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* local users only
A small guide to the 70cm telescope

Start the telescope

  • Switch on voltage, Urgan (tracking), etc. at control panel left to the door. (set all upper switches vertical.)

  • Open dome: switch on the right hand side of the control panel at position 'auf'. If open put switch in horizontal (off) position.

  • Open windows and fix(!) windows.

  • Fill the dewar and open the front cover with the telescope in horizontal position.

  • Open the CCD entrace window: pull out black knob at the black flange box.

  • Check if the CCD and temperatur control (grey box) is on. If not switch it on (black switch on the back side).

  • If not yet, switch on PC. You can select monitors in the dome and control room with a switch.

  • Check the telescope-computer's system time by comparing it to one of the separate radio clocks! If there is a difference of more than 1s, you should check if the clock itself (on a long cable connected to the parallel port, normally lying on the small table next to the computer) has the correct time.
    • (A) If so, you should open the radio-clock control-window on the Windows-GUI of the control computer and press the "i"-button (on the lower right) -- if necessary repeatedly -- until the computer reads the time.
    • (B) If the radio clock doesn´t have the correct time, reset it by shortly removing the battery. After a few minutes without showing anything, there should be the correct time. Proceed then to case (A).
    • (C) If the clock doesn´t show the time after performing (B) for quite a while, set the computer time manually, either from within Windows or from the DOS-shell with the command "time HH:MM".
      In this last case it is absolutely necessary to write down reference times, because the internal clock of the computer is really bad!

Point to a target
  • Light the R.A. and declination scales (switch at the front panel)
  • Siderial time clocks are very likely to be wrong

  • Right ascension:

    • Calculate hour angle at the PC:
      • login in onto 'baerbel' (the mac in the control-room) with 'tnvt' (in 'Hauptgruppe')
      • use the command 'ut2st 10,26,27.5' to
        calculate hour angle for R.A. 10h26m27.5s at the next full minute

    • Use the hand set for the clamps (Entklemmung), press button for hour angle `Std.` and move the telescope with wheel on the mounting to approximate position

    • Fine adjustment of the hour angle at the scale on the east side of the mounting (direction to the door, where the switches for the dome rotation are.). Subtract 12 hours from your nominal value!
      The other (western) scale is wrong!!!

    • Lower R.A. scale:
      • numbered ticks -> every 10 minutes
      • small ticks -> minutes

    • Upper R.A. scale:
      • Nonius with seconds from 0 to 60

    • Match upper 0 tick with lower minute tick to set hour angle to a full minute

    Declination:
    • Use clamps (Entklemmung) button 'Dec'

    • It is necessary to subtract 42 minutes from the nominal Dec value!
      (At least this is the case in the 'normal' telescope position, where it is on the north side of the mounting when pointing to the east. In the case of the alternative position (on the south side of the mounting when looking to the east), you have to add 42 minutes to the nominal DEC value.)

    • Dec Scales:
      • left (to the telescope) scale:
        • big numbered ticks -> full degrees
        • small ticks -> 20 and 40 minutes
      • right (to the mounting) dec scale: Nonius with minutes from -20 to +20
      • Upper minute tick must match some lower tick to set this minute plus 0, 20 or 40.

    • Switch off scale illumination.

Find your object
  • Set CCD format with command 'CCDFMT 1 1 333 333 3 3' or alias 'ccd7'.
  • Create a new window (menu or ctrl-n).
    (The above two steps are now done during pmis start-up.)

  • Select filter with commands 'filx'. where x can be u,b,v,r,i for standard filters or 'o' for white light.

  • Take a short exposure 10-20 sec (e.g. comand 'obs 10000').
  • If you don't see any stars (only bias), turn the diversion mirror out (a wheel next to the knob for the ccd entrance) and check if the CCD entrance window is opened.

  • The field of view is ~ 8x8 minutes of arc. North is left and east is at bottom.

  • Rotate your finder 90o counter-clockwise to match it with the monitor.

  • Use fine-motion (Feinbewegung) to center your target (see below, Sect. Misc items) The buttons directly at the telescope work in the opposite way than described in Section Misc. items!.

  • Check if focus is ok.


Taking a sequence of pictures
  • One Filter

    • Look into the database
      (wifraid# ~rsc/bin/linux/70cm_objects)
      if your target is already there. If so use the object-ID for the seq command below.
    • Use the following command in the DOS-box to create the macro:

    • 'seq <object-ID> <exposure time [s]> (<number of exposures>)'
      e.g.: 'seq RBS1955 60`

      If your target is not in the database, choose an unique and meaningful name for object-ID (preferentially the name of your target). The number of exposures is an optional parameter, defaulted to 1000.
      The script looks into a directory c:\rsc\<date> -- which it creates if it doesn't exist -- to determine the index of the latest image named 'sciXXXX.fits'.
      The new sequence will create images named 'sciXXXX.pmi' starting with an index increased by 1.

    • Start sequence in pmis with command 'go'

    • If you want to start a new sequence after finish or cancellation, first execute the 'seq' script! Otherwise the existing images will be overwritten!!!

  • Two alternating filters
    • For alternating filters use the DOS macro in the MSDOS-box:

    • 'seq2fil <object name> <filter1> <filter2> <exposure time filter1 [s]> <exposure time filter2 [s]> (<number of exposures (both filters)>)'
      e.g. seq2fil RBS1955 r b 60 120 60

      The script looks into a directory c:\rsc\<date> -- which it creates if it doesn't exist -- to determine the index of the latest image named 'sciXXXX.fits'.
      The new sequence will create images named 'sciXXXX.pmi' starting with an index increased by 1.

    • The number of exposures should be lower than 60, because longer sequences are not executed correctly by PMIS (a bug there...).
    • Start sequence in pmis with command 'go2fil'

    • If you want to start a new sequence after finish or cancellation, first execute the 'seq2fil' script! Otherwise the existing images will be overwritten!!!

  • BIAS images
    • There is a command 'bias' to be executed in the MSDOS-box. This creates a script callable also with 'go' in PMIS, which creates 5 bias images.


  • FLAT fields
    • For flatfields use the 'seq' script as described above for the one-filter case. (Start exposures with 'go' in the PMIS window.)
      As object names one should use one of 'ffu', 'ffb', 'ffv', 'ffr', 'ffi', or 'ffo'.
      Don't forget to move the telescope during the read-out to have eventual stars o different positions!


  • Cancelling a sequence
    • Activate the PMIS main window (title-bar must be blue) by clicking into it. It may take a while after clicking ...
    • Hold down the Escape key
    • Press the 'Abort'-button of the progress-indicator of the exposure (only visible for exposures longer than 20s!). If necessary, repeat this step.
    There should appear a pop-up window asking whether to continue or cancel the sequence.



  • Check if there is enough disk space on c: (at maximum there is about 1.5 GByte available). You can use also the d:, e:, f: and g: (8 Gbyte) and move old data from c:\rsc there.

  • Check if the system-clock of the computer shows the correct time by comparing the time shown in the radio-clock window to one of the external radio-clocks. If the difference is larger than 1s, proceed as described in section "Start the telescope".
    Anyway, write down shutter opening times, exposure times and filter used for some files. You should hear the shutter opening from the control room, when the TV-camera is switched on.

  • Rotate the dome slit. You can use the TV-camera from the control room.

  • Keep the target on chip. Use fine-motion (Feinbewegung) between two exposures.

  • Stop a running sequence: Abort from current exposure. Close complete pmis-session (Alt F4). Restart pmis from main-group (Hauptgruppe).


Online quick reduction
  • make sure that the ftp server on nina is running
  • Login to the Mac (baerbel)
  • Open two ssh connections to wifraid (ssh -X)
  • create a directory on wifraid, where you want to reduce the data
  • change dir to that directory in both terminals
  • in the first terminal start the ftp download of the data with the command:
    wifraid# ~rsc/bin/scripts/pmis_get X Y
    where X ist the name of the current data directory on nina (C:\rsc\X) and Y is the time in seconds between data downloads (should be greater than the exposure time). Caution: The ftp server on nina get problems if the number of connections exceeds 240. Keep that in mind if you choose the download interval.
  • If not already done for the seq script, look into the database for the (Pipeline) ID of your target:
    wifraid# ~rsc/bin/linux/70cm_objects
  • Start the online reduction in the second terminal with:
    wifraid# ~rsc/bin/scripts/robo_phot .
  • If you did not use the proper object ID in the seq script, use:
    wifraid# ~rsc/bin/scripts/robo_phot -object <Object-ID> .
    where <Object-ID> is the ID from the database, not the ID you used for the seq script.

  • If your target is not in the database:
    You can add new objects with the command 70cm_objects. The syntax is:
    wifraid# ~rsc/bin/linux/70cm_objects <ident> <ra> <dec> <masterlist> <stars> <longname>
    The parameters are:
    <ident> is the object id, which is given in the seq script
    <ra> right ascension in hh,mm,ss
    <dec> declination in dd,mm,ss
    <masterlist> the master list of stars
    <stars> the index number of variable, comparison and check star in comma separted list
    <longname> A longer name of the observed target

    Typically the masterlist and the index of stars is not known before the first night of observation. Enter then a keyword 'none' for both parameters and the reduction pipeline will try to create a new master list for you.

Determining exposure times
  • make an exposure with the estimated exposure time
  • go to the PMIS image window, choose "Plot" and then "Row"
  • move the horizontal line down, so that it intersects your target (for flatfields: move the line to somewhere in the middle of the image)
  • press left mouse button
  • a window pops up, showing the counts in the CCD row which corresponds to your line
  • for flatfields: the count rate should be between 15000 and 40000 (don't be confused by the grey coding of the image. It swaps above 32000)
  • for targets: you have to find a compromise between S/N and exposure time. The actual (relative) count rate of the target depends on several factors (background, scientific aim of the observation,...). Rule of thumb: the target count rate should be at least 150 counts above the background.
  • Don't choose exposure times longer than 2 minutes. Due to the imperfect tracking of the telescope the images will be distorted.

Misc items
  • The mini-mac in the control room is called "baerbel". The user-name is "observer" and the password is sticking to the monitor.

  • If it is really cold and you have to spend some time in the open dome, you may want to use the overalls, which are available in two sizes (46 and 52), and currently stored in a box under the control-room table.

  • The fine-motion buttons have the following effects (After the last repairing the buttons directly at the telescope work in the opposite way! The buttons in the control room work correctly.):

    • STUNDE VOR -> MOVE TELESCOPE TO THE WEST
      -> MOVE STARS DOWN ON THE MONITOR

    • STUNDE ZURÜCK ->MOVE TELESCOPE TO THE EAST
      -> MOVE STARS UP ON THE MONITOR

    • DECL. VOR -> MOVE TELESCOPE TO THE NORTH
      -> MOVE STARS RIGHT ON THE MONITOR

    • DECL. ZURÜCK -> MOVE TELESCOPE TO THE SOUTH
      -> MOVE STARS LEFT ON THE MONITOR



  • FUNDAMENTAL PMIS COMMANDS
  • - OBS 1000 1 SEC EXPOSURE
    - ISAVE C:\RSC\APR1\A_IMAGE.PMI SAVE AS PMI FILE
    - FIL[U,B,V,R,I,O] SET FILTER
    - CCDFMT XORG YORG XSIZE YSIZE XBIN YBIN FORMATING THE CCD
    - CONTR-N OPEN IMAGE WINDOW
    - FOCUS REPEATED EXPOSURES
  • TO SET THE FOCUS
    • PRE-DEFINE A SHORT EXPOSURE TIME WITH OBS COMMAND (E.G. 'OBS 2000' AND SELECT SMALL REGION AROUND A BRIGHT STAR (IMAGE WINDOW MENU: ROI -> NEW).
    • START FOCUS SEQUENCE WITH COMMAND 'FOCUS'.
    • CHANGE FOCUS WITH RED AND GREEN SWITCH ON THE UPPER TELESCOPE CONTROL PANEL.
    • ABORT FOCUS SEQUENCE WITH MOUSE CLICK INSIDE THE IMAGE WINDOW.

SHUT DOWN THE TELESCOPE
  • SWITCH OFF 24V (VOLTAGE), URGAN (TRACKING), ETC. AT CONTROL PANEL LEFT TO THE DOOR. (SET ALL UPPER SWITCHES HORIZONTAL.)

  • CLOSE DOME: SWITCH ON THE RIGHT HAND SIDE OF THE CONTROL PANEL AT POSITION 'ZU'. IF CLOSED PUT SWITCH IN HORIZONTAL (OFF) POSITION.

  • SWITCH OFF THE CAMERA-CONTROLLER (GRAY BOX ON THE TELESCOPE SHOWING THE CAMERA TEMPERATURE).

    • LEAVE THE CAMERA-CONTROLLER ON AS LONG AS THERE IS LIQUID NITROGEN IN THE CAMERA, I.E. THE CAMERA IS AT -110 C.

    • DON'T SWITCH OFF THE TELESCOPE COMPUTER AS LONG AS THE CONTROLLER BOX IS ON! OTHERWISE IT COULD BE SERIOUSLY DAMAGED.

    So, if you cannot switch the controller off when you're leaving the telescope, write a mail to a colleague to have it done in the morning.

  • CLOSE WINDOWS.

  • CLOSE THE FRONT COVER AND THE CCD ENTRACE WINDOW (PULL IN THE BLACK HANDLE AT THE BLACK FLANGE BOX).

  • FILL IN SHORT NIGHT REPORT AND UPDATE LIQUID NITROGEN FILLING.

  • LOCK THE DOOR.

DID YOU REALLY SWITCH OFF TRACKING AND CLOSED THE DOME??? GOODNIGHT.

IMPORTANT PHONE NUMBERS
ROBERT 0178/1865452
AXEL 030/3357392
MATTHIAS MÜLLER 0173/8764541
(ANDREAS 030/2945907)
(EMIL POPOW 033205/46098)

The dome has number 0331/7499-256, while the control room can be reached via 0331/7499-275.

For ordering liquid nitrogen you can call the company Linde at
03461 - 853 128 (Linde AG Leuna)
Costumer-ID is 8658218 / 'Sternwarte Babelsberg'.

The new telephone number for ordering is now Linde Augsburg at 0823-08902 58


Last change 2009/09/14