Processing math: 100%

SKY_FLAT

Creates and files a flat field derived from jittered frames

Description:

This recipe makes a sky flat for UKIRT imaging from a series of sky or object frames which are combined using one of a selection of statistics. It expects one dark frame followed by jittered sky frames.

It performs a null 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. In contaminated sky regions, recipe SKY_FLAT_MASKED will greatly reduce artifacts appearing in the resultant flat.

Notes:

Output Data

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 jittered frames is fewer than 3. []
USEVAR = LOGICAL
Whether or not to create and propagate variance arrays. [0]

Related Recipes

SKY_FLAT_FP, SKY_FLAT_MASKED, SKY_FLAT_POL.

Implementation Status: