WTTM Manual
Contents
1. polynomial Surface type xxorder 4 Order of x fit in x xyorder 4 Order of x fit in y xxterms half X fit cross terms type yxorder 4 Order of y fit in x yyorder 4 Order of y fit in y yxterms half Y fit cross terms type reject INDEF Rejection limit in sigma units calctype real Computation type verbose yes Print messages about progress of task interactive yes Fit transformation interactively graphics stdgraph Default graphics device cursor Graphics cursor mode ql Then the geoxy task could be used to find the Error Sensor coordinates for a given pair of CCD coordinates 212. This is normally set to the same frequency as the APD Frequency DIO Update This value sets the frequency in Hertz that the DIO values in the WttmGetTaskValuesVI panel are updated Typically this is set to the same value as the APD Update frequency Focus Interval This value sets the interval in Seconds over which the focus signal is averaged to determine the incremental focus corrections once the focus control loop is locked Guider Interval This value sets the interval in Seconds over which the commanded tip tilt mirror position is averaged in order to determine incremental X and Y guider corrections X and Y milligain These values set the relative conversion factor between computed X and Y errors and the additive offset in volts applied to the current mirror tip tilt position that generates the next commanded tip tilt mirror position Z milligain This value sets the relative conversion between the computed focus error and the additive offset in microns applied to the telescope secondary position by way of the WIYN router to the SecTilt client REPORT PARAMETERS is a debugging aid and returns nothing of interest to the average user SAVE PARAMETERS and RESTORE PARAMETERS save and recall these 9 items to the file home wttm development wttmrc The START ACQUISITION and STOP ACQUISITION buttons are analogous to the pause and resume functions in the cli Indeed you can still use the weli pause and weli resume should you
3. feedback loop is closed for motion on the focal plane and any image motion on the focal plane is annulled for the guide star and the star is reasonably close to focus the observer should take another focus sequence with small increments 10 or even 5 step increment Since WTTM tries to extract the maximum seeing it is crucial to focus it very accurately before starting Request the operator to go to the best focus wait for about half a minute for WITM to know its reference focus from where it starts calculating the focus signals and then lock the focus for updating only by WTTM by the command wiyn wttm gt wszl 11 1 locks 0 unlocks Set the Z milligain and then hit Start acquisition 1 4 1 Closed Loop Focus Control 17 Setting a focus interval of 30s is seen to be good for most purposes under reasonable seeing 0 7 1 0 arcsec For worse seeing you may decrease it and vice versa How ever until the focus is locked the updates will not be carried out I am not sure it works exactly this way but I think so correct if I am wrong WIYN has an autofocussing option too generally operated by the telescope operator But when you are using WTTM you would like WITM to make any focus corrections for you so ask the operator to turn the autofocus off while you are using WTTM 1 5 Starting a science exposure Once the tip tilt is working good it is now time to go back to Navajo and take science exposures The only command you really
4. need is observe give full description or refer to MIMO manual when to take dflats zeros if different filters are used for the same field do you unlock the focussing do another focus seq and then lock again 1 6 Monitoring System Performance What to look for 1 6 1 Tip tilt Performance If the tip tilt is working properly you should get decent number of counts in each APDs The counts in all the APDs should be nearly balanced The errors for all three X Y and Z axes should be scattered randomly close to zero Any increasing decreasing trend in time points towards something going wrong Usually we look at the Raw APD errors rather than the Accumulated errors because the accumulated errors average over an interval of time whereas raw errors are snapshots of errors in the APDs taken after fixed time interval 1 6 2 Guiding The guide signals also should be small and randomly scattered around zero Any observed trend points towards the fact that either the APDs lost the star the counts should go down in wttmGetTaskValuesVI panel maybe due to clouds or the image motion is too large to compensate for try increasing the X and Y milligains and reducing APD DIO frequency 1 6 3 Focus As intuitively expected the values of the focus signal sent to the telescope should also be small and randomly scattered around zero when the focussing is working properly 1 7 Shutting the system down Once you are done with a pa
5. so wish The EXIT button in this panel is the main button that sets wttmExit to TRUE and thus terminates all other GUIs Note that terminate here means stops the GUIs running and does not imply removes the GUIs from the screen The GUIs should be removed by the wlv stop command Figure 1 wttmControlVI Panel 3 3 2 WttmGetTaskValuesVI This panel is the main system monitor and shows the X Y and Z errors as well as APD counts for each channel The following items can be identified from the bottom up LOGGING If checked all incoming values are appended to taskVI dat in the data sub directory of home wttm development These files can grow quite large and should be expunged regularly DIO COUNT is the number of times the DIO task has been through its programming loop DIO HW ERROR is a flag to indicate a DIO hardware violation detected by the real time core A zero value indicates no error a non zero value is undesireable DIO HW TIME is the typical time take to access DIO hardware from the real time core expressed in microseconds DIO HW TIME is the typical time take to complete 1 complete programming loop for the DIO task in the real time core APD COUNT is the number of times the APD task has been through its programming loop APD HW ERROR is a flag to indicate a APD hardware violation detected by the real time core A zero value indicates no error a non zero value is undesireable APD HW T
6. to kpno noao edu Writing CDROMs You can also take your data home on CDs but be forewarned that you will need about 4 5 CDs per night of observing They hold only about 650 Mbytes of data Instructions for writing CDROMs can be found at http claret kpno noao edu wiyn cd write html Note that you should use the CD writer on sand rather than pearl otherwise the instructions should work You can then check the CDs by placing them in the CD reader on sand and displaying from the directory mnt cdrom 4 Issues about Astrometry and Photometry Appendix A Recognizing when things go wrong and what to do Appendix B Calibrating the CCD Error Sensor Coordinates The CCD Error Sensor Coordinates are calibrated by uniformly illuminating the lights for dome flats are good an array of 5 x 5 pinholes each of 5u dia placed at the Nasmyth focus of WIYN The CCD position of each pinhole was noted by briefly exposing the chip Then their corresponding positions on the Error Sensor were found by putting the tip tilt correction on and jogging around see the xyManVI GUI till the x and y tilts were effectively nulled out This procedure shouldn t be required unless there is any physical disturbance to the WITM unit However it might be a good to check this calibration from time to time in order to make sure everything is fine As a starting point for a calibration run use the earlier input coordinate file es_trans dat to assess the Error Sensor coo
7. 2 The Optical Path 2 2 Error Sensor 2 2 1 Design and Optical layout 2 2 2 How it works 2 2 3 Sensing Focus 2 2 4 APD Safety Issues 2 2 5 Performance Metrics 2 3 Science Camera 2 3 1 System Description 2 3 2 System Performance and Specifications 2 3 3 FOV Why it looks the way it does 2 3 4 Beam splitters for Science 3 Software Control System The WTTM software system operates under the Linux operating system currently Redhat v6 2 on a dual 500mhz Pentium III CPU machine The computer chassis is located under the telescope azimuth skirt and is named wiyn wttm Also located below the wiyn wttm chassis is the error sensor X Y stage control chasis 3 1 Real Time Linux 3 2 Command Line Interface cli The WTTM has an extensive command line interface as documented in the appendices These notes are extracted directly from the self documenting code Note that most commands accept a h parameter to provide a single line of help text All such commands begin with the wttm identifier and usually match their function For example to change the task frequencies the command is wttmSetTaskFrequencies Clearly this amounts to a lot of typing so soft links are also created which usually follow the form of the command Thus wttmSetTaskFrequencies becomes wstf using the soft link If in doubt use the h parameter to get a one line help text on any particular command or use wttm help to get
8. IME is the typical time take to access APD hardware from the real time core expressed in microseconds APD HW TIME is the typical time take to complete 1 complete programming loop for the APD task in the real time core APD COUNTS is a graphical representation of the APD counts as a snapshot taken every APD update rate in Hertz The 4 APDs are colour coded 0 yellow 1 green 2 pink 3 purple and explicit values are also shown in the color keyed indicator boxes at the lower right of the graph Xis the main graphical representation of X errors The average error is shown in the upper panel and the variance in the lower panel The variance is 0 0 and hence undefined when the number of available data points is lt 2 Data displayed in this graph can be changed using the ring buffer widget called XYZ Graph Y is the main graphical representation of Y errors The average error is shown in the upper panel and the variance in the lower panel The variance is 0 0 and hence undefined when the number of available data points is lt 2 Data displayed in this graph can be changed using the ring buffer widget called XYZ Graph Zis the main graphical representation of Z errors The average error is shown in the upper panel and the variance in the lower panel The variance is 0 0 and hence undefined when the number of available data points is lt 2 Data displayed in this graph can be changed using the ring buffer widget called XYZ Graph XYZ GRAPH con
9. WIYN TIP TILT MODULE USER MANUAL KPNO SYSTEM Version July 02 2002 Chuck Claver and Dipankar Maitra With contributions from The rest of the world The Ring Nebula send comments on manual to claver noao edu Overview Quick Start General Characteristics Arrays Image size Pixels size Read noise DQE Dark current Read out time Cosmetics Filters Saturation Gain 2048 x 4096 EEV CCD thinned engineering grade 2048 x 2500 16 bits plus header overscan 10 58 Mbytes 13 5 um 0 1125 pixel 4 65 e 86 peak at 6500A find this 5 e pixel hr find this 2 6 minutes Fair to good about half a dozen bad columns a dozen or so small 1 2 pixel bad areas PA x PA Typically linear to 0 1 to 100 000 e 1 983 e ADU WIYN Parameters Count Rates FOV Scale Image quality Artifacts Typical focus ADC At UBVRI 20th mag U 35 B 330 V 340 R 410 I 225 e sec find this 3 8 x4 2 XIMTOOL Orientation North up East left 0 1125 pixel at center determine field distortion PSF quite constant across the FOV but will vary with distance from guide star less than 10 Bright stars will show a ghost plus 100 pixels in x from the back surface of the beam splitter Not currently used Data Acquisition Acquisition commands are given on computer named Navajo Analysis commands are given also on the same computer All the Commands That Are Likely To Be Nee
10. WIYN command 65a5 telescope focus move 4860 00000 Now Moving secondary to 50 microns TETN focus 4860 00000 First focus exposure finished WIYN command 65a6 telescope focus move 4840 00000 Now Moving secondary to 19 microns TETT focus 4840 00000 additional focus exposure finished WIYN command 65a7 telescope focus move 4820 00000 Now Moving secondary to 20 microns ae eae focus 4820 00000 additional focus exposure finished WIYN command 65a8 telescope focus move 4800 00000 Now Moving secondary to 20 microns TETT focus 4800 00000 additional focus exposure finished WIYN command 65a9 telescope focus move 4780 00000 Now Moving secondary to 20 microns ween focus 4780 00000 additional focus exposure finished WIYN command 65aa telescope focus move 4760 00000 Now Moving secondary to 20 microns saa focus 4760 00000 additional focus exposure finished WIYN command 65ab telescope focus move 4740 00000 Now Moving secondary to 20 microns oa wus focus 4740 00000 REMINDER The double space marks the beginning of the sequence Figure 8 A focus run centered at 4800 and step size 20 1 2 Selecting a guide star Select a fairly bright star my between 10 15 near you object of interest Try to make sure that the star you chose is not variable why Type mscexamine on the IRAF 15 Data Reduction Window The cursor turns to blink on the Ximtool window Position the curs
11. a screen full of commands at a glance The cli commands are issued by the observer logged in the computer wiyn wttm from the terminal of Almond For a greater detail on the cli commands from a programmers point of view refer to WTTM Users Guide by P N Daly this should be in the WIYN Control Room However all the working of WTTM can also be controlled with user friendly GUIs developed using Labview as described below 3 3 Labview Interfaces 3 3 1 WttmControlVI This panel allows the user to send the main 9 elements to the real time core When these parameter values are set the button labeled SET PARAMETERS must be pressed once to send the values to the core otherwise they are not sent Remember that some values can be adjusted whilst the system is in closed loop mode and some cannot APD Frequency This value sets the frequency in Hertz for the reading of the 4 APD counters and the computation of the 3 error signals X Y and Focus The system must be in idle e g paused from pressing the stop acquisition on this GUI in order for this value to be sent to the real time Linux core APD Update This value sets the frequency in Hertz that the APD values in the WttmGetTaskValuesVI panel are updated more on the consequences relating to this value later DIO Frequency This value sets the frequency in Hertz that the DIO task updates the position of the tip tilt mirror via the Physique Instrumente control chassis
12. age Average Average Variance Y Variance Z Variance io MZ Antoscale Giessas Figure 2 wttmGetTaskValuesVI Panel 3 3 3 WttmGuiderVI This panel shows the value of the guide signals sent to the telescope control system It can be restarted by clicking the local exit button and then clicking on the usual LabVIEW run arrow The upper panels show the X and Y guide adjustments and the lower panel the associated variance if applicable all in seconds of arc The Logging options appends incoming data to guiderVI dat in the data sub directory of home wttm development If the value of guidelnterval is zero which it is by default no data is sent to the telescope control system and this GUI remains inactive 5 x route bone kpno noao edu IC riXguide 3 rtYguide rtVariance y p Variance Figure 3 wttmGuiderVI the guider panel 3 3 4 WttmFocusVI This panel shows the value of the focus signal sent to the secondary control system It can be restarted by clicking the local exit button and then clicking on the usual LabVIEW run arrow The panels on the left show the incoming raw data value upper and variance lower if applicable The right hand side panel shows the effective target upper taking into account the desired Z target if set and the desired Z offset if set These values are set with the cli commands wszt t lt val gt and wszo o lt val gt The lower panel shows the ad
13. ctional arrows 10 File Edit Operate Tools Window Help i gt Close Servo Loop ABORT KILL I7 step iog J20 A HOME 0 20000 40000 60000 command response Iv step jog J 20 80000 ia 100002 200002 300004 400004 s0000 e0000 700004 800007 Figure 6 xyManVI panel after resizing the window 11 3 3 6 WttmPublish This panel shows the published data stream items that have changed since WTTM This panel can be restarted wttm publish restart wttmPublish wttmPublish ct updated wttm apd frequency to 250 OK wttmPublish ct updated wttm dio frequency to 250 OK wttmPublish ct updated wttm apd update to 20 OK uttmPublish ct updated wttm dio update to 20 OK wttmPublish ct updated wttm gain x to 50 OK wttmPublish ct updated wttm gain y to 50 OK wttmPublish ct updated wttm gain z to 1000 OK wttmPublish ct updated wttm focus interval to 1 OK EE updated wttm guider interval to 1 OK Figure 7 wttmPublish Panel 4 Setting up and Obtaining Data 4 1 Initial start up tasks 4 1 1 Starting the Software Full operation of the WTTM requires the observer to use two computers viz Almond and Navajo Almond is the computer used for remote observing and serves only as a display console for the WTTM computer wiyn wttm Navajo serves as the data acquisition computer that runs the HARCON CCD control system 4 1 1 1 Co
14. ded Observing Commands on wiyn ccd Observe Doobs Mosdither More Test Object Zero Dark take one or more exposures prompting for the exposure type a script which takes flats objects for a list of filters takes typically 5 dithered images in a single filter to fill the gaps in array take more exposures just like the last one take a test exposure The output image test is overwritten each time take one or more object exposures take one or more zero bias exposures take one or more dark exposures Dflat take one or more dome flats Sflat take one or more sky flats Focus take a focus frame Recover recover data if possible following a crash during readout Exposure Control Commands Pause pause exposure e g clouds do not ABORT or STOP from within pause resume resume a paused exposure then ABORT or STOP if necessary tchange increase or decrease the exposure time Stop stop an exposure and sequence of exposures reading out the detector Abort abort an exposure or sequence discarding the data pictitle change the title of the picture Quick look and Taping Commands driftwood pecan mscdisplay display an entire mosaic frame mscexamine general tool for examining images mscwfits write mosaic frames to tape in multi extension FITS format Caution Tape your data as you go DLT 7000 250 images tape and Exabyte drives 35 images tape are available Write time 75 seconds image to DLT 3 minutes image to E
15. different Filters FILTER HIGH LAMP EXPOSURE s Approximate Count INTENSITY ADUs zoo 20300 1500 20 600 Harris I 20 000 Gunnr 0 20 80 Gunn I 20 500 Gunn z 22 300 1 1 Getting on Sky 1 1 1 Initial Focus After you get to your field take a quick snapshot of the field by typing in the data acquisition window cl gt test Do a quick focus sequence When you take a focus frame with the ARCON software at WIYN you typically take a short 3 10 sec exposure of a 11 12 mag star clock the charge down 30 rows decrease the focus value take another exposure clock down the charge decrease the focus etc for a series of 7 9 exposures The frame is then read down the the image examined with mscexam mscfocus to determine the best focus value Note that the double space gap occurs after the first exposure A sample run is shown in Fig 6 14 1 1 2 Acquiring your field details of observe command already there in MINIMO manual cl gt observe Exposure type zero dark object comp pflat dflat sflat focus object focus Exposure time 0 3 9 Title of picture test field V V focus frame Number of focus exposures 7 Middle exposure number 4 of sequence to have Focus value 4800 Focus increment 20 Filter in wheel one V WIYN command 65ai1 filter position move 2 Got filter move completion from FSA 2 Setting shutter mode to normal Got filter move completion from FSA 2 Filteri V
16. enerally an APD DIO frequency of 200 Hz is a good point to start once you are at the star Try to bring the APD counts somewhere between 20 40 for each APD Increasing the APD DIO frequency will reduce counts and vice versa APD DIO update rate of 10 20 Hz should be good for most purposes our eyes hardly notices anything faster so increasing this wouldn t help much 1 3 3 Selecting a gain At low frequencies you will need a larger value of gain to correct for image motion Keeping X and Y milligains to 50 for APD DIO frequency around 50 200 HZ is reasonable For higher frequencies a lower value of 10 or 5 should be good Similarly if the seeing is not very good say 1 arcsec or higher the Z milligain should be high around 1000 When the seeing is quite good 0 6 arcsec or lower even a value of 500 should be good 1 3 4 Telescope Guiding Usually the guiding in WIYN is done by choosing a guide star nearby the field and the autoguider tracks the star However for WITM we don t need any extra autoguiding our star chosen above for doing the tip tilt correction itself acts as a guide star A Guider Interval of 5 seconds is should be enough under most circumstances So after closing the X Y and Z loops and before setting the focus interval to a non zero value one must ask the telesccope operator to make sure the autoguiding is off Once operating WTTM itself will take care of that 1 4 Final Focussing Once the gains are set i e
17. hrough this GUI that user feeds all the inputs to control the WTTM The rest are mainly for visualizing the outputs and checking for erroneous behaviour if any The user may want to minimize the WttmPublish as it is the least needed in fact not at all if things are going fine The other windows may also be moved and resized to use the monitor screen efficiently Now type wiyn wttm gt xyManVI amp to start the GUI to position the error sensor Fig 5 shows the window that comes up However the user may resize it to resemble Fig 6 without any loss in efficiency This completes the initial startup process for the WITM and now the observer may proceed to setup Navajo the computer used for data collection Configuring Navajo The data acquisition takes place in Navajo Login as wiyn_ccd The password should be posted on the monitor Along with various ARCON windows an IRAF Data Acquisition Window and another IRAF Data Reduction Window opens up An Ximtool window also opens up which shows the most recently acquired image Right click and Re start ARCON if it is not already running 4 1 2 Initial Configuration In the WttmControlVI set the APD DIO frequencies and APD DIO update rates as shown in Fig 1 But keep the X Y and Z milligains to zero to keep the loop open Hit the Set Parameters button and then Start Acquisition The user will notice that the APD counter in wttmGetTaskValuesVI becomes alive However the counts in all 4 APDs i
18. justment in microns taking into account the conversion factor to microns and the Z axis gain The gain can be set with the cli command wsg _z lt val gt The right hand side panel is activated by use of the lock facility When unlocked the graph is disabled When locked the graph is enabled assuming the focusInterval is non zero too The lock can be set with the cli command wszl _l lt val gt where a zero value indicates unlock and a non zero value indicates lock The Logging options appends incoming data to focusVI dat in the data sub directory of home wttm development If the value of focusInterval is zero which it is by default no data is sent to the secondary control system and this GUI remains inactive wttmFocusVivi O O OOOO bone kpno noao edu rtFocus 3 eTarget Variance Derived Focus Microns Figure 4 wttmFocusVI the focus panel 3 3 5 XyMan VI Error Sensor position control This GUI controls the position of the error sensor ans is used to move the errors sensor to the location f the desired guide star The current x and y positions of the error sensor is shown at the top of the panel The user can input a pair of coordinates in the middle box and hit the GO button to send the error sensor at the requested position The user can also jog around some position by entering the amount to jog in the input box 2units 1 micron physically and then clicking on one of the four dire
19. min_sigdigit 7 Minimum precision of output x and y coordinates mode ql Run geoxytran and input the CCD coordinates to get Error Sensor coordinates Set the coordinates in xyManVI and go there The counts in each APD should rise as the error sensor gets to the star The counts may not be balanced in each APD to begin with but as long as you are getting a good number of counts in at least one APD you are fine because once you close the loop it will center the star properly and the counts will balance However even after taking the error sensor to the right coordinates if you don t get substantial number of counts in any APD you may jog the error sensor around in steps of 100 units 50 microns physically to get to the star This may happen rarely if the calibration file hasn t been updated recently or there is a slight error in the calibration file Appendix B discusses how the calibration is done 1 3 Closing the loop 1 3 1 Setting Parameters Dos and Don ts 16 The control parameters are set from the wttmControlVI panel Fig 1 shows the panel with some typical values used for the parameters used All the parameters can be changed any time however you better not change parameters while in the middle of a science exposure To change any parameter first change its value in the box then hit Stop Acquisition followed by Set Parameters Then you are ready to Start Acquisition again 1 3 2 Selecting a frequency G
20. nfiguring Almond wiyn wttm The first task to do is to start up the Tip tilt software on wiyn wttm with its display being sent to Almond Start by logging onto to Almond as observer The password should be the normal mountain user password and should be posted on the monitor Once logged in open a new terminal by clicking the right mouse anywhere on the screen and choosing the open new terminal menu In this terminal window type almond gt xhost wiyn wttm This allows Almond to accept X windows from wiyn wttm almond gt rlogin wiyn wttm l root this will be changed wiyn wttm gt export DISPLAY Almond 1 This is a bash shell command that tell wiyn wttm top send all X window display from this session to Almond s screen number 1 Note On Almond the default login screen is the 24 bit display and is referred to as Almond 1 where the alternate 8 bit display is referred to as Almond 0 At this point Almond and wiyn wttm should be configured to start WITM software 12 4 1 1 2 Starting WITM software on wiyn wttm In the wiyn wttm terminal window type wiyn wttm gt wlv start This will start the WITM Labview software which enables the user to control the operation of the tip tilt module A few messages will appear on the terminal followed by opening of five GUIs with titles WttmPublish WttmControlVI WttmGetTaskValuesVI WttmGuiderVI and WttmFocusVI The WttmControlVI window is the most important of all these because it is t
21. or on the star and type a to get its coordinate written on the data reduction window To get the error sensor coordinates from CCD coordinates obtained from mscexam one needs to go to the IRAF Data Reduction Window or open a new IRAF xgterm on Navajo and type the following cl gt immatch cl gt Ipar geoxytran The parameters for geoxytran should look like input STDIN Input coordinate files to be transformed output STDOUT Output transformed coordinate files database ES CCD trans fit The GEOMAP database file transforms ES CCD trans dat Names of the coordinate transforms in the da geometry geometric Transformation type linear geometric xref INDEF X input origin in reference units yref INDEF Y input origin in reference units xmag INDEF X scale in output units per reference unit ymag INDEF Y scale in output units per reference unit xrotation INDEF X axis rotation in degrees yrotation INDEF Y axis rotation in degrees xout INDEF X output origin in output units yout INDEF Y output origin in output units xshift INDEF X origin shift in output units yshift INDEF Y origin shift in output units xcolumn 1 Input column containing the x coordinate ycolumn 2 Input column containing the y coordinate calctype real Data type for evaluation coordinates xformat Output format of the x coordinate yformat Output format of the y coordinate
22. rdinate for a given CCD coordinate Remember to open the loop set X and Y milligain to zero before moving from one pinhole to another As the keen observer has surely noted the CCD chip has 2048 x 2500 pixels whereas the XY Error Sensor scale ranges from 0 to 80 000 in either directions as seen in the xyManVI window Actually the transformation from CCD coordinates to Error Sensor coordinates is not just linear but has higher order terms it However this calibration is already done beforehand and the user doesn t have to worry about it However the user must supply the error sensor coordinates of the star he she wishes to use as a guide star 20 The most recent data file for calibration file is es_trans dat where these files are there should be a common repository for these files The transformation from CCD to Error Sensor coordinates is done by the geomap task in the IRAF immatch package An lpar on geomap should look like the following input es _trans dat The input coordinate files database es trans fit The output database file xmin INDEF Minimum x reference coordinate value xmax INDEF Maximum x reference coordinate value ymin INDEF Minimum y reference coordinate value ymax INDEF Maximum y reference coordinate value transforms es trans The output transform records names results The optional results summary files fitgeometry general Fitting geometry function
23. rticular field and want to move to another field first open the loop by setting the gains to 0 Then unlock the focus with the command wiyn wttm gt wszl 10 18 Now you are ready to request the telescope operator to move to your next field After getting to the next field repeat from Sec 4 2 1 When you are done using WTTM for the night power the APDs off by wiyn wttm gt wttm_pwr apd off You may want to shut the software down by issuing the command wiyn wttm gt wlv stop This will close all the GUIs pertaining to ccontrolling WITM except xyManVI remember we started it separately To close xyManVI click the STOP buttom then go to File menu and choose Quit 2 Data Reduction 3 Saving the data Right now the DAT tape drive is mounted on Sand So the observer has to ftp all his data to Sand Both Exabytes and DATs are available These are mta for the Exabyte drive and mtb is the DAT drive The DAT supports DDS 4 densities 20 Gbytes per tape The DAT on sand is internal to the tower box while the Exabyte is external Because of the multiextension format of WITM data although actually it is only a single CCD with one amplifier you must use the IRAF mscwfits and mscrfits commands Do a cl gt allocate mtb from Sand The parameters for mscwfits are shown in Figure In order to check to see what is on the tape you can list the titles quite easily Simply do a cl gt mscrfits mtb 1 999 list short original to see
24. s zero because during the startup the power in the APDs is off by default to increase the longevity of the APDs To turn the power in the APDs on issue the command wiyn wttm gt wttm_pwr apd on Similarly wiyn wttm gt wttm_pwr apd off turns power in the APDs When the power in the APDs is turned on a brief surge of counts from each APD is seen why After this brief surge the counts will come down to 2 or 3 counts for each APD This ensures that the system is working properly 13 4 1 3 Calibration Data Before after the science exposures the observer should take some calibration data for the CCD This invloves taking dome sky flats To take the dome flats you will have to tell the observing assistant first that you intend to do so Once you get his green signal you should right click anywhere on the desktop on Navajo and select the Domeflat menu Once the GUI comes up need a screenshot of that turn the high lamp on at your selected intensity Table 1 may be a useful starting point Once the lamps are on you can actually see them in the TV in the control room You may use either the observe command or the dflat sflat and zero command to take dome sky flats and the bias frames respectively Usually 5 10 biases every night and five dome flats through each filter aiming for a count of 20 000 ADUs in each should be good enough This should flatten your data to better than 1 Table 1 Dome Flat Lamp Settings and Exposure Times for
25. trols what is displayed in the X Y and Z graphs above There are 4 options Raw APD Errors are snapshot values at the cadence of the task update rate For example if the APD update rate is 20 Hz and this option is selected then snapshot raw values are placed on the buffer by the real time core every 1 20 s and these values are displayed in the X Y and Z graphs Raw DIO Errors are snapshot values at the cadence of the task update rate looks same as above which one is correct For example if the DIO update rate is 10 Hz and this option is selected then snapshot raw values are placed on the buffer by the real time core every 1 10 s and these values are displayed in the X Y and Z graphs Accumulated APD Errors are average data at the cadence of the task update rate For example if the APD task frequency is 1000 Hz and the APD update rate is 20 Hz then 1000 20 50 data points are averaged and the result and variance displayed via the X Y and Z graphs Accumulated DIO Errors are average data at the cadence of the task update rate For example if the DIO task frequency is 500 Hz and the DIO update rate is 25 Hz then 500 25 20 data points are averaged and the result and variance displayed via the X Y and Z graphs It gets more complicated than that however if the DIO task is not running at the same frequency as the APD task as the DIO task can accumulate APD values check the source code for an explanation Aver
26. what s there To direct this output into a file you can add a gt tapelist to the end and then you can print that list on the lineprinter by a simple Iprint tapelist NOTE If you do write additional files to an old tape one containing useful data but which had previously been removed from the drive make certain that the software IRAF and Unix is aware that the tape has been rewound before starting to write to the tape or your old data may be overwritten To safeguard against this possibility we suggest that you ALWAYS swap tapes by first cl gt deallocate mtb or mta Physically swap tapes cl gt allocate mtb or mta Safe Taping We recommend the following safe taping procedures 1 Each night write data to tape 2 Read the tape using cl gt mscrfits mtb list to substantiate everything is there 19 3 Deallocate the drive remove the tape and stick it under your pillow 4 Make a second copy of your tape This tape could be an accumulative copy of the data throughout your run Check this tape with mscrfits 5 Only now delete the data from disk if necessary Save the Bits All data taken at WIYN and the other Kitt Peak telescopes are automatically saved to tape Extracting a night s worth of data from these tapes is laborious and labor intensive and we strongly emphasize the need for the safe taping procedures above But if you ever do need to recover a night s worth of data take heart You can send email
27. xabyte DDS 4 DAT drive available on Pecan 4m write time 40s image Please be off the computer by noon of your last day You can buy DLT and Exabyte tapes on the Kitt Peak but bringing your own is cheaper Calibration data Take dome flats or preferably twilight flats night sky flats work even better Take dark exposures of similar length to your science exposures Take zeroes i e biases Darken the dome for darks and zeroes 1 Introduction The WIYN Tip Tilt Module WTTM is attached at the Nasmyth focus of the 3 5m WIYN telescope Physically the module is installed at the WIYN port which also houses the Mini Mosaic Camera The design permits rapid change from wide field CCD imaging and multi object spectroscopy to higher resolution imaging over a 5 arcmin field of view and integral field spectroscopy as science objective and atmospheric seeing dictates As a result of the active optics system already installed on WIYN control of the local environment and location of the telescope the image degradation is primarily a result of upper atmospheric turbulence of which measurements indicate that for an aperture of this size image motion is a major contributor The WIYN tip tilt system corrects this motion in real time and has the potential of reducing median seeing of 0 8 to 0 5 at R and produce nearly diffraction limited images at H 2 WTTM Instrument Description 2 1 Optical System 2 1 1 Principles of Design 2 1
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