Recipe muse_flat: Combine several separate flat images into one master flat file, trace slice locations, and locate dark pixels.

Data Structures

struct  muse_flat_params_s
 Structure to hold the parameters of the muse_flat recipe. More...

Typedefs

typedef struct muse_flat_params_s muse_flat_params_t
 Structure to hold the parameters of the muse_flat recipe.

Detailed Description

Author:
Peter Weilbacher (based on Joris Gerssen's draft)

This recipe combines several separate flat-field images into one master flat-field file and traces the location of the slices on the CCD. The master flat contains the combined pixel values of the raw flat exposures, with respect to the image combination method used, normalized to the mean flux. The trace table contains polynomials defining the location of the slices on the CCD.

Processing trims the raw data and records the overscan statistics, subtracts the bias (taking account of the overscan, if --overscan is not "none"), and optionally, the dark from each raw input image, converts them from adu to count, scales them according to their exposure time, and combines the exposures using input parameters.

To trace the position of the slices on the CCD, their edges are located using a threshold method. The edge detection is repeated at given intervals thereby tracing the central position (the mean of both edges) and width of each slit vertically across the CCD. Deviant positions of detections on CCD rows can be detected and excluded before fitting a polynomial to all positions measured for one slice. The polynomial parameters for each slice are saved in the output trace table.

Finally, the area between the now known slice edges is searched for dark (and bright) pixels, using statistics in each row of the master flat.


Typedef Documentation

Structure to hold the parameters of the muse_flat recipe.

This structure contains the parameters for the recipe that may be set on the command line, in the configuration, or through the environment.


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