Changes between Version 10 and Version 11 of Durham_MDS_Testing4

Timestamp:

Dec 1, 2009, 7:09:12 AM (17 years ago)

Author:

shaun.cole@…

Comment:

--

Durham_MDS_Testing4

@@ -9 +9 @@
 NB - looks like variable PSF fitting was switched on between 29871 and 30204.
 
-[[Image(30204.jpg,400px)]]
+[[Image(30204.jpg,400px)]] [[Image(30204v29871ap.jpg,400px)]]
 
-Shown is the SDSS comparison for PSF mags on the ps1-md MD08 skycell 041 i-band stack 30204 (left) and Heather's previous stack (29871) on the same cell. Blue points are SDSS classified stars. Both have nominally the same exposure time (equivalent to 41 240sec exposures) and we assume come from the same set of exposures. However, the seeing is 2.0" on 30204 but only 1.4" on 29871, and the zero points differ by about 0.4 mags (note: the zero point for 29871 has the expected value).  Clearly there are problems with the stellar photometry being non-linear.
+
+Shown (left) is the SDSS comparison for PSF mags on the ps1-md MD08 skycell 041 i-band stack 30204 (left) and Heather's previous stack (29871) on the same cell. Blue points are SDSS classified stars. Both have nominally the same exposure time (equivalent to 41 240sec exposures) and we assume come from the same set of exposures. However, the seeing is 2.0" on 30204 but only 1.4" on 29871, and the zero points differ by about 0.4 mags (note: the zero point for 29871 has the expected value).  Clearly there are problems with the stellar photometry being non-linear. ADDED LATER: the image on the right shows the same comparison but for aperture mags (for SDSS stars only). We used the SDSS Ap7 values, which are rather large at ~15" diameter, hence the high scatter. The comparisons both seem linear. 
+
+
 
 [[Image(30204-v-29871-ap.jpg,600px)]]