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Home > Astronomy > Jacobus Kapteyn Telescope > Basic Observing Guide

  1. Introduction
  2. Getting ready
  3. Observing
  4. Other stuff
  5. Before bed
  6. Trouble shooting


This document is a basic "need to know" guide for the 1-m Jacobus Kaypten Telescope and supplements the normal support provided. This guide was last updated July 10, 2003.

For more info see:

General JKT page
Command Dictionary
UltraDAS Manual
SITe1 Parameters
Observers Guide to the JKT and JAG-CCD Camera

Here are examples of the TCS, DAS, and ICS windows.

Systems prompts will appear in the text as type writer fonts, in the following format:

	USER>commands to TCS
	*USER>commands common to TCS and ICS   
	SYS>commands to ICS after startobssys
	TO>commands to ICS for Telescope Operator (identical to SYS)
	cl>IRAF commands 	
	GSS>Guide star server  
	$>any other window eg: xgterm

Getting Ready

Quick Startup

To startup the telescope in the afternoon:
  • Turn telescope power on (key).
  • Run oil pumps (green button).
  • Cancel alarms and reset (little red button "cancel", then little green button next to emergency stop).
  • Zeroset HA and Dec telescope axes.
  • Switch to Computer mode (turn key).
and you are now ready to go. This whole process is described in more details below:


The telescope is left by the engineering staff in a "ready to go" status. However, its always good to know how to turn the thing on/off. It's the best way to solve a problem.

Shutting down the Systems:

Follow this order...
  • In ICS (pink window: Observing System):
    could go to SUNMICROSYSTEMS prompt, but not needed.

  • In DAS (orange window: JKT Ultradas Terminal):
    could go to SUNMICROSYSTEMS prompt, but not needed.

  • TCS:


Starting the Systems:

Follow this order...
  • TCS:

    Open telnet to lpas1


    	PASSWD: sticker on monitor
    At next menu type START.

    This will bring back the Telescope status display and the USER> prompt

  • UltraDAS and ICS:

    If you are logged out, login to lpss10.

          USERNAME: jkt_obs
    	PASSWD: sticker on lpss10 monitor

    If Ultradas window (orange) and Observing System window (pink) are not present right click on background and select them from the menu.

    In orange window (JKT Ultradas Terminal):

    menu 1 (choose system, 4 at the moment).
    menu 2 (choose detector, SITe1 option 5).

    wait until finished then...

    In pink window (Observing System):

    menu 1 (choose system, 4 at the moment).
    menu 2 (choose detector, SITe1 option 5).
    tip: you may want to turn the screen saver off. In an open bit of the screen, press the right mouse button. Go to PREFERENCES, MISCELLANEOUS.
Other things that are good to do here:

	SYS>rspeed fast
set readout speed to "fast" (79 seconds, unwindowed & unbinned).

	SYS>zeroset mainfilt
zeroset the filter wheel


If the TCS is shut down the telescope needs to be told where it is on startup.
  • Turn telescope power on (key)
  • Run oil pumps (green button)
  • Cancel alarms and reset (little red button "cancel", then little green button next to emergency stop).
  • In engineering mode (press button)
Drive telescope as follows for ~3degrees (buttons).


Type in TCS window:

        USER>zeroset ha tar
        USER>zeroset dec tar
(tar is short for target).

Return to buttons

DEC- (until beep from TCS)
HA- (until beep from TCS)

Put telescope in computer mode (turn key).


The cryostat needs to be filled before you begin your observations, and before you leave for bed in the morning. If the weather interferes, and you leave early, please file a fault report to have the cryostat filled in the morning.


  1. Raise floor. Check everything is clear from edge and that all trip switches are correct (gate, ladder, sliding door) and that the emergency switch on the control is not in.
  2. Put on safety equipment
  3. Unzip black bag.
  4. Insert long thin pipe on the nitrogen tank into cryostat (all the way). It will stay in the cryostat due to a bend in the pipe.
  5. Connect earthing cable to earthing point on the side of the telescope.

Filling up.

  1. If valve 1 is open (running along pipe) close it. (gas to outside).
  2. Open valve 2 (liquid to gas).
  3. Open valve 3 (liquid to gas regulator).
  4. Open valve 4 (gas down tube to cryostat).

    Note: Use valve 3 (regulator) to keep gas pressure below 1bar. Cryostat is full when Nitrogen is pouring out the bottom, you can hear the spatter of liquid on the floor.

Stopping filling.

  1. Close valve 4 (no more gas to cryostat).
  2. Close valve 3 (regulator closed).
  3. Close valve 2 (no more liquid to gas).
  4. Open valve 1 to release gas pressure to outside (loud).

Don't forget to:

  1. Take out pipe, remove earthing cable.
  2. Wheel back nitrogen tank.
  3. Do black bag up
  4. Lower floor. (Until the top of ladder rail is level with the telescope mounting).
  5. Log the time of filling the cryostat in the Observing Log Book by the TCS.

Dome Seeing

The JKT has a dome seeing problem. To reduce the temperature difference between the mirror and the outside, open the door to the roof access and the door to the dome. This will create a through draft when the dome shutters are open. The best seeing (~0.7arcsec) can be obtained when the temp difference is less than 2 degrees.

There are also 4 dome fans under the observing floor that may be turned on to improve the dome seeing. The power switches are located on the wall of the control room (switch on the 4 green light indicators in manual mode).


  1. Open dome shutters (hold button down until backlit in green)
  2. Open mirror covers (press button once, check no sticking).


To take a bias, on the ICS (lpss10):

In "fast" this will take 79 seconds to readout

For more than one bias:

	SYS>multbias n
where n is the number you want.

(note: the engineering staff will take one bias during the afternoon checks, this will appear in the log).

Reducing the Readout time

To play sounds (eg to signal the end of a run) you can use the audioplay command. The audioplayer will automatically play sounds located in the /soft/audio_sounds directory. Eg. run 1800 "long exposure"; audioplay .

Viewing the Data

IRAF is the most commonly used task for manipulating data. This can be started as follows:
  1. Open an xgterm (or change to home dir $>cd in an existing xgterm). This can be done from any window with $>xgterm -sb & , or with the right mouse button PROGRAMS.XGTERM
  2. Start IRAF with
  3. Open an image viewer
    	cl>!ximtool &
  4. Change to the dir where the data is stored
    	cl>cd /obsdata/jkta/YYYYMMDD 
    	cl>cd /obsdata/jktb/YYYYMMDD
    There are two jkt data discs (a and b). A directory with todays date is automatically created in the form YYYYMMDD.
    will show what is in the directory, in the form:
    UltraDAS FITS files contain FITS image extensions. To display the image from IRAF, you need to specify the fits extension.
  6. Choose a file to display (look at the log if unsure what is what)
    	cl>disp r000001[1] 1
    This displays the image extension 1, which will be the whole image for a full frame readout
    	cl>disp r000001[2] 1
    This displays the image extension 2 (the second window of a multi-windowed readout)
    Open the ximtool control panel to zoom in/out, change colours/intensities etc.

To log out of IRAF:


More instructions for using IRAF to look at your data from the reduction worskstation are available.


One at a time:

To add sources to the object catalogue, type at the TCS window

        USER>source name ra ra ra dec dec dec equinox
Then, to send the telescope to the target

        *USER>gocat name

The whole lot:

If you have a file with all your sources (.cat extension) in the form

         name ra ra ra dec dec dec equinox
         sa113 21 42 35.001 00 16 45.99 j2000
You may include the entire catalogue by copying it to /jkt/cat (note: use spaces, not tabs, in a .cat file, or it will not run).

        $>cp /jkt/cat
Then in the TCS window

        USER>inc jkt:[cat]
To go to a target

        *USER>gocat sa113
Current targets in the TCS an be displayed with
        USER>out term

Dome Flats

Before taking any expoure, always remember to check that the TV mirror has been taken out of the light path. Remove it by typing ccd or tv off at the SYS> prompt. Following some instructions on how to obtain dome flats:


  • telescope: from Zenith park, increase DEC until AM=1.7.
  • dome: 235 degrees

Each exposure was aimed to reach a mean pixel value of 20000ADU, consistent with 1/3 of the saturation level of the SITe2 chip. The readout speed was set to QUICK.

Band: U (RGO 203)
lamps: Main dome lights on
dial: -
exposure time: 125s
mean: 19109
stddev: 8689
midpix: 23046

Band: B (Harris 28)
lamps: 1,2,3 & 4
dial: 10
exposure time: 5s
mean: 18672
stddev: 8474
midpix: 23410

Band: V (Harris 31)
lamps: 2 & 3
dial: 5
exposure time: 11s
mean: 21729
stddev: 10063
midpix: 27046

Band: R (Harris 39)
lamps: 2 & 3
dial: 2
exposure time: 5s
mean: 17914
stddev: 7941
midpix: 22045

Band: I (Harris 44)
lamps: 2 & 3
dial: 1
exposure time: 2s
mean: 18241
stddev: 8001
midpix: 22375


  • lamps: There are four domelamp lights situated on the top ring of the telescope. Their controls are below the emergency stop button (labelled 1,2,3 & 4). The far right button must be depressed in order for the lights to come on.
  • dial: To the left of the dome light controls are three dials. The one labelled "DESK" controls the intensity of the dome light, and ranges from 1 to 10.
  • mean: Mean pixel value as decribed by iraf.imexam
  • stddev: standard deviation of pixel values as decribed by iraf.imexam
  • midpix: Median pixel value as decribed by iraf.imexam


To calibrate the pointing:

        USER>cal last
This loads the last calibration results and outputs the results. Accept these before starting a new calibration test or alternatively if the results are good (i.e. less than or equal to 20 arcsec) you can skip the calibration test.
This will start a seven star interactive calibration. The telescope will move to the first star, which you will need to center in the target on the TV monitor (REF). The TCS prompt will also go into HANDSET mode.

To use the TV:

        SYS> tv on
Turn on TV:
  1. Gain right down
  2. Black power button
  3. TV power button.
Center star:

The cursor keys on the TCS keyboard will allow you to move the stellar image in the TV screen. Once star centered, press the HANDSET key on TCS keyboard. Telescope now goes to the next star. After 7 stars you will be asked:

Where all stars centered? (Y/N)
Answering y will display pointing details which should then be added to the logbook.

DON'T forget to put the light path back to the ccd:

        SYS>tv off

Sky flats

Add list of blank fields to the TCS catalogue:

         USER>inc newblank38
  • Go to a "blank" part of the sky:
    	*USER>gocat blankname
    where blankname is the name of the blank field (coordinates can be obtained by typing "out term" in the TCS, or from the list on the notice board).

    The saturation level of the SITe1 is 65535. Sky flats want to have counts between ~15000 and ~35000. If you are unsure of the exposure times then set;

     	SYS>window 1 "[1000:1100,1000:1100]"
    This sets a 100pix2 window, readout ~ 10sec. (note: Clearing takes 12sec).
    	SYS>glance 2
    This will take a 2 sec exposure and write it to in /obsdata/jkta(b)/YYYYMMDD Each new glance overwrites the previous glance, nothing is written to the log.
    	cl>display s1[1] 1
    Find the count level (box in bottom right corner of ximtool) and scale your next exposure time accordingly. Don't forget to SET YOUR WINDOW BACK. The full frame is re-invoked with;
    	SYS>window 1 disable
    	SYS>window 1 "[1:2088,1:2100]"
    A flat is started with:
    	SYS>flat t "your text here"
    where "t" is the exposure in seconds. In between different flat exposures in the same filter, it is convenient to offset the telescope to account for stars, which will then be removed by median averaging the various flat fields:
    SYS> offset arc xx yy 
    will offset the telescope xx arcsec in the X direction, and yy arcsec in the Y direction. Note that the offsets are absolutes to the telescope pointing, so that reissuing the same offset a second time will not move the telescope.

    When you feel you have enough exposures (3 is good), change to a different filter and repeat. E.g. filter, window, glance, window, flat, offset, flat,...

     SYS>filter n 
    where n is a number 1-6 written on the white board.

    Tip: Narrowband filters (eg Halpha) need longer exposure times, so start them first in the evening, and last in the morning. Broadband filters are sensitive in UBVRI order (where I is the most sensitive, ie do last). You have ~25 minutes from dusk till dark, you need to be on the ball. Remember there is always the morning...


    To determine the best telescope focus the observer should select a suitable stellar field (e.g. landolt standard - see red folder in control room, or


    A window will pop up: enter the number of exposures, exposure time, start focus position (mm), focus increment steps (mm), and number of arcseconds to offset the telescope between each exposure.

    Hit RUN in the quickfocus window.

    This will begin taking an exposure for each focus step while offseting the telscope by the number of arcseconds chosen. When finished, quickfocus will write the focus image to the next run number (eg

    To analyze focus image go to iraf. You may use the task jkt_qstarfocus, located in the ing package.

    To run jkt_qstarfocus type the following in iraf:

            ing>jkt_qstarfocus 'filename'

    Select the desired stars to anaylze by choosing the first exposure of each star (the one with the greatest offset) with the 'm' key. Press 'q' when finished. See what the jkt_qstarfocus chose as the best focus.

    Now set the telescope to the new focus value! (It is a good idea to glance the field and check out the new focus using imexam) Remember to note the focus value in the Observing Log Book by the TCS.

            SYS>focus 39.70


    Finally ready to start on your targets/standards. Find a target that has the lowest airmass (compare LST to RA of target, diff as little as possible).
    	*USER>gocat yourtarget
    change to the filter you want
    	 SYS>filter n
    Exposing: For exposures longer than about 120 seconds you need a guide star, without it your target will become smeared across the image.
    	 SYS>run t "Your text here"
    For multiple exposures
    	SYS>multrun n t "Your text here"
    Changing a run once it's in motion:

    hit cntr-z

    Now type one of the following:
    	SYS>abort        to kill the exposure
    	SYS>finish       to readout the exposure, keeping the data
    	SYS>newtime t    to change the exposure time
    Note:A fault that occasionally occurs with the JKT is that of the integration time exceeding the given exposure time and continuing to integrate until told to "finish". This is more prone to happening with a multrun, so it is wise to keep an eye on the ICS "SITe1 on JAG" window. As always, please issue a fault report if this occurs, stating the run number in question.

    The Auto Guider

    The autoguider consists of a mirror surrounding the focal point, and a camera controlled by X and Y probes. A guide star position is found from the GSS (X/Y probe positions) and monitored by the camera. In good seeing the camera can detect 13th Magnitude stars.

    GSS (guide star server).

    To find the x / y probe positions:

    Open a telnet session to lpvs1 or lpvs3:

    	$>telnet lpvs1
    (password on whiteboard)

    you are now faced with:

    Which telescope (WHT, INT or JKT)? jkt
    Which instrument? ccde
    At the $ prompt:
          GSS>config jkt ccde
          GSS>search RA RA RA DEC DEC DEC equinox (of your target)	
    you will then have this displayed:
     Key: * = star, blank = non-star, ? = ambiguous object
     Target:                      Equinox  PA   Tel  Focus
      0  0  0.00  + 0  0  0.00    J2000.0  0.0  JKT  CCDE      
       Date       Apx     Apy  Vmax  Vmin
     2000.268     0.0     0.0   5.0  12.0
        RA2000       Dec2000     Mag        x         y  
      0  0 13.79  + 0 13 11.78  11.74    17155.    24516.  *
    $ lo


    If you don't fancy typing in the coordinates for each of you targets, then you may search a catalog created by you, in the form:

             search RA RA RA DEC DEC DEC equinox
    Save this with a .COM extension in /home/jkt. Now open an ftp session to lpvs1, cd to SYS$SYSDEVICE:[GSS.JKT.CCDE], and mput yourfile.COM here. Close the ftp and carry out the above GSS procedure. Instead of typing
             GSS>search RA RA RA DEC DEC DEC equinox
             GSS>do yourfile.COM

    To print this file you will need to move it to a unix machine (i.e. ftp to lpvs1 from lpss10).

    In the example above the X / Y probe positions are 17155 24516.

    To send the probes to that position:

            SYS>autoxy 17155 24516
    Now turn on the autoguider (big red button marked on/off), and the autoguider TV.

    To scan for the guide star:

    To acquire the guide star:
    Wait for the "Okay to guide?" prompt:
    Now initiate the autoguider by hitting F18 on TCS keyboard or type:
    	*USER>autoguide on

    To STOP autoguiding hit F17 on TCS keyboard or type:

    	*USER>autoguide off


    Scripts can be written to do almost anything. Any command that can be issued at the ICS can be used. Simply edit the script file with # as a comment character and one command per line. E.g.
    filter 1
    run 40 ``NGC1234 B40''
    filter 2
    run 40 ``NGC1234 V40''
    filter 3
    run 40 ``NGC1234 R40''
    filter 4
    run 40 ``NGC1234 I40''
    echo ``finished''
    To run the script (which will be saved to /home/jktobs)
    	SYS>source myscript.csh


    Offsetting the telescope can be done by
    1. Press "Handset" on the TCS keyboard
    2. Press "own" to change the offset increment (arcsec)
    3. Press the cursor keys to offset
    4. Press "handset" when finished

    Zenith Park

    To park the telescope at zenith:
    	*USER>park zen

    Scratch Area

    If you want to manipulate your data you need to do it in a scratch partition. cd to /scratch/jkta or b and mkdir todaysdate. cp your data here and do what you want to it.


    The JKT is prone to jumping in the west (look at the turntable position) especially at high zenith angles. The TCS will beep twice, and the guide star will be lost after the occurrence of a jump. Stop the guiding, send the telescope back to the target, reacquire the guide star and try again (or change target). If you encounter telescope jumping, please give details in a fault report so we can keep a record of the frequency of this. N.B: This problem was thought to have been solved in the summer of 2002, but a few occurences are still reported every now and again. Check your data often!

    Non-observing related Computing

    For any computer work not involved with observing, the reduction sparc in the far corner of the JKT control room should be used. Choose jktr telnet session from menu, and login as jktguest (passwd: jkt_guest) to ensure the required setup is initiated. Do not use lpss10 for any memory intensive tasks, e.g. data reduction.

    Data Tapes

    You can simply use a tar to save your data. Put a tape into the DAT drive, open an xterm or xgterm window, go to the directory where data are, and type the command

    	SYS>tar cvf /dev/rmt/0

    More information on the use of fitsinit and fitsout commands is available.

    Observing Log

    The night log can be saved to file file->print->print to file, you can then do what you want with it (print/mail).

    Night report form

    To generate a night report, use the "File" menu in the ICS observing log window, followed by "Night Report". This opens a window to fill in the header data (observer, proposal,etc.). When you click on "Create Log", the program will collect ephemerides and Met data, and generate a night report which is stored locally, and under ~lplogs/logdata.

    It is important to fill in any time lost due to weather, technical or other problems in the night report, and to submit a fault report detailing all problems so they can be fixed and traced.

    Fault database

    Any problems should be reported to the engineers via the fault database. This is very important! Please remember to fill in the time lost due to technical problems. You could also use this facility to check past faults and find out how they were remedied.

    Feedback Form

    At the end of your run please fill out the feedback form.

    Closing up

    • Switch the JAG lightpath to CCD to protect sensitive TV system
      	SYS>tv off
    • Turn the TV and Autoguider off
    • Zenith Park the telescope
      	*USER>park zen
    • Close mirror covers
    • Close dome shutter
    • Rotate dome to aviod unexpected bad weather
      	USER>dome 235
    • Switch to engineering mode and type acknowledge TCS
    • Turn off oil pumps, cancel alarms
    • Turn off telescope power
    • Fill out night report form
    • Start writing tapes
    • Refill cryostat
    • Turn off dome lights
    • Go to bed.

    General Faults

    Most of the faults can be cleared by typing in the pink observing system window:

    SYS> startobssys

    If this fails to work carry out the Shutdown procedure followed by the startup procedure.

    Common faults are autoguider probes sticking or problems with changing the filters.

    A/G Probes

    If you experience problems with the probes sticking, reissue the "autoxy x y" or if this fails try "zeroset autox", "zeroset autoy" or dasreset command. If this fails refer to the General Faults.

    Filter Wheel

    If you experience problems with the filter wheel sticking and not initialising a filter. First try zeroset mainfilt if this fails refer to the General Faults. If the filter wheel is mechanically stuck and does not respond to software resets, then please contact the duty engineer.

    Moving Telescope

    Sometimes you may find that you can't move the telescope. This typically happens at the beginning or end of the night and is not a fault, it is either due to the oil pumps being off or the reset button has not be pressed after canceling an alarm. However, if the telescope has reached one of its limits the telescope is stopped by the horizon limit switches and a warning is shown on the TCS display. It is then neessary to :

    1. Switch telescope to engineering mode.
    2. Press the clear alarm (glowing red) button and reset (glowing green) button
    3. Turn the key marked LIMITS NORM/OVERRIDE [left hand panel] and simultaneously move out of the limit using the appropriate HA and DEC buttons.

    Once out of the limits the telescope will need a fresh ZEROSET and CALIBRATE.

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    Last modified: 18 December 2010