Changes between Version 13 and Version 14 of Durham_MDS_Testing3

Timestamp:

Nov 23, 2009, 12:32:56 AM (17 years ago)

Author:

shaun.cole@…

Comment:

--

Durham_MDS_Testing3

@@ -34 +34 @@
 Points to note: the stars on Heather's stack show a scale error wrt SDSS. Pauls nightly stack before the clipping fix was problematic. After the fix the photometry is much improved, but still shows more scatter than the original data.
 
+'''Warp-warp comparisons:''' 
+We examine the input warps to Paul's nightly stack 25532. We use 14462(1), 14464(3), 14465(2), 14466(6), 14467(7), 14468(5), 14469(8), 14471(4) - the numbers in brackets indicate those used in the table below. Unfortunately these are not the identical warps used by Paul, although they are from the same original exposures. Paul has a later reprocessed set which have not been magiced, so we cannot access them. In the table below we compare IPP aperture magnitudes (AP_MAG) between pairs of warps. The RMS is probably the more interesting figure, as the Mean just tells you whether it was photometric or not (or whether the seeing varied). The comparisons are restrictred to AP_MAG magnitudes between -14 and -10 and the differences are clipped at +/-0.20 to remove outliers.
+
+|| Pair || Mean || RMS ||
+|| 1v2  || -0.047 || 0.030 ||
+|| 1v3 || -0.028 || 0.030 ||
+|| 1v4 || -0.028 || 0.032 ||
+|| 1v5 || -0.031 || 0.029 ||
+|| 1v6 || -0.019 || 0.029 ||
+|| 1v7 || -0.015 || 0.028 ||
+|| 1v8 || -0.022 || 0.031 ||
+
+
+'''Clipping:'''
 Below is an example of a remaining problem with the clipping. This is the weight map round a star on Paul's fixed 25532 8-exposure stack. Successive gradations in the levels indicate how many warps are contributing to a particular pixel (with at most 8 warps it is easy to see the difference in levels) - brighter means fewer warps. Notice how, as one approaches the star radially, successively fewer and fewer warps appears to contribute (note: in the very centre the star is no longer sky noise dominated so the quantisation is no longer seen - I have set this area to be white).