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ALFOSC Sequencer Command Documentation

Go to the SEQUENCER Reference Manual Main Page.

Instrument : ALFOSC
Observing Mode: ANY IMA SPEC POL
Command Type: ANY DATA DET DISP INST TEL
Usage: BASIC GENERAL STAFF
Description: SHORT LONG

SystemCommandArgumentsDescriptionType
alfosc abort [-d] Aborts an ongoing exposure (see also expose). DET
alfosc addtime [-d] <nn> Adds <nn> seconds to an ongoing exposure (note that <nn> can be negative too). DET
alfosc ampl [-d] <x> Sets the active amplifier to <x>, where <x> can be A, B, AB DET
alfosc bin [-d] <n> Sets the binning factor in both X and Y directions to <n>. DET
alfosc calibexp [-e] [-f] [-n <nn>] [-o <ObjName>] [-lmi] <lampID> <tt> Script for making a calibration spectrum with ALFOSC. Possible arguments are:
  • -e      echo mode: do not execute commands, only echo them
  • -f      fast mode: script will return during the readout of the last exposure
  • -n <Nexp>   optional number of exposures (default=1)
  • -o <ObjectName>   optional ObjectName
  • -lmi   if set the mirror will stay in the beam at exit
  • <lampID>       with <lampID>=He/Ne/HeNe/ThAr/Halogen
  • <exptime>   exposure time
Sets the ALFOSC calibration items (mirror & lamps) up for a calibration spectrum, takes the calibration image(s) of which the last one in the background, switches off lamps, and per default takes calibration mirror out at exit. Switches autosave_on, and leaves it on. Moves FAPOL out if necesary. Sets header IMTYPE to FLAT/WAVE . If an <ObjectName> is given (double quoted if containing spaces), then the string will be added to the already present lamp specifier in the OBJECT FITS keyword. If CNTR-C is pressed the ongoing exposure will be aborted, and the calibration mirror will be moved out of the beam. NOTE: the last exposure will be taken in the background, so that instrument setup can be done during readout.
Usage example:
  alfosc.calibexp -n 2 Halogen 15   Makes 2 halogen flatfield images with individual exposure time of 15s.
DET
alfosc cirpolexpose [-e] <Nang> <ObjName> <tt> <Ncyc> [-nowindow] Sets up and executes a set of circular polarimetry imaging exposures with <Nang> angles, exposure time <tt> and <Ncyc> cycles. If optional argument -nowindow is used, no windowing is applied. Available number of angles: 2 (0°, 90°) and 4 (0°, 90°, 180°, 270°). DET
alfosc cirpolspec [-e] <Nang> <ObjName> <tt> <Ncyc> Sets up and executes a set of circular polarimetry spectroscopy exposures with <Nang> angles, exposure time <tt> and <Ncyc> cycles. Available number of angles: 2 (0°, 90°) and 4 (0°, 90°, 180°, 270°). DET
alfosc dark [-d] [-t] [-f] <tt> Makes a dark exposure of <tt> seconds. To abort the exposure press "Control-C". If the option [-f] (fast mode) is used, the prompt will be returned when the exposure time is over and before the readout begins. DET
alfosc dither [-e] [-t] [-nowakeup] <pattern> <offset_size> <tt> Takes single exposures at each pointing of a dither pattern. The pointings in a dither pattern are symmetrical around the initial pointing, except for the ABBA scripts, which starts with an exposure on initial pointing. It is possible to specify a negative offset size, in which case the offsets are performed in the opposite direction.
  • [-e]: Echo script on stdout, do not execute
  • [-t]: Simulate exposure only
  • [-nowakeup]: no astrowakeup at the end of script
  • <pattern> predefined dither pattern.
  • <offset_size> telescope offset in arcsec between each exposure.
  • <exptime> exposure time at each pointing.
The dither pattern can be one of the following listed below:
  • 2X : 2-point (X)
  • 3X : 3-point (X)
  • 5X : 5-point (X)
  • 2Y : 2-point (Y)
  • 3Y : 3-point (Y)
  • 5Y : 5-point (Y)
  • 5D : 5-point (dice 5)
  • 4G : 2x2 grid
  • 9G : 3x3 grid
  • 16G : 4x4 grid
  • ABBAX : A-B-B-A (X)
  • ABBAY : A-B-B-A (Y)
Usage example:
  alfosc.dither 3X 20 15   Makes a 3-point X dither pattern with a 15s exposure at each dither point and a 20" offset between each exposure.
DET
alfosc expose [-d] [-t] [-f] <tt> Makes an exposure of <tt> seconds. To abort the exposure press "Control-C". This command checks if ALFOSC, FASU and FAPOL are ready before beginning the exposure. If 90 seconds occurs and it is not ready this command will time out. If the option [-f] (fast mode) is used, the prompt will be returned when the exposure time is over and before the readout begins. If [-f] is used, make sure that "alfosc.wait-camera-state idle"-command is given before any "alfosc_camera_commands". If the exposure time is larger than 300 seconds, the time left until the rotator reaches its limit will be checked. If there is not time enough to complete the exposure, an error will be generated and the exposure will not start. DET
alfosc focuswindow [-e] Script to set the ALFOSC CCD to readout only a central 800x800 pixel unbinned window. DET
alfosc gainhi [-d] Sets the gain mode to high gain. DET
alfosc gainlo [-d] Sets the gain mode to low gain. DET
alfosc linpolexpose [-e] <Nang> <ObjName> <tt> <Ncyc> [-nowindow] Checks if polarizer and Calcite are in and moves them in if necessary and does cycles of exposures. The object name is set to <myobject> and the current polarizer angle is added (e.g. "<myobject> 0deg"), object name is cleared when script ends. By default, the script windows the read-out using alfosc.polwin, with option -nowindow, no windowing is applied! Available number of angles: 4 (0°, 22.5°, 45°, and 67.5°) 8 (0° to 157.5° in steps of 22.5°) 16 (0° to 337.5° in steps of 22.5°) DET
alfosc linpolspec [-e] <Nang> <ObjName> <tt> <Ncyc> Checks if polarizer and polarimetry slitlet are in and moves them in if necessary and does cycles of exposures. The object name is set to <myobject> and the current polarizer angle is added (e.g. "<myobject> 0deg"), object name is cleared when script ends. Does NOT window the read-out! Available number of angles: 4 (0°, 22.5°, 45°, and 67.5°) 8 (0° to 157.5° in steps of 22.5°) 16 (0° to 337.5° in steps of 22.5°) DET
alfosc mdark [-t] <tt> <nn> Makes <nn> dark exposure of <tt> seconds. To abort the exposures press "Control-C". The image type (IMTYPE keyword) will be set to "DARK" if the exposure time is non-zero and "BIAS" if it is zero. DET
alfosc mexpose [-t] <tt> <nn> [<imtype>] Makes <nn> exposures of <tt> seconds. To abort the exposures press "Control-C". The <imtype> option (IMTYPE keyword) is optional and must be a text string without spaces. There are reported problems with this command that have not yet been solved. If you experience this, please use the alternative command single-mexpose. If the exposure time is larger than 300 seconds, the time left until the rotator reaches its limit will be checked. If there is not time enough to complete the exposure, an error will be generated and the exposure will not start. DET
alfosc polwin Windows the readout, optimized for imaging polarimetry. DET
alfosc readout [-d] Closes the shutter and reads out the ccd. You have to put the exposure in the background first. This is achieved by pressing Ctrl+Z in the sequencer where the expose command is running, followed by running the command bg. Note that this command does not work correctly when using a window in Y direction: data from a wrong window will be saved to file. DET
alfosc readspeed [-d] <readout_speed> Sets the CCD readout speed to <readout_speed> kpix/second. Valid values for <readout_speed> are 100, 200, 400 or 800. DET
alfosc resetxy [-d] Resets the ccd binning to 1, the X and Y size to maximum and the X and Y beginning to 1. DET
alfosc single-mdark [-t] <tt> <nn> Makes <nn> dark exposures of <tt> seconds. To abort the exposures press "Control-C". The image type (IMTYPE keyword) will be set to "DARK" if the exposure time is non-zero and "BIAS" if it is zero. DET
alfosc single-mexpose [-t] <tt> <nn> [<imtype>] Makes <nn> exposures of <tt> seconds. To abort the exposures press "Control-C". The <imtype> option (IMTYPE keyword) is optional and must be a text string without spaces. This command is an alternative to mexpose that can lead to errors. DET
alfosc xbeg [-d] <nn> Sets the X beginning to <nn>. DET
alfosc xbin [-d] <n> Sets the binning factor in the X direction to <n>. DET
alfosc xsize [-d] <nn> Sets the X size to <nn>. DET
alfosc ybeg [-d] <nn> Sets the Y beginning to <nn>. DET
alfosc ybin [-d] <nn> Sets the binning factor in the Y direction to <n>. DET
alfosc ysize [-d] <nn> Sets the Y size to <nn>. DET

In scripts, the syntax alfosc.<command> should be used.
If a part of a command is written in <angle brackets>, this is an argument that should be replaced with a value.
If a part of a command is written in [square brackets], this is an optional argument or flag.
When available, the optional flag -d will write extended debugging information to the log.
When available, the optional flag -e will show the script on standard output instead of executing the commands.
When available, the optional flag -t will only make a simulated exposure. Useful for testing scripts.

Type definitions:
DATA: All commands related to handling/modifying data (editing fits-headers, post-processing etc.).
DET: Commands related to operations with the detector.
DISP: Commands related to displaying images on the instrument computer.
INST: Commands related to operations with the instrument.
TEL: Commands related to operations with the telescope.

Back to top Last modified: November 23 2011