From: Roc Cutri Subject: Re: S/N (repeatability) vs mag vs b (fwd) Date: December 1, 2012 3:24:50 PM PST To: Peter Eisenhardt , Josh Bloom , Christopher Klein , Frank Masci , Ned Wright All, I have added some data points for the photometric repeatability vs. galactic latitude and longitude, per Peter's note. I used the WISE All-Sky Catalog data to determine these estimated values, not the pass 2 Post-Cryo Single-exposure data like Frank did. We know that the Post-Cryo W1 and W2 sensitivity is within 10% of that during the Cryo mission, so the All-Sky Catalog should be representative. I extracted all W1 and W2 detections in 2 degree diameter circular regions centered at 90, 180 and 270 glon and -5, 0 and +5 deg glat at each longitude. I computed the trimmed average values of w1sigP1 and w2sigP1 in bins of 0.2 mag of w1mpro and w2mpro, respectively. The w?sigP1 values for each Catalog source are the RMS (root variance) of the fluxes measured on all of the individual frames contributing to a source (including upper limits), expressed in magnitudes. I then determined the w1mpro (Catalog profile-fit magnitude) at which the average RMS of the frame measurements was 0.054, 0.109 and 0.217 mags (SNR=20,10,5). The attached table gives the W1 and W2 magnitudes for each "SNR" level at each location. I estimate the accuracy of these numbers are of order 0.05-0.10 mags. Roc ---------------------------------------------------------------------------- glon glat SNR20(W1) SNR10(W1) SNR5(W1) SNR20(W2) SNR10(W2) SNR5(W2) (deg) (deg) (mag) (mag) (mag) (mag) (mag) (mag) 90 0 13.16 14.26 15.17 12.10 13.20 14.20 90 -5 13.50 14.55 15.50 12.34 13.45 14.30 90 +5 13.40 14.40 15.40 12.20 13.29 14.20 180 0 13.65 14.65 15.55 12.35 13.35 14.25 180 -5 13.70 14.75 15.65 12.50 13.47 14.38 180 +5 13.69 14.70 15.60 12.50 13.50 14.37 270 0 13.35 14.40 15.35 12.19 13.25 14.18 270 -5 13.50 14.60 15.50 12.35 13.40 14.30 270 +5 13.65 14.75 15.60 12.55 13.55 14.42 ----------------------------------------------------------------------------