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SKY_FLAT

Creates and files a flat field derived from dithered frames

Description:

This recipe makes a sky flat for LCOGT imaging from a series of sky or Lambert flat frames which are combined using one of a selection of statistics. It expects a series of dithered sky frames in different filters.

It performs debiassing, bad-pixel masking, and dark subtraction before combining normalised frames pixel by pixel using the median. Details of the flat are filed in the index of flats for future selection and use of the flat. See the "NOTES" for further details.

For best results the field observed should contain few stars and no bright ones. Ideally the telescope should have been pointed to the "flat spot" - usually 5 to 10 degrees away from the zenith in the anti-solar direction to minimize gradients in the resultant flat.

Notes:

Configurable Steering Parameters :

NUMBER = INTEGER
The number of frames in the jitter. If absent, the number of offsets, as given by header NOFFSETS, minus one is used. If neither is available, 5 is used. An error state arises if the number of dithered frames is fewer than 3. []
USEVAR = LOGICAL
Whether or not to create and propagate variance arrays. [0]

Output Data

Implementation Status: