Reducing UIST IFU standard star frames
A raw frame of a standard star should look something like the image shown below (this image was taken in fairly poor seeing conditions, if the seeing is better then fewer slices will be illuminated).
Once you have an object-sky pair the frames will be subtracted and the wavelength calibration will be applied to give every row of the image a common wavelength scale. The slices are also re-ordered so that the order corresponds to the order in which they cover the field of view. The spectra are extracted from this 2d image using optimal extraction and filed as a standard star spectrum.
The slices are then cut out and formed into a datacube (the gu(UTdate)_(num)_cub group file). You can look at this file in gaia if you wish, though it will appear as a chain of a thousand images and probably won’t be of much use (visualisation software is being developed!). However, the datacube is collapsed in the wavelength direction and a “white-light” image is displayed. This will allow you to confirm that your star is centred on the IFU field of view (as discussed earlier and in the section on source acquisition). The white-light image will be displayed in a Gaia window – its the gu(UTdate)_(num)_im file. Try playing with the cuts on the display; you may also need to zoom in quite a bit…
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