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StanCam and ALFOSC together

The StanCam web page

The ALFOSC web page

StanCam is in principle always prepared when ALFOSC is mounted, but if you plan to use it, please, state so explicitly in your NIRF . StanCam is per default equipped with standard UBVRIz and H-alpha filters.
This is a quick reference for using StanCam and ALFOSC together, see details from the StanCam cookbook

  • Save current TCS settings for ALFOSC, if needed, by typing <filename> . The data file will be stored in the current working directory. If the file already exists, it will be overwritten.

  • In the tessa xterm type startobssys stancam.
    A window will pop up asking for the TCS access code. This code is found on the TCS in status page 1 which you get by typing sh 1 on the TCS command line. The code is shown on the top part of the screen as: Access Code xxxxxxxxxxx. Type it in. Note that you have to do this every night, as with all instruments.

  • In addition to the 3 StanCam BIAS windows, also a Sequencer window and a Talker will be started up. If the talker is already running for ALFOSC on the other desktop, it will not be visible on this desktop. (The plan is to have this window sticky on all desktops by default.)

  • Start the electronic observation log: In an xterm type cd /data/stancam/ followed by obslog-stancam STnnmm\*.fits where "nnmm" is the image prefix of the night.

  • To setup the TCS correctly for StanCam imaging, in the Sequencer window type: tcs.setup-tel-stancam
    If you wish to know the content of this script, it is explained here. Please, note that the default telescope focus value for StanCam (23040) is used. (Telescope power should be on when you run this script.)

  • Select the StanCam filter from the sequencer window by typing ccd-filter or from the TCS CCD-fil and the number corresponding to the filter you want (U=1,B=2,V=3,R=4,I=5,Ha=6, SDSSz=7), e.g. [obs@tessa]$ ccd-filter 4 (sequencer window) or CCD-fil 4 (TCS command line).

  • Focus the telescope and the guide camera:

    • If default focus is good enough then use foc-del on the TCS. The focus offset between ALFOSC (no filter) and the StanCam R-band filter is -260 units, in the sense that going from ALFOSC to StanCam you apply foc-del -260.

    • If the optimum StanCam focus is required then use a focus star close to zenith (e.g. from the blanks catalog) and start a focus sequence with the BIAS command focus (start value) (focus step-size) (exptime) (e.g. focus 22920 80 12) **do not autoguide**. The resulting image gives a number of exposures at different focus values (the last one is offset by two steps), and you can evaluate which is the best focus (see focussing StanCam). If necessary, iterate.

    • Finally, correct the focus on the guide TV if autoguiding is needed. Start with tv-foc 415 and adjust with steps of 10.

  • Make an exposure by typing expose followed by the time in seconds (see STANCAM SEQUENCER Command Reference). Take single target exposures or run your scripts.

  • When finished with StanCam restore the ALFOSC TCS settings by typing tcs.restore-tel <filename> .
    This command restores saved TCS settings, stored by <filename> The data will be read from file in the current working directory.

  • When you want to exit from the StanCam Sequencer type shutdownobssys stancam.

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