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The Observing System

The observing software consists of several windows:

The pink window is your most useful window, where you can control LIRIS mechanisms and take all types of exposures. See Observing Commands for the most commonly used commands for taking exposures and also Imaging Scripts and Spectroscopy Scripts.

Real-time Display (RTD)

This displays LIRIS images in real-time. It is described fully on its own page.

A&G Display

Between the telescope and LIRIS is the A&G-box, which contains amongst other things the autoguider, a set of neutral density filters, a tungsten and two arc lamps for wavelength calibration. In addition, there are a couple of mirrors which lead the light into the currently mounted Cassegrain instrument, in this case LIRIS.

The current status of the A&G-box is displayed in the A&G-box status window. You can control the configuration of the A&G-box by writing commands in the pink observing system window.

If you want to take spectroscopic flats with the tungsten lamp, or arc spectra with the arc lamps, then you have to move in the Acq/Comp mirror. This can be achieved from within the first (or the second) menu tab (A&G, or  A&G observer). Alternatively, you can use the agcomp command in the pink window. Moving the mirror into the beam takes about 20 seconds. The light path in the A&G-box display will be updated correspondingly. Note that with the Acq/Comp mirror in place, LIRIS cannot see the sky anymore. To move the Acq/Comp out again, just click the same push button again and confirm the action (or use the agmirror out command).

Autoguider Filter

You can select the filter used for the autoguider. This is largely irrelevant for imaging, since exposure times are very short. However, for spectroscopy using the I-band filter which is closest to the near-IR and will help to minimise differential tracking effects at higher airmasses due to atmospheric dispersion. The telescope operator (OSA) takes care of all aspects of autoguiding, so please do not change the autoguider filter.

Neutral density filter

If you observe very bright sources you may want to consider using a neutral density filter. You can choose from a broad range of ND filters from the A&G tab. However, be aware that these filters lead to significant vignetting. In addition, the density has been evaluated for the optical only. The transmission in the near-IR can be higher than expected (and may not be neutral any more), also because these filters are warm and not cold. Hence, instead of using the A&G-box ND filters, using a LIRIS narrow-band filter is probably a better alternative if high flux levels  are a problem. Consider the jc-, hc- and kc-continuum filters.

The LIRIS camera server window

The black camera server window shows under the LIRISCASS tab the current status of the LIRIS camera. Apart from showing if communication with LIRIS has been established successfully, it also shows:
  • total exposure time of a started exposure
  • elapsed exposure time of the current exposure
  • current exposure number of a sequence of exposures
  • read-out speed
  • read-out mode, i.e. CDS (correlated double sampling) or MNDR (multiple non-destructive reads)
  • store mode
  • detector windowing

The 2 LIRIS status mimics

  • shows the current filter/slit/grism configuration of LIRIS. This can be restarted with lmchstat
  • shows if the arc lamps are switched on or off, and the temperatures inside the cryostat   

The observing log

You do not need to take notes about all the exposures you take, as all the information is written automatically to a nightlog. At the end of the night you will create a night log which contains all relevant information. You can see the night log at any time during the night and put comments into it by clicking once on the line you wish to comment on, which brings up a small window where you can type in your comments. It should be running all the time, but in case you need to restart it type:

SYS> obslog &

Telescope info: TCS

You can ask the OSA to send you a window showing the current status of the telescope, the TCS display (Fig. \reftcsdisplay). Here you can see the RA and DEC coordinates or your target, UT, ST, azimuth and elevation, airmass etc. If you need to, you can start the TCS display  with:

SYS> tcsinfo &


If the camera server says that LIRIS is not responding, which will be indicated in big red letters, then this can usually be fixed with a dasreset or a startobssys in the yellow DASxx console (currently DAS31 is in use, but this can change). If you want to save your CCD settings before a dasreset use the command  saveccd liris filename, and to reload these settings use the command  setccd liris filename. Ask your OSA or OSS for help, or see the Troubleshooting section.

In the very unlikely case that the entire observing system is down and you have to bring it up yourself,

Log on to the Sun workstation taurus (next to the ICL computer):
LOGIN: whtobs
PASSWORD: provided by the OSA or the SA
An xterm orange window will appear, with multiple tabbed menues. Swith to the tab menu that corresponding to the DAS (Data Acquisition System) which controls LIRIS (get its name from the white board above the ICL computer).
Start the Data Acquisition System:
Type obssys in the DAS (orange) window. It defines the software to use and will then prompt you to select the observing system. Type number "1" for manual instrument selection and select LIRIS and wait until the prompt DAS> appears.

To start the software, type:
DAS> startobssys
Wait for the prompt and minimise this window (it is not needed until you shut down
the system).
Start the system computer by typing obssys in the pink window.
Enter the same option number as in the orange DAS window and wait to get the SYS> prompt.
Type SYS> startobssys

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Contact:  (LIRIS Instrument Specialist)
Last modified: 19 January 2014