Changes between Version 40 and Version 41 of Sa10Problems

Timestamp:

Dec 11, 2012, 5:06:38 PM (14 years ago)

Author:

eugene

Comment:

--

Sa10Problems

@@ -44 +44 @@
      * a. FOr the 12% that have raerr > 0.1, the majority come from (ng+nr+ni+nz+ny) = 0 or only a few suspect the calculation is goofy because there are few points to calculate raerr. '''(GENE??)'''
      * a. For the 70% that have ra = 0, I did a count(*) and grouped by objInfoFlag. I repeated this for raerr!=0.  Here's what I find:  if 0x00090000 (avg position used and fitted) is not set, it has raErr = 0 (this is the majority of things).  If 0x0040000 (mean astro could not be measured) is set, may fall into either, with a preference for raerr!=0.  why do so many not have 0x00090000? are those entirely the stacks? the majority of those have a detection in a filter (for the raErr=0, and flag = 4194304).  If I do a similar query but without the restriction on flags (same raerr = 0), I find a whopping majority have NO ng/nr/ni/nz/ny, ie, they are stacks.
-       *  '''We need to make it very clear that raErr / decErr is calculated from an average of single frame detections, and may not be present at all when it is a stack with no or few single frame detetctions ''' 
+       *  '''We need to make it very clear that raErr / decErr is calculated from an average of single frame detections, and may not be present at all when it is a stack with no or few single frame detetctions '''
+       * '''EAM update : if we only have stack measurements, and they are forced to match a single input (ie, y-band), all ra/dec values will be identical (because the skycells have the same astrometry and the matched detections use the coordinate of the referring source), thus the stdev will be 0.0.'''
   * A3: 0.1% have ndetections = -999 (one specific patch in ra & dec)
      * a. This is due to a failed batch (outside of PSPS's ra/dec range)  I thought it had been fixed (conrad?)