Target Selection of F Star Photometric Standards

We select F type stars as photometric standards. In the following, we use PSF magnitudes. Magnitudes are extinction corrected linear mags defined as

m = 22.5 – 2.5*alog10( psf_flux ) m = m – extinction

Star Selection

We select stars by demanding objc_type == 6.

Flag Cuts

F star standards must be

 STATIONARY     in OBJECT2 objc flags SURVEY_PRIMARY in RESOLVE_STATUS flags PHOTOMETRIC    in CALIB_STATUS flags.

Standards must not be

 in OBJECT1 objc_flags BLENDED, TOO_MANY_PEAKS, CR, SATUR, BADSKY in OBJECT2 objc_flags2 PEAKS_TOO_CLOSE, NOTCHECKED_CENTER SATUR_CENTER, INTERP_CENTER, PSF_FLUX_INTERP INTERP

and must fall in these magnitude and color ranges:

  • 15.0 < r < 19
  • [((u–g) – 0.82)2 + ((g–r) – 0.30)2 + ((r–i) – 0.09)2 + ((i–z) – 0.02)2]1/2 < 0.08