For those unaware, hscPipe 5.x is based on LSST 13.0 (it actually branched a little later, but before the big pybind change).
A single FITS image covering 64 square degrees probably wouldn’t work, so our pipeline divides the sky up into “tracts” which are essentially defined by their projection center, plate scale, and projection scheme. Each tract is divided into “patches”. Each patch within a tract shares the
Wcs of the tract, but have different integer offsets, with overlaps so we don’t run into edge issues. We have different schemes for generating tracts (tessellating the sphere); in my opinion, the two most useful are:
rings: the sphere is divided up into bands of declination, and tracts lie along each band. This is used by the HSC Survey, and is therefore the default for HSC data.
discrete: tracts are placed at positions nominated by the user (perhaps through the data, if you use
You’ll need to decide which is suitable for your science. While
discrete would allow you to create the “single stacked mosaic” you desire (using a single tract to cover your survey area), you’ll need to decide whether the distortion at the edges is tolerable. If you want to use
rings, you run
rings is the default for HSC); if you want to use
discrete then it’s easiest to run
makeDiscreteSkyMap.py (that sets the projection center and size based on the data; if you’re interested, there’s an alternative means to set those explicitly to values you choose). Then it’s just a matter of running
coaddDriver.py to create the coadds. Don’t worry about
assembleCoadd.py — that runs just a single element of what
coaddDriver.py will run.
Now, your specific problems:
I haven’t seen an error like that in a long time, and never in this context. You might check your shell limits on the number of open file descriptors (
ulimit -n). Can you provide some more details, like the command-line you’re running?
I believe the “size scatter” refers to the PSF ellipticity residuals. Our reductions of HSC images are aimed at producing good data for weak lensing studies, so images for which we have trouble modeling the PSF are not included in the coadd. You can adjust the threshold as Bob has indicated (there are ways to turn that behaviour off, but it’s more complicated and probably unnecessary).