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P70-508 Probing the diversity of the smallest building blocks of the Solar System

PI: G. Fedorets

ALFOSC imaging photometry and spectroscopy of fast-moving targets.

SoftToO and ToO observations. Either of two modes will be used:

  • With auto-guiding (standard use of tcs.asteph)
  • Blind tracking and updating rates (tcs.asteph used with -g update)

Instrument setup required for ALFOSC:

  • Filters: SDSS g'r'i'z'
  • Grism #4
  • Slit: 2.5"

Observing instructions:

For some modes "tcs.asteph" will output ephemeride files, for the time being the file is called "hitandrun.input" and is stored in the current directory where asteph is running (overwriting old files).
The ephemeride file will be used by the script "hitandrun" for pointing and updating the differential tracking rates for fast-moving targets. These are observations without auto-guiding.
For more information see Fedorets_additional_instructions as well as the author's ASTEPH documentation.

  1. Open 3 seqterms and to the directory
      cd ~/scripts/70-508
    In all of them. List the available OB scripts
      ls -lrt

  2. In the first window start the target OB script, when it tells you to do the pointing, go to step 3.

  3. In the second window run tcs.asteph is indicated by the PI. For completeness we show below the usage with all possible options (the first option in each flag is the default)

          tcs.asteph [ -t < asteroid|comet|planet|unconfirmed|horizons > ] [ -m < ima|para|along-slit|optimal-ll|optimal-lr > ]
                     [ -r < full|half > ] [-g < on|blind|update >] [-e INTIME] -n TARGET
          
    The PI is responsible for giving you the the exact input for asteph (see OB comments), and it is typically one of the following:

    • A) tcs.asteph -n targetname (default mode: asteroid imaging with ag-on)

    • B) tcs.asteph -t unconfirmed -g update -n targetname (OpenOrb ephemerides for unconfirmed targets to be used with script hitandrun)

    • C) tcs.asteph -t asteroid -g update -n targetname (JPL ephemerides to be used with hitandrun)

    EXAMPLE:
    > tcs.asteph -t asteroid -g update -n 68548
    ...
    Your input target is                        -  68548
    Your observatory is Nordic Optical Telescope, La Palma.
    Retrieving data from JPL Horizons...
    Data retrieved successfully from JPL Horizons.
    The object being searched for is  68548_2001_XR31
    Prefix for file names will be  2023-Oct-04.68548_2001_XR31
    Today is  2023-10-04
    Your computer says time is  11:53  UTC.
    ***************************
    These tasks should be given to the TCS:
    ***************************
    tcs.append-object 68548_2001_XR31-1 17 06 18.91 +78 39 35.7 2000.0 0.0 0.0 17.314
    tcs.ag-off
    tcs.guide-object 68548_2001_XR31-1
    tcs.reposition-guide-probe 193.864 41.25260
    Remember to switch on the hit and run script
    tmp.hitandrun.input  100% |********************************************************************|
    
  4. If you are running mode A), classical asteph with autoguiding, do as follows:
    • cut and paste the 4 output lines in the sequencer window, one by one
    • when differential tracking and autoguiding has started, go back to the OB script and press return to start ALFOSC setup and data taking.
    When the OB finishes, you are done.

  5. If imaging with modes B) and C) you now start PRE IMAGING as follows:
    • In the second window, cut and paste only the 3 first lines output from asteph
    • when autoguiding is ok, run the script griz-calib-images
    It takes 4 ALFOSC griz images (120s, 40s, 40s, 120s).

  6. If spectroscopy with modes B) or C) there is no PRE IMAGING, but the PI
    will probably ask for asteph mode -m along-slit and in that case the output lines from asteph
    will give an angle in the line "tcs.guide-object -f *** objectname"
    and this angle must give given as the last parameter (field-rot) to the hitandrund script.

  7. In the third window do pointing and tracking with differential rates and rate-updating as follows:

     hitandrun targetname hitandrun.input 'UT-string' update-rate N-updates field-rot
         
               targetname  (give a name without space)
    	   UT-string   (use the exact format as shown in the example below, a future time)
               update-rate (given by the PI, if not, use 10)
    	   N-updates   (given by the PI, must be enough to last for whole observation)
    	   field-rot   (given by the PI, see options below)
         
    EXAMPLE: hitandrun CAXA292 hitandrun.input '2024-Oct-02 20:24:00.000' 10 300 ima

    Here the rates are updated every 10 seconds a total of 300 times, i.e. it goes on for 3000 sec. Can be Ctrl-C'ed.
    The UT-string must be exactly on the format above and given a minute or two into the future, to let the telescope arrive in time!
    The field-rot values are either ima for default N up E left orientation, para for parallactic angle, fixed for current rotator position,
    or an angle xx.x degrees for setting a specific field-rotation angle, used if tcs.asteph is requested with the -m flag set to "along-slit"
    to have the tracking direction along slits (for ALFOSC horizontal slits).

    NB! Press return when auto-guiding is on,
    the script then waits for the "right moment" (your UT input),
    the playphone rings when this happens, the target is now supposedly in the FOV,
    differential tracking is started, and at this moment you are ready for step 8.

  8. Go back to the first window where the OB was started and press return to start data acquisition.
    When the OB finishes with an astrowakeup, and if you did imaging, go to step 9.

  9. If you did imaging with modes B) or C) then do POST IMAGING: as follows:
    • Ctrl-C the hitandrun script (switches to sidereal tracking)
    • TCS UIF: g-g-s 1
    • TCS UIF: auto-pos-retry
    • in the second window start again the script griz-calib-images

  10. If you did spectroscopy, there will most likely be another OB of a solar analog to be observed. This is just a normal OB.

    At this point, all is done!


  • For more general information on how this works, see the section "Moving Targets" in the ALFOSC Cookbook.
  • Check also if there is a standard star OBs with today's date , which is typically asked for spectroscopy.

  • Please, fill in the ToO or SoftToO tracking log.

    Thank you for your help!

    P70 tracking


    Program Tracking
    Proposal 70-508
    Semester P71: 20250401 - 20251001
    Principal Investigator Grigori Fedorets
    Programme Probing the diversity of the smallest building blocks of the Solar System
    Instrument ALFOSC
    Time Allocation 6 x 2h hard ToO + 6 x 2h SoftToO
    Total Nights 24h
    Type ToO+SoftToO
    Notes
    Total Time Spent (hh:mm)
    Proposal Date Time Type Targets Files Comments Status
    Empty table: no tracking data available (yet)

     

    The above information is collected from the ToO/Mon reports that have been created by the observer.

    Should any of the observations have been carried out using the OB system, you will find additional information HERE

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