Observing at Gemini

Kathryn at Gemini

Priority Visitors

In October 2017 we were privledged to be "Priority Visitors" at Gemini-N, and were trained on how to carry out queue observations with NIRI, GNIRS, and GMOS. The main reference is The Gemini North Visitor Observer's Guide. (A private copy is squirreled away here.) Although the Guide is very useful, there's a lot that was left out. This page is intended to serve as a re-introduction were we to ever get to go back!

The Screens

On the wall there are a number of extremely large screens that allow you to judge the weather conditions. One of the most useful is a set showing the views in various directions as well as a "difference movie" of the sky, which allows you to judge the cloud cover. CC50 means it's photometric--no clouds! CC70 means there are some thin cirrus around. In addition, there's a plot showing what amount of water vapor is present, as some NIR programs place WV demands.

But most of what you're looking at are the 8 large computer monitor screens. We never actually ran the startup script "startup astro"; things were always up and running when we arrived. In addition to the 8 screens, there are multiple desktops for each of them. You can't move a window from one screen to another but you could kill it and restart it by going to the little "G" icon located at the (bottom-left?) on each of the monitors. Here's what we found to be the typical layout:

Typical Observing Sequence

Observing at Gemini was probably the most intense observing I've ever done. There's a ton of stuff going on.

Data Quality Assessment

A big part of the Observer's task is to assess the quality of the data. What this really means is that you look at every single frame and make sure it's not awful. For instance, GNIRS has this unfortuante tendency to develope a "bias flash." If you're very lucky two adjacent exposures will cancel (there's persistence), but you need to look at every frame.

After you're satisified give each image a "pass" rating under the analysis tab in the observing log in the OT. If the image is okay but (say) of the wrong object, give it a "usable."

At the end of the night

Maybe you need to do sky flats. I don't remember how you find those. When all is said and done you need to load the daytime calibrtions which hopefully you've queued up as you've gone along; you now need to add the "bias all" stuff. There's a "load a bunch of stuff" object in seqexec. You want the biases to be the last thing for reasons I never did understand.