I’m excited to see the excellent DP1 release and its detailed draft documentation. I see that DP1 reports ~2.3 million distinct astrophysical objects and uses the Monster catalog for astrometric and photometric calibration.
As an amateur, I’ll be bold and ask whether there is an estimate of how many of the detected objects were previously detected in other surveys (e.g., Pan-STARRS, DES, HSC) versus how many are “new” (not detected in any prior public survey catalogs)?
At a superficial level, I guess that someone might have counted the number of monster catalog entries in the areas that were observed for DP1. Is that available anywhere?
Next, I guess one could do a cross-match analysis at the level of individual objects.
Has that been done? Is it planned for future data previews or DR1, or is that left up to the science collaborations and/or individuals?
The Monster catalog is meant for calibration (which is done with stars with high signal-to-noise in single visits), so I don’t think it goes very deep, and it shouldn’t contain galaxies. The vast majority of objects in the extragalactic fields are and will be faint galaxies just from the steep shape of the apparent magnitude distribution for galaxies. Similarly, galactic fields will have many faint stars, though not as large of a proportion as with galaxies.
We have done crossmatching for several of the fields in DP1 and a brief summary of some of those results is in the paper draft. Part of ECDFS is covered by very deep HST & JWST imaging and so there probably aren’t many new detections there. Outside of that area, the DP1 catalog is deeper than the corresponding Legacy Survey (i.e. DECam) and Euclid Q1 catalogs but I would hesitate to quote a specific number of new detections because deep fields like ECDFS have been covered by many instruments and surveys and we have not done an exhaustive crossmatch to every public catalog. Like I said earlier, there are a lot of very faint galaxies and you need to be careful selecting objects near the detection limits.
Hi Maciej, no, I have not tried matching against other ground-based catalogs. This is something I’d encourage DP1 users to try if they are interested. Similarly, if someone were to produce a kind of omnibus catalog for CDFS like COSMOS2020/2025, we (Data Management) would surely use it, but it’s more effort than we can spare to do ourselves at the moment.