INT-IDS Operation Manual

Introduction

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1. The system prompts will appear in the text as typewriter fonts, in the following format:

   USER> Commands to TCS (grey window on the Telescope Control System)

   SYS> Commands to ICS (pink window on the Instrument Control System)  

   ecl> IRAF commands on INTDRPC1

   $> Any other terminal window eg: xgterm

   Typewriter text indicates that the command exactly as it written in this page should be used. For variable input, curly braces will be used, e.g. {your_input}. Hence, in this web page it will be written:

     SYS> arc {time}

   to take an arc of {time} seconds exposure time. So, for taking an arc of 10 seconds, at the ICS prompt you should type:

     SYS> arc 10

2. Words in green correspond to actual buttons to be pressed.


3. Words as hyperlinks go to corresponding pictures or web pages with further details.

Safety

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1. Before starting to work at the INT telescope it is essential that you carefully read the Safety Information. Please also print, read thoroughly and sign the page of Safety checklist for INT visiting astronomers. If you need more information ask your Support Astronomer (SA). To be able to work at INT, all the visitor astronomers that will be at INT for the run must agree to all the items by signing the page. After sign please hand the document to your SA. Note that ALL the observers that will be at the INT for the run should sign this page.

2. You MUST always follow the instructions given to you by your SA or the WHT Telescope Operator (TO) (e.g. abandoning site in bad weather or regarding the operation of the telescope and instrument).

3. Please use a lone worker alarm when you are alone at the INT. Your SA will explain you how it works on the first night of your run. It can be found on the back wall of the control room (see here). The lone worker alarm should never be taken away from INT building. In case of a real emergency, press simultaneously both orange buttons on the side (until you hear the beeping), it will call the Incident Officer who will immediately try to contact you.

4. Please do not use the elevator outside the Operations Team working hours (9:00-15:30 hrs) nor on weekends. For safety reasons there is a laser curtain installed in the elevator that will stop it if the light path is broken by a person or object. If this happens you may be stuck in the elevator. If for any reasons you will need to use regularly the elevator during your run please inform this to your SA.
   

Troubleshooting

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1. A Troubleshooting Guide is available with instructions to solve known problems or situations that may can occur at INT while observing with IDS.


2. Several faults (and their solution) that occurred in the past are described in the Fault Database. Login as guest to search for previous fault reports. Call to the WHT OSA for advice (int 452) about possible ways to solve the problem. Please use this database to log any faults you encounter. See the section Reporting/Searching faults at ING Fault Management System for more information.


3. In case of problems that you cannot resolve easily by yourself:
   • On the first night of your run your INT SA will be available anytime by telephone. Before leaving the INT, your SA will inform you the room number from the Residencia and a mobile to contact him/her.
   • On subsequent nights, or if you cannot contact your SA, call the WHT OSA  (white phone 2559 or grey phone 452) who will try to assist you as much as possible. Note that the WHT OSA might be busy at the WHT and may not to be able to visit the INT directly to solve problem or you may have to wait for a while.

Areas of the Telescope

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1. The Engineering Rack:
   • Manual telescope movement control
   • Remote dome movement
   • Dome sutthers operation
   • Open/close mirror cover
   • On/off dome fans
   
   
2. The Engineering Console:
   • Dome lights
   • Emergency Stop and reset buttons
   • Computer/Engineering mode switch
   • Engineering indicator button lights
   • TV showing the dome inside
   • Speakers for dome inside sounds (check the volume).
   
   
3. The Meteorological Data Screen


2. The Whiteboard with important/useful information


3. The main desk with the following computers (from left to right):
   • The TCS (Telescope Control System) and slit-viewing acquisition camera computer (inttv): one screen and a keyboard
   • The ICS (Instrument Control System) computer (lpss7): two screens and a keyboard
   • The Data Reduction PC (INTDRPC1): one screen and a keyboard

Preliminaries

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1. In the control room, every day, check the Operations Logbook (usually on top of the main desk) for any restrictions that may be still in force.


2. In the upper-left corner of the Operations Logbook, write the names of ALL observers who will be at the telescope at night. This should be repeated for every night.


3. Turn on the dome lights (MAIN ON/OFF) from the Engineering Console and raise the control room blind.


4. Go inside the dome and make a mindful visual inspection of the observing floor to check that the telescope is free to move e.g. no ladders or steps are close to the telescope, test instruments connected, etc.


5. Clear any emergency overrides by pressing the RESET button next to the EMERGENCY STOP button on the Engineering Console.


6. Turn on OIL PUMP from the Engineering Rack.
   
   IMPORTANT! The oil pump MUST be switched OFF at the end of the night or when the telescope will not be moved for more than an hour (e.g. if the dome had to be closed due to bad weather).
   
   A few seconds after the oil pump is turned off an alarm will sound. This alarm should be cleared by hitting the ACCEPT button on the Engineering Console.


7. Before starting observations check in the INT Cass Mimic window, that you have the correct IDS configuration: central wavelength, slit width, grating camera shutter open, no ND filter, etc. Also check in the detector window, that correct detector configuration is set: binning, read out speed and window.
   

Filling the IDS cryostat

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1. The telescope should be parked at Zenith.


2. On the dewar top, check that the SILVER valve (gas vent) is closed. Vessels must be left pressurised.


3. Use the indicator on top of the dewar (by pressing and holding the black rubber button) to check the dewar contains enough LN2 (>25%). If it is lower, the second dewar must be used. Please, in this case fill in a Fault Report.


4. Check the pressure valve on the top of the dewar. The pressure should be between 0.5 and 1.5 bar. If this is not the case, use the other dewar. Please, in this case fill in a Fault Report.


5. Slowly wheel the dewar over to the cryostat.
   
6. Connect the dewar to earth; use the earthing point on the Cassegrain rotator, located above and to the left of the cryostat. 
7. Fully insert the filler tube into the cryostat hole. Take care to hold it by the metallic tube and not the hose.
8. On the dewar top, check that the GREEN pressure build valve is CLOSED. Then fully OPEN the BLUE decant valve. Turn the valve back one half turn from fully open, to prevent the valve freezing in this position as will be difficult to close it later.  
9. Wait until liquid nitrogen is starting to leak out of the cryostat and spilling on to the floor.
10. CLOSE the BLUE valve.
11. Wait for the filler tube to warm up (until it is not rigid anymore) and remove it from the cryostat.
    
12. Move the dewar back to the position where you found it (out of the telescope way).
13. Write down in the Operations Logbook the time the cryostat was filled and your name.

Zerosetting the Encoder

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• Complete Zeroset

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  1. Ensure the telescope is in the zenith position.
  
  
  2. The HA and DEC dials should be correctly located, e.i. on the rear-side of the labeled arrows, so that it is possible to move the telescope through the zeroset position in the direction indicated by the arrows.
     
     If necessary, practise the action of moving the telescope through the zeroset position using the 'minus' button for HA and 'plus' button for DEC (the lights above the dials will flash). Make sure you return the dials to the correct position, ready for the zeroset, before continuing.

  3. In the TCS User window, enter:

      USER> zeroset ha target         [or: zero ha tar]

      USER> zeroset dec target        [or: zero dec tar]

     Note: These commands need to be typed one after the other in this order.

  4. Using first the HA[-] button with SLOW motion selected (both QM and SM buttons will be lit up when slow motion clamps are engaged), move the telescope so that the dial pointer move through the zeroset mark in HA. After that do the same pressing the DEC[+] button, also in SLOW motion. Ensure you zeroset the axes in the same order as the commands were typed in the TCS (in this example should be HA first and then DEC).

     NOTE: Normally, when the dials move through the zeroset positions the yellow led lights will flash and beep to acknowledge the position. Although, it might happens that the leds flash but the beep does not sound, in this case the procedure is still fine as soon as the TCS acknowledges that the zeroset was completed for both HA and DEC. On the contrary, if the leds DO NOT flash, then the entire zeroset procedure must be finished first and then repeated again. The complete Zeroset needs also to be respeated if, for any reason, the TCS does not acknowledge that the zeroset was completed for both HA and DEC, or if the TCS was re-started to solve a problem.
     

  5. To finish off the zerosetting procedure, the pointing model should be loaded, to do so in the TCS User window, after the zerozet was completed in both HA and DEC axis, type:
     
     

      USER>  calibrate default        [or: cal def]

     
     to set the default TCS pointing model.
     
     
  NOTE: Sometimes the DEC arrows in the engineering rack are not moving correctly. In this case, please follow the procedure described in the INT-IDS Troubleshooter (Problems zerosetting the DEC encoders section) for doing the Zeroset.
  
  

• Abbreviated Zeroset

  ---

  On subsequent nights of the observing run, and if the TCS has not been restarted, type:
  
  

   USER>  calibrate last        [or: cal last]

  to load the previous TCS pointing model.



Back to Top

Switching the TCS between Computer and Engineering Mode

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• To set the telescope into Computer Mode, turn the COMPUTER/ENGINEERING key on the Engineering Console the left (the COMPUTER position). The green section of the ENG/COMP push button switch should illuminate showing that Computer Mode has been selected. The system only switches to computer mode only if the following three conditions are fulfilled:
  • the OIL PUMP is on
  • Thre are active NO emergency override (press the RESET button close to the ENG/COMP button)
  • HA and DEC slow motion controls (SM) are active.
  
  If the telescope is in Computer Mode the TCS window will say Telescope STOPPED .



• To switch back to Engineering Mode, on the TCS type:
  
  USER> eng
  
  The ENG/COMP push button should return to yellow, showing that the TCS is in Engineering Mode. If the telescope is in Computer Mode the TCS window will say Telescope ENG .

Setting up the Acquisition Camera

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DAS6@miranda> bin 3 3

SYS> tvxy 498000 500000

Loading Catalogues

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      USER> out term 

      USER> erase 

[object] [ra] [dec] [epoch] [!comments]

sn1987a 05 35 27.9 -69 16 10.00 J2000 ! comment  

      your_laptop$ cd {directory_containing_catalogue}

      your_laptop$ scp {your_catalogue}.cat intguest@intdrpc1:/home/intguest/Desktop

      intguest@intdrpc1$ cd Desktop 

      intguest@intdrpc1$ scp {your_catalogue}.cat intobs@lpss7:/int/cat/

      USER> include {your_catalogue}   

      USER> source sn1987a 05 35 27.9 -69 16 10.00 J2000 

      USER> add

      USER> remove {object_name} 

      USER> out file {your_catalogue}  

Setting up CCD parameters

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In the ICS, check that the CCD readout speed, readout window and binning are the desired ones.

To set CCD readout speed (choices: slow or fast)

To set on-chip binning:

where the first number is the on-chip binning in the spatial direction and the second number is the on-chip binning in the dispersion direction. For example: SYS> bin 2 1 will bin x2 in the spatial direction and x1 in the dispersion direction.

To set readout window size (in pixels) from 785 to 1150 in the spatial direction, from 1 to 4200 (the whole CCD) in the dispersion direction. These values are independent of the binning set.

For further information on commands regarding the CCD, refer to the UltraDAS documentation.

Preparing for autoguiding

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Suitable guide stars can be found using a graphical user interface to the Guide Star Catalog. If the GSS2 interface is not already visible, open an xterm in the ICS machine and type:

Opening Up

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1. Check that the weather conditions allow for opening the dome:
   
   
   • Weather should be stable (for about the last 20 minutes before opening) with humidity lower than 90%
   • Wind below 80km/h
   • Local Mast sensor should be "DRY" (NO rain or wet)
   .
   In case of doubt call WHT OSA for advice.
   
2. Set the humidity alarm to 75%. If the humidity is higher than 75% then set the alarm to 90% and immediately close the dome if humidity rises higher than 90%.


3. Ride the lift down at least one floor and turn the lights off.


4. Open the south doors, latching them safely to the walls. South doors can be opened only if:
   
   • The humidity is below 75%
   • The wind speed is below 40km/h
   • The wind gusts are below 48km/h
   In case of doubt call WHT OSA for advice
   
   
5. Switch all dome lights off, as well as the lights in the far end of the control room.


6. Rotate the dome towards the East (in the direction of the doors to the lift) using the DOME ROTATION CW (clockwise) and CCW (counter clockwise) buttons found just right of the UPPER SHUTTER panel.


7. On the UPPER SHUTTER panel (located on lower engineering rack), use RAISE MICRO until the MAIN OVERTRAVEL light underneath turns off and you hear a 'clunk'. Then push RAISE MAIN until the shutter stops moving. To fully open the upper shutter push RAISE MICRO until the shutter stops moving again.


8. Push and hold the MIRROR COVER OPEN button. The light below the MIRROR COVER buttons will change from green (closed) to red (open) when finished.


9. Push the DOME VENT FAN ON button to enable dome ventilation. The red light will go OFF when the ventilator is on. If the humidity rises above 75%, the dome fans must be turned off.


10. Close the control room blind.

Single star calibrate of telescope pointing

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Since we only want to do a single star calibrate, we must break out of the HANDSET menu when it appears in the TCS window. To do this press <ctrl-z>

If the star appears directly on the green cross + (which marks the rotator centre), the pointing is fine and you can skip the rest of this section. Otherwise, you need to use the 'HANDSET'  button again to centre the star on the green cross +.

Neutral-density and order-sorting filters

 SYS> asnd {position} 

Focusing the telescope

Below are described the two possible procedures to determine the best telescope focus: i) Focus run using the script and ii) Manual focus run. In both cases it is necessary to point the telescope to a suitable star (V~9-11) at low airmass. You can select a target from the ING Spectrophotometric catalog.

Set the filter configuration to be used for the science exposures (the best telescope focus may change significantly for different filters).

Point the telescope to the selected star:

1. Call the script that acquires the images for the focus run:
   
   SYS> focusrun.py
   
   Four questions will be prompt in the screen to set the parameters for the script:
   
   
   • Question: what starting value would you like for the focus?
     Example of anwer: set a value 0.2mm below last known focus (see white board)
   
   
   • Question: what step size would you like for the focus?
     Example of answer: 0.05
     
     
   • How many steps do you need?
     Example of answer: 9
     (Note that this is actually the number of images that will be taken)
     
     
   • what exposure time (in s)
     Example of answer: 10
     
   
   After setting these parameters all the focus run images will be acquired.
   
   
2. In an IRAF terminal run the ids_starfocus script as follows:
   
   ecl> !ids_starfocus
   
   (note the use of the exclamation mark '!' at the beginning of this command)
   
   This script will prompt a short series of simple instructions in the screen to guide you to obtain the best telescope focus. Basically, the script will ask the first image run number (e.g. r1059172) and the number of images taken in the focus sequence. The first image will be displayed in ds9, then you should point the cursor in the continuum of the star, around the center of the image in the dispersion direction (y~2100 pix) and press 'g' to measure the spatial profile at that position. All images in the focusrun sequence will be displayed in turn and for each one a Gaussian fit will be performed and displayed. Once the images are measured, a window will open showing a plot of the measured values of FWHM versus the telescope focus and a parabolic fit. The best empirical and fitted telescope focus values will be printed in the IRAF terminal as well. Check these results and choose the appropriate focus value and close the plot window (you can save the plot if you want, the script will ask).


3. Once you have chosen the telescope focus set its value by typing
   
   SYS> focus {xx.xx}
   

ii) Manual focus run

1. Set the focus to a value 0.2 mm below the nominal focus value:
   
   SYS> focus {xx.xx}


2. Take a 10 second exposure labeled with the current focus position. Do not take exposures shorter than 8 seconds to avoid sampling the seeing variations:
   
   SYS> run 10 "focus {xx.xx}"


3. Display each image in IRAF:
   
   ecl> display r{run number}[1] 1; imexam
   
   Along the dispersion direction, choose a region around the middle of the detector and measure the FWHM of the spatial profile of the spectrum by placing the cursor over spectrum and pressing the 'j' key. Make sure to measure the FWHM of the same point in the spectrum by creating a region in the ds9 - this can be done by a simple left-click.
   


4. Keep incrementing the focus value and taking exposures incrementing the focus value by 0.1 mm (or 0.05mm if the seeing is good) and measuring the FWHM until you notice that the FWHM is clearly getting worse.


5. Once you have found the minimum FWHM, set the telescope focus to the value that gave the smallest FWHM.
   
   SYS> focus {xx.xx}
   

Observing

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Remember that the lower shutter starts vignetting at ZENITH DISTANCE >57 degrees (ELEVATION <33 degrees) - the system does not warn you! If you need to observe at ZENITH DISTANCE > 57 degrees, please follow the instructions described in Section 18.

talkerBellINT command

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Acquisition

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Ensure your target is included in the catalogue loaded in to the TCS (see Loading Catalogues section). To slew to your target type:

The telescope will point to that target in your catalogue. Note that spectrophotometric standards and other lists of bright stars are included by default  in the system catalogue. 

This moves CASS rotator mount to xx degrees, which corresponds to the position angle (PA) of the slit in the sky.

DO NOT try to move to a position angle between 138 and 142 degrees, as it will push the rotator out of its limits. Instead use angles from 318 to 322 degrees.


Press TV in the "SDSU Autoguider on AG0" grey window to start the continuous readout mode of the slit-viewing camera. You can adjust the exposure time for each frame in the top box - press RETURN to initiate the new exposure time.

Use the HANDSET mode (F6) to move the target on to the slit centre (red cross '+').

TV camera filters:

where 'x' is the filter position.

The numbers associated to each TV filter are listed in the following table:

0	Clear
1	Green (BG38)
2	Blue (BG28)
3	Red (RG630)

Hence,

will deploy the blue (BG28) filter (which is in position 2).

Orientation of the sky with Cass TV slit-viewing camera

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   sky PA = 0     sky PA=90       sky PA=180      sky PA=270


 
    ------> N     E <------               E       N      
   |                       |              ^       ^               
   |                       |              |       |
   |                       |              |       |
   V                       V              |       | 
   E                       N     N <------         ------> E

Acquisition of faint targets

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If the science target is too faint to be acquired directly into the slit, then a blind offset should be used.

The limiting magnitude for an effective acquisition is around V = 17 mag, for dark/grey sky brightness and bad seeing conditions (~ 2 arcsecs). If the seeing is good, it can be possible to go a little bit fainter.
Note that the acquisition of fainter targets is possible, but the longer exposure times (>60 secs) on the acquisition TV may not be efficient.

To acquire with a blind offset it is necessary to select a bright target as close as possible from the faint target and include it in the catalogue. To avoid loosing night time, it is highly recommended to have previously prepared the bright targets for blind-offset and have included them already in the catalogue. Nevertheless, if necessary, it can also be done on the fly using source and add commands.

For the blind-offset to work properly it is necessary that the coordinates of the science target and the bright target used for the blind-offset are from the same astrometric catalogue and that the proper motions of both targets are taken into account.

Note:

• Up to 8 arcminutes, the blind offset has proven to be extremely accurate.
• Further more, untill 15 arcminutes it still works well (within 0.5" shift).
• For more than 20 arcminutes, the difference becomes noticeable (the shift can be ~ 1-1.5") and is not recommended unless you will use a wide slit.

Most probably, if you require to use a blind-offset for acquisition, then you will guide during the exposure. Therefore, the procedure to acquire a target and start guiding using a blind offset is as follows:

1. To be able to start the Autoguider immediately after the blind offset, first you need to find a suitable guide star at the position of the faint target. To do so, proceed as follows:


• Point the telescope to the bright blind-offset target and set the PA of the science target:

SYS> gocat {catalog_blind-offset_target_name}
SYS> rotate sky {xxx}


• Acquire the blind-offset target as good as possible. That is, enter the HANDSET mode and centre the blind-offset target in the slit position you would like the science target to be.


• Search for a suitable guide star in the GSS2 interface, entering there the science target coordinates, the corresponding SkyPA and in the Aperture Offset for X and Y you should write the offsets made with the HANDSET to positioned the blind-offset target well in the slit and press SEARCH.


• Choose from the displayed list a suitable guide star and centre the autoguiding probe at its X/Y position:
  
  SYS> autoxy {xxxxxx} {yyyyyyy}
  
  
• Check now that the blind-offset target is still in the good position in the slit (otherwise fine-tune the position if necessary) and bring the faint science object into the slit with the command:
  
  USER> blind {catalog_science_target_name}

Note that you won't see the faint science object in the acquisition camera.


• Take an image of the field in the Autoguider and start guiding:
  
  SYS> field
  
  SYS> guide on star {xx}
  
  This will guide on the star marked as star {xx}, where xx is the number that appears in the Autoguider image after have taken the field.
  


• Once the guiding is stable (e.i. the x/y errors does not get lower anymore) proceed to take your science images. Usual guide x/y errors displayed in the TCSinfo are about ±0.1/±0.2 arcsec. Note that these numbers depend on the current conditions (e.i. the guide star, sky transparency, exposure time for the guiding, etc.) and are quote here only as a reference.

Guiding

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1. While the telescope is slewing to your science target (including the correct SkyPA), in the Guide Star Search Interface window (GSS2) enter the coordinates of the target.



2. Select INTCass from the Configuration menu.



3. Fill in the Rotator SkyPA box with the Mount PA shown on the TCS DISPLAY screen (not the parallactic angle).



4. Ensure that both X and Y aperture offset values are set to 0 (or to the respective X/Y HANDSET offsets if you have already acquired the target and moved it with the HANDSET) and click SEARCH.



5. The GSS2 Interface will now display a list of potential guide stars. Select a guide star ideally between 11-13th mag and highlight the X/Y position which automatically copies text and execute the following commands:
   
   SYS> autoxy xxxxxxx yyyyyyy
   
   This centres the autoguiding probe at the X/Y position xxxxxxx yyyyyyy. This is the position copied from the GSS2 in the previous step (to paste it just press mouse middle button).
   
   SYS> field
   
   This takes an image in the autoguider and searches for potential guide stars at this position (be aware that some detections can be hot pixels and not real stars!). Sometimes it might be necessary to change the exposure time in the autoguider to obtain a good signal for the autoguider to work properly.
   
   SYS> guide on star xx
   
   This will guide on the star marked as star xx, where xx is the number that appears in the Autoguider image after have taken the field.
   

Exposing

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Test exposures

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Calibration frames

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Sky flat exposures:

It is advisable to point the telescope to a blank field before taking sky flats. A print-out of blank fields can be found on the engineering console. If you are using a high resolution grating, you can begin taking sky flats before sunset. Sky flats for lower resolution gratings can commence shortly after sunset.

SYS> sky 10	Takes a 10 second sky flat. Aim for approximately 30,000 - 40,000 counts in any single exposure.
SYS> offset arc 10 10	Dither the telescope by 10 arcseconds in the x and y direction (this is recommended between each sky flat exposure). Note that offsets are all absolute with respect to 0,0 and not relative to the last offset position.

In general it is not recommended to use sky flats, because there are many absorption lines from the atmosphere. Tungsten lamp flats should be used instead, see below.

 USER> gocat {object_name}

 USER> diff_rates dRA dDec

 USER> next

 USER> diff_rates 0 0

         $> scp intguest@intdrpc1:/obsdata/inta/yyyymmdd/r{number}.fit /your/directory

         $> rsync -av intobs@intdrpc1:/obsdata/inta/yyyymmdd/ /your/directory

 SYS> compfilta {position} 

 SYS> compfiltb {position}