"Color terms of Y-band DECam vs UKIDSS LAS photometry for stars with g-r<0.8 are within 0.04 (TBC) of values predicted from synthetic photometry using expected component wavelength responses. "
This is primarily a test of how well we understand the DES Y passband system response curve.
This is essentially a duplicate of Cal-R2, but for the Y band.
The same as for Cal-R2.
The procedure is the same as for Cal-R2, with the additional caveat that the SDSS Stripe 82 field(s) used for Cal-R2 should overlap the UKIDSS LAS and/or (preferably) the regions of the PreCam Survey that have been covered in Y-band.
The values of the fitted color ("b") terms must be within 0.04 mag/mag of the synthetic values.
As for Cal-R2, if the measured (fitted) values color terms are out of tolerance with their synthetic values, we will need to identify the source of error. This will likely require involvement by the DECal team.
See "Other Notes" from Cal-R2.