4.1. Example 1 - Datasets descriptions

4.1.1. One Point Source in Standard Resolution

This is a GHOST observation of the star XX Oph obtained in standard resolution IFU-1 is pointing at the star, IFU-2 is stowed. This observation was obtained during the April 2023 commissioning run.

GHOST can require a lot of calibration files. Also, the raw data bundle the red and blue channel data, as well as the slit-viewer data.

The calibrations we use for this example are:

  • Biases. We need biases that match the binning and read mode of the science frames. We also need biases that match the binning and read mode of the flats and the arcs. The matches must cover both the red and blue arms. The slit view camera has only one configuration, so the match is guaranteed for the slit view images.

  • Flats. The flats must match the read mode of the science. The binning must be 1x1. They will be binned in software to match the science. The matches must cover both the red and blue arms.

  • Arcs. The binning for the arcs must be 1x1. The read mode does not matter, but they require their own biases and flats and it is therefore simpler if they have the same read mode as the science data.

  • Spectrophotometric standard. The binning must match the science.

  • BPMs. The bad pixel masks are found in the Gemini Science Archive instead of being packaged with the software. They are associated like the other calibrations. Separate BPMs are required for the blue and red arms. There is no BPM for the slit-viewer camera.

Here is the breakdown of the files. All the files are included in the tutorial data package. They can also be downloaded from the Gemini Observatory Archive (GOA).

Science
S20230416S0079 (blue:2x2,slow; red:2x2,medium)

Science biases
S20230417S0011-015

Science Flats
S20230416S0047 (1x1; blue:slow; red:medium)

Science Arcs
S20230416S0049-51 (1x1; blue:slow; red:medium)

Flats Biases
S20230417S0036-40 (1x1; blue:slow; red:medium)

Arc Biases

Standard (CD -32 9927)
S20230416S0073 (blue:2x2,slow; red:2x2,medium)

Standard biases
In this case, the calibrations for the science can be used for the standard star.

Standard flats

Standard arc

Std flat biases

Std arc biases

BPMs
bpm_20220601_ghost_blue_11_full_4amp.fits
bpm_20220601_ghost_red_11_full_4amp.fits

** Not in data package. Need to be retrieved
** from the archive.

4.1.2. BPMs from the archive

You can download them from here: https://archive.gemini.edu/searchform/GHOST/notengineering/cols=CTOWBEQ/NotFail/not_site_monitoring/BPM

Put them in playdata/example1/.