nirwals 0.0.5

basic instrument signature removal for the NIRWALS instrument on the SALT telescope

nirwals_reduce - instrumental detrending pipeline for SALT NIRWALS

How to run

rss_reduce [options] file.fits

Available options

--maxfiles=N specifies the maximum number of files to open for a given up-the-ramp group. This is mostly to limit RAM usage. Default is no limit.

--nonlinearity=file.fits Apply non-linearity corrections to the reference-pixel/first-read subtracted dataset. The reference file should be a file generated via the rssnir_fit_nonlinearity tool to contain the pixel-level corrections in the correct format

--flat=flat.fits Specify a flatfield frame. Not implemented yet.

--dark=dark.fits Subtract a dark-current correction from the entire input data cube. Use rssnir_makedark.py to generate the dark calibration frame.

--output=suffix When generating the output filename, the specified suffix is inserted into the input filename. Example: for input file rss_test.fits the output filename would be _rss_test.suffix.fits. Default is "reduced".

--refpixel Use the reference pixel in the first & last 4 rows and columns to subtraced an instrumental pedestal level off all the input data. If not specified the first read is considered to contain this zero-exposure offset.

--dumps Mostly used for debugging. When provided the tool also writes a number of intermediate data products to disk that allow testing and verification.

Example call:

/work/rss/rss_reduce.py --refpixel --maxfiles=70 SALT_data_RN_20220606/20220606_RN_URG_2reads_9dB.540.1.20.fits

output:

rkotulla@legion:/work/rss/salt> ../rss_reduce/rss_reduce.py --refpixel \
    --maxfiles=70 SALT_data_RN_20220606/20220606_RN_URG_2reads_9dB.540.1.20.fits
/work/rss/salt/SALT_data_RN_20220606/20220606_RN_URG_2reads_9dB.540.1.20.fits
/work/rss/salt/SALT_data_RN_20220606/20220606_RN_URG_2reads_9dB.540.1.1.fits
 -- /work/rss/salt/SALT_data_RN_20220606/20220606_RN_URG_2reads_9dB.540.1.2.fits
 -- /work/rss/salt/SALT_data_RN_20220606/20220606_RN_URG_2reads_9dB.540.1.3.fits
 -- /work/rss/salt/SALT_data_RN_20220606/20220606_RN_URG_2reads_9dB.540.1.4.fits
...
 -- /work/rss/salt/SALT_data_RN_20220606/20220606_RN_URG_2reads_9dB.540.1.247.fits
 -- /work/rss/salt/SALT_data_RN_20220606/20220606_RN_URG_2reads_9dB.540.1.248.fits
 -- /work/rss/salt/SALT_data_RN_20220606/20220606_RN_URG_2reads_9dB.540.1.249.fits
 -- /work/rss/salt/SALT_data_RN_20220606/20220606_RN_URG_2reads_9dB.540.1.250.fits
Limiting filelist to 70 frames
(70, 2048, 2048)
Applying non-linearity corrections
No nonlinearity corrections loaded, skipping
No linearized data found, using raw data instead
No dark correction requested, skipping
diff stack: (70, 2048, 2048)
Identifying bad pixels
Cleaning image cube
calculating final image from stack
Writing reduced results to 20220606_RN_URG_2reads_9dB.540.1.reduced.fits
all done!

Caveats and limitations

• Not yet supported are fowler-reads of any kind, in particular when combined with up the ramp sampling.
• Watch out when running on large numbers of up-the-ramp samples to avoid running out of memory (RAM). At this time the tool is optimized towards computing time at the expense of memory demand. If in doubt or to begin use the --maxfiles option to limit the number the number of open files and thus the memory footprint.