Get the data


We have already provided you with the data you will need to complete this tutorial, even some necessary pre-reduced data. (See the last section of installation chapter, Data package.)

For you own program, you will have to collect your data yourself, so here is a little primer on how to do that.

Searching the archive

The primary search criterium is your program ID. Just typing that in the Program ID box will return everything that was in your Phase 2 and that was observed.

Then you can refine your search to focus on specific targets and observation sequences.

Raw biases

We start by refining the search with the date of the observation and the Obs. Class, or “observation class”. Setting the Obs. Class to science returns the on-target observations only, none of the calibrations that were part of the sequence. We will get those later. For now, we want to find the raw biases associated with the science observations specifically.


Today we will use only one frame. To focus on a single frame, use the full data label for the observation in Program ID. To get the list of compatible biases we switch to the Load Associated Calibrations tab.


We get a list of compatible calibrations, starting with the raw biases. For some reason, some biases end up with a value for EXPTIME in their headers that is not zero. This is not understood. Those biases in general look fine. Nevertheless, there are plenty more biases, pick the ones with zero exposure time.



Staying on the same page, scroll down until you find the associated arc lamp observation.



For GMOS IFU observation, the flat field is taken right before or after the science observation. It is part of the observation sequence. To figure out which flat goes with which science observation, we identify the “observation ID” and input that in the Program ID search box.


From this sequence, it is clear that the first flat goes with the first science frame, the flat in the middle goes with the second and third science frame and the last flat with the last science frame.

In our case, our science-flat pair is #43 and #44.

Standard star

The spectrophotometric standard is defined in the program as a “partner calibration.” This means that we can find all the standard star observations of our program with the “program ID” and by setting Obs.Class to “partnerCal”.


Then we can scroll to find the standard star sequence that matches our data. Our science data uses the “B600 : 0.629” configuration so that is the one we pick.


Since it is observed just 4 days after the science, a search for raw biases will result in essentially the same raw biases as for the science frame; here we will use the same master bias for both science and standard.

Prepared tutorial data

All the data needed for this tutorial is provided in the data package, data_pkg_GMOSIFU_Tutorial-v1.0.tar.gz available for download at:

See the last section of the Installation chapter, Data package, for details.