% @(#)computsky.hlq 17.1.1.1 (ESO-IPG) 01/25/02 17:18:47 \se SECTION./COMP \es\co COMPUTE/SKY 05-JUL-1989 AL/RHW \oc\su COMPUTE/SKY infram1 infram2 caltab method sky_factor compute the sky background and restitute the frame \us\pu Purpose: Compute the sky background and restitute the frame \up\sy Syntax: COMPUTE/SKY infram1 infram2 caltab method sky_factor \ys\pa infram1 = first input frame \ap\pa infram2 = second input frame; if method = 3 then infram2 = infram1 \ap\pa caltab = calibration table containing calibration coefficients for thr characteristic curve. This table can be created with CONVERT/DTOM \ap\pa method = method to be used:\\ 1 = PDS scan after 14/4/1984 (descriptor O_TIME set to 1984.5 \\ 2 = PDS scan before 14/4/1984\\ 3 = only one input frame, second frame is equal to first frame; only desciptor SKYBGR is update; this is the default;\\ 0 = same as 1 but no pixel replacement \ap\pa sky_factor = sky_factor; default 1.4 \ap\no Note: With the two input frames A and B (where B is a subset of A) and the calibration table, containing the coefficients the following will be done:\\ a. A flat sky background will be through the intensity level lower than the highest intensity level in the histogram of frame A multiplied by sky_factor. The background is determined inside 8 rectangualar areas surrounding frame B and within two concentric circles;\\ b. get the PDS density population of the upper 5 and 10 percent in the intensity distribution in B;\\ c. Determine the centroid of these pixel distributions. \\ If infram1 = infram2 only part of the operations is done. \on\exs Examples: \ex COMPUTE/SKY GAL1 GALSUB GALTAB 1 2.0 \xe \sxe