NEOWISE-R Electronic Gain and Read-noise calibration Basically, the method performs a linear regression to the lower envelope of the distribution of robust frame pixel variance versus background; then derives the electronic gain and read-noise from the fitted slope and intercept. For details, see secIV.4.a.ii.1 of the AllSky supplement. Below are derivations using different sets of scans throughout neowiser. GAINs are in e-/DN and read-noise (RN) sigmas are in DN. Multiply the latter by the respective gain to get e- units. Here are a few trend plots of the below: W1/W2 trends in electronic gains W1/W2 trends in read-noise values W1/W2 electronic gain versus temperature ------ scan range: 44948a - 44988a (~Jan 6, 2014), 9763 framesets; *** uses OLD cals! *** W1: GAIN= 3.8547 RN= 2.9785 W2: GAIN= 4.1221 RN= 2.8271 W1 robust variance vs bckgnd W2 robust variance vs bckgnd ------ scan range: 45084a - 45141a (~Jan 14, 2014), 14007 framesets; *** NEW cals used hereon *** W1: GAIN= 3.2542 RN= 2.8985 W2: GAIN= 3.6186 RN= 2.6970 W1 robust variance vs bckgnd W2 robust variance vs bckgnd ------ scan range: 46374a - 46448a (~Feb 23-24, 2014), 17610 framesets W1: GAIN= 2.9039 RN= 2.8752 W2: GAIN= 3.2465 RN= 2.5202 W1 robust variance vs bckgnd W2 robust variance vs bckgnd ------ scan range: 46625b - 46690a (~Mar 3-4, 2014), 15866 framesets W1: GAIN= 2.7075 RN= 2.8354 W2: GAIN= 3.0528 RN= 2.4177 W1 robust variance vs bckgnd W2 robust variance vs bckgnd ------ scan range: 46826a - 46896a (~Mar 10-12, 2014), 16841 framesets W1: GAIN= 2.6677 RN= 2.8408 W2: GAIN= 3.0509 RN= 2.4672 W1 robust variance vs bckgnd W2 robust variance vs bckgnd ------ scan range: 47421a - 47571a (~Mar 29 - Apr 3, 2014), 35942 framesets W1: GAIN= 2.3602 RN= 2.6525 W2: GAIN= 3.0452 RN= 2.3809 W1 robust variance vs bckgnd W2 robust variance vs bckgnd ------ scan range: 51869a - 52069a (~Aug 22 - 29, 2014), 47251 framesets W1: GAIN= 2.8631 RN= 2.7282 W2: GAIN= 3.4574 RN= 2.4784 W1 robust variance vs bckgnd W2 robust variance vs bckgnd ------ scan range: 53654b - 53953b (~Oct 21 - 30, 2014), 71621 framesets W1: GAIN= 2.7762 RN= 2.7226 W2: GAIN= 3.3732 RN= 2.4387 W1 robust variance vs bckgnd W2 robust variance vs bckgnd ------ scan range: 54790a - 55289b (~Nov 26 - Dec 13, 2014), 118533 framesets W1: GAIN= 3.2141 RN= 2.7953 W2: GAIN= 3.6491 RN= 2.5703 W1 robust variance vs bckgnd W2 robust variance vs bckgnd ------ scan range: 57361a - 57760a (~Feb 19 - Mar 04, 2015), 94061 framesets W1: GAIN= 2.6396 RN= 2.6800 W2: GAIN= 3.2855 RN= 2.3245 W1 robust variance vs bckgnd W2 robust variance vs bckgnd ------ scan range: 59265b - 59681a (~Apr 23 - May 06, 2015), 98034 framesets W1: GAIN= 3.0513 RN= 2.7335 W2: GAIN= 3.4770 RN= 2.4051 W1 robust variance vs bckgnd W2 robust variance vs bckgnd ------ scan range: 61149b - 61598a (~Jun 24 - Jul 08, 2015), 105895 framesets W1: GAIN= 3.1513 RN= 2.7453 W2: GAIN= 3.5516 RN= 2.4653 W1 robust variance vs bckgnd W2 robust variance vs bckgnd ------ scan range: 63064a - 63490a (~Aug 26 - Sep 08, 2015), 101348 framesets W1: GAIN= 2.8391 RN= 2.7524 W2: GAIN= 3.4217 RN= 2.4871 W1 robust variance vs bckgnd W2 robust variance vs bckgnd ------ scan range: 65492a - 65990a (~Nov 13 - 29, 2015), 117294 framesets W1: GAIN= 3.0655 RN= 2.7639 W2: GAIN= 3.6719 RN= 2.5695 W1 robust variance vs bckgnd W2 robust variance vs bckgnd
F. Masci, 11/30/2015