sndrizpipe version 1.2

sndrizpipe v1.2 : Bug fixes and new features.

• we were weighting by ERR instead of EXP or IVM, which led to suppressed flux in the output sources.
• this is now fixed, and tested with std star aperture photometry, compared to synphot mags.

• when new flt files appear in the flt dir, we update the existing _epochs.txt file, adding new epochs as needed (but never such that we would have to renumber any existing epochs).
• Two new columns now record the exposure time and the angular separation from the target ra,dec to the image RA_TARG, DEC_TARG. These are helpful for identifying bad or superfluous exposures.

• mkscaledtemplate.py has become pseudodiff.py

Various other small improvements and bug fixes.