case of specific questions concerning your service mode observations and proposal preparation please contact the User Support Department at ESO through email usd help eso org For questions concerning your visitor mode
21. G435 81 Help Mask Info OK e Enter Mask eXchange Unit mode of FORS2 We assume that there is already an underlying image e pop up status window e Switch labels on e select grism select order separation filter e show available technical masks e pop up the file select widget e in the filename Filter Entry form e select the technical mask for ECHS e on the green circle move and rotate the mask as in all other modes e specify reference targets e start the save sequence e for the number of reference slits e Continue as explained in the MOS target ac quisition sequence Table 16 Session 15 MXU technical mask acquisition Special MXU masks can be shifted rotated as in all other modes with a fixed mask as e g LSS In case the center slit option is ON the MXU technical mask slit can be centered on the object Special mask set ups can be saved as a sky user defined science mask set ups When saving a set up of a special mask no Gerber file is created Technical masks from the set listed in table 15 are not offered for science observations with FORS2 FIMS Manual VLT MAN ESO 13100 2308 B List of Acronyms CCD DSS ECHS ESO FIMS FORS HIT HIT MS HR HST IMG IPOL ISF LSS MMU MOS MXU OB OCC P2PP PMOS PSO SCT SR TAF USNO WCS WFPC2 Charge Coupled Device Digital Sky Survey ECHelle Spectroscopy European Southern Observatory FORS Instrumental Mask Simulator FOcal Reducer low dis
22. RS2 Config Layout Slit Width 2 00 FORS2 Config Layout Slit Length real e close grism info e popup wavelength range window e enter wavelength range in nm required for all targets e activate new wavelength range and redraws the target selection field close the window e select a common slit width of 2 arcsec for all 19 slits e we don t require a lower limit of the sky back ground area around the target spectra Table 4 Session 2 MOS target acquisition configure instrument mouse buttons on green circle Explanation B2 rc B1 move otate Shift B2 rotate e move and rotate the mask by clicking in the green circle e Try to match following values RA 08 00 03 993 e DEC 00 01 26 37 and ROT 30 Table 5 Session 3 MOS target acquisition move mask FIMS Manual VLT MAN ESO 13100 2308 35 buttons Explanation FORS Reference Targets show ok e show the reference target list with coordinates FORS Reference Targets add e add further reference targets to the list ON e Use the MOS 10 slit in the acquisition image for high accuracy alignment The MOS 10 would occult reference tar
23. S y EUROPEAN SOUTHERN OBSERVATORY E Organisation Europ ene pour des Recherches Astronomiques dans lH misph re Austral O Europ ische Organisation f r astronomische Forschung in der s dlichen Hemisph re ESO European Southern Observatory Karl Schwarzschild Str 2 D 85748 Garching bei M nchen Very Large Telescope Paranal Science Operations FIMS Manual Doc No VLT MAN ESO 13100 2308 Issue 92 0 Date 04 07 2013 H M J Boffin Prepared aaga E eh a e e dee e En Date Signature A Smette Approved aeta be ade kde me beden werde Kies Date Signature C Dumas else reeet ne A is IDE de Date Signature This page was intentionally left blank Change Record Issue Rev date sections affected Reason Remark 1 0 1 5 various all FORS1 2 User s Manual fims manual included as chapter 4 2 0 Sep 17 2000 all major revision separated fims manual from FORS1 2 User s Manual first issue FORS1 2 FIMS Manual MXU included 2 1 Dec 27 2000 few some figures removed some small corrections index added 22 July 3 2001 all P68 update 2 3 Jan 6 2002 all P69 update MIT CCDs for FORS2 no HIT no ECHS 2 4 May 22 2002 all P70 update no more fims for LSS amp IPOL 2 5 Dec 24 2002 1 2 4 5 P71 update no more fims for LSS amp IPOL 2 6 June 30 2003 all P72 update 2 7 Nov 4 2003 all some new functions for P73 2 8 June 30 2004 all pdf format 3 Nov 28 2004 P75 update no change 3 Aug 30 20
24. The first block of lines gives the instrument characteristics at the focal plane Then follow two lines giving the wavelengths in nm From left to right 1 The lower A boundary as given by the grism filter combination This is the shortest wavelength that makes sense for the given grism filter combination 2 The user specified lower A boundary defined by the Wavelength Range button 3 The central A as given by the grism filter combination and which appears at the center of the CCD 4 The upper user defined A boundary defined by the Wavelength Range button 5 The upper A boundary as given by the grism filter combination This is the longest wavelength that makes sense for the given grism filter combination FIMS recognizes that the user defined lower value value 2 line 9 is not inside the interval given by the instrument value 1 and corrects it to the lowest permitted value from 200 0nm to 435 0nm in the second row The second line also shows the grism name and the filter name note that this information is only for information and is not passed onto P2PP FIMS Manual VLT MAN ESO 13100 2308 14 The line labelled DISP the grism dispersion in different units where mmfc means mm in the focal plane and mmCD means mm on the CCD The next two lines give the blue BLU and the red RED part of the user defined and FIMS corrected wavelength range again in different units In our example the blue part of
25. U mode only Create a slit on all targets of the user provided catalog if the target is within the field of the mask There is no verification if the spectra will overlap The user has to interactively remove the slits for which the spectra will overlap This option was primarily created to allow to create masks for which the length of the spectra is reduced by the use of an interference filter 6 6 3 STATIC Take the current mask coordinates RA and DEC and position angle PA search for targets in the user defined local catalog and push slits to appropriate target positions If there is more than one target per slit blade pair available then the object closest to the slit blade center line is used If the target list provides the prio column then targets with prio 1 are preferred even if a prio 0 target would be closer to the slit blade center The two blue lines indicate the CCD area for which the instrumental wavelength range fully matches the CCD Automatic positioning takes only targets within this area into account since spectra of objects beyond this area will be cut due to the CCD edge The instrumental wavelength range is defined by the combination of grism order separation filter If only a fraction of the available wavelength range is of scientific interest the fractional wavelength range can be specified via the FORS Config Layout WaveLength Range button Since this user defined wavelength range is smaller than the instrumental wav
26. WaveLength n menu The sky area limit for which the user defined wavelength range fits within the CCD is marke by two additional blue lines Spectra of targets with MOS slit positions beyond the left right blue line will be cut at the blue or red end of wavelength range The two forbidden target selection regions at both sides of the CCD are indicated by a large blue cross or in other words spectra of slits positioned in the blue crossed area will by cut by the edge of the CCD 3 3 1 About the screen output Each time a new grism a new filter or a new wavelength range is selected the grism info output is updated in the log window A sample output looks like Wave Limits INS_DISP 5 0 mm nm FOCSCALE 1 901679 arcsec mm PIX 0 030 mm pix binned CCDscale_standard 0 250124 arcsec pix CCDscale_highres 0 1250626 arcsec pix FORS CCD Frame 435 0 lt 200 0 lt 590 0 lt 730 0 lt 870 0 435 0 lt 435 0 lt 590 0 lt 730 0 lt 870 0 GRIS300V 10 GG435 81 gt DISP 110 0 A mmCD 3 3 A pix 13 2 26 4 A 6 9 13 9 A mmfc gt BLU 1550 0 A 466 7 pixel 116 7 1 945 61 380 mm fp gt RED 1400 0 A 424 2 pixel 106 1 1 769 55 800 mm fp gt USD 2950 0 A 893 9 pixel 223 6 3 727 117 179 mm fp gt SPE 4350 0 A 1300 0 pixel 325 2 5 419 170 986 mm fp Field Stop total range 4516 1 A SR 5354 4 A HR CCD total range 6788 2 A SR 6782 6 A HR
27. and requirements for the use of target lists 5 1 How to generate target lists Target lists can be created in four ways 1 A local catalog can be created with EnterObject where the positions are determined by the center gauss method from the underlying image It is recommended also to include the reference targets in the same catalog to make sure that science targets and reference targets use the same coordinate system 2 Catalogs are also available from the web see Data Servers When plotted over the FORS frame they might be shifted with respect to the optical position a consequence of the VLT pointing accuracy It is generally possible to use automatic MOS slit positioning using external catalogs However it might be necessary to edit the table header keywords see section 6 6 for the requirements Again it is important that the reference targets must be taken from the external catalog as well and not from the optical position in the frame 3 Load the preparation image into ESO MIDAS and use the inventory package to create a target list The target list can be converted to the Skycat format See the midas2skycat sh script in the delivery package 4 The output format of the widely used Source EXtractor software is already compatible with the Skycat catalog format FIMS Manual VLT MAN ESO 13100 2308 22 5 2 Example target list The target list is an ASCII file where individual columns are se
28. ant width over the full slit length but show some deviations at the slit edge Using a visually reduced MOS slit length avoids target positioning at the critical MOS slit edges This option can also be used to define small reserved strips which could during the observations with this mask be used for jitter offsets along the MOS slits The real option returns to the full slit length of the MOS unit For MXU this option determines the real slit length and for HIT MS this can only be 5 or 10 Slit Shape This is only enabled for MXU Choose one of the 3 currently supported slit types TRAIGHT CIRCLE or CURVED Note modifying curved slits in the FIMS display needs some patience and the display update may be slowed down Please do not rush It is possible to create more than one curved slit but it is not possible to modify the curved slit created Some kind of strategy for the creation of curved slits is advisable The maximum number of MXU slits is 1000 including the 6 reference slits Working with curved slits modifying etc can slow down the update of the FIMS display Be patient and do not rush if you do so you are told by the computer that it needs more time WaveLength Range Specify the Wavelength Range in nm for one of the spectroscopic modes MOS PMOS MXU HIT MS and reset the mask with the new wavelength region boundaries Note that the wavelength range is not a physical instrumental c
29. argets e load the target set up file again e Create a target list from the online ESO archive The following steps are mandatory for AutoSlit positioning e Take initial search starting point from the FITS image e specify the circle to search in the archive e using empty fields to take all targets available e default e 192 objects are found and plotted e copy this catalog to disk Here we use the name USNO ptl e close the USNO catalog e clear catalog drawings on the screen e load USNO ptl now as local working catalog FORS AutoPos STATIC USNO ptl Ok FORS AutoPos SHIFT USNO ptl Ok FORS AutoPos ROTATE USNO ptl Ok e the mask position and the position angle will be retained e select the USNO catalog and acknowledge 18 slits will be positioned except MOS 5 e the mask position angle will be retained but not the mask position e select the USNO catalog and acknowledge 18 slits will be positioned except MOS 10 e the mask position will be retained but not the position angle e select the USNO catalog and acknowledge 18 slits will be positioned except MOS 5 Table 10 Session 8 MOS AutoPos target acquisition FIMS Manual VLT MAN ESO 13100 2308 39
30. at of the standard mode Therefore only the cross disperser grisms XGRIS 600B and XGRIS 3001 are used The wavelength range of the grisms is slightly different from that of the standard 600B and 3001 This is primarily caused by the asymmetric mount of the FORS2 MIT CCD mosaic which is off centered by 33 Both MIT or E2V mosaics can be used The user can define two 5 long slits allowing 41 pairs of spectra per CCD readout or a single 10 long slit Any slit width can be defined in the range 03 30 The position angle of the rotator is determined so that the target and comparison slits fall onto adjacent x pixels on the CCD The y pixel positions of the two slits are determined by the offset between the target and the comparison star This offset also determines the relative spectral coverage of the two spectra Offsets in the range 5 300 are possible but it is recommended to choose a comparison with a separation of lt 60 to ensure a reasonable flux calibration The two slits are defined inside a fixed area toward the left side of the field of view and should be placed on the main scientific target and on a comparison star for slit loss determination The reference targets for mask alignment must be defined in the area of the master chip An Example Session of HIT MS is given in Table 14 4 5 2 Creating slits Besides the basic key bindings for mask positioning see section 3 1 and the usual menu buttons for grism and filter sel
31. avoid this situation the number of available guide stars for the user defined pointing and active optics corrections can be retrieved using the on line GSC 2 catalog Press the following buttons Data Servers Catalogs GSC 2 at ESO Specify the mask central position but do not use the button Set from image when the mask has been moved away from the initial central position Specify the inner and outer search radius in arcmin as well as the magnitude range of 10 0 lt my lt 13 0 Press the Search button to get all guide stars If the number of guide stars is less than 3 another pointing a small offset of about 20 may result in an improvement in the quality of the delivered data FIMS Manual VLT MAN ESO 13100 2308 15 4 Mask preparation mode specific functionalities 4 1 MOS mode The MOS mask consists of the 19 movable slit blade pairs the green central circle to move and rotate the whole mask and the focal field projected on the CCD blue square 4 1 1 Positioning MOS slits After having selected the collimator slit width grism optionally a filter and the wavelength range the positioning of the slits is done just by pressing the left mouse button B1 on the desired target position When a slit is positioned it is automatically marked and the current position RA and DEC is stored Marked slits are labeled by their slit number in case the label option i
32. by FORS1 2 itself or by HST WFPC2 wmosaic of iraf will provide world coordinates implemented as FITS header keywords If there is no frame available or if the frame is not in FITS format it is possible to use the Image Server facilities of Skycat in order to download a sky image from one of the available on line archives Note that also here the requirement for positional accuracy applies as stated in section 2 4 1 FIMS Manual VLT MAN ESO 13100 2308 7 The usual astronomical orientation for sky maps is North at the Top East at the Left meaning RA is decreasing with increasing pixel number image fits header keywords CD1_1 lt 0 and CD2_2 gt 0 or equivalently CDELT1 lt 0 and CDELT2 gt 0 If the input frame does not support world coordinates the FITS header can be edited by using either a FITS header editor or Emacs Verify this step very carefully A faulty or inaccurate setting of the frame s world coordinates will be carried over in all further steps In particular the frame scales CD matrix are very sensitive while an offset between the WCS and the optical positions read in the frame of less than 10 can be corrected by the alignment procedure To verify the correct setting of WCS keywords load your modified frame into Skycat select File Open and watch the a and 6 values in the panel when moving with the mouse over the sky field For further verification you can use the AstroCat facilities to download e g all ap
33. e input file being either the master or the slave image taken with the detectors fsmosaic hV v input output Optionally an output filename can be given if the resulting merged image is to be kept on disk By default the result will be written to file fsmosaic fits The verbose mode flag v the help flag h and the printout of the fsmosaic version flag V are optional FIMS Manual VLT MAN ESO 13100 2308 SkyCat Tool FoRS mask FIMS plugin lt mode gt lt project gt fims project cat lt mode gt S lt project gt p targ lt mode gt lt project gt p_focf lt mode gt lt project gt p_gbr FORS1 Instrumental Package FORS2 Instrumental Package P2PP tool project obx project tpx project odx Figure 1 Interaction between Skycat FIMS and P2PP input and output files FIMS Manual VLT MAN ESO 13100 2308 4 2 2 2 Environment variables Two important environment variables can be set to select the fims version and to select the Skycat versions in your working environment In general the variables should be automatically set after the installation of the tar ball which includes all phase 2 related support software The variables can be redefined with the setenv tesh or export bash commands of your UNIX operation system The Skycat version can be set with command setenv SKYCAT_VER 2 7 3 The FIMS version can be selected in the following way this should be
34. ection the following bindings are provided e press B1 to create a HIT MS slit e press B1 on the slit number label at the edge of the focal field to purge the slit e press B1 on the slit width label to configure the the single slits e press B2 on the slit number label next to the slit to purge the slit Only the the slit type STRAIGHT is supported rectangular slit optionally rotated with respect to the dispersion direction Center Slit option The center slit option selectable from the configuration menu will significantly improve the slit positions for point sources and other relatively compact targets A Skycat feature with the centroid algorithm a single click on the target and the centroid might fail Click somewhere with the left mouse button B1 hold the button while moving the mouse wait until you see the target in the center of the pick object window and release the mouse button now 4 5 3 HIT MS reference slits The reference slits can be created anywhere within the master chip area and outside the fixed area where the science slits are to be created In this case the six small square reference slits on the bottom of the upper master CCD are not created because they would create additional spectra that would interfere with the science ones Reference slits must be within the master chip field of the pre image It is necessary for the reference slits to fall withi
35. elength range the CCD area for which the smaller user defined wavelength range matches the CCD is larger The STATIC method does not move or rotate the instrumental mask The mask with the new slit positions will be redrawn This method is appropriate when the underlying sky frame has the same size as the FORS mask like images obtained with FORS itself in IMG mode All other Auto Slit methods vary the mask position as an outer loop but call the basic STATIC method for each given mask position For P MOS positioning the target closest to the MOS stripe central line is chosen In MXU mode STATIC is the only available mode for AutoPos since MXU provides a much larger range of slit positions than the MOS For crowded fields the AutoPos set up for MXU is dependent on the target sorting order of the catalog Hence besides the initial mask position the mask position angle the priority and the magnitude flag of each individual target also the sorting order of the catalog Options Set sort columns in the catalog window can be varied to optimize the MXU set up 6 6 4 SHIFT Trial and error analysis This method does not keep the user defined mask position but the position angle is retained Find best fit mask position by using each target of the catalog as a telescope pointing For each position the STATIC method is called The mask is shifted to the best fit position This method is useful if either
36. els button 6 2 Reset Mode This menu item initializes the instrumental mask again by shifting the mask to the initial world coordinates with the initial orientation position angle zero Usually the initial position will be the telescope pointing of the underlying frame The telescope pointing will be extracted from the FITS header keywords CRVAL1 CRVAL2 If one is working with extracted images the telescope pointing may be outside the frame In this case the mask will be put to the frame center 6 3 Refresh Mask This option is to be used to simply render the graphics again in case the display becomes confused It does not perform any real action on the configuration 6 4 Load SetUp This menu item configures the mask according to a set up file Set up files are created with the Save button Load files with the fims extension e g mos 15 myprojec fims FIMS Manual VLT MAN ESO 13100 2308 25 mode default target INS keyword type set up filename IMG img2 lt ec gt lt PN gt fims INS MOS lt i gt POS INS MOS lt i gt WID MOS mos2 lt ec gt lt PN gt fims INS TARG lt i gt ALPHA INS TARG lt i gt DELTA PMOS pmos2 lt ec gt lt PN gt fims INS TARG lt i gt ALPHA INS TARG lt i gt DELTA I I MXU mxu2 lt ec gt lt PN gt fims INS TARG lt i gt ALPHA INS TARG lt i gt DELTA HIT MS hitms2 lt ec gt lt PN gt fims INS TARG lt i gt ALPHA INS TARG lt i gt DELTA
37. f the focal field is projected on the CCD The CCD matching area is indicated by the thick blue square Since the collimator change is the most time consuming instrument set up the collimator will be set already during the preset meaning during the telescope pointing and mirror adjustments Therefore for some acquisition templates the collimator must be specified by FIMS and is included in the p_targ set up file which consists of the TCS keywords e OS Filter Select one of the order separating filters or none In MXU appropriate interfer ence filters can also be selected The filter is dynamically chosen among the ones defined in the ISF file e Grism Select one of the available grisms which are dynamically loaded from the ISF file The filter and grism selection has been introduced because of a link back problem The MOS HIT MS and MXU acquisition templates are only to specify the MOS slit blades and MXU HIT MS mask ID respectively and are therefore independent of the grism and order separation filter used later in the observation template However an optimized MOS MXU HIT MS preparation with FIMS needs to know the wavelength range which is specified in the subsequent observation template Therefore it is advisable to select the filter grism and optionally the user defined fractional wavelength range for the CCD window e Camera Select either the MIT Red Default or the E2V Blue detecto
38. fely fsmosaic INPUT_ FILE OUTPUT_ FILE The merged output files could be now combined with standard software such as imcombine eg for IRAF imcombine a median of the jittered files with the offset parameter set to wcs should give satisfactory results for the mask preparations First fsmosaic and then imcombine Pipeline support The quality control group is delivering pre reduced science frames to applicants which have requested pre imaging runs with the MIT mosaic The reduced and merged files can be combined with the standard data reduction tools 2 4 3 Built in Astrometric Corrections for FORS1 or FORS2 pre images The astrometric transformations are done automatically The methods are summarized here as a reference for a better understanding of the procedure During the mask preparation the pixel coordinates are converted linearly into world coordinates reading the transformation parameters from the fits header of the pre imaging files This is done for FORS images and contributed images from other telescopes or catalogs In the case of FORS images the radial distortion coefficients none linearity of the image scale are read from the fits headers if available Hard coded default values are used if the keyword is not found in the fits header of the pre imaging file The corrected coordinates are written into the fims output files p_focf p_gbr p_targ which will be used during the target acquisition and mask preparation procedure T
39. get acquisition software will automatically measure the positions of the six pre defined reference slits on the bottom edge of the upper master CCD These reference slits ensure we have a baseline that is long enough to correct for this rotation A general rule for the selection of reference stars For all multi object observations MOS MXU HIT MS PMOS it will be required to correct rotation offsets between the pre image and the actual telescope position with a high degree of accuracy Therefore we suggest that the user defines at least 5 reference stars These should be widely spread over the field in which the science slits have been set For imaging applications IMG and slitless spectroscopy the pointing of the telescope and therefore the selection of reference stars should be uncritical The procedure how to select reference stars is explained in section 6 8 After the upgrade to the mosaic detectors all reference stars must be selected on the upper master CCD Fims forces the users to do it right by hiding all other parts of the input images For any application it is mandatory to select unsaturated point sources as reference stars There should be no brighter star then the reference star within about 10 arcsecs and the reference stars should be about 10 arcsecs away from the edge of the field of view and about 10 arcsecs away from MOS slit 10 if this slit is used to define a new reference slit position during the target acq
40. gets hence this sky region is forbidden Ok e first read then click Repeat this sequence up to ten 10 times Pick object e in the EnterObject pop up window to select reference target via PickObject method Bi e click on bright point source in the main window Watch the PickObject sub image before you release B1 and check fit re sult If the center gauss has failed The red Can t do message appears in the FWHM la bel of the PickObject window press either the Pick Object button in the PickObject win dow or the Pick Object button in the En terObject window to select the Reference Target anew Enter e in the EnterObject window Close e in the EnterObject window to continue Enter e empty entry field in the EnterObject window to finish OK e in the Warning window ignore it Close e in the EnterObject window to finish Close e in the PickObject window FORS Reference Targets verify e verify reference target positions Follow the messages and press OK e in the verification message window Table 6 Session 4 All modes Select reference targets FIMS Manual VLT MAN ESO 13100 2308 36 Button Explanation Ziz e Zoom your preferred sky region and B1 e click on the position you want the slit to be B2 e click on the slit number label 4 of the slit to de select MOS 4 B1 e click on the slit number label
41. gly the same masks can be used with different filters and grisms which are selected later in p2pp FIMS Manual VLT MAN ESO 13100 2308 29 6 10 1 Instrumental configuration options Slit Width spectroscopy with slit initializes the MOS MXU HIT MS mask with a new common slit width for all slits The slit width can be between 0 3 and 6070 spectroscopy without slit P MOS slit widths of 1070 22 0 30 0 4570 60 0 are in tended for slitless spectroscopy Finally the open option takes all MOS slit blades out of the focal field by default Like in IMG mode MOS slit blades can again be individually positioned to obscure the spectra of bright foreground sources Use the transparency layout option to better visualize the slit arms in the field of view Slit Length initializes the MOS MXU HIT MS mask with a new common slit length for all slits For MOS the actual slit length is physically fixed in the instrument The slit blades are 22 wide but the decker on top of the blades effectively reduces the length of the even MOS slits down to 20 The FIMS option to diminish the MOS slit lengths is only virtual to visualize a preferred background region in the slit for the targets e g if a sky background region of an offset of at least 5 is required select 10 arcsec 20 2 x 5 background offset area on each side of the target spectrum Some of the MOS slit blades do not build a slit with a completely const
42. gt 4 62 4 ae 50 a e a a A SS 4 2 2 4 Interaction between Skycat FIMS and P2PP input and output files 4 2 2 5 Instrument Summary File 4 29 7 PIMS lee 2 A eat i ae a a Baa ha Re ee BO ae Ge ee as 5 E Te Modes s iio maniis maaa i a ANE a i e Iaa aE h a A da ai e aA E 5 2 3 2 FIMS or fast mode target acquisition alternatives a 5 24 Input memes end catalogs cos sico sen are Bae Ma le we be ed de We 5 2 4 1 Astrometric requirements 5 24 2 Pre images with FORSI or FORS2 0 0 lt lt an en 50 5 2 4 3 Built in Astrometric Corrections for FORS1 or FORS2 pre images 6 2 4 4 Requirements for Contributed Input Images World Coordinate Systems 6 2 4 5 Input catalogs and frameless mode 2 0000022 aes 7 3 Mask preparation common functionalities 9 3 1 Basic movements and functionalities o aoaaa ee 9 3 2 Reference stars and target acquisition e eee a 9 3 3 Spectroscopy Setting Configuring Slits Grism Filter and Wavelength Range 12 g eegent B a SOS 13 341 Finding puide stars for the MLT oa coce aur E dera kde awa 14 4 Mask preparation mode specific functionalities 15 EL MOS Me 24 654 454 Tad ew Aw eR REDE Ree ed EASE SEEKS T 15 all Positionime MOSSINS cn arn Sd ee ea a ee ee ee ab a ele we 15 ALE Saving E CEET 15 A13 Moding slits ins sc oo su ara a RR BR ok aa a 15 ALA olitless spectroscopy lt ioc cocada eek ee A Rl ae Be Ee d 16 42 PMOSmode 2 24 48
43. he fims file which is used to save the mask configuration and to reload the masks contains the uncorrected distorted coordinates to simplify the reload procedure During the target acquisition procedure the inverse conversion of the coordinates is used This is done with the coefficients valid for the instrument and CCD with which the observations are taken The observation software predicts the position of the reference stars and reference slits in MXU mode on the CCD It will then search and center the reference stars and slits around the predicted positions Translation rotation and image scale offsets are then calculated from the observed and predicted positions of the reference stars using an analytical method it is not a fit The rotation and translation offsets are applied to the telescope control system to center the mask on the sky Image scale offsets can not be corrected but are only displayed on the user interface to warn the support astronomer about a possible astrometric problem The resulting internal accuracy is typically below 50mas but this doesn t include instrument flexures which have to be corrected with an image taken through the slit mask 2 4 4 Requirements for Contributed Input Images World Coordinate Systems Images obtained by FORS1 can be used as pre images to prepare observations for FORS2 Images from other telescopes require careful and accurate astrometric calibrations and WCS fits headers Frames obtained
44. he FORS2 User s Manual Mode Observation type IMG imaging with occulting bar masks MOS multi object spectroscopy using 19 movable slitlets PMOS multi object spectro polarimetry MXU multi object spectroscopy with laser cut masks HIT MS high time resolution spectroscopy of target and comparison star Table 1 FIMS modes 2 3 2 FIMS or fast mode target acquisition alternatives The use of FIMS is mandatory for MOS MXU HIT MS and imaging with occulting bars It is also mandatory for polarimetric multi object spectroscopy PMOS but not for single target spectro polarimetry IMG LSS IPOL and PMOS can be done with fast acquisition templates The tradi tional blind offset method locating a bright object on the slit and applying a known offset from that telescope position to the scientific target can be used for faint targets with the fast mode templates as well It is recommended to use the fast modes whenever possible 2 4 Input frames and catalogs 2 4 1 Astrometric requirements For preparing observations with FIMS a FITS file with appropriate world coordinate keywords World Coordinate System WCS in the FITS header is required Alternatively input catalogs can be used in frameless modes Accurate target coordinates are required The target positions must be very well known relative to the coordinates of reference stars A maximum astrometric error of 1 6 of the slit width can be tolerated Every single ta
45. identifier of the current slit If there is no target list loaded or no target is found in the target list FIMS assigns NN as default target name for the current slit e Automatic Positioning puts P MOS MXU slits to positions of the target list The optical position of the frame is ignored This task does not change the current target list e frameless mode Usually the WCS used by FIMS is generated by the FITS header keywords of the underlying frame When a target list is plotted without underlying frame a WCS is generated which can be used as a play ground for FIMS instead frameless observation preparation This task does not change the current target list The optical positions on the frame pixel and the WCS are sufficient to determine the correct positions of the slitlets Even if there is a shift in the WCS with respect to the underlying frame the prepared MOS slitlet positions will be very accurate mean positioning accuracy 0 07 pixel since the reference targets used for the alignment and the science targets in the slits are determined in the same possibly shifted WCS For situations where MOS MXU set ups have to be prepared with e g 100 science targets in one single FORS image it might be useful to find automatically the best mask positions in order to optimize the slit positions and to reduce the number of MOS exposures For this purpose astronomical catalogs are required See also section 6 6 for further explanations
46. inearly from the WCS scale derived from the small size FITS frame header This means less accurate dimensions of the instrumental mask e The MOS slit blades can only be positioned inside the frame in MOS mode e The center of the non occulted strip the center of the very wide slit must be inside the frame 2 4 5 Input catalogs and frameless mode A frameless mode is also offered No FITS frame is required but a WCS area is defined for the FORS mask This mode can be used when there is a target list available with high astrometric quality The reference stars have to be selected from stars with the coordinates known in the same astrometric coordinate system Proceed as follows e File Clear to clear the display and to purge the WCS e Data Servers GSC 2 at ESO or load another target catalog with reliable astrometry sat isfying the requirements of section 2 4 1 e specify the virtual field RA DEC rmin rmax and Search lin Emacs do not add further lines lt carriage return gt in the FITS header descriptor FIMS Manual VLT MAN ESO 13100 2308 8 e scroll with B1 the color bar to highlight the virtual field e FORS Enter Mode and proceed further as in frame mode Please note that the plot symbols in skycat need to be set explicitly for the user provided input catalogs FIMS Manual VLT MAN ESO 13100 2308 9 3 Mask preparation c
47. ircle move and rotate the mask as in all other modes B1 e on a target to create a slit on the target B1 Enter Close e on the slit width label 1 4 to edit length width and position angle of slit B1 e on the slit number label 1 at the rim of the focal field to purge the slit again Config Layout Center slit e switch on the center slit option and wait until the pick object window appears B1 e press and drag as usual and release B1 to carry out the center gauss If the object is inside the current focal field a new slit will be created and centered to match the target position Session 4 e specify reference targets Save e start the save sequence OK e for the number of reference slits e Continue as explained in the MOS target ac quisition sequence Table 14 Session 14b HIT MS sky mask acquisition FIMS Manual VLT MAN ESO 13100 2308 43 A PSO Internal information Beside the possibility to create a specific mask for the science purpose there is a possibility to use so called technical masks which are permanently stored at Paranal but not necessarily continuously available in the instrument A set of technical masks are provided They are listed in the Table A There are technical masks like 900001 and 900 002 for maintenance and technical masks for science like 900 003 900 010 Most of the technical masks consist only of one single sl
48. it for ECHS or HITS This means FORS2 ECHS mode can be scheduled either with two MOS slits or with the technical MXU mask 900 009 containing a single 44 arcsec long slit hence simulating the 2 MOS slits All available FORS2 technical masks are coded as a FORS aperture definition file They are copied from the default directory FIMSROOT 1ib fors to the SET_DIR directory each time FIMS is started After having specified the grism and the filter a technical masks can be used to prepare observations Just press the Load SetUp and edit the filter entry field in the file select menu from the default filename extension fims to fad and load the technical mask as any other user defined set up When e g the FIMSROOT 1ib fors mxu2 004 standard fad aperture definition file is selected FIMS will recognize the fad file extension and will change to MXU technical mask mode Each Reset Mode will switch back to the default MXU normal mask mode MASK ID Tag ADF mode contents 900 001 SCAL 4sl mxu2 001 standard fad MOS 4 slits 900 002 SIEB 1 0 mxu2 002 standard fad technical mask 19x19 circles not offered for science observations 900 003 HITC_0_5 mxu2 003 standard fad HITS 0 5 slit center 900004 HITC_1_0 mxu2 004 standard fad HITS 1 0 slit center 900005 HITC_5_0 mxu2 005 standard fad HITS 5 0 slit center 900 006 HITB_0_5 mxu2 006 standard fad HITS 0 5 slit bottom 900 007 HITB_1_0 mxu2 007 s
49. itten with the rotate mask function FIMS Manual VLT MAN ESO 13100 2308 32 7 FIMS Cook Book and Example Sessions In this section the use of FIMS is demonstrated by a button list with some explanations Not all examples may be offered in the form in which they are demonstrated here In general a FIMS session consists of 6 main parts 1 Select Mode Select from choice of e IMG MOS MXU PMOS HIT MS 2 Configure Instrument We propose the following sequence a b select Camera Red or Blue ee select collimator for IMG only select slit width for spectroscopic modes MOS MXU HIT MS PMOS d select slit length optional for MOS MXU HIT MS PMOS Cc TN aen e select grism f 8 EN SC select order separation filter specify wavelength range 3 Position Telescope Move and rotate the mask with the central green circle 4 Position Slits The MOS slits can be positioned by e cursor a FITS image is required default e a center gauss method a FITS image is required e an automatic positioning method a target list is required 5 Select Reference Stars and Slits For the alignment of the masks with the field of view e select up to 10 reference stars to be used for the field acquisition While the absolute minimum is 1 reference star we recommend a minimum of 5 for best results e select alignment method for MOS with out slit 10 for MXU reference slits 6 Save
50. le to use the MOS slit blades to occult bright sources in the field in order to avoid CCD saturation with charge overflow In the standard resolution mode all slit blades are out of the image as an initial position For the high resolution mode slit blades 1 to 5 and 15 to 19 are fully in the focal plane as a field stop to reduce scattering light in the instrument Slit blade pairs 6 to 14 are shifted into the focal plane up to the edge of the CCD frame indicated by the blue rectangle The bindings for the green handling circle are as described for the MOS mode section 4 1 The positioning of the individual slit blades is done via mouse button B1 and B2 Unlike in the MOS mode only one slit blade is positioned to the mouse pointer Pressing BI B2 at a position between the two slit blades will move the Left Right slit blade to the mouse pointer position Pressing B1 or B2 on the slit blade itself will recede the corresponding slit blade out of the field to the current mouse pointer position Pressing BI on the slit number marker on the left or right edge of the mask or B2 on the slit number on the blade itself will fully retract the blade For the HR collimator retraction of a slitlet to park position may require its interactive repositioning to the HR field stop mask limit if deemed necessary for the observations When saving the IMG target set up file all blades ending near the border
51. lescope control system In the majority of cases this will be done automatically but in some cases we will have to identify one of the reference stars interactively We therefore request that the reference stars are identified on all user provided finding charts The absolute reference positions of MOS slits in the focal plane of the instruments are given by reference images typically taken during daytime with the telescope at the zenith In MOS mode the MOS slit 10 can be optionally placed very quickly into the focal plane during the acquisition image without taking an additional exposure With a red or infrared broad band filter or without filters the MOS10 option can therefore improve the acquisition with limited observation overheads A through slit image taken after the target acquisition sequence is mandatory This is required to verify that the acquisition was successful and for the final optimization of the target positions on the slit The through slit image will be taken after the acquisition when the mask is put into the focal plane immediately prior to the spectroscopic observations In the case of the MXU and HIT MS modes a reference slit image is taken during daytime by the observatory staff This image will be used to measure the actual position and rotation angle of the mask in the focal plane of the telescope The invar masks are sometimes slightly rotated when they are mounted into frames after manufacturing For MXU only the tar
52. m the underlying image The reference targets used for pointing the telescope must originate from the same source as the science targets Either both from the underlying image or both from the same catalog Auto Slit SIMPLE section 6 6 2 STATIC section 6 6 3 SHIFT section 6 6 4 ROTATE section 6 6 5 ALL not used The full list of auto slits above is available for P MOS while only SIMPLE and STATIC are available for MXU and SIMPLE for HIT MS 6 6 1 Requirements Automatic P MOS MXU HIT MS slit positioning on target catalogs works for several on line cata logs like GSC SIMBAD NTT archive USNO as well as on user defined target lists In addition to the requirements for astrometric accuracy section 2 4 1 and target catalogs to be used with Skycat FIMS Manual VLT MAN ESO 13100 2308 26 section 5 the catalog must also meet the following requirements to be used for automatic positioning with FIMS The table header keyword for right ascension must be RA or ra The table header keyword for declination must be DEC or dec The table header keyword for the target name must contain one of the following strings to be recognized by FIMS ID target name object or Id The target name may contain blank characters as e g object names in SIMBAD e the optional keyword for brightness must be MAG or Mag the optional keyword for the priority flag must be PRI or Pri 6 6 2 SIMPLE MX
53. more than one MXU slit side by side along the dispersion direction In this case FIMS plots a short stripe at the position of the expected spectrum It is recommended to define side by side MXU slits along decreasing dispersion direction Center Slit option The center slit option selectable from the configuration menu will significantly improve the slit positions for point sources and other relatively compact targets A Skycat feature with the centroid algorithm a single click on the target and the centroid might fail Click somewhere with the left mouse button B1 hold the button while moving the mouse wait until you see the target in the center of the pick object window and release the mouse button now Slits behind the green circle The left mouse button while used on the location of the green circle is defined to move the mask It is only possible to put a slit behind the green circle with the Center Slit functionality as described above click somewhere keep the left mouse button pressed while moving the mouse behind the green circle wait until you see the target in the pick object window and release the mouse button 4 4 3 MXU reference slits FIMS will define six small square reference slits on the bottom of the upper master CCD The slits are used to calculate residual rotation and translation offsets of the mask in respect to the expected position in the focal plane of the telescope These slits ca
54. n not be modified by the users and users should not put target slits at the same position FIMS will display the positions of the reference slits as indicated in the following figure 3With the help of a deep image taken with the same filter it will be in theory possible to set slits on top of almost all targets for which it will be possible to take spectra in a reasonable time but with the sky suppressed by a factor of 6 8 x 60 slitwidth compared to slitless spectroscopy FIMS Manual VLT MAN ESO 13100 2308 18 Reference slits must be within the field of the pre image It is necessary for the reference slits to fall within the boundary of the input pre image no matter if vignetted or not due to the method in which skycat converts pixel to world coordinates FIMS will remove the slits which are out of the field to allow to save the mask The reference slit will be removed from the list also for the next masks unless the reset mode function in menu FORS2 is called interactively Please reset the mode after this sort of events fims will issue a warning message The masks with one or two removed reference slits can still be used for the science observations 4 4 4 Files and numbers Each slit mask has a mask identification number MASK_ID which is a 6 digit number between 900000 and 999999 the first 100 being reserved for technical masks and a mask name MASK_NA which is MASK_ by default This number will be cut in the same way
55. n the boundary of the input pre image no matter if vignetted or not due to the method in which skycat converts pixel to world coordinates FIMS will remove the slits which are out of the field to allow to save the mask The reference slit will be removed from the list also for the next masks unless the reset mode function in menu FORS2 is called interactively Please reset the mode after this sort of events fims will issue a warning message The masks with one or two removed reference slits can still be used for the science observations FIMS Manual VLT MAN ESO 13100 2308 20 4 5 4 Files and numbers Each slit mask has a mask identification number MASK_ID which is a 6 digit number between 900000 and 999999 the first 100 being reserved for technical masks and a mask name MASK_NA which is MASK_ by default This number will be cut in the same way as the slits into the invar mask sheet at a position outside the focal field When saving a HIT MS set up FIMS creates four files with extensions p_ targ p_gbr p_ focf and fims The file format is the same as the MXU output apart from the p_ targ file which is the same format as the MOS output ie in one long string rather than a PAF The gbr file contains the slit set ups the default mask id and the mask size in the extended Gerber format GerberX format or RS274X format This file will have to be included in the OBs for the MXU via P2PP At Paranal this file will be used by the Pa
56. nce moves the mask as a whole The function of mouse button B3 is still for measuring distances as in the original Skycat Note When large zooming is used the green handling circle might be no longer visible on the canvas In this case there are three possibilities e zoom out the canvas using z e drag the white rectangle in the upper right pan window to scroll the canvas to the appropriate position e use the scroll bars of the canvas only if Skycat has been started with the with scroll com mand line option which is set by default 3 2 Reference stars and target acquisition The selection of appropriate reference stars within fims will be the most important task to ensure that the science targets will be on the slit For all fims based observing modes reference stars have to be selected and centered on the input frame which was used for the mask preparation These reference stars will be automatically identified on the acquisition image taken within the target acquisition sequence From the positions measured on FIMS Manual VLT MAN ESO 13100 2308 10 MOS slit labels M d me u FIMS plug in main menu Auto slit menu View Graphics Gi Data Servers FORS Help Fe ee E Enter Mode pe E E At Rn IA Reset Mode ENER H l Load SetUp gt Quit Mode Auto Slit P MOS MXU Pi STATIC hel SHIFT ROTAT Status Demo P at ES B config Layout LES Slit Width P MOS MXU Save Setup Reference Targe
57. of the focal field will be automatically set to the park position meaning either set to fully open or fully closed An example is given in Table 11 4 4 MXU mode 4 4 1 Basic information The mask exchange unit of FORS2 is only offered with the SR collimator This mode is distinctly different from all other modes from an operational point of view Slit masks have to be manufactured and masks have to be inserted like optical components into the instrument before the OB can be executed FIMS Manual VLT MAN ESO 13100 2308 17 4 4 2 Creating slits Besides the basic key bindings for mask positioning see section 3 1 and the usual menu buttons for grism and filter selection the following bindings are provided e press B1 to create a MXU slit e press B1 on the slit number label at the edge of the focal field to purge the slit e press B1 on the slit width label to configure the the single slits e press B2 on the slit number label next to the slit to purge the slit At the moment three MXU slit types are supported STRAIGHT rectangular slit optionally rotated with respect to the dispersion direction CIRCLE just a circle and CURVED a third order Bezier polynomial To use the MXU mode to obtain the highest multiplex gain largest number of spectra one can use a interference filters or other filters to reduce the length of the spectra One can therefore position
58. ommon functionalities In this section we describe the common basics of the mask preparation common to all observing modes Figure 2 shows a MOS mask prepared and displayed with FIMS 2 x together with the sub menus of the main pull down menu added to Skycat The main menu and sub menus have slightly different labels and or entries in versions 3 x some of them are shown in Fig 3 for the MOS mode A typical FIMS session would consists of the following steps 1 to load a FITS frame 2 to select an instrument mode 3 to configure the slits grisms display options 4 to prepare the mask position slit configuration 5 to select reference targets 6 to save the setup this creates the files for P2PP 3 1 Basic movements and functionalities The central green circle has the function of handling the mask as a whole In the following the 2 mouse buttons left middle are designated B1 and B2 Their functions when clicking on the central green circle are e BI mark current mask position e B2 rotate the instrument and hence the whole mask counter clock wise on the screen The default step size is 5 The step size can be controlled from the Rotation Step button in the FORS Config Layout menu e Shift B2 rotate the Instrument and hence the whole mask clock wise e Bi and move Changes telescope pointing position and he
59. onfiguration option but is only used as a graphical aid see Auto Slit button and MOS mode The real spectrum length is usually limited by the CCD borders The default wavelength range as given in the pop up window shows the available wavelength range either limited by the order sorting filter or by the grism efficiency 50 for the central slit FIMS uses half this range as the default but this range can be modified to check at which wavelength the cutoff by the CCD occurs It is not possible to choose wavelength limits beyond the ones given in this pop up window When using the low dispersion grism GRIS_150I in connection with MOS the zero order spectrum can be projected onto the left hand side of the CCD when the MOS slit is positioned to the right more than 44 from the optical axis The zero order can easily become saturated on the CCD and will bleed into neighboring MOS spectra hence simulating spectral lines in the neighboring MOS spectra To avoid the zero order on the CCD use an upper wavelength limit of Amax 1160nm in the wavelength range window to indicate the correct MOS position limit for which the zero order of the spectrum no longer falls within the CCD FIMS Manual VLT MAN ESO 13100 2308 30 e Collimator use either the standard resolution collimator COLL_SR 6 or the high resolution collimator COLL_HR 7 This option is enabled only for P MOS and IMG In high resolution collimator mode only the central part o
60. only needed if more then one fims version is installed setenv FIMSROOT HOME fims 2 2 3 Start up of FIMS Once installed FIMS is started with the command e fims sh R for FORS2 with the MIT mosaic e fims sh B for FORS2 with the E2V mosaic 2 2 4 Interaction between Skycat FIMS and P2PP input and output files In practice Skycat handles the FITS images and optionally a user defined target catalog while FIMS handles the definition of the FORS focal plane instrumental mask MOS MXU HIT MS OCC and PMOS and its positioning FIMS will write the subsequent focal plane setup commands into output files it will also set the FORS collimator to be used for the observations FIMS outputs a number of files that are necessary to successfully define an Observation Block OB a target set up file suffix p_ targ a focal field set up file suffix p_focf and in the case of MXU a mask manufacturing file also known as a gerber file with suffix p_ gbr These files are inserted in the observation blocks using P2PP or are used to control the manufacturing of the MXU masks i e they have a direct impact on the execution of the observations with FORS One additional fims file is used to save the complete mask design to be reloaded by the users in case that masks are to be modified after some time or on the fly in visitor mode observing runs Further instrument components like filters or grisms are not saved from the actual FIMS ses
61. ord i e this is the focal plane set up file e gbr contains the slit information in MXU mode in Gerber format Please keep all output files produced by FIMS they could be useful later if a problem occurs while constructing the OB During the save procedure in a first step the reference targets are verified and the user is asked again if the set up should be saved Follow the recommendation and don t save set ups that will fail at Paranal In MXU HIT MS mode at least one but for better alignment accuracy better 5 7 reference slits must be specified before saving the mask The following sub items exist in this menu e P MOS MXU If the AstroCat interface is active the slit blade positions are compared with the entries of the user defined local catalog The search area is two times the MOS slit width Since Skycat version 2 5 3 provides the usage of more than one user defined so called local catalogs you have to select one of the active local catalogs from which the slit positions will be deleted Note The save command only considers top level catalogs loaded by the Data Servers menu bar button in the Skycat toplevel window Catalogs loaded from the Data Servers menu bar button in a catalog window will not be considered 4 All targets with coordinates matching one of the slit positions are deleted from the loaded version of the user defined target list If the currently local target list is saved with the
62. parated with Tabs If you do not have a target list you can use the Skycat AstroCat facilities to download a target list from one of the available online catalogs You can save this online catalog as a local catalog e g press File Save as in the GSC 2 at ESO window Load this file again as a local catalog Data Servers Local Catalogs Load from file and edit it with the Edit button in the local catalog window An example for a user defined target list is given below ID lt tab gt RA lt tab gt DEC lt tab gt MAG lt tab gt PRI lt tab gt lt tab gt lt tab gt lt tab gt aa NGCO815_001 lt Xtab gt 00 28 3 lt tab gt 05 01 18 lt tab gt 27 0 lt tab gt NGCO0815_002 lt tab gt 00 27 3 lt tab gt 05 01 17 lt tab gt 20 0 lt tab gt NGC0815_003 lt tab gt 00 33 3 lt tab gt 05 01 19 lt tab gt 19 2 lt tab gt NGC0815_004 lt tab gt 00 13 3 lt tab gt 05 01 17 lt tab gt 20 7 lt tab gt NGCO815_005 lt Xtab gt 00 20 3 lt tab gt 05 01 16 lt tab gt 25 0 lt tab gt NGCO0815_006 lt tab gt 00 25 3 lt tab gt 05 01 17 2 lt tab gt 22 3 lt tab gt NN NA AN N zm OO Oto CN where lt tab gt means pressing the Tab key The first three columns are necessary while the latter two mag and pri are optional The priority column pri can be used for further selective constraints in the automatic positioning task in MOS mode If the target lis
63. persion Spectrograph HIgh Time resolution mode HIT multi shift mode High Resolution Hubble Space Telescope IMaGing Imaging POLarimetry Instrument Summary File LongSlit Spectroscopy Mask Manufacturing Unit Multi Object Spectroscopy Mask eXchange Unit Observation Block OCCulting mode Phase 2 Proposal Preparation tool Polarimetric Multi Object Spectroscopy Paranal Science Operations SkyCat Tool Standard Resolution Target Acquisition File US Naval Observatory World Coordinate System Wide Field Planetary Camera2 45 FIMS Manual VLT MAN ESO 13100 2308 46 C World Coordinate System Information The header of the FITS file used for preparing a FORS target mask with FIMS should contain the following keywords for a linear scale The standard notation for FORS for WCS FITS header keywords is the CDi_j notation CTYPE1 RA TAN tangential projection type CRVAL1 12 345678 x coord of reference pixel RA in deg CRPIX1 512 0 x coord of reference pixel PIXEL CTYPE2 gt DEC TAN tangential projection type CRVAL2 12 34567 y coord of reference pixel DEC in deg CRPIX2 525 5 y coord of reference pixel Pixel CD1_1 3 185E 5 partial derivative CD1_2 5 616E 5 partial derivative CD2_1 5 616E 5 partial derivative CD2_2 3 185E 5 partial derivative EQUINOX 2000 0 equinox Besides this there is the CROTA CDELT notation CTYPE1 gt RA TAN tangential projection
64. propriate targets from catalogs like the Guide Star Catalog 2 or the USNO catalog Data Servers Catalogs GSC 2 at ESO Set from Image Search and compare the optical positions in the frame with the catalog positions The WCS FITS header keywords describe a linear map projection scale hence non linear effects caused e g by the telescope or instrumental optics generally are not accounted for The WCS FITS header keywords of FORS1 and FORS2 images contain the local scale in the center of the focal field center of the CCD the optical axis The non linear scale contributions due to the optical distortion of FORS are axially symmetric with respect to the optical axis The optical image distortion of FORS2 is known to FIMS and will be corrected when a set up is saved Image distortion of preparation frames of other origin e g from HST WFPC2 or DSS is not known to FIMS and hence cannot be corrected FIMS supports frames with at minimum size of 1 x 1 This means that images obtained by FORS1 using the high resolution collimator and mosaic frames obtained with the WFPC2 of the HST can be used as underlying sky images for FIMS If the image size is close to the lower size limit several restrictions apply e Coordinate translations in particular the positions of the mask elements outside the frame are no longer calculated via the built in WCS package but are extrapolated l
65. r This should be done before the mask is designed as it will cause the mask to be reset It sets important parameters like the gap and relative orientation of the two chips 6 10 2 Graphical layout options e Reset Layout By clicking here all menu options that follow ROTATION STEP COLOR TRANS PARENCY BAD PIXEL Map LABELS CENTER SLIT will be reset to their default or initial values PROJECT NAME and SETUP DIRECTORY options are not changed e The effect of this option is purely cosmetic it does not change anything in the mask or the setup e Rotation Step of the mask Default is 5 degrees mask rotation position angle per click with B2 clock wise or shift B2 anti clock wise on the green central circle of the mask e Color Change the colour of the mask The colour of the green handling circle and the blue square CCD area is not influenced Default Yellow Blue 6 10 3 Special options e Labels configuration option of the active mask The orientation of the mask is shown In MOS PMOS and IMG mode the slits are numbered at the edge of the mask whilst in MXU HIT MS they are placed next to the slit Positioned specified slits are also labeled directly at the slit position Unspecified slits are not labeled e Center Slit This option re centers the slitlet when positioned by the cursor When this option is used a PickObject
66. ranal mask preparation software to produce the mask with the Mask Manufacturing Unit MMU Finally the mask will be inserted into FORS2 before the observations are scheduled Mask name Mask id Mask NAID When saving a setup for the HIT MS the keyword INS MASK NAID will be created and included to the setup files The value is Mdddeeeeeeeetdddddd or M lt INS MASK NA gt lt INS MASK ID gt where ddd is the FIMS internal counter as a three digit number Its the same number that appears in the name of the well known p_focf file The cccccccc is a 8 char long string Its the user defined project name which also appears in the name of the p_focf file By default the first 8 chars of the fits file name is taken The dddddd is a six digit random number between 900101 and 999999 When a mask is manufactured the six digit INS MASK ID is the only identification FIMS Manual VLT MAN ESO 13100 2308 21 5 Target Lists It is not necessary to have a target list when working with FIMS However it is highly recommended in order to avoid target misidentification Automatic positioning in P MOS and MXU mode will require a user defined target list FIMS interacts with a target list during the following tasks e Save P MOS MXU slit positions are compared with the target list If there is a match the target is deleted from the loaded version of the catalog but not from the target list on the hard disk and the target name is copied to the target
67. re type circle e The same event bindings for the labels as for a straight slit e select aperture type curved slit e on the slit width label 1 4 and enter 15 slit width e on one of the three cyan Bezier grid points to drag the cyan circle and modify the shape of the curved slit Note Slow cursor movement e on the slit width label 15 and reduce slit width to the desired slit width of e g 1 0 e specify reference targets e start the save sequence e for the number of reference slits e Continue as explained in the MOS target ac quisition sequence Table 13 Session 14 MXU sky mask acquisition FIMS Manual VLT MAN ESO 13100 2308 42 Button Explanation FORS Enter Mode HIT MS e Enter HIgh Time resolution Multi Shift mode of FORS2 We assume that there is already an underlying image Status Demo Status e pop up status window Config Layout Labels e Switch labels on Config Layout Grism XGRIS_3001 91 e select grism XGRIS_600B 92 or XGRIS 300191 Config Layout 0S Filter 0G590 32 e select order separation filter OG590 32 if de sired for grism XGRIS 300191 Config Layout Slit Width 1 4 e select common slit width Config Layout Slit Length 5 e select slit length 5 for two slits or 10 for one slit Bi e on the green c
68. rget coordinate w r t the reference stars must be known to better than 0 2 if a 172 slit width is used Compromises in the astrometry will cause slit losses 2 4 2 Pre images with FORS1 or FORS2 Pre images taken with both FORS instruments can be typically used for the mask preparations There are a few important aspects to be considered during the data reduction of pre images taken with FORS Shift and add only The mask preparation for FORS MOS PMOS HIT MS and MXU modes will require that the original scale and field distortion is the same for the reduced data as it was for the raw data This is required since the FIMS tool will correct for the scale distortion in case of FORS pre images at the time when the masks are saved Advanced techniques to combine jitter images such as drizzle will require some distortion corrections before the techniques will be applied It is strongly FIMS Manual VLT MAN ESO 13100 2308 6 recommended only to use clean shift and add techniques eg RAF imcombine to reduce images which are to be used for FIMS mask preparation MIT E2V mosaic don t cut the edges In case of pre imaging data taken with the MIT or E2V mosaic detectors it will be required to keep the original file format of the pre images Vignetted parts of the images pre and over scan regions must not be cut before using the files with FIMS The plug in function fsmosaic delivered with the fims software can be used to merge the two files sa
69. roject name FORS Config Layout Set upDir e change from the default output directory fims SET INSROOT INS_USER SET_DIR to a new output directory e g home tralala The newly specified directory is not created by FIMS It will stay for the rest of the session if not re defined again Enter Close e enter directory name and close widget FORS Save imgl e start the target acquisition saving sequence OK e for the reference targets OK e to save set up files to the new Set upDir FORS Reset Mode e Reset Mode FORS Load SetUp e load set up from the new Set upDir home tralala to verify the set up file FORS Save imgl e start the target acquisition saving sequence OK e for the reference targets Edit e Edit the Set upDir and the out put file name again eg from home tralala img 5 NGC_330 to fims SET img2 17 PhiPer again The file extension fims should be omitted Warn ing you can overwrite any file on the disk Therefore we recommend not to use this option FORS Reset Mode e Reset Mode FORS Load SetUp e load set up from the new Set upDir fims SET FORS Quit Mode e exit IMG mode Table 12 Session 10 IMG save acquisition and change Set upDir
70. s on FORS Config Layout Labels To position slits on well defined objects one can have them centered automatically using the FORS Config Layout Center Slit option described below and in sec tion 6 10 3 The white and gray circle as well as the orientation labels can be clicked to move and rotate the mask When the whole mask is rotated or shifted by pressing B1 or B2 on the green circle all slits will be unmarked and de selected again Marked slits can be de selected via the B2 button The unmarked slit will be moved beyond the focal field into a park position Center Slit option The center slit option selectable from the configuration menu will significantly improve the slit positions for point sources and other relatively compact targets A Skycat feature with the centroid algorithm a single click on the target and the centroid might fail Click somewhere with the left mouse button B1 hold the button while moving the mouse wait until you see the target in the center of the pick object window and release the mouse button now Slits behind the green circle The left mouse button while used on the location of the green circle is defined to move the mask It is only possible to put a slit behind the green circle with the Center Slit functionality as described above click somewhere keep
71. sion to the p_targ p_focf and p_gbr files but are only used to visualize focal plane restrictions for the user defined wavelength ranges This allows that FIMS mask set can be combined with different filter and grism setups ignoring any constraints on wavelengths and similar 2 2 5 Instrument Summary File The Instrument Summary Files ISFs reflect the status of the instrumental database and are pre defined for the respective observing period The ISFs are part of the FIMS distribution package They contain the dimensions of the field of view the properties and physical locations of the longslits and the available optical components for each CCD mosaic Recent changes in the instrument configuration will be only updated in the most recent software release and therefore the recommended versions of FIMS should be used exclusively FIMS Manual VLT MAN ESO 13100 2308 5 2 3 FIMS Modes 2 3 1 Supported Modes For practical reasons the released FIMS version contains two trains one for the R ed sensitive MIT CCD mosaic and one for the B lue sensitive E2V CCD mosaic The two FIMS trains are specific for the respective detector mosaic i e they reflect the options for the observations using the corresponding detector mosaic as well as the small differences in the focal plane geometry of the instruments The FIMS modes as listed in table 1 are supported with the actual release Details on the available instrument components can be found in t
72. t does not contain a column with mag or pri use the FORS button of the menu bar in the catalog window to add columns to the local catalog When creating a local catalog from a target list where the coordinates are only given in CCD pixel positions you can use the Edit Enter new object Pick object commands to create your target list step by step During a FIMS session the user defined target list will contain the targets which are not yet stored in a target acquisition file TAF Each time the mask position is saved the matched objects will be purged from the target list It is therefore highly recommended to use a local copy of the target list during the preparation of observations with FIMS 5 3 Saving target acquisition files Saving a TAF in MOS or PMOS mode invokes a search of all selected slit positions in the local catalog In PMOS mode odd numbered slits cannot be selected and are omitted for the search If one of the slit positions the RA DEC position inside the slit where the user has clicked not necessarily the center of the slit is found in the user defined target list the corresponding object will be purged from the target list The local catalog contains at any moment all objects not yet selected for an observation block At the end of a FIMS session after several mask configurations all targets are stored in TAFs and an empty target list remains It is therefore highly recommended
73. t until you see the target in the pick object window and release the mouse button ProjectName is used when storing the output files with the Save option lt projectname gt is an 8 character long user defined name The default project name consists of the 8 first characters of the FITS file name If no image is loaded as is the case for observation preparation in frameless mode the default project name is no_image The project name is a FIMS internal way to distinguish between different set up files This FIMS internal project name is not the project ID released by the OPC Transparency Toggle the reticule showing the slit positions Bad PIxel Map Show the map in white color Setup Directory The default directory for saving the fims p_targ p_focf and p_gbr files is the INTROOT fims SET which is defined in the fims sh start up file This entered value will become the saving directory for the whole session This directory is not automatically created if it does not exist All other functions are kept as convenient as possible All positioning actions can be done by pointing with one of the two mouse buttons B1 B2 to one of the graphical elements The function of mouse button B3 is still for measuring distances as in the original Skycat The Skycat function of B2 canvas scrolling is overloaded but not overwr
74. tandard fad HITS 1 0 slit bottom 900008 HITB_5_0 mxu2 008 standard fad HITS 5 0 slit bottom 900 012 HITI_5_0 mxu2 012 standard fad HITI 5 wide stripes 900 013 SIEB 0 5 mxu2 013 standard fad technical mask 0 5 circles not offered for science observations 900014 HIEC_1_0 mxu2 014 standard fad technical mask 1 trailing not offered for science observations 900 015 HITS 0 5 HITS fast 0 5 85mm left 900016 HITS 0 7 HITS fast 0 7 85mm left 900017 HITS 1 0 HITS fast 1 0 85mm left 900018 HITS 1 3 HITS fast 1 3 85mm left 900019 HITS 1 7 HITS fast 1 7 85mm left 900020 HITS 2 0 HITS fast 2 0 85mm left 900 021 HITS 5 0 HITS fast 5 0 85mm left Table 15 MXU standard technical masks and aperture definition files ADF In MXU technical mask mode as well as in modes with a fixed mask like LSS and HITS the complete mask will be shifted in such a way that the corresponding slit will be centered on the target FIMS Manual VLT MAN ESO 13100 2308 44 mouse buttons on green circle Explanation Load SetUp fims SET fad mxu2 010 standard fad B1 Save OK Session 4 FORS2 Enter Mode MXU Status Demos Status Config Layout Labels Config Layout Grism GRIS_600z 23 Config Layout OS Filter G
75. the left mouse button pressed while moving the mouse behind the green circle wait until you see the target in the pick object window and release the mouse button 4 1 2 Saving the setup When selecting the save menu item FORS Save mos 3 all marked slits together with the slit width and the slit position will be saved in the acquisition file or set up file Unmarked slits will be generally out of the focal field in a park position in order to close the focal field and to reduce light scattering in the instrument 4 1 3 Modifying slits The slit width is initially selected in the FORS Config Layout Slit Width menu item and is by default the same for all slitlets The mask position the mask orientation and the 19 MOS slit positions is retained when changing the slit width The width of MOS slits can also be changed individually just by pressing B1 on the slit width label of the desired slit e g 1 0 The minimum allowed slit width is 0 2 arcsec Each MOS slit can be de selected un set either by pressing with B1 on the slit number label at the rim of the focal field e g 4 or by pressing with B2 on the slit number label of the slit itself Pressing B1 inside the slit will move the slit to the cursor position Use the zoom buttons z and Z or use the white frame in the pan window when positioning the slit blades in detail The FORS
76. the underlying sky FITS frame is much larger than the FIMS Manual VLT MAN ESO 13100 2308 27 FORS field and or if the distribution of targets in the field is no longer random e g concentrated as a ring around a stellar cluster 6 6 5 ROTATE Take the current mask position RA and DEC and position angle PA Vary position angle in the interval PA 30 PA 30 with a step size of APA 1 For each position angle the STATIC method is called If one of the tested position angles result in a larger match quality the mask will be redrawn with the new PA 6 7 Save This saves the current mask settings and creates a number of files in the INSROOT fims SET direc tory or in a directory specified by FORS Config Layout Setup Directory consisting of the form lt mode gt lt counter gt lt projectname gt lt ext gt where lt mode gt is one of mos2 img2 pmos2 mxu2 hitms2 for the notations see Table 2 lt counter gt is incremented with each save operation in order to avoid overwriting previous set ups of the same project name lt projectname gt is an 8 character user defined name See section 6 10 3 lt ext gt is one of fims p_targ p_focf p_gbr where e fims is the file which FIMS uses to re load a set up e p_targ contains the value for the INS TARG keyword i e this is the target set up file Used to preset the telescope e p_focf contains the value for the INS FOCF keyw
77. to use a copy of the target list for a FIMS session 5 4 More about fims preparation with target lists Reference stars In frameless mode the coordinates of the reference stars have to be typed into the reference star panel which will show up when the Reference Star Add function is started Set Plot Symbols After loading the input catalogs it will be required to set the plot symbols This task is started from the options menu of the catalog panel First select the catalog columns from the not used field then select a column like id to be displayed and the size of the symbols like 10 or 18 mag if the size should be scaled with the magnitude Finally press Add Symbol and Apply FIMS Manual VLT MAN ESO 13100 2308 23 High multiplex MXU observations with grism and filter It is possible to create masks with a larger number of slits if the length of the spectra is reduced by a filter One could select the 1200R grism with an H o filter to observe several columns of slits in parallel First load the images and catalogs and set the grisms filters slit width slit length and wavelength range of choice Next select the SIMPLE option from the FORS2 autoslit menu Then reject some of the overlapping slits The result would look like the following mask with the rectangles indicating the position of the spectra on the CCD Graphics 00
78. tors In case that a new mosaic image is loaded the function will automatically look up the actual working directory for the associated master or slave images it will merge the two files based on shift and rotation given in the fits headers and display it into the Skycat FIMS window It will also recognize files which were already merged earlier with fsmosaic and display the file directly to the Skycat window The fsmosaic function has to be in the PATH of the working environment which can be verified with UNIX command which fsmosaic Keep the working directory clean fsmosaic will get confused if raw data reduced data and intermediate reduction steps are kept on the same directory Please copy the images which are thought to be used for the mask preparation to a clean directory such as fims PREP Keep the input data formats fsmosaic will work in coordinates of the detector plane and the vignetted parts of the MIT E2V detectors or the over scan regions must not be removed before the files are being merged For more information concerning the safe use of pre imaging data see section 2 4 Using fsmosaic as a stand alone function Despite being designed as a plug in to fims it is also possible to use fsmosaic as a stand alone tool to merge the two files of the MIT E2V detectors for further investigations or as a quick look tool to display the full field of view The fsmosaic function can be used in the following way with th
79. ts D Slit Length P MOS MXU p Slit Width LSS a Slit Width HITS gt E Slit Type MXU Le WaveLength Range CIRCLE Collimator CURVED OS Filter a Grism i Camera Rotation Step Color Transparency BadPixelMap P Labels Center Slit ProjectName SetUpDir Detector window Main confi Mask orientation for full wavelength Move and rotate 9 menu coverage Mask button Figure 2 Screen snapshot of the FORS instrumental mask simulator FIMS and ESO Skycat valid for versions 2 x of the software FIMS Manual VLT MAN ESO 13100 2308 File View Graphic F Zoom Object Abell_545_cen 00 05 32 33 856 11 27 05 86 Equinox 2000 Min 0 High 65535 Auto Set Cut Levels 4 Grid Skycat version 2 7 3 fsmosaic_ 1195697068 fits 1 s Go Enter Mode Reset Mode Refresh Mask Load Setup Quit Made Auto Slit Save mos Reference Targets Status Demo Slit Width Slit Length Slit Shape Collimator OS Filter Grism Camera WaveLength Range Open Blades ose Blades Reset Layout Rotation Step Color Transparency Bad Pixel Map i Labels Center SI Project Name D Graphical Layout ofthe FORS Mask Figure 3 Same as Fig 2 for the P85 FIMS version 11 FIMS Manual VLT MAN ESO 13100 2308 12 the acquisition images the translation and rotation offsets will be calculated automatically and the derived offsets will be send to the te
80. type CRVAL1 12 345678 x coord of reference pixel RA in deg CRPIX1 512 0 x coord of reference pixel PIXEL CTYPE2 gt DEC TAN tangential projection type CRVAL2 12 34567 y coord of reference pixel DEC in deg CRPIX2 525 5 y coord of reference pixel Pixel CDELT1 3 234E 5 x scale degrees per pixel CROTA1 10 0 rot in degrees from N to E CDELT2 3 234E 5 y scale degrees per pixel CROTA2 10 0 rot in degrees from N to E EQUINOX 2000 0 equinox CTYPE1 gt RA TAN tangential projection type CRVAL1 12 345678 x coord of reference pixel RA in deg CRPIX1 512 0 x coord of reference pixel PIXEL CTYPE2 DEC TAN tangential projection type CRVAL2 12 34567 y coord of reference pixel DEC in deg CRPIX2 525 5 y coord of reference pixel Pixel CDELT1 3 234E 5 x scale degrees per pixel CDELT2 3 234E 5 y scale degrees per pixel PC001001 0 9848 cos CROTA PC001002 0 1736 sin CROTA PC002001 0 9848 sin CROTA PC002002 0 1736 cos CROTA EQUINOX 2000 0 equinox Transformation formulae between the different keyword notations are given in A Users Guide for the Flexible Image Transport System FITS version 3 1 NASA Definition of the Flexible Image Transport System FITS NOST 100 1 2 and the Data Interface Control Document GEN SPE ESO 19400 0794
81. uisition sequence 3 3 Spectroscopy Setting Configuring Slits Grism Filter and Wavelength Range FIMS will visualize the focal field boundaries within which slits can be placed for a given wavelength range and filter grism combination Some configuration steps will be required to enable the function ality Slits can be set beyond this boundary anyway but some parts of the specified spectral range will be lost For spectroscopic modes the default grism order separation filter combination is none none the selection of grisms and filters is done from the Config Layout menu The Help Grism info shows the proposed wavelength ranges for each grism filter combination as read from the Instrument Summary File ISF This wavelength range reflects mostly the grism efficiency but wavelength cut off due to the order separating filter is taken into account This wave length range is larger than the CCD for the high dispersion grisms hence only a fraction of the default wavelength range is covered by the CCD The operation team has already seen spiral arms around reference stars and blooming bright stars which was fatal for the acquisition in all cases which were reported so far The observatory staff will have to reject all these stars interactively to fix the problem FIMS Manual VLT MAN ESO 13100 2308 13 A smaller wavelength range can be chosen via the FORS E

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