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| Joint Astronomy Centre |
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MEF filesDownloaded image files from the WSA are currently Rice-compressed Multiextension FITS files, in which four extensions correspond to the four WFCAM detectors. The file name format is typically w<date>_<num>_sf_st.fit. This page shows how to (i) reverse the Rice compression to get an uncompressed MEF, and (ii) how to then convert into Starlink SDF files.Disk spaceFirst, make sure you have enough disk space (because a single 5-point jitter with 2x2 microstepping will, when uncompressed, weigh in at more than 130 Mbyte per camera).ConvertingGet and install the imcopy programme referred to on the WSA site,The conversion from compressed MEF into SDFs for the individual cameras is a two-step process. Undo the Rice compression and extract the individual camera images as follows: imcopy
w<date>_<num>_sf_st.fit temp.fit
then run up the Starlink conversion routines and use fits2ndf to effect the conversion: convert
fits2ndf
in='temp.fit[1]' out='w'
fits2ndf in='temp.fit[2]' out='x' and so on. Starlink files w.sdf, x.sdf, etc. are then the individual camera mosaics. |