Science Operations

Observing Procedure

This section will guide you through the basics of observing with LUCI. There are sub-sections for Imaging, Longslit Spectroscopy, and MOS spectroscopy.

We assume you have already opened the software as described in the software pages in this section.

Start of Night

Provide the OSA with the coordinates of your first target before the start of the night, preferably at or before sunset. Once it is dark enough, they will use the coordinates provided to slew to a nearby bright star and correct pointing and collimation, then turn the observing over to you.

If taking twilight flats, notify the OSA in the afternoon upon arrival so they can ensure the telescope is ready at sunset.  Details about taking twilight flats are available here.

About Scripts

Imaging scripts are the most straight forward.  There are two main types which are both treated the same way when running them at the telescope: On and off source dithering, best for extended objects, and on source dithering for sparse fields.  When dithering off-source keep the guiding and wavefront sensing in mind.

LUCI spectroscopic scripts contain both the acquisition imaging and spectroscopic observations. A normal faint object MOS mask or longslit alignment requires four images: sky, source, slit, and source+slit.

Sky frames may be omitted from bright source acquisitions.  In the case of very bright sources like telluric standard stars, crossed filters may be used to minimize the chance of saturating the detector.

In the OT, the acquisition is prepared as a separate observation element and then combined with the science observation element when the script is generated.  You should preview the acquisition sequence in the queue panel to confirm the script performs the sequence you desire.
All images in the sequence should be taken with the same readout configuration.

Running Scripts

Script execution is controlled from the Queue Action Buttons on the observer GUI.  Use of these are described here.  Select the “Load” Queue Action Button.  In the dialog box, maneuver to the directory containing your observing script.  Either double click your script or select it and hit open in the dialog box.  Review your script in the Queue Execution Panel.

Depending on the type of observation, the acquisition/verification may be performed differently. If an Imaging continue here, if a Long-Slit acquisition continue here, and if a Multi-Slit acquisition continue here.

End of Night

If you plan to take darks the next afternoon, move the blind mask into the FPU, otherwise just leave whatever mask is in the FPU or have all masks in storage to minimize MOS motions. In all cases, configure LUCI with both blind filters and the mirror to block most light and stop grating tilt stabilization. Watch the status panel to make sure it completes.

It is best to close at least the main Observer Panel and GEIRS windows when you are done and start with a fresh login at the beginning of your next night. All windows can be closed by clicking the “X” at top right or selecting close from the File menu