STScI Logo

yratio stsdas.hst_calib.fos



yratio -- Take ratio of each group of an FOS ACCUM with first group.


This is a prototype task to take the ratio of each group of an FOS ACCUM observation with the first group. The input is the science image of an FOS observation. The output is an image containing the same number of groups as the input. Each group will contain the ratio of that group divided by the first group.

yratio will determine the level of calibration done to the data. If the input is the raw science, i.e., the .d0h image, yratio will assume each group had the same exposure time and will multiply the first group by the appropriate scale factor.

If the input is the calibrated science data, i.e., the .c1h file, yratio will check to see if CNT_CORR was performed. If CNT_CORR were performed, there is no need for exposure time normalization; the calibration has already done it. If CNT_CORR is not PERFORM, then yratio will use the value of the keyword EXPOSURE to determine the appropriate scale factor to multiply to group 1 before dividing it into each subsequent group.

yratio will check to see if this is FOS data. However, it currently will not check what ground mode the observation was taken, etc.


input [file list]
List of FOS science data images to ratio.
output [file list]
List of output image names to place the ratios. There must be equal number of output names specified as input names.
(verbose = "yes") [boolean]
If "yes", yratio will describe its progress. If "no", yratio runs silently.


Prototype only.


Need further checking of FOS observation modes.

Needs to be written as a compiled task for speed.


Jonathan Eisenhamer


For assistance using this or any other tasks, please contact or call the help desk at 410-338-1082.

Package Help · Search Form · STSDAS