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We can see m=M+mu=22=22 so threshold mu should be 44, corresponding to z of around 0.8. Wow. That's a detection threshold. For getting a decent color we need better than 10% photometry in each band so let's go out to 0.5 for now.
| Object | RA (J2000) | DEC (J2000) | z | notes |
|---|---|---|---|---|
| Abell 2218 | 16:35:52.4 | +66:12:52 | 0.176 | |
| Abell 370 | 02:39:50 | -01:35:08 | 0.375 | |
PSZSPT J0117-5053 | 019.29320144653 | -50.88529205322 | unknown | Planck + SPT cluster but no SPT counterpart so likely low-z |
PSZSPT J0109-4552 | 017.36057472229 | -45.87871932983 | 0.02  | really low-z, likely hard to pick out cluster members? |
Typical cluster sizes are a few arcmin so a stacked image that is 1 deg x 1 deg would be plenty to get comparison regions as well.
tasks:
1) find ATLAS magnitudes of isolated SDSS LRG galaxies and construct photo-z estimator (like redmapper) for these objects.
2) Make star-galaxy discriminator perhaps by including WISE data?
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