Create program to rescale dark file

[benj]

We need a program that will read in a dark frame file, rescale it to mimic that for a different integration time and then output the new file.

Basic level: Read in data file, multiply by a user-specified scaling factor (except pixels 1 & 2 on band 1 for each line), output new data file.

What we really want: Same, but calculate scaling factor from differential of integration times - check relative data values for existing dark files to try and work out if the result of changing the integration time is just a linear scaling (hopefully) or something more complicated, then implement appropriate algorithm. The user should also be able to specify a scaling factor as above if they prefer.

Gold-plated: Same, but also account for changes in framerate and in spectral/spatial binning. May be worth spending half an hour to check whether the effects of altering these are also just linear scaling, but if they're not then don't include them (assume constant).

Related tickets: #218 #249

[jatt]

Basic level script has been completed and is at:-

~jatt/scratch/scripts/darkframes_scale_basic.py

Tested using:

• ~arsf/arsf_data/2008/flight_data/vocals/VOC_08-2008_310_Chile/hawk/SWIRshvoc08_31008-4dark.raw
• ~arsf/arsf_data/2008/flight_data/vocals/VOC_08-2008_310_Chile/hawk/SWIRshvoc08_31008-4dark.hdr

and a scale factor of 2

New output darkframes file is at:

• ~jatt/scratch/ARSF/newdark_test.raw
• ~jatt/scratch/ARSF/newdark_test.hdr

[benj]

Hawk dark frame values varying with integration time

[benj]

Jane's script suggests that the Hawk dark frame values are linearly proportional to integration time. Regression suggests that the dark frame value is in the region of 320 times the integration time. Actual values obtained from gnuplot's curve (well, line) fitting:

Final set of parameters            Asymptotic Standard Error
=======================            ==========================

m               = 322.077          +/- 3.197        (0.9925%)
c               = -30.1481         +/- 41.63        (138.1%)

Graph:

[jatt]

My script suggests that the values for Eagle are constant within the range of 51 - 62 regardless of binning and integration time.

[mggr]

Push this code into ~arsf and close the ticket?

[benj]

We actually wound up not needing this code - Eagle frames didn't need rescaling (dark frame values constant irrespective of integration time), and for Hawk the rescaling can be done within azspec.

Closing ticket.

[mggr]

Added convenience links for later memory assistance ;)