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FIES Cookbook

Last updated September 19 2017
Please refer to the online version for the latest update

Table of Contents


 
 
 
 
 
 
 
 
 

 
 
 
 
 
 
 
 
 

Preparing Observations

Observing scripts

Observing scripts can be generated automatically through the Observing Script Generator or crafted manually. If done through the web, the script will be uploaded and within a few minutes available in ~obs/scripts/proposal-ID, where proposal-ID refers to the proposal ID entered in the web form (e.g. 38-042). If the directory does no exist, it will be created. If you make your observing scripts manually, first make the proposal ID directory (using mkdir) and place them therein.

The scripts are executed from the sequencer window, from the directory where they are placed. Note that if you are saving scripts or files elsewhere in the ~obs account, the directory will be cleaned up after every run and it will not be possible to recover them.

Create a TCS Target Catalogue

A source catalogue can be made well in advance of your observations by using the web interface, NOT Source Catalogue Creation. Note that it is also possible to enter targets on-the-fly and create a catalogue directly on the TCS while observing (See section, Loading Target Catalogue).

Exposure Time Calculator

The Exposure Time Calculator can be used to estimate the required exposure times for ALFOSC, NOTCam, FIES, MOSCA and StanCam (both in imaging and spectroscopy mode, where it is available).

Afternoon Preparations

Overview of everyday afternoon tasks

  • Update the TCS target catalog if necessary, and upload it to the TCS.
  • Find out the TCS access code of the day on TCS status page 1
  • Shutdown the FIES+STANCAM Sequencer, and shutdown the ALFOSC Sequencer: open a new terminal window, and do
    [obs@tessa]$ shutdownobssys alfosc
    [obs@tessa]$ ssh verushka
    [obs@verushka]$ shutdownobssys fies
  • Kill all remaining windows on the lisa display
  • Startup the FIES+STANCAM Sequencer, and (always!) startup the ALFOSC Sequencer (for overrides)
  • In all FIES/STANCAM Sequencer windows change the working directory to the one assigned to your program, for instance
    [obs@tessa][STANCAM]$ cd ~obs/scripts/38-025
    [obs@verushka][FIES]$ cd ~obs/scripts/38-025
    as in this directory your FIES observing scripts can be found, created, and executed.
  • Edit and test your scripts.
  • Run the fies-calibs script in the FIES Sequencer, and possibly take more calibration frames.

  • In case of an ALFOSC override:
    • In the ALFOSC sequencer switch to the directory associated with the override program, for instance
      [obs@tessa][ALFOSC]$ cd ~obs/scripts/38-035
    • Run any calibration scripts that are required by the override program

Loading the TCS Target Catalogue

  • On the TCS, press the catalogue button CAT to view the object catalogue. If you want to erase the current catalogue that is displayed, type erase-catalogue on the TCS.
  • Load a source catalogue by typing read-catalogue catname.cat on the TCS, where catname is the name of the catalogue. A source catalogue can be created by using the web interface or the objects can be added directly to the current TCS catalogue by pressing the key, Enter Object (2) and then type according to the example below:

    Name RA DEC Epoch ProperMotionRA ProperMotionDec Magnitude

    SN1995N 14:49:28.27 -10:10:15.40 2000.0 0.00 0.00 0.00
    The proper motion should be given in arcseconds/year

  • Add a catalogue of blank fields, if needed, for obtaining twilight flats fields by typing read blanks on the TCS.
  • To select an object, press the catalogue button CAT on the TCS, and then use key number 1 or 7 to move to the next or previous object, or use the Prev/Next buttons to scroll up/down an entire page. The telescope will move to the selected target when pressing the key Preset to selected (4), or if observing on the parallactic angle, pressing the key Preset to par ang (6).

TCS access code

Any instrument computer which needs access to the TCS, for instance to move the telescope during slit acquisition or dithering, will ask for the current TCS access code at start-up. This code is updated every day (around lunch time). When you are asked to supply the TCS access code, do the following:

  • On the TCS VT510 terminal, make sure that the brightness is turned up
  • On TCS type: Show-Page and then 1 (or type sh 1 for short)
  • The TCS access code is shown on the top part of the screen as: AccessCode xxxxxxxxxx

Starting the FIES and STANCAM software

  • On lisa choose tessa in the XDMCP host-menu and log in as user obs .
  • Then open a terminal window and type
    [obs@tessa]$ ssh verushka
    to login to verushka.
  • To start the observing system type
    [obs@verushka]$ startobssys fies
    and type in the correct TCS accesscode in the popup window.
     
    This will start the FIES and STANCAM observing software. For each instrument there will be 2 white Sequencer windows where commands can be entered, a BIAS DS9 image display, a beige BIAS CCD status window, a small grey postprocessing UIF, and a blue observing log.
     
    Aditionally the FIESTA status window, the Sequencer's Talker window, and the TCS Status Display are started. These programs allow to monitor system status.
     
    Finally a small window with an orange 'handset' is started, which allows to tweak the star towards the fiber.
     
    In the Talker you will find information about the correct start of the different software components or a corresponding error. If any errors about a program not starting are seen, please shut down the observing system and start it again.

  • In all the SEQUENCER windows change the working directory to the one assigned to your program, for instance
    [obs@verushka][FIES]$ cd ~/scripts/38-053
    as in this directory your FIES observing scripts can be found, created, and executed.

  • To activate the observing logs press the 'Load images' button and enter the proper date specification in the FITS file names, for example
        FIrk23*.fits (for the FIES log)
        STrk23*.fits (for the STANCAM log)
     
    Note that the FIES log can be restarted in a terminal window with
    [obs@verushka]$ cd /data/fies
    [obs@verushka]$ obslog-fies
    and similarly for STANCAM:
    [obs@tessa]$ cd /data/stancam
    [obs@tessa]$ obslog-stancam
  • For a list of available SEQUENCER commands type 'help' on the SEQUENCER terminal windows or see See also a list of handy FIES SEQUENCER scripts.

  • Click (twice) on the ScreenShot below to zoom in.
FIES obssystem layout

 

Starting the FIEStool reduction software

    As of the beginning of 2015, a headless version of FIEStool is always running to provide reduced data that is written to the data DVDs. It is still possible for astronomers in the control room to start an additional normal FIEStool instance, which allows the user to tweak some parameters if needed.

  • On florence login as user guest.

  • Then open a terminal window and type
    [guest@florence]$ ssh postprocess@alona "cd datared; ./FIEStool.py"
    Ask the necessary password from your support person.

  • Once FIEStool has started up:
    - choose a mode (default 'advanced')
    - optionally define a wavelength region to plot
    - switch on the small "Autocheck new files" button
    - choose an appropriate output directory,
        e.g. /raid1/data/reduced/fies/manual/visitor
        or /raid1/data/reduced/fies/manual/service
        but please do not use /data/reduced/fies/auto/ !
    - and click the large "START processing" bar

  • Additionally, a separate viewer for incoming FIEStool-reduced merged spectra can be started on florence,
    which displays the spectra reduced by the automatically running headless version of FIEStool:
    [guest@florence]$ fiestool-viewer /data/reduced/fies/auto/

Starting the ALFOSC software

For Nordic telescope time, ALFOSC needs to be ready for Target Of Opportunity observations.
Select a different workspace on Lisa, and follow these instructions, starting from point 4).

When the ALFOSC software is running, re-activate the FIES obslog with

[obs@verushka]$ fies.showlog

 
 

Choose the science fiber(s)

      For the current fiber bundle C the fibers are numbered as follows:

Fiber-bundle C correspondence table
  fiber 1 low-res R=25000 2.5 arcsec
  fiber 2 med-res R=45000 1.3 arcsec, optional sky fiber
  fiber 3 med-res R=45000 1.3 arcsec
  fiber 4 high-res R=65000 1.3 arcsec
  fiber 5 high-res R=65000 calibration fiber

Fiber #5 does not run to the telescope but to a dedicated calibration unit. This fiber provides the ThAr light for the simultaneous-ThAr mode.

It is possible to use only one science fiber or to use two adjacent science fibers at the same time. The latter option is to obtain a target spectrum with a simultaneous sky spectrum (fibers 3 and 2).

Use the SEQUENCER scripts setup-fibN-star, setup-fibN-halo, setup-fibN-thar (where N is 1,2,3,4,5) to move the arm and mask in the correct position, and to switch on any required lamp.

Obtaining calibration frames

For FIES it is recommended to obtain at least one set of calibration frames. This can be done using the script fies-calibs, which by default will obtain 7 biases and 21 flats. The script takes about 45 min to run, and can be issued from the FIES sequencer in the following way:

[obs@verushka][FIES]$ fies.fies-calibs [-fib 1-4]

For more information see: fies-calibs documentation.

And possibly take more calibration frames.
At night, single ThAr and Halogen frames are easily obtained using scripts easythar and easyhalo.

Start of the night

Overview of things to do at sunset

  • Open the dome, and power-on the telescope following the procedure in the Cookbook

  • In case of an ALFOSC override:
    • Once the telescope power is on, switch to ALFOSC. Run the script
      [obs@tessa][ALFOSC]$ tcs.setup-tel-alfosc
      in the ALFOSC Sequencer window.
    • Starting at sunset, run any sky-flat scripts that are required by the override program.
      See the ALFOSC sky-flat instructions

  • Once the telescope power is on, and possible ALFOSC flats have been taken, run the script
    [obs@verushka][FIES]$ tcs.setup-tel-fies
    in a FIES/STANCAM Sequencer window. The script setup-tel-fies needs to be run after every swap between instruments (e.g. for overrides) as well.
  • When it is dark outside, switch on the two guiding monitors, and activate the guider at the TCS terminal :
    tv-on
    Note that tv-on needs to be issued every time the telescope has been parked at zenith.

Telescope Startup Procedure

Return to the dome at least 30 minutes before twilight and follow the instructions below.

Weather precautions

Humidity Wind Dusty Wind Temperature
> 90% - Close telescope

After 20min < 90% the telescope can be reopened.
12 m/s - Close sideports and lower hatch 10 m/s - Close sideports and lower hatch If the humidity is > 90% and the temperature is
< 0° C close telescope and do not open until all ice has melted on the outside of the dome.
15 m/s - Observe down wind 12 m/s - Close telescope
20 m/s - Close telescope

Telescope Control System (TCS)

  1. Turn up the brightness of the TCS screen (on right-hand side, below the screen).
  2. Look at the top-left of the TCS screen. If the item ST isincrementing, then the TCS is running, if not - then the TCS needs rebooting (rebooting the TCS should be done under guidance of a staff member). Type refresh if the screen looks strange.

Telescope power-on and Dome Opening

  1. Check the safety system in the computer room. Reset the system by turning the left key (marked as "First") and then the right key (marked as "Second"), one at a time (See TCS Manual Sect. 10.1 for procedure). If you hear a repeated clanking sound then the system has not reset, check the red lights above the keys to see if a safety stop or other item is set.
  2. Type on the TCS, power-on and confirm with y for yes. Look at the status page number 1 (type sh 1). On this page the status of the power units for the telescope motors can be viewed. When the TopUnitPower is on and the telescope is Idle, the telescope is ready to use. The power-on procedure takes about one minute in total.
  3. At sunset, if weather conditions are OK, open the upper hatch with the mirror covers closed. Press the key, START/STOP on the TCS and then the key Open Upper Hatch (7). Confirm by typing y for yes. It takes about 3.5 minutes to open the upper hatch.
  4. In the dome (While the upper hatch opens):
    • Open the side ports (only if weather conditions are OK). Do not use too much force and use the handle for lifting the ports if needed (Note that the side ports are easily damaged).
    • Check that nothing is in the way of the telescope motion (altitude: 6.5° - 90°).
  5. Open the lower hatch (only if weather conditions are OK). On the TCS, press the keys Start/Stop and Open Lower Hatch (8). Confirm with a y. It takes about two minutes to open the lower hatch. The TCS will not allow opening of the lower hatch before the upper hatch has completed opening. In case you can only open the upper hatch, the maximum zenith distance for unvignetted observing is 55°, and at a zenith distance of about 70° roughly half of the mirror is vignetted.
  6. The mirror covers can be opened at the same time as the lower hatch. On the TCS, press the keys Start/Stop and Open Mirror Covers (9). Confirm with a y. It takes about 50 seconds to open the mirror covers. Please note that the power for hatches and mirror covers is completely independent of the telescope power and the electronics in the control room.

Set default telescope parameters

  1. This should be done in any sequencer terminal with
    This sets amongst other items, the default telescope focus and rotator angle, and auto-pos-full for fully automatic autoguiding when pointing to an object.

Field Rotator

In an alt-az telescope the field rotator is used to keep the orientation on the sky fixed while tracking. When the field rotator is in automatic mode, which is the default, the TCS command field-rotation value sets the rotator such that value is the angle between the sky and the instrument. The default value of the Field Rotator is different for each instrument and can be found in Table 1. The field-rotation value will be set to the default angle when executing the script setup-tel-fies

The rotator-position is the physical position of the rotator with respect to the telescope fork, and it has a limit at +- 200 degrees. Its current value is shown on the TCS status display together with the time-to-reach-limit in minutes. Before reaching the limit, the TCS will send a warning and suggest you to turn the rotator 360 degrees at any convenient moment. This can be done manually with the TCS command ro-tu-360 after switching off autoguiding with ag-off. Note that this is possible only in the overlapping ranges [-200,-160] and [160,200]. If the limit is reached, the TCS will eventually, after repeated warnings, perform the full rotation automatically (whether or not an observation is ongoing).

The exposure commands for ALFOSC, FIES, MOSCA and StanCam check whether the rotator limit is reached within the exposure time, if this is larger than 300 seconds. For NOTCam, where typically multiple short exposures are made, this is not the case. If you want to follow the same target continuously for many hours, and you wish to avoid having to turn the rotator, for instance because you want your target on exactly the same pixels all the time (transit light curves), you might consider using a different field-rotation value, based on the time-to-reach-limit value displayed on the TCS UIF.

For the case that right after the telescope pointing the rotator will start off in the overlapping rotator range, the telescope can be told to automatically point using the rotator position that allows for maximum tracking time, with tcs.set-rotator-standard, which is the default behaviour. For details see the TCS documentation. If you have many pointings with relatively short exposures or you keep pointing towards the same region of the sky, you may save some pointing overheads by making the TCS choose the fastest rotator slew to reach either of the overlapping rotator ranges: set the rotator to fast mode using tcs.set-rotator-fast, which is a sticky command. To go back to the default mode, use the command tcs.set-rotator-standard .

Note that for FIES programs that aim for accurate radial-velocity measurements we point the telescope using a fixed rotator position. This is achieved when using the command tcs.guide-object-with-parallactic in the sequencer, or preset-with-parallactic in the TCS interface.

Camera Probe

The Camera Probe is used for the standby Camera (StanCam) and for FIES and should be put in park position for all other instruments. Put the Camera Probe in the correct position by typing the TCS command as indicated in Table 1. The correct Camera-Probe position will be set when executing the script setup-tel-fies

AutoGuiding

It is recommended to have the telescope autoguide on an optical source close to your target object. The TCS is automatically selecting a star from the HST guide star catalogue. The guide probe is then automatically placed at the correct position to auto-guide on this star.

  1. After obtaining sky flats, switch on the two Guide TV monitors above the TCS monitor. When it is dark outside, type tv-on on the TCS to power on the TV guide camera. The TCS command tv-off switches the TV camera off.
  2. On the TCS, type auto-pos-full to choose the fully automatic guiding mode. Note that this is the default guiding mode as set in tcs.setup-tel-<inst>. In this mode, a guide star will be automatically found, centered on the screen and autoguiding will be switched on (ag-on).
    If the guiding does not start automatically but you see a guide star on the TV monitor, type auto-pos-retry.
  3. The TV filter can be adjusted to the intensity of the guide star by typing tv-filt name on the TCS, where the options for name is Open, Closed, Grey, Red, Yellow or Blue. Choose an appropriate TV filter based on the brightness of the guiding object and keep an eye on the guide monitors during your observations so you can change TV filter after weather conditions and brightness of the guide stars.
  4. The autoguider TV focus is also set by the script tcs.setup-tel-<inst>. The TV focus is depending on instrument and can be adjusted by typing tv-foc value on the TCS, where the value for default focus is found in Table 1.
    If you wish the TV-focus to follow the telescope focus type au-t-f (Automatic-TV-Focus, default setting) on the TCS, else to restrict to only manual TV-focus settings type ma-t-f (Manual-TV-Focus).
    In automatic mode, after every pointing of the telescope the TV-focus will be set to a default value that takes the telescope-focus position into account. If that value is not adequate, you can recalibrate the TV-focus on the spot: after adjusting the tv-focus type calibrate-tv-focus in the TCS interface.
  5. If you want to choose a new guide star, type get-guide-star 2 (or 3,4,5, etc.) to get a new guide star from the guide server at the current pointing, followed by auto-pos-retry.
  6. On the TCS, the monitor signal strength from the autoguider is shown as a number. A guiding value between 1 and 23 is useful. Put in a filter if the signal is above 24, otherwise the TV filter will be set to grey automatically. If the signal is close to 1 the autoguiding is not reliable (e.g. clouds and/or bad seeing). Set tv-filt open and check for clouds.
  7. Make sure that the smaller box, the sky box is placed outside the star box. If needed, move the sky box by selecting the function Sky Box with Change move mode (5) and move the box with the keystroke combination, Alt Function + arrow keys.

    Always turn-off autoguiding (ag-off) before moving the telescope.

Hints for manual guiding and tweaking of telescope pointing

If guiding mode is set to auto-pos-off, the guiding has to be activated manually. Furthermore, in case that the pointing is not optimal, some manual tweaking may be required.

For manual choosing of a guide star, start with preseting to target. Find a guide star on the screen and move the star box to the star by pressing the key change move mode (5) on the TCS several times until the option Star Box is shown. Move the box by using the keystroke combination Alt Funtion + arrow keys. Alternatively, choose the move mode Guide Probe to move the star into the box, or use the command move-g. To set the step size of the Guide Probe, type probe-step-size x y on the TCS, where x and y are in arcseconds.

In case the telescope pointing is not optimal, in particular if the guide star ends up outside the screen, a pointing correction can be made with the move mode called Telescope: press the key change move mode (5) on the TCS several times until the option Telescope is shown, and move the star by using the keystroke combination Alt Funtion + arrow keys. The step size of the Telescope is set with the command offset-size on the TCS UIF.

Alternatively, if no guide star can be found on the screen, use get-guide-star 2 (or 3,4,5, etc.) to get a new guide star from the guide server at the current pointing.

When the star is placed in the starbox, type ag-on on the TCS to switch on autoguiding. To switch off the autoguiding, type ag-off.

Guiding on moving targets

If you are observing moving targets, view the page Tracking of Moving Targets, in the Appendix.

On-fiber guiding

As of the Summer of 2014 we have activated a new guiding mode, using the FIES target itself to give additional low-frequency guiding corrections. This mode can only work properly when normal guiding (see above under AutoGuiding) is enabled.

Apart from giving additional guiding corrections, the fiber guider can position the star on the fiber much faster than in manual acquisition mode (the orange buttons, see the Target Acquisition section below).

In order for the fiberguider to work properly, the observer has to check the position of the fiber at the start of the acquisition procedure. If necessary, the command stancam.fibpos-man should be used to interactively reposition the guiding hotspot, i.e. the green cross.
This is especially important after switching to another fiber, or after putting a different filter in the STANCAM beam.

During acquisition and the subsequent FIES exposure, the fiber guider will analyse the continuously incoming STANCAM fiberviewing images, and will overlay the derived positions of the target and fiber on the postprocessing DS9 display:
green cross: guiding hotspot, should be placed on the center of the fiber
blue cross: computed fiber position (only after a few movie images are recorded)
red cross: computed target position

In case more than one object is visible in the on-fiber guider FOV, the fiberguiding needs to be switched off manually on the orange-button handset.

           

Focusing the Telescope with FIES

The telescope focus depends on temperature and zenith distance. These relations have been measured to a high accuracy and the corresponding corrections are applied in real time by the TCS (note that you will not see these corrections in the focus value displayed on the TCS since this value is kept constant to avoid confusing the observer).

The telescope should be focused while in fiber-viewing mode (camera-probe-fies). Note that this means that the images will not be in focus in StanCam (camera-probe-stancam).

For routine operation of FIES, use the default telescope focus for FIES (see Table 1). The default telescope focus will be set when executing the script setup-tel-fies. For more detailed information, follow the link and read about how to focus FIES manually.

Start Observing

When the telescope is focused it is time to start the observations. Visit the individual pages for instrument specific information: FIES

Overview: observing an object at night

  • Consider using the ADC.
  • Point the telescope using the TCS terminal, or use the tcs.append-object and tcs.guide-object or tcs.guide-object-with-parallactic commands in a Sequencer window.
  • Put the target on the fiber using the Acquisition Hints, or use script stancam.acquisition
  • Take a FIES spectrum and possibly some wavelength calibrations
  • Switch-off autoguiding with
    [obs@verushka][FIES]$ tcs.ag-off
    before pointing the telescope to the next object

  • In case of an ALFOSC override:
    • Switch to ALFOSC. In the ALFOSC Sequencer window, run the script
      [obs@tessa][ALFOSC]$ tcs.setup-tel-alfosc
    • If requested focus the telescope
    • Run any scripts that are required by the override program
    • When ready, switch back to FIES. In a FIES/STANCAM Sequencer window, run the script
      [obs@verushka][FIES]$ tcs.setup-tel-fies

The Atmospheric Dispersion Corrector (ADC)

If you plan to observe targets at airmass larger than 1.5 you may consider using the ADC. The ADC consists of a pair of rotating wedges that counter the effect of atmospheric dispersion, and thus ensure minimal wavelength-dependent fiber losses. The wedges have to be adjusted according to the altitude and rotator angle of the telescope.

To use the ADC, issue the following commands before pointing to a new target:

[obs@tessa][STANCAM]$   tcs.adc-arm-in
[obs@tessa][STANCAM]$   tcs.focus-delta 560
[obs@tessa][STANCAM]$   tcs.adc-mode-automatic-when-presetting

The ADC will then adjust itself while presetting to new targets.

 

To have the ADC adjust itself to the current telescope altitude, e.g. when following the same target for an extended period:

[obs@tessa][STANCAM]$   tcs.adc-actual

but never do that during an exposure, as the target will move somewhat with respect to the fiber.

 

To stop using the ADC issue the following commands:

[obs@tessa][STANCAM]$   tcs.adc-arm-out
[obs@tessa][STANCAM]$   tcs.focus-delta 0

 

Target acquisition

Fiber-viewing with StanCam (camera-probe-fies).
Left: hole 1 (low-res, 200 micron) and hole 2 are open, the calibration arm is at hole 4 (high-res).
Right: hole 3 (med-res) and hole 4 are open, the arm is at hole 1.
The small dark holes are the apertures to the fibers, and are 1.3 arcsec and 2.5 arcsec diameter for the 100 and 200-micron fibers respectively. The goal of target acquisition is to get the star on one of the fiber apertures. The images above were taken with the dome lights on, such that it is possible to see the calibration arm.


Target acquisition: a 100x100 pixel StanCam (camera-probe-fies) window around hole 1 (low-res fiber, 2.5 arcsec aperture diameter), with the star 5 arcsec away from the aperture (left) and almost centered on the fiber (right).

Essential info for target acquisition

  • Approximate positions of the fibers on the StanCam CCD:
    Fiber positions for camera-probe-fies
    fiberCCD X-posCCD Y-pos
    1 low-res 496147
    2 med-res 479318
    3 med-res 491489
    4 high-res524656
    Fiber positions for camera-probe-stancam
    fiberCCD X-posCCD Y-pos
    1 low-res 4401020
    2 med-res 410790
    3 med-res 430580
    4 high-res470330

  • Image scale on StanCam with camera-probe-stancam: ~0.18 arcsec/pixel
  • Image scale on StanCam with camera-probe-fies: ~0.24 arcsec/pixel
  • Approximate telescope focus with camera-probe-fies : 22720
  • Approximate guide-tv focus with camera-probe-fies: 550
  • Approximate FOV diameter of holes in fiber mask: 20 arcsec
  • Approximate diameter of hole in mirror of the low-res fiber: 2.5 arcsec
  • Approximate diameter of holes in mirrors of the med- and high-res fibers: 1.3 arcsec

  • Field orientation for 'field-rot = 0' on the StanCam movie with camera-probe-fies:
    Field orientation


    S


    W
    E


    N

  • Step sizes between fibers for camera-probe-fies:
    Teloffset between fiber positions for camera-probe-fies
    DirectionCommand
    from fiber #1 to #3 stancam.teloffset 2 83
    from fiber #1 to #4 stancam.teloffset-6 123
    from fiber #3 to #1 stancam.teloffset-2 -83
    from fiber #3 to #4 stancam.teloffset-8 40
    from fiber #4 to #1 stancam.teloffset 6-123
    from fiber #4 to #3 stancam.teloffset 8 -40


Acquisition hints

  1. To setup the telescope for FIES run the following script after switching on the telescope power, or after using other instruments for science exposures:
    [obs@tessa][STANCAM]$   setup-tel-fies

  2. Note that these commands are already done as part of the script setup-tel-fies .
    Set the default focus for FIES, put in the blue STANCAM filter, and set the default rotator angle
    [obs@tessa][STANCAM]$   focus-position 22720
    [obs@tessa][STANCAM]$   ccd-filter 2
    [obs@tessa][STANCAM]$   field-rotation 0
    You have to use either a BVR or the Clear filter (filter positions 2, 3, 4, 8): else the fiber entrance will not be in focus on StanCam.

  3. If using the the ADC, make sure the ADC is in the beam and the corresponding focus offset is applied. See above for instructions.

  4. Slew the telescope to a target, and start guiding.
     
    For programs that require an accurate radial-velocity zero-point (planet-host RVs, etc.) we advise to make minimal use of the telescope rotator.
    In this case the telescope pointing should be achieved with
    [obs@tessa][STANCAM]$   guide-object-with-parallactic MyObject
    This implies that the StanCam acquisition image will not have North=Up, but this can be forced by using stancam.wcs-align command after the image has been displayed on the postprocessing DS9.
     
    For programs that do not require accurate radial-velocities, the telescope can be pointed using
    [obs@tessa][STANCAM]$   guide-object MyObject
    which will bring North=Up on the StanCam acquisition image.


    The commands of steps 5-9 below are grouped together in the script stancam.acquisition.

  5. Setup the fiber mask and calibration arm for observing with fiber number N (= 1,2,3,4), and switch to STANCAM direct-imaging mode
    [obs@tessa][STANCAM]$   setup-fibN-star
    [obs@tessa][STANCAM]$   camera-probe-stancam
  6. Take a full frame image with StanCam (e.g. binned by 2). The image will be grossly out of focus, but that does not matter.
    [obs@tessa][STANCAM]$   autosave_on
    [obs@tessa][STANCAM]$   resetxy
    [obs@tessa][STANCAM]$   bin 2
    [obs@tessa][STANCAM]$   exp 0.1   (or longer for faint stars)
  7. Move the star close to the projected X,Y coords of the fiber of choice (see top of this page), using the fiboff routine:
    [obs@tessa][STANCAM]$   fiboff N
    where N is 1,2,3,4.   This uses the postprocessing DS9 display; please follow the instructions in the Sequencer terminal to tweak the telescope position. After the telescope moved, press 'q' in the postprocessing DS9 window to stop the fiboff routine.

  8. Switch to fiber-viewing, and switch on STANCAM 'movie mode'
    [obs@tessa][STANCAM]$   camera-probe-fies
    [obs@tessa][STANCAM]$   fibNmovie exptime hicut
    where N is 1,2,3,4, exptime∼0.5, and hicut∼500
    You can tune the color cuts while the movie is ongoing, using the Sequencer commands hicut, locut, and zscale. Note that at any time you can restart a movie, for instance to reset the exposure time, using the fibNmovie or fork-fibNmovie commands; any ongoing movie will be safely killed automatically by these commands.

    • in case Fiber Guiding is not activated,
      use the orange guide-probe offset keys to move the star onto the dark spot (= fiber).

      The star can be held centered on the fiber with or without TCS autoguiding being on.
      In both cases, the telescope will be offset to center the star. If autoguiding is on, the guideprobe will be used to improve the precision of the offset.
      The window with the orange buttons also has an information field and two buttons ("AG on" and "AG off") apart of the arrow buttons.
      Messages to the user are shown in the information field.
      When the "AG on" is pressed, the TCS autoguiding is turned on. Similar, when the "AG off" button is pressed, the TCS autoguiding is turned off. When the autoguiding has been found to be turned off, a orange message in the information field saying that "autoguiding is off" will be blinking. Every time a button has been pressed and the TCS is busy executing the requested action, a message saying "=== Wait ===" will appear in the information field.

    • in case Fiber Guiding is active, the FibGuider will pull the star onto the fiber.
       
      Check that the green cross is properly pointing at the center of the fiber, and if it is not then use the command stancam.fibpos-man fiberNr to interactively reposition the guiding hotspot, i.e. the green cross.

If you have to start at step 1 then the whole process can take about 10 minutes. Experienced users will manage to do target acquisition in less than 3 minutes.


Making target and calibration exposures: short guidelines

When you have centered the target on the fiber, and have autoguiding switched on, you can either expose on the target or take calibration frames.
To make on-target exposures:

[obs@verushka][FIES]$   object "my favourite object"
[obs@verushka][FIES]$   exp 1200   (for example)


Calibrating the science fibers

The special SEQUENCER script called fies-calibs can be used to automatically obtain a full set of calibration images in the afternoon and in the morning.

At night, the SEQUENCER scripts setup-fibN-halo, setup-fibN-thar, and easyhalo, easythar can be used to simplify the calibrations. Below are some basic commands to make calibration images.

  • Halogen flat:
    • setup-fibN-halo   (where N stands for 1, 2, 3, or 4)
    • object Halogen
    • expose X               (where X stands for the number of exposure seconds)
    • lamp 6 off
    or
    • setup-fibN-halo   (where N stands for 1, 2, 3, or 4)
    • easyhalo
    • lamp 6 off

  • ThAr calibration:
    • setup-fibN-thar   (where N stands for 1, 2, 3, or 4)
    • object ThAr
    • expose X
    • lamp 7 off
    or
    • setup-fibN-thar   (where N stands for 1, 2, 3, or 4)
    • easythar
    • lamp 7 off

  • Change back to on-sky observing:
    • setup-fibN-star   (where N stands for 1, 2, 3, or 4)

A table of typical exposure times for the calibration frames can be found here.


Simultaneous-ThAr mode: science exposures and calibrations

As the distance between echellograms of the target and the ThAr lamp is only 9 pixels, some ThAr light will scatter onto the target spectrum. This is particularly evident in spectra of faint stars. Affected spectral regions may have to be avoided in the analysis of the spectra.

For this mode there is a special SEQUENCER script called simulthar to automatically allow some ThAr light into fiber #5 during a science exposure, at fixed intervals.

The special SEQUENCER script called fies-calibs can be used to automatically obtain a full set of calibration images, including a minimal set of 1 ThAr and 1 halogen both through fiber #5.
Alternatively, the SEQUENCER scripts setup-fib5-halo, setup-fib5-thar can be used to simplify the calibrations.

Required calibration: to trace the ThAr spectrum you need a separate flatfield exposure with fiber #5.

  • Halogen flat:
    • setup-fib5-halo
    • easyhalo
    • lamp 1 off

Required calibration: to calibrate the wavelength offset between the science fiber and the calibration fiber #5 you need an exposure with both ThAr lamps directly after eachother (e.g. in the afternoon).

  • ThAr calibration:
    • setup-fib5-thar
    • easythar
    • setup-fibN-thar   (where N stands for 3 or 4)
    • easythar
    • lamp 4 off
    • lamp 7 off

A table of typical exposure times for the calibration frames can be found here.


Simultaneous-sky mode

Note that we do not yet have much experience with the reduction of data obtained in this mode. The distance between the target and sky echellogram orders is 9 pixels. Due to the fact that the inter-order distance decreases towards the red, the sky and target spectra of neighbouring orders will get too close for comfortable reduction redwards from 6300Å.

To observe in this mode the target should be centered on fiber 3, while the fiber mask needs to be positioned such that both fiber 3 and 2 are opened. This is achieved with:

    • setup-fib23-star

For calibrations we advise to calibrate fibers 2 and 3 separately, as described above.


Using the exposure meter

Since fall 2008, FIES is equiped with an exposure meter that can be used to monitor the count rates during an ongoing exposure. The exposure meter picks off light inside the spectrograph that otherwise would have fallen outside the bottom of the CCD. As the red orders are longer than the blue orders, and hence more red light is falling off the CCD, the exposure meter is more sensitive for red stars than for blue stars.

Use the FIES exposure-meter count calculator (EMCC) to find out what is the exposure-meter count value that corresponds to the required peak S/N in the FIES spectrum of your star.
The dark current of the exposure meter is on the order of 150 counts per second, and has not been accounted for in the exposure-meter count calculator.

The most useful Sequencer commands to operate the exposure meter are the exposure command 'exp-count', and the counter commands 'expmcount' and 'expmstopcount'. For example, to expose an M star to reach CCD counts peaking at approximately 32000 ADU, which corresponds to a peak S/N=sqrt(32000*0.7*4)=300, the EMCC tells you that 50 million exposure-meter counts are needed. Then use the command

[obs@verushka][FIES]$   exp-count 50000000 1800

which will readout when the exposure meter has reached 50,000,000 counts or when 1800 seconds exposure time have elapsed.
Above the expected S/N per extracted spectral bin is computed as S/N=sqrt(peak-ccd-counts * ccd-gain * profile-width), with the profile width 7 pixels for the low-res fiber and 4 pixels for the other fibers. See the FIES EMCC.

The exposure meter counts and count rates can be monitored graphically on a separate page of the FIESTA window.

Unfortunately the exposure meter cannot yet be used with the simultaneous ThAr mode.

End of the night

Overview of things to do at the end of the night

  • In case of an ALFOSC override:
    • Switch to ALFOSC. In the ALFOSC Sequencer window, run the script
         
      [obs@tessa][ALFOSC]$ tcs.setup-tel-alfosc

    • Run any sky-flat and/or calibration scripts that are required by the override program            

  • Close the dome, and power-off the telescope following the procedure in the Cookbook
  • Kill any ongoing StanCam movie
    [obs@tessa][STANCAM]$ stopmovie
  • Switch off all FIES calibration lamps:
    [obs@verushka][FIES]$ lamp 1 off
    [obs@verushka][FIES]$ lamp 4 off
    [obs@verushka][FIES]$ lamp 6 off
    [obs@verushka][FIES]$ lamp 7 off
  • Run the fies-calibs script in the FIES Sequencer, and possibly take more calibration frames.
  • Fill out the EON and/or EOR reports
  • If convenient, please close down the FIES/STANCAM observing system. Open a new terminal window, and do
    [obs@tessa]$ ssh verushka
    [obs@verushka]$ shutdownobssys fies

Closing Down Procedure

Closing the telescope

  1. Before obtaining morning flats fields, turn the guide TV off by typing tv-off on the TCS.
  2. Put the telescope to zenith by pressing the key Start/Stop and then Zenith (0). This will park the guide probe and it also sets rot-man. Wait for Rotator -90°.
  3. Park the building by pressing key 4, Park Building. This process can take up to 8 minutes. Building will stop at Az ≈ 119°, Alt ≈ 90°.
  4. Close the mirror covers by pressing key 3, Close Mirror Covers. This takes 42 seconds.
  5. Close the lower hatch by pressing key 2, Close Lower Hatch. This takes about 3 minutes.
  6. Close the upper hatch by pressing key 1, Close Upper Hatch. This takes about 5 minutes. If timeout occurs or hatch does not move, see TCS Manual p. 43.
    NB: When the upper hatch has closed the dome cooling will start and the staircase cooling will stop.
  7. Close all 4 side-ports in the dome. Please, do not use violence. If the ports are stuck, use the handle to lift them before closing.
  8. Power down the telescope. After all of the above have been completed, type power-off on the TCS, then type sh 1 to display the telescope power units. Wait until all the telescope power displays show "off".
  9. Turn down the TCS screen brightness. Use the knob on the right-hand side of the TCS monitor, near the power switch. Never turn the TCS monitor off.
  10. Turn off monitors. Turn off the two autoguider monitors and dome TV camera monitor.
  11. Turn on the control room webcam and the dome webcams. Make sure that the webcams in the control room as well as in the dome are turned on before you leave.
  12. Have a look in the dome at hatches and telescope, to check for any faults that might have occurred.
  13. Complete the WWW report forms. Fill in and submit Internet NOT End-of-Night Report. Be sure to include any faults that occurred and submit a fault report, so we can attend to problems promptly. If it is the last night of the observing run, also fill in and submit Internet NOT End-of-Run Report.
  14. Lockup the dome. Lock the outer dome door when you leave the building.
  15. Clean up the kitchen/lounge area in the service building and switch off all lights when you leave.
  16. Lockup the outer door in the service building before leaving for the Residencia.

Data saving and retrieval

As of 2005 all data acquired using ALFOSC, NOTCAM, STANCAM, MOSCA, and FIES is written to DVD every morning by staff. It is the duty of either the allocated support astronomer or duty technician to put the data on DVD. No one other than the above personnel may use the DVD burners in the NOT service building. DVDs for visiting observers will be placed in the visitors mailbox in the NOT service building.

One copy of each night's data of a run will be made for the visiting observer, free of charge. Each DVD holds a maximum of 4.7 Gbyte of data, generally one DVD is used per night. One copy of each night's data will additionally be made for the NOT archive. Observers requiring access to data from the NOT archive should contact NOT staff for details of the required procedure. General information on NOT FITS-headers can be found here.

Accessing raw and reduced data at night

The computer called florence is setup for you to make a quicklook analysis of the incoming data, e.g. using IRAF. For the different instruments we have on-line reduction programs running, that deposit the reduced products on a disk accessible through florence.
The raw and reduced data files can be found on florence under directories
  /data/<instrument-name>/
  /data/reduced/<instrument-name>/

To copy the new data products over wifi to your own mobile computer, while in the NOT control room, use for example
  scp guest@florence:/data/fies/FI\*0001.fits .
  scp guest@florence:/data/reduced/fies/auto/FI\*0001.fits .
  scp guest@florence:/data/alfosc/AL\*0001.fits .
  scp guest@florence:/data/reduced/alfosc/sAL\*0001.fits .
  scp guest@florence:/data/notcam/NC\*0001.fits .
  scp guest@florence:/data/reduced/notcam/sNC\*0001.fits .
on your own mobile computer.

Archival requests

To obtain NOT data from our archive, first compile a list of file names of the calibration and science data to be retrieved, using our FITS archive. Note that this archive does not show the data obtained in the latest twelve months, due to the propriatary period.
Then please contact staff and send the list of file names to be retrieved, such that we can locate the data in our archive and make them available through FTP.

Compensation for override observations

If your program was interrupted by a Target-of-Opportunity or another override observing program, you are entitled to payback time. Such compensation for time lost during your allocated observing run (whether in visitor or service mode), is claimed back through the submission of Observing Blocks (OBs) using our OB Generator. The observations will be executed accordingly in service mode by staff during Nordice Service nights, and you will be informed by email when observations are made and where to retrieve the data.

Using the OB generator to claim payback time

Access the Observing Block Generator and login to your account, or if you are a new user, please register. When you are logged in, add your proposal for which you claim compensation time. There are help buttons at every level of the OB generator, and you can also get support and give feedback through obsupport@not.iac.es. If you have questions about how to define OBs and/or Observing Sequences, please contact service@not.iac.es.

For your OBs to be carried out as compensation for time lost to overrides, please make sure to select OB Group type "Payback".

Troubleshooting

If you have ...

  • ... cannot reset the safety system:
  • ... no light on the CCD -- check:
    • Dome open, mirror cover open
    • Lower hatch not obstructing at low altitude
    • Guide probe out of light path
    • Camera probe in correct position
    • FASU shutter open (if using ALFOSC)
    • Correct filter in instrument
    • Correct telescope focus
    • If it is cloudy
    • Check all the above again. If there still is a problem, then phone duty staff.
    • If MOSCA or StanCam image has a count level of 0, this can actually mean saturation and you should reduce the amount of light falling on the detector.
    • StanCam shutter controller has power (if using StanCam)
  • ... wrong field on CCD -- check:
    • Coordinates of field
    • Epoch of coordinates
    • No typos in entering coordinates in TCS
    • Field rotation is correct
  • ... no guide star on guide probe screen -- check:
    • Dome open, mirror cover open
    • Guide probe in correct position
    • Field and rotator angle
    • TV switched on
    • TV filter open
    • TV focus correct
    • Try typing in the X and Y values of another Guide Star fromthe The 10 brightest currently available Guide Stars
    • If it is cloudy
  • ... lost tracking/guiding:
    • How close to the zenith are you? (Good guiding and tracking is guaranteed only 5 degrees or more from zenith).
  • ... changing tv filter does not work:
    • at TCS type in the command 'Initialize-TV-Filter'.
  • ... ctrl x', 'ctrl g', 'ctrl t' and 'ctrl v' commands on the TCS give incorrect functionality, e.g. telescope offset rather than star box movement.
    • wrong function key menu on the TCS keyboard press keypad key 5.
  • ... "building crash":
  • ... other TCS problems
    • Press the keypad key labelled Log and then keypad 2 to see the latest entries in the TCS log.
  • ... acquisition: slitoff/fiboff unresponsive
    • Using the mouse to set the contrast while image is loading?
      Using the mouse to set the contrast while this process takes place can cause DS9 to crash. Best procedure is to wait tuning the contrast level until the image has been fully loaded into DS9, and zoom / contrast levels set.
      A DS9 crash while in 'imexam' while leave the postprocessing system in a non-workable state.
      Rather than shutting down the whole observing system to recover, it is in most cases sufficient to run the sequencer command 'killimexam'.
      See also next item.
  • ... ds9 shutting down while doing acquisition
    • Using the mouse to set the contrast while image is loading?
      Using the mouse to set the contrast while this process takes place can cause DS9 to crash. Best procedure is to wait tuning the contrast level until the image has been fully loaded into DS9, and zoom / contrast levels set.
      A DS9 crash while in 'imexam' while leave the postprocessing system in a non-workable state. Rather than shutting down the whole observing system to recover, it is in most cases sufficient to run the sequencer command 'killimexam'.
  • ... "sequencer/obssys" does not respond or behaves badly:
    • Standard procedure in such circumstances is to restart the observing system using 'shutdownobssys' (from a terminal window) followed by 'startobssys'.
  • ... lisa frozen, not responding, e.g. can not log out using the foot icon
    • if you have a working terminal, try "$ killall panel", wait until the panel restarts and then logout as usual
    • if there's no terminal available, you can use florence to ssh as obs into the observing computer you've been using, and type the killall command.
    • if you have no terminal available, etc. press the "Ctrl" and "Alt" keys and then press "Backspace". That will kill the X server and force a logout

If you encounter a fault or a problem with the instrument, the computers or the telescopeduring the night, then fill in a Fault Report.

Trouble shooting the FIES/STANCAM system

Problem: Guide star obscured for STANCAM direct image (camera-probe-stancam)
Problem:
Commands to FIES BIAS hang
Problem:
STANCAM direct image seems vignetted
Problem:
No light from Top Halogen/Thar on FIES images
Problem:
No starlight on FIES images but FIESTA indicates that all is OK
More
known problems...

Appendix

Tables for Instrument Settings

instrument field-rot i-p-a camera probe foc-pos tv-foc orientation c-w-h
ALFOSC +90 0 (horizontal slits)±90 (vertical slits) c-p-p 22400 480 North ↑ East ← Horizontal slits: E-W (P.A. = ±90) 0.75
FIES 0 N/A c-p-s 22720 530 North ↓ East ← N/A
NOTCam -90 -90 c-p-p 22560 495 North → East ↑ 0.95
MOSCA -90 N/A c-p-p 22210 450 North ↑ East ← 0.55
StanCam 0 N/A c-p-c 22150 430 North ↑ East ← N/A
SOFIN 0 -90 c-p-p 22600 520 N/A 0.9
TurPol 0 N/A c-p-p 24300 650 North ↑ East → 0.12

Table 1a shows the values of the: field rotation(field-r), instrument-parallactic-angle (i-p-a), ccd probe, focusposition (foc-pos), TV focus (tv-foc), field orientation andcounter weight height (c-w-h) for the different instruments. On the TCS, type thecommand followed by the value, for instance field-r -90. The default focus value stated for NOTCam is for the K band in imaging mode using the WF camera (internal camera focus of 5650).

From To foc-delta
ALFOSC no filter StanCam R-filter (#10) -260
MOSCA R-filter (#106) StanCam R-filter (#10) -155
NOTCam Ks-filter (WF) StanCam R-filter (#10) -380

Table 1b shows the default focus offsets between the instruments.


Commonly Used Instrument Commands

Command Comments
CNTR-C kill ongoing command or script
abort kill ongoing exposure

object text Sets the value of the FITS keyword OBJECT to text
autosave_on Turns on autosave. For off, type autosave_off
rempath link Sets the remote saving path to specified link
remsave_on Turns on remote saving. For off, type remsave_off
bin n Sets the binning factor in both X and Y directions to n
xbeg n Sets the X beginning to n (use ybeg for y).
xsize n Sets the X size to n (use ysize for y).
expose t Makes an exposure of t seconds. To abort the exposure press Ctrl-C and type abort in the sequencer window.
mexpose t n Makes n exposures of t seconds
dark t Makes an dark exposure of t seconds
mdark t n Makes n dark exposure of t seconds
teloffset n m Offsets the telescope in the CCD X,Y direction by the amount n in the X direction and m in the Y direction. n and m are given in arcseconds.
resetxy Resets the CCD to unbinned full-size readout
For more commands, view the Sequencer Reference Manual.

Command Comments
fies.fies-calibs takes full set of calibration files (use in afternoon/morning)
fies.setup-fib?-star sets up the arm and mask for a stellar spectrum
fies.setup-fib?-thar sets up the calibration unit for a ThAr spectrum
fies.easythar takes a ThAr spectrum of appropriate line strength
fies.simulthar takes a stellar spectrum with simultaneous ThAr
fies.exp-count takes a stellar spectrum, while using the exposure meter
stancam.acquisition start target-acquisition sequence
stancam.fib?movie start the StanCam movie
stancam.stopmovie stops the movie
stancam.hicut adjust the colour cut on the DS9 display
For detailed info on the invocation of these commands see the FIES Sequencer Reference .

Commonly Used TCS Commands

Command Comments
ag-on Turns autoguiding on
ag-off Turns autoguiding off
auto-positioning-full Turns the guide star auto positioning to full-automatic
auto-positioning-retry Try again to bring the guide star in the guide box
camera-probe-stancam
camera-probe-ccd
Moves the camera probe to ccd position (for StanCam)
camera-probe-park Moves the camera probe to park position (for ALFOSC)
camera-probe-fies
camera-probe-split
Moves the camera probe to split position (for FIES)
field-rotation fieldangle Sets the field rotation to fieldangle
focus-position n Moves the telescope to focus position n
focus-delta n Applies a focus offset to the current telescope focus
instrument-parallactic-angle n Defines the parallactic angle for following presets
read-catalogue name.cat Reads the catalogue
tv-on Turns on the guide TV
tv-filter name Selects the guide TV filter where name can be either closed, grey, open, red, yellow or blue
tv-foc pos Changes the guide TV focus to position pos


append-object string appends an object to the TCS catalog
goto-object Object moves telescope to "Object"
find-object selects an object in the TCS catalog
preset-with-parallactic-angle-to-selected moves telescope to the selected object, with parallactic angle
For more commands, view the TCS SEQUENCER Command Reference.


Tracking of Moving Targets

At the NOT there are two main modes of tracking a moving object (planet, comet, asteroid, satellite): 1) differential tracking with auto-guiding and 2) differential tracking without auto-guiding. Which of these to use, depends in practice on the target speed.

Differential tracking with auto-guiding

In this mode, the telescope tracking is set to the differential rates, and in addition, the auto-guider is used with the star-box set in motion with the same rates. This works for as long as the box stays within the auto-guider TV-screen (approximately 70" field). When the limit is reached, auto-guiding is no longer working. It is possible to reposition the star-box without affecting the telescope tracking, but there is a limit to how many times this can be done before reaching the limit of the available guide probe area. This depends on the RA/DEC rates, the field-rotator angle, and the initial location of the guide star inside the guide probe area.

If your target moves less than 70" over the execution time of your observations, you can safely use this approach. If not, you need to keep an eye on the star-box and (for the time being) manually re-position it by typing a command (see point 7).

Both the telescope tracking rate and the box-motion rate are given in RA/DEC coordinates, i.e. dDEC/dt and dRA/dt (in arcsec per hour), and the cos(DEC) correction is taken care of internally by the TCS. (In other words, if your RA-rate is given as dRA*cos(DEC), you have to divide by cos(DEC) before entering its value.)

  1. Calculate your object's coordinate motion in RA and DEC rates in advance (rates are in arcseconds per hour).
  2. Preset to your object, wait until guiding and then switch off guiding:
    tcs.ag-off
  3. Start the differential tracking of the telescope to the RA/DEC rates:
    tcs.set-rate RA-rate DEC-rate
  4. Position the star box in the optimal position for the longest possible uninterrupted differential guiding at the current pointing, with the current field angle and for the RA/DEC rates:
    tcs.optimal-box-position RA-rate DEC-rate
  5. Start box motion with the correct RA/DEC rates:
    tcs.box-motion-start RA-rate DEC-rate
  6. Move the guide probe to put the guide star in the box:
    tcs.tcs-command "Move-Guide-Probe-To-Put-Star-In-Box"

    or on the TCS UIF simply mo-g
    Wait until the star catches up with the moving box and the telescope is actually guiding before starting exposures.
  7. If this is a relatively fast target, i.e. moving more than 70" during the time your observations take, you will have to make sure that the star box does not reach the other edge of the TV screen, in which case it will stop guiding. Before it does, you can run the script:

    tcs.reposition-guide-probe RA-rate DEC-rate

    in another sequencer window, while observing, or in between exposures, to reposition the box and the guide probe without affecting the telescope tracking.
  8. Stop differential guiding by tcs.box-motion-stop (or in short on the TCS UIF b-m-sto).

    NB! Note that this does not reset the telescope set-rate and if you wish to stop the differential tracking, as well, then do tcs.set-rate 0 0. This is done at every new telescope preset.

Tracking without auto-guiding. Rapidly Moving Targets

For more rapidly moving targets, use the set-rate command on the TCS to continuously move the telescope from a pre-calculated change in position. RA-rate and DEC-rate as above. In this mode auto-guiding is not used.

  1. Preset to your object.
  2. Set the rate of change by set-rate RA-rate DEC-rate (rate in arcsec per hour). The maximum rate is 60,000 arcsec/hour (≈ 17 arcsec/s).
  3. Make the exposure.
  4. Reset by typing set-rate 0 0 on the TCS.

For Experts Only

If the target has an unknown or rapidly changing motion, you might want to adjust the rate of change in RA and DEC while tracking. Use the set-rate command on the TCS and use command recall with the up/down keys and edit the set-rate.

  1. Preset to object.
  2. Guess the starting set-rate RA-rate DEC-rate values.
  3. Do as described above with command recall.
  4. Do set-rate 0 0 or just preset to another object.

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