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encounts stsdas.hst_calib.ctools



encounts -- Compute encircled energy.


encounts input output


This task computes the encircled energy (actually counts) for all the sub-images in an fextract output image. The fgauss task can then be run to determine the best focus position.


input = "" [string]
Name of the input image. The output from the fextract task provides the input to this routine.
output = "" [string]
Name of the output text file which will contain two values per row: the refoc mirror position (read from the input header) and the sum of the counts within the specified radius for all stars at that focus position. The pixel position and encircled energy for each sub-image are also written to the output file, but they are commented out by the "#" character. fgauss ignores these commented lines.
(radius = 4.5) [real, min=0., max=INDEF]
The radius in pixels within which counts will be summed. The default of 4.5 is 0.1 arcsecond at f/96.
(cboxsize = 0) [integer, min=0, max=INDEF]
If cboxsize is greater than or equal to 3, then the Mountain Photometry Code (MPC) centering algorithm will be used to determine the position of each star; otherwise, the center of the sub-image will be taken as the position. A value of 9 or 15 is reasonable, but be sure that it is no larger than the size of each sub-image, i.e., the smaller of BOX1 or BOX2 from the input header.


1. If "f48_220.hhh" is an output image from fextract with sub-image size of 21 x 21, compute encircled energy within 0.1 arcsecond and write the output to "f48_220e.lis".

	fo> encounts f48_220.hhh f48_220e.lis radius=2.2 cboxsize=15

The file "f48_220e.lis" would then be passed to fgauss in order to find the best focus position.



This task was written by Phil Hodge.


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