Fix Version/s: None
Team:Data Release Production
Current image processing runs the skyCorrection.py routines to produce an improved background map. This process, in brief, 1) adds back on the original calexpBackground to its calexp (essentially undoing any visit-level background subtraction); 2) bins all CCDs for a single visit into 8192x8192 pixel superpixels, fits an Akima spline to these clipped-mean values and subtracts this bgModel; 3) fits and subtracts a sky frame across the entire focal plane; and 4) performs an additional background model subtraction (bgModel2) as in 2), but using smaller superpixel sizes of 256x256 pixels.
In Aihara et al. 2019, the bin scale of this bgModel step is given as 1024x1024 pixels. Since then, this step has split into two: an initial large-scale subtraction of 8192x8192 pixels (step 2 above) and a second medium-scale subtraction of 256x256 pixels (step 4 above). This ticket explores the effects of increasing this medium-scale bin size to 1024x1024 pixels as indicated in the Aihara et al. 2019 paper.
All three RC2 tracts have been reprocessed with the following config modifications:
Beginning with w_2020_34/
DM-26441 data, these processing steps have been run:
As a prior reference dataset, I'm again refering to the data processing in w_2020_34/
DM-26441. For this round of testing, all 26 visits which contribute to the GAMA HSC-I band tract (9615) were reprocessed. Further analysis of relevant figures is found in the comments below.
In summary, it appears that the current configuration produces more optimal outputs than the proposed change (i.e., bgModel2 set at the current 256 pixel value is superior to the proposed 1024 pixel value). This is due to the coadd outputs looking to be more stable, and producing fewer stacking edge artefacts. No further action is recommended in modifying bgModel2 at this time.
All outputs are available on lsst-devl at: /project/lskelvin/bgModel2, on the RSP at: /home/lskelvin/bgModel2, or at this web link: https://lsst.ncsa.illinois.edu/~lskelvin/project/bgModel2.