Changes between Version 7 and Version 8 of IPP_Progress_Report_20100816

Timestamp:

Aug 23, 2010, 9:31:02 PM (16 years ago)

Author:

watersc1

Comment:

--

IPP_Progress_Report_20100816

@@ -5 +5 @@
 
 === Eugene Magnier ===
+IPP Code Updates
+
+We are in the process of switching the operational IPP code to a new
+software release.   The new tag is ipp-20100823.
+
+This update includes a number of features and fixes to issues which
+have been in progress for some time.  Here is a summary list of the
+main salient points:
+
+1) a new "staticsky" distribution component : this is the method by
+which we will be distributing the results from the full photometry
+analysis of the static sky images.
+
+2) Full extended source analysis!  psphot is now able to produce
+acceptable measurements of all of the extended source parameters on
+our list.
+  a) for all sources, we are now including Kron parameters (Kron flux
+and error in an aperture 2.5 times the first radial moment (R1), plus
+the flux within 1 times R and 4 times R1, as well as the value of R1.
+  b) in the static sky analysis, for all sources we now report the
+radial aperture measurements (this was available in the earlier MD04
+example set).
+  c) Petrosian and elliptical surface brightness profiles for a subset
+of extended sources (S/N above some cut off to be defined, probably
+based on galactic latitude)
+  d) PSF-convolved model fits for a subset of extended sources for
+Exponential, DeVaucouleur, and Sersic models.
+
+3) fixed the forced photometry non-negative flux bug
+
+4) added some other new stats:
+ a) for PSF fits, we now have "psfWeightNotPoor" and "psfWeightNotBad"
+: the first gives the fraction of psf-weighted unmasked pixels
+considering any mask bits (except the internal 'mark' bit), while the
+former considers only 'bad' mask bits -- these are written to QF_PSF
+and QF_PSF_PERFECT in the CMF / SMF files.  This may help to exclude
+false sources in subtracted burn regions (SUSPECT mask bit) or sources
+too close to a mask edge (CONV.POOR mask bit).
+ b) raw aperture magnitudes (in addition to the curve-of-growth
+corrected version) for PSF measurements.
+ c) in diff images, we now have several additional statistics related
+to the proximity of a diff detection to an input image source:
+DIFF_R_P, SN_P : distance and S/N of nearest bright source in the plus
+image, DIFF_R_M,SN_M : same for the minus image.
+ d) for PSF sources, we have added several higher order moments:
+MOMENTS_M3C,S (third moments cos & sin theta), and same for 4th
+moments.
+
+5) somewhat better CR / EXT tests, including use of Kron magnitude as
+test for source size (CR vs EXT) instead of PSF-based aperture.
+(though these are not yet reported as a probability).
+
+6) save the radial profile aperture sizes in the headers
+
+7) swap read order in dvomerge to loop over the available input tables
+and merge them with existing output tables
+
+8) allow dvomerge to operate on only a region of the sky
+
+9) update to dvomerge to allow different average photcodes in the
+inputs and the output database.
+
+10) some important issues in ppSub that were resulting is somewhat
+poor matches when the IQ difference between the two images was large:
+  a) ensure masked pixels are NANed in output diff image
+  b) define separate penalties for each image (based on their fwhm values)
+  c) define separate apertures for each image for flux normalization
+  d) choose aperture based on curve-of-growth (was based on fixed
+fraction of full aperture flux, and thus noisy)
+  e) some fine tuning of the penalty factor (this still seems
+arbitrary, and results are somewhat sensitive to the right value)
+
+Note that there are three new output formats that are needed to make
+all of these features part of the standard products:
+
+for chip-image processing: PS1_V3
+for staticsky processing: PS1_SV1
+for diff processing: PS1_DV2
+
+I would like to run with the old versions for a few days to check that
+there are no problems, and to give people a bit of a warning.  we need
+to be particularly careful that the MOPS folks do not get torqued by
+the diff output changes.
+
+Data Samples:
+
+I am placing two example data set (simulated images) that illustrate
+the extended source analysis and the difference image analysis
+
+rsync://pikake.ifa.hawaii.edu/psphot.extended.simtest  :  this
+directory contains a set of images with fake galaxies (a range of
+sersic parameters, convolved with a Gaussian seeing kernel) and psphot
+fits to those same images. (inputs are image.fake.NN.fits, outputs are
+image.fake.pcm.x2.*)
+
+rsync://pikake.ifa.hawaii.edu/ppsub.samples.simtest : this directory
+contains an extensive set of images with different PSFs all
+differenced against each other with the newly-updated psphot.  There
+are two classes of images: those with .fg in the name have Gaussian
+PSFs (range of sizes, axis ratios, and angles), while those with .fp
+use the PS1_V1 model (a wingier PSF meant to mimic PS1).
+
+rsync://pikake.ifa.hawaii.edu/ppsub.samples.simtest.oldcode : the same
+set of input image pairs diff'ed using the previous version of ppSub.
+
+We will attempt to run MD04 with the static sky analysis tomorrow for
+people to play with.
+
+MD04 Photometry
+
+I have done some investigation of the high systematic photometry
+errors in the MD04 stacks as reported by Nigel M.  Some of the plots
+related to this study can be found here:
+https://svn.pan-starrs.ifa.hawaii.edu/trac/ipp/wiki/MD04_Stack_Photometry_20100819
+
+I first checked that the PSFs of the stars had a consistent shape by
+overlaying the normalized PSFs, and confirmed that they are indeed
+consistent.
+
+I next examined the impact of different PSF models, to check the
+impact of the choice of model shape (ie, is the photometry more
+consistent the more accurately the PSF is modelled).  This did not
+have a huge impact on the photometry (the bright-end sag was still
+apparent), but the bright end photometric scatter is less in my
+analysis (PSF - AP) than in Nigel's (PS1 - SDSS).
+
+I then ran the same tests using non-poisson weights.  This addresses
+the bright end sag, and perhaps tightens the photometry a bit.
 
 === Serge Chastel ===