User Guide
Contents
1. Point the telescope to your first target Start star spectrum acquisition Do the same for all your targets Atthe end of the night launch a new reference sequence to prevent any change in the spectrum position The image processing can be made automatically but it can also be done manually When you choose automatic processing it is highly recommended to respect the above order of acquisition this way images will be processed in real time For high accuracy radial velocity you may prefere to take a Thorium Argon calibration frame before and after each target acquisition Processing will then be less automatised but it has been a proven solution 4 Software presentation Eshel software is a key element of eShel solution Of course you can use alternative software for acquisition and or processing But we ve put all our experience in this software our goal is that you focus on your observations when the software takes care of all technical staff Of course we don t want image processing to be a black box and we let you the full control of your observations Eshel software should be considered as a module of Audela a general purpose software for Astronomy Audela and eShel softwares are Open Source written in TCL TK language In this document we clearly focus on eShel software But if you need to get general information about Audela please refer to its documentation http www audela org Of course you ca2. _ INSTRUMENTS echelle spectrograph User Guide August 2009 F Cochard O Thizy Shelyak Instruments Les Roussets 38420 Revel France T l 33 4 76 41 36 81 http www shelyak com Email contact shelyak com Shelyak Instruments eShel User Guide Versions history Version Date Author Comment 1 0 March 11 2008 F Cochard First version O Thizy 2 0 August 9 2009 O Thizy Second version english screen shots eShel spectrograph user guide DCOOO9B page 2 15 Shelyak Instruments eShel User Guide Table des matieres TREO UCM it A A ea A 4 2 Description of eShel SOIMMON Sui ss Sands he cadacetsdue ds aida eda Gatewseasesiaassiadeedats 4 3 ODSEEYV ATION SESSION dd 7 4 Software presentation annie e a a eee 7 AL FES CON Classe llo niet ds ire 8 4 2 Software organisation 252 uvisrrreminoanervudend ie Vue nine one event 8 ASS CSSIOM DUTON O 9 4A Acquisition Para Meter sir sas i ariana tienne doi ARR EATE 9 4 5 Spectra processing DUO ici ue Mansion men ots 10 4 6 Instrument parameters DU ON issus siennes reel 10 4 7 Spectra profiles DUNN umi 10 A8 Images DUttOM A ea ai teeta secant ha Ca aies 11 5 Before starting observationS s sssssssssrrssossssssnsnrrrosannnnroossssnnnnnrnsenennnnnrene 12 6 Observations sasara a O 13 7 AC the end of the nights i iyini yaa odias 13 8 Annexes some useful Tcl Tk scripts 13 8 1 Apply a mirror in all FITS
3. console affiche resultat Traitement du r pertoire console affiche resultat Saudace rep images console affiche resultat An select all FITS file in current AudeLA directory set liste fichier glob dir Saudace rep images tails fit set nbre fichier llength liste fichier if nbre fichier gt 0 for set i 0 Si lt nbre fichier incr i set nom fichier string tolower lindex liste fichier i loadima nom_fichier mirror both ways you can change the way you need it to be mirrorx mirrory saveima nom_fichier console affiche resultat nom_fichier console affiche resultat An else console affiche resultat pas de fichier no file to process n 8 2 Extract spectral domain This script has been used to process a serie of spectra of a pulsating star Each spectra have been processed and merged profiles have been exported in our eShel software into a single FITS profiles Outcome is a serie of text files with continuum rescaled to 1 0 global audace console affiche resultat Processing directory console affiche resultat audace rep images console affiche resultat An select all FITS file in current AudeLA directory set liste fichier glob dir audace rep images tails fit WoW set prefix fichier x set nbre fichier llength liste fichier eShel spectrograph user guide DCOOO9B page 14 15 Shelyak Instruments eShel User
4. 20090109 18493900 CALIB 510 check fe Image jage 20090109 18493900 CALIB 5x10 s A 20090109 18592900 FLAT 5x120 it 3 Di sft 200901 09 20021000 En x ae E 200901 09 20030200 BIAS 5x0 s fit 200901 10 0031 3800 BIAS 5x0 s fit Cee FLAT si os fit 1728 5120 Ime ER 17422500 CALIB 5 10 des kft 20090111 17422500 CALIB 5x10 s fit 20090111 19464700 FLAT 5x120 fit 20090111 20021400 CALIB 5x10 check fit 20080111 23295200 FLAT 5x120 fit 200901 11 23502300 CALIB 5x10 check fi 200901 11 23502300 CALIB 5x10 s fit 200901 12 00000000 Ge to ibs a 20090112 00921400 DARK age 2009012101481000 DARK 18120 iR ES en fete a ee ana ele d El pe ees ee mel ele s 5 der TS ee ie se e AAA LL E me CALE LL LL COUO mm e CR RS eo ovens 4 225 X 518 I 73 000000 0 Y 325 14 01 09 23 23 02 TU gt 5 order I cale obs eShel spectrograph user guide DC0009B page 11 15 Shelyak Instruments eShel User Guide We have used the following convention for the intermediate steps P_1A extracted profile without wavelength calibration P_1B extracted and wavelength calibrated profile P_1C extracted wavelength calibrated and instrumental response corrected profile _ 32 33 _50 _51 order number _FULL merged spectrum Depending on your application you may want to use one or the other HDU P_1C_FULL will work for overall spectrum w
5. You can see the reminding duration during the exposure When a serie is launched if exposure number is greater than 1 all files of the serie will be tagged in the header eShel spectrograph user guide DCOOO9B page 9 15 Shelyak Instruments eShel User Guide 4 5 Spectra processing button At this location you can choose to make the processing automatically or manually It will be strictly equivalent at the end of the day When auto option is selected a processing step is launched after each serie acquisition When clicking on spectra processing button the following window will appear eShel Processing visu1 Manual command Generate and stat processing Processing roadmap Raw images Reference images Processing roadmap PROCESS OUTPUTFILE STATUS COMMEN They are two buttons First generates the list of processing tasks based on available files in the raw sub directory Concretely the software scans the sub directory identifes consistent series of images and if required reference data are available define the task to do see below Second executes the processing defined in previous step and moves the images to proper sub directories The software will optimize the processing and look for the Dark Bias master frame which have been taken the closest to the target to process for exemple in terms of exposure time and or date time 4 6 Instrument parameters but
6. file in directory 13 8 2 Extract spectral do Malbuisson RS 14 eShel spectrograph user guide DCOOO9B page 3 15 Shelyak Instruments eShel User Guide 1 Introduction Eshel spectrograph is a complete solution for astronomy spectrography Beside the echelle spectrograph itself it includes the Fiber Injection and Guider Unit a remote controled calibration unit optical fibres and a dedicated software The intend of this document is to help observers to prepare their observations We assume the instrument is tuned and ready for observations If this is not the case refer to the Installation and Maintenance Manual We also consider that you have some basics in spectrography Proper usage of the instrument requires a good understanding of its principle and its image processing method It is designed to automatically process the images when you launch an acquisition you get a fully calibrated spectrum not only images even if of course all raw images are carefully archived We present the instrument in a first step and then the software 2 Description of eShel solution A spectrograph is an instrument which spreads out the light to analize its source The key component is a diffraction grating a block of glass on which a high number of lines per mm are engraved Some optics components are used to focused the resulting image on the sensor in our case a CCD camera An Echelle spectrograph is a little bi
7. the individual exposure time and the number of exposure eventually select to repaat the acquisition multiple time e At the end of each serie acquired your spectra will be processed if you are in auto mode and you can see the result in the console as well as the processed subdirectory use the Visu Images module to visualize the processed spectra You can lunch the processing window if you are not in auto mode and manually request a processing when you want 7 At the end of the night Remember to switch off CCD camera guiding camera and the calibration module It is recommanded to backup your data but leave in the references master files as they can be of use for the next user 8 Annexes some useful Tcl Tk scripts Here are some example of Tcl Tk scripts we find useful Look at Tcl Tk general litterature and AudeLA documentation for general knowledge on this language 8 1 Apply a mirror in all FITS file in directory Imaging you have acquire spectra but they are not well oriented You may want to do a mirror on all those file Here is a Tcl Tk script file you can use to perform this in the current directory be careful this current directory may different from your session directory set it up in the setup general menu Be careful as the script doesn t rename the output files eShel spectrograph user guide DC0009B page 13 15 Shelyak Instruments eShel User Guide global audace
8. Guide if nbre fichier gt 0 for set i 0 Si lt nbre fichier incr i HEH HEH ttt ttt set nom fichier file rootname string tolower lindex liste fichier i define continuum value to set all spectra to continuum 1 around H beta area set continuum value spc_icontinuum nom fichier 4970 4990 Crop spectrum spc select nom fichier 4775 5090 rescale spectrum so continuum is equal to 1 0 loadima S nom fichier sel mult expr 1 continuum value saveima S nom fichier sel Convert FITS file into a text file DAT format spc_fits2dat nom_fichier sel else console affiche resultat pas de fichier no file to process n End Of document eShel spectrograph user guide DCOOO9B page 15 15
9. appears You can select observers names observation site and image directory If needed you can create a new site form Observers and site data will be copied in the files headers then it s important that they are updated every day You may want to recover Bias and Dark master frame from previous session if you run the camera at the same temperature this will save some obsering time Simply copy the two files from previous reference sub directory to the new one and the program will take this into account assuming you do not change anything in the equipment configuration 4 4 Acquisition parameters You can select the type of image to acquire If you choose One image only one image will be taken and not recorded if you want to record it go to file save menu This option is commonly used to chek that image is what you expect before launching a long serie We also use it to determine the optimal exposure time For other options object dark flat you can can define a number of exposures The only difference between these options are The proper keyword object dark flat calib is setup in the image header If required the lamp flat or calibration is switched on and the calibration mirror is moved in the Fiber Injection amp Guiding unit For the darks the shutter is kept closed For the objects the object name is required Of course the acquisition is launched by clicking Go Acq button
10. e drop list in the acquisition section Typical users create a serie for Thorium one for Flat one for Bias amp Dark together This gives flexibility to end users e switch on the flat lamp and the calibration mirror and reduce the guiding camera exposure so you can see the optical fibre hole Check it s in proper focus and save its position This can be done during the night if the user loose the optical fibre position note if the fiber tip moves around in the eShel spectrograph user guide DC0009B page 12 15 Shelyak Instruments eShel User Guide guiding image this is an indication the guiding camera is not firmly mounted on the Fibre Injection amp Guiding unit e Select processing in auto mode or not depending on your choice 6 Observations Here is a quick checklist of things to do during an observation e point a star with telescope and focus the telescope using the guiding camera image e if available start the autoguiding note a autoguiding module is available in latest eShel version e type in the name of the object e do an object preview of typically 10sec to check your star and determine the maximal exposure Try to stay below 40000 counts on your spectra but this depends on your camera AntiBlooming or not for exemple Check the level by drawing a square on the spectrum and right click to select the statistics function you can keep the window the same during all night e Select
11. lyak Instruments eShel User Guide All the elements described above are linked together like this Telescope Fibre Injection amp Guiding Unit Power Supply Calibration Unit 8 Telescope Acquisition Control 1 Telescope mounting T mount 45mm backfocus here a Schmidt Cassegrain f 6 3 focal reducer and a Variable T adapter to mount the Fiber Injection amp Guiding unit 2 Object optical fibre 50um diameter 3 Guiding video camera connected to the telescope control PC can be the same as the acquisition Autoguiding software control the telescope to ensure the star light goes into the optical fibre 4 Calibration optical fibre 200um diameter 5 Cable to activate the mirror inside the Fibre Injection amp Guiding unit 6 Cable to control telescope not included in eShel solution 7 USB Interface for the CCD camera controled by the eShel software 8 Serial connection to the Calibration unit eShel spectrograph user guide DCOOO9B page 6 15 Shelyak Instruments eShel User Guide 3 Observation session When you start an observation session you have to do following tasks Switch on all the elements telescope spectrograph calibration module Run the eShel software and connect camera amp calibration module Define your session parameters ie set up new directory Check focus of the spectrograph see below Start a reference sequence acquisition Bias Dark Flat ThAr
12. n duplicate eShel software as much as you want Audela is based on many tools like acquisition image processing focusing guiding specific application King method supernovae detection and so on Eshel is one of these tool You can setup the software to make it start by default with eShel tool click on Tools menu select tools selection and select F2 in front of eShel You can also select your language french or english are currently supported for eShel spectrograph user guide DCOOO9B page 7 15 Shelyak Instruments eShel User Guide eShel module eShel software works with FITS files Specific keywords are setup in the files headers that are used for the processing Resulting files are multi HDU FITS files they contain 2D images each order profiles merged profile order geometry and calibration coefficients and so on The files structure is detailed at the end of this document If you want to process images that have not been taken through eShel software you may fill the specific keywords manually there are some helpful tools to do it 4 1 First contact When running eShel software you are in front of this window Aud ACE visu The blue window is the main one where images are visualized On top you have general Audela functions On bottom part you have dynamic informations about the image linked to the cursor movement On the left you have
13. or which will insert a miror in front of the object fibre to insert the calibration light in The specificity of astronomy spectrograhy is that we have a very low level of light This means that we constantly need to take care of the light collection and transportation to get the best S N ratio possible Eshel spectrograph is fiber optics feeded This means that the star light collected by the telescope is transported towards the spectrograph through a fiber optics This have several advantages The spectrograph is in a quiet place with no movement The spectrum image is always at the same position in the image this is why automated image processing is possible The light collection and the light analysis are totally split it s easier to manage The light collection is made through the Fiber Injection and Guiding unit This device have a guiding camera which look at fiber entrance you can control permanently even automatically that star light enter in the fiber Never forget the better the light collection is made with Fiber Injection and Guiding unit the better the SNR will be Eshel solution is able to work automatically White and calibration lamps can be activated remotely When they are switched on a small mirror is moved in the FIG to send reference light towards the spectrgraph it s key that this light goes exactly the same way as the star light eShel spectrograph user guide DCOOO9B page 5 15 She
14. ork but you may notice some difficulties due to the echelle technology to properly merge all orders and some specific line profile work would be better using the individual P_1C_ orders Tip in the Visu window double click at the right of the horizontal bar above the filenames for automatic column width Tip on spectral profile zoom by using the right click left click to unzoom 5 Before starting observations Here is a quick checklist of things to do before starting an observation e switch on CCD camera setup the camera in the software to connect it and start cooling it e switch on calibration unit and take a Thorium preview to make sure the connection works Advanced users can also go into the instrument setup menu Select the proper COM port check on your windows device manager to find which one is allocated and click on ON buttons to test it e check CCD camera focus by taking a Thorium preview Installer may want to provide a typical FWHM for a specific line as a check for end user to perform before the night Or define a typical power of resolution which are displayed after taking and processing a Thorium calibration serie e once camera is cooled you can start taking reference files typically a series of Flat and Calibration files Note reference batch are created in the instrument setup panel This is normally done by the installer but user may have a need to modify add them They will then appear on th
15. t more complex but the basics is the same The grating is used at high orders typically 32 to 52 The result is a high dispersion spectrum in which a lot of orders are mixed We use a second disperser so called cross disperer to separate the orders Of course the instrument is designed in order to have a little overlap between orders then we can rebuid the complete spectrum The advantage is obvious we get high resolution in the same time as high bandwidth The result in the image is that you can see dozens of horizontal and curved lines in your image eShel spectrograph user guide DCOOO9B page 4 15 Shelyak Instruments eShel User Guide You can read the spectrum like a book but starting by the bottom line low wavelengths blue part of the spectrum is the bottom line You should start to read from bottom line from left to right and then the above and so on The extraction of the spectrum which consist to transform the 2D image in a line profile calibrated in wavelength requires to detect where are exactly each order and each wavelength in each order In order to have accurate measures we ll use white light which makes a continuous spectrum and then calibration lamp ie Thorium to find these informations These lights are send to the spectrograph through the fibre injection and guiding unit and brought there from the calibration unit by a calibration optical fibre A cable brings power to a small activat
16. the eShel tool the one that we describe now 4 2 Software organisation Eshel software is mainly made of two parts Acquisition and Processing It uses several sub directories that are automatically created when you select your images directory in session menu All newly acquired images are stored in the Raw sub directory The processing automatic or manual identifies series of images and detect the type of image offset dark flat thar object defined in IMAGETYP keyword Based on the available files it decides which processes are required and launch them Depending on the images the result will be put in specfic sub directory reference for processed dark flat offset thar eShel spectrograph user guide DCO0O009B page 8 15 Shelyak Instruments eShel User Guide processed for resulting spectra After image processing the raw images are transferred to the archive sub directory A key point in eShel software we never modify a raw image This is very important to keep raw data intact to allow later processing with new tools and or new parameters Even if you have processed the images automatically you always can re run the processing simply by copying the archived images to raw directory Now let s look at each button of the eShel tool 4 3 Session button This button should be used once per observation session When you click it the session window
17. ton This button allows to change some parameters of the spectrograph This must be done by a qualified person If you need to change or at least check one of this parameter please refer to Installation and Maintenance Manual 4 7 Spectra profiles button This button is used each time you want to read the resulting files This is an advanced tool which can read all the HDU included of the resulting FITS files If you read the resulting file with the file open menu in the main window or with any basic FITS viewer you ll see the 2D image which is the first HDU but not eShel spectrograph user guide DC0009B page 10 15 Shelyak Instruments eShel User Guide the other ones profiles calibration parameters When you load a file you see by default the first HDU which is the 2D image You can then select any HDU refer to resulting file format specification at the end of the document 4 8 Images button This button makes easy to scan all images in the image directory and sub directories For reference Flat or Calibration files use the order calc and obs button to display the order number the calculated theoritical position for the catalog Thorium lines and the actual observed ones Aud ACE visu C temp eshel reference 2009011 1 20021400 CALIB 5x10 s fit Fichier Affichage Anah AA o r 0 Aa F oder Y cale W obs C Atemp eshel 1eference Nom Type R pertoire
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