MIRI mosaic images not quite flagging correctly

[stscijgbot-jp]

Issue JP-1421 was created on JIRA by Misty Cracraft:

While testing a fix against JP-164, I noticed that the combined mosaic image for a set of four MIRISim images (at two dither positions), had a few quirks. The fix was to mark any pixels flagged as NON_SCIENCE by the flat field step as bad and not include them in the image combination. While it did accurately reject the pixels in the region of the 4QPMs, the Lyot spot and bar and the section between the Lyot subarray and the Imager have values around -20 while the rest of the 'good' regions have values around -10 or so. The Lyot spot and bar were flagged as NO_FLAT_FIELD while the region between the Lyot and Imager portions were flagged as both NO_FLAT_FIELD and NON_SCIENCE by the flat applied.

 

What we would like to see happen is for any regions in an overlap (if two of four images cover the Lyot spot for example), the good science pixels are used to mosaic data where available. In regions where there are no good science pixels (part of area between the Lyot and Imager), it should be zero like the 4QPMs. I'm not entirely sure what is happening in those regions right now.

I have included the files det_image_seq1_MIRIMAGE_F1130Wexp1_151test_cal.fits (seq 1 and 2, exp1 and 2) which are the images that made up the mosaic as well as the combined file starfield_151_combined_i2d.fits in the directory above for analysis.

I also attached a screen grab of the combined mosaic science image.

 

[stscijgbot-jp]

Comment by Misty Cracraft on JIRA:

Attached screen grabs of the context and weight maps of the combined image for reference.

 

[stscijgbot-jp]

Comment by James Davies on JIRA:

I believe this issue is fixed now, as the weight map now reflects the inverse variance weighting and the DQ flags are handled correctly. See attached stage 3 _i2d.fits image below showing the sci and wht arrays from regression test data process nightly. This was fixed in

#5738

and was available in B7.7.1.

!sci.png|thumbnail!

!wht.png|thumbnail!

Misty Cracraft would you be able to confirm this is fixed for your datasets as well?

[stscijgbot-jp]

Comment by Misty Cracraft on JIRA:

I just ran a new set of simulations this week, and the combinations are looking much better. When I have four images such that the mosaic covers the region of the lyot bar and hole in the middle, I no longer see the hole or bar in the combined image.

gal_starfield.png attached is the latest data run.

[stscijgbot-jp]

Comment by James Davies on JIRA:

Great! I'm going to call this resolved then. If you agree, you can close the issue.

[stscijgbot-jp]

Comment by Karl Gordon on JIRA:

Looks much better! Great.

[stscijgbot-jp]

Comment by Howard Bushouse on JIRA:

Fixed by #5738