3 unique AstroDrizzle errors for WFC3/IR when skymethod='match'

[mackjenn]

MAST pipeline drizzle reprocessing failed for ~300/150,000 IR associations when changing skymethod from 'localmin' to 'match' in the MDRIZTAB reference file. The WFC3 team requests that these be looked at by @mcara so that the remaining drizzled data products will be generated.

Datasets and a readme file have been provided for each type of error in the directories below with priority from highest to lowest:

Error 1: Perfect overlap between exposures in the ASN (no dither or RPT-OBS) /user/mack/for_mihai/14074_error_perfect_overlap/

• File "/Users/mack/miniconda3/envs/astroconda/lib/python3.5/site-packages/spherical_geometry/graph.py", line 392, in _sanity_check
• assert len(node._edges) >= 2
• “No module named 'mpl_toolkits.basemap”

Error 2: Overlap between some, but not all exposures in the ASN /user/mack/for_mihai/15153_error_some_overlap/

• "Keyword 'MDRIZSKY' not found."

Error 3: No overlap between any exposures in the ASN (only 1 dataset has this) /user/mack/for_mihai/15146_error_no_overlap/

• "Arrays cannot be empty"

[mackjenn]

I've tested the updates, and all 3 errors are resolved pending this change to sky.py

subtracted_sky = skysubimage[extname,extver].header[skyKW]

subtracted_sky = skysubimage[extname, extver].header.get(skyKW, 0.)

[mcara]

@mackjenn Thank you for testing!