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LBTtools.IRTC IRAF package

Observing Interface

This is the documentation for Dave Thompson's LBTtools.IRTC IRAF package which is the observing interface for the IRTC.

Only occasional observer interaction is needed with the enginneering interface of IRTC. See RunningTheIRTC.

This IRAF package communicates with TCS/IIF through Jose Borelli's DirtI interface to the IRTC. See document 609g012.

The next section of this document is a copy of /home/dthompson/iraf/LBTtools/IRTC/ which should always be the latest version.

IRTC package under LBTtools

D.Thompson - LBT Observatory, 12 MAR 2008

The IRTC package is intended as an easier to use 'wrapper' for the IRTC interface written by Jose Borelli for communicating with the infrared test camera as well as the TCS through the IIF. You should be familiar with the use of IRAF and the syntax of IRAF commands!

LBTtools parameters

The main parameter to change in the LBTtools package is the camera identifier. At the moment, the options include:
  • LBC
  • IRTC (assumed to be at LFBG)
  • DGTEST (assumed to be at left directGregorian)

IRTC parameters

The IRTC package has only two relevant parameters at this time: the telescope side on which the IRTC is located (default left, but the camera will be moved so this option is available) and the name of the internal source catalog (the default is set to "IRTC$/Catalogs/"). This catalog contains Wallace & Terrett pointing stars (wt*), a set of bright (M5*) most with associated off-axis guide star catalogs to help with the initial set up and calibration of the AGw unit, and selected other named source (e.g. Vega, Arcturus, etc., not there yet). A printout of the sources in this catalog is available at the telescope for reference (white notebook).

As with the LBTtools, the IRTC commands all keep log files as they are run, and they all expect a particular directory structure to be available in the current working directory. The general suggestion is thus to create a directory named by the UTdate and within that directory to run the 'prepdir' command in the LBTtools to create the needed subdirectories.

Your own sources can called by the IRTC pointto task (see below) if you set up a catalog text file in the proper format. We suggest you copy the default catalog to your local working directory and follow its format to add your own targets, then change the catalog parameter in the IRTC package to point to your local catalog (e.g. IRTC.catalog = "./"). Any subsequent call to the pointto task will then use this new catalog.


The "register" task replaces the old irc command "authorize". You must "register (cameraname)" before irc will let you send any other commands to IIF.


The pointto task will read from a source catalog the coordinate information for a star given its catalog name. Optionally, a numbered guide star is read from another catalog corresponding to this source, if both requested and available. Proper motions are applied from 2000.0 to today's date as needed. The PA can also be set. If a guide star is found and no PA is given, then the PA defaults to that needed to put the guide star in the AGw patrol field. If a PA is given with a guide star, then the supplied PA is used. The telescope mode can also be set (currently restricted to STATIC, TRACK, GUIDE, and ACTIVE). The pointto comand executes the following sequence of IRTC calls:

  • ClearStars
  • SetHotspot 384.0 256.0
  • SetStars target.dat
  • PresetTelescope POSITION <IRTC.Telside>


The offset task takes delta-RA and delta-DEC arguments in arcseconds, plus an optional rotational offset in degrees and applies them to the current position. A switch is provided to force these offsets to be in Alt-Az coordinates rather than the default RA-Dec. The offset command executes the following IRTC calls (with some assumed defaults for additional parameters):

  • OffsetPointing

But be careful - the iraf offset command changes the order of the arguments (dRA and dDec are required parameters, dROT is not but can be set on the command line.


The focus task currently just applies an offset to the current focus position. The focus command executes only one IRTC call:

  • StepFocus 1.03 <IRTC.Telside>

A series of focus frames can be taken by repeated calls to both focus and takepic (see below), with subsequent analysis of the images in iraf. This functionality may be placed in a 'focusseq' task, but for now they are separate.

focusseq (not implemented yet!)

The focusseq task takes a series of images with the focus stepped between them. currently just applies an offset to the current focus position. The focusseq command repeatedly executes two IRTC tasks (focus and takepic) with the supplied parameters.

  • focus
  • takepic

At the end of the sequence, the FWHM of the brightest source in the images is determined automatically and a plot of the FWHM vs. focus is produced. A parabolic fit is also done to the data points and the best focus position printed out, as well as a focus command that can be cut-and-pasted in order to set the focus to the best focus position.


The takepic task queries and prints out the camera parameters as they are currently set, then sets the exposure time and frame rate before taking a single exposure. The other camera parameters (subarrays, filter, FOV, etc., are all set on the camera GUI running on the windows control computer and are not set through the IRTC interface. The takepic command executes the following series of IRTC calls (the 2300000 is the exposure time in microseconds):

  • GetIRParam
  • GetFilter
  • GetFOV
  • SetIRParam 2300000. 1.
  • GetImage

A configuration option can be set to auto-display the resulting image in an open ds9 window. Eventually this task will be turned off and the image displayed from within iraf to allow for interactive recentering of a source on the image.

mosaic (not implemented yet! - there is a "spiral search" work around for this)

The mosaic task will help get the IRTC initally pointed to a source. It is designed to take either an MxN (Pattern='MxN') rectangular mosaic or a spiral pattern (Pattern='Spiral') centered on the initial pointing.

A step parameter allows one to take a sparsely sampled mosaic (e.g. images with non-zero gaps between them) to cover more area on the sky, in case the initial alignment is not good.

Defaults: If 'MxN' is requested and N is zero, then an MxM mosaic is obtained. A zero M will exit the task with an error. If the spiral pattern is selected, then M designates the numbers of times around the pattern to go. The mosaic command cycles through two other defined iraf tasks:

  • offset
  • takepic

with appropriate offsets applied to construct the requested mosaic. The offsets are calculated from the supplied parameters (Pattern, M, N, and step), and the camera exposure time is set by another parameter (exptime) in the same manner as takepic. If exptime is not supplied, whatever is currently set in takepic will be used, and if that is not set it will default to 1 second.

The display option will display each image in ds9 as it is taken, without erasing the current display so that the progress through the pattern can be monitored and the task aborted once the source you are looking for is located. Note that the task, if allowed to run to completion, will return you to the initial position. If aborted, the 'pointto' task will be needed to return to the nominal pointing for this source.

takeEFpair (in progress)

EF requires a pair of images, one taken on each side of the nominal focus, on which to do a curvature-sensing analysis of the delivered wavefront. The takeEFpair task assumes that you start at the nominal (best) focus and does the following:

  • focus -offset
  • takepic
  • focus +2offset
  • takepic
  • focus -offset

The last step is to return the telescope to the nominal focus.

Starting IRAF

If you are using the LBTO observing account, you open an xgterm (there is icon on the task bar for this) and a ds9 window (also an icon for this as well). In the xgterm, type "cd iraf" and then "cl". That starts the iraf session. To load the LBTtools package, type "LBTtools" (there are package parameters you should edit at some point to make things work correctly, epar LBTtools). The IRTC package is in there and can be loaded with "IRTC" (it too has editable package parameters, "epar IRTC"). If you are passingly familiar with iraf, use of the IRTC commands should be straightforward.

If you are using a "shared resource" like the LBTO observing account and you do not necessarily know the state of the saved parameters or who used it last, it is best to start the night off by "unlearn"ing the package. So, after logging into iraf on the xgterm, type: unlearn LBTtools and then proceed as usual to edit the package parameters (epar LBTtools) and load the package (:go). Repeat with the IRTC package. That way you start with a known configuration.


If your commands are apparently executed very quickly without errors and without effect, it could mean that you have forgotten to start the irs server. Or you might have the defaults set in the IRTC package to not send commands to the telescope or irtc. (epar IRTC)

This LBTtools package depends on having the IRC client in verbose=0 mode, while the AOwithIDL commands use verbose=2 mode. We've setup the ~LBTO/.cshrc file to distingish the two based on the existence of the IRAF file when a new shell is started for the xgterm window.

-- JohnHill - 16 Apr 2008
Topic revision: r14 - 03 Jun 2010, KatherineRueff
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