Summary of MD09.refstack.20130613

(back to MediumDeepFields summary)

Similar to the MD09.GR0 (MD.GR0) refstacks for the 2011/2012 season, these include recent improvement and input cuts to help constrain the convolved stacks as well. Overall fewer inputs to the refstack were done this round and may not be as deep as last season.

MD09 observations:

• starting late June 2013, pre-observations in late May and early-mid June
• early June 2012 through late Dec. 2012
• late June 2011 through early Dec. 2011
• late June 2010 through mid-Dec. 2010
• early June 2009 through end Sept. 2009
• (some 2008 but pre-survey)

Filter	N total	N FWHM<8 pixels	N (FWHM<8 pixels for 2012
g
r
i
z
y

• 2012 wasn't a great season for MD09 either (like MD08)

Status:

• 04/0/13 selected exposure reprocessing chip->warp for refstack started (late due to power outage and messy system crashes)
• 04/14 reftests finished, full refstack started
• 04/15 refstack finished, checked and problem skycells found/fixed if possible. staticsky single filter only finished and mappings started
• 04/16? mappings finished, reftest+refstack to distribution
• 04/19? refstack setup, recently missed exposures setup for diffims

MD09.V3 Processing (chip->warp + refstack)

Exposure reprocessing was done for only a limited number (~150) of the best images from 2010-2012 to provide a balance of N input warps versus best seeing, excluding exposures with large background, low zeropoints and large elongation.

Processing chip-warp and the refstack itself has the same label, data_group

• label: MD09.refstack.20130613 --> once set as active refstack for diffims, stack label will change to MD09.refstack, chip/cam/warp label will remain the same
• data_group: MD09.refstack.20130613

The ipp-20130307 tag used still.

Histograms of the FWHM major and minor and elongation from camera stage value (full exposure) for the sample of reprocessed exposures (red) and used for refstack.20130613 (top blue) and used for refstack.20120831 (bottom blue) in grizy order

Test stack (reftest) sample also made again for skycell.055 with different number of input warps.

• label: MD09.reftest.20130613
• data_group:
  • MD09.reftest.20130613.c#f<FWHM cut> where #=comparison run, <FWHM cut>=cut <fwhm_major from camProcessedExp x10>
  • MD09.reftest.20130613.all.<FWHM cut> where all means 05/2010+2011+2012 data possible, <FWHM cut>=cut <fwhm_major from camProcessedExp x10>
  • MD09.reftest.20130613.2012.<FWHM cut> where 2012 means 2012 data only for season stack example case, <FWHM cut>=cut <fwhm_major from camProcessedExp x10>
• the main field center shift was through ~Dec 2009, but is a very small shift. Excluding 2009 since usually not very good, or uncharacteristically too good (avoiding problems basically)
• c1 cuts

  filter: (FWHM set), elongation, zeropoint, background limits
  y: (3.6, 3.9, 4.1, 4.5), 1.3, 22.8, 4000 -- 
  z: (3.6, 3.7, 3.8, 4.0), 1.3, 24.0, 3000 --
  i: (3.9, 4.1, 4.2, 4.4), 1.25, 24.3, 2000 --
  r: (4.1, 4.3, 4.4, 4.6), 1.25, 24.3, 600 -- 
  g: (4.6, 4.8, 4.9, 5.1), 1.25, 24.3, 400 -- 
  

Summary comparison table with the approximate FWHM (major) as the PSF FWHM from a center field skycell (V3=055) after running psphot on the stacks.

| data_group                    | filter  | stack_id | warps_in | warps_rej |  FWHM_MAJ   IQ_FW1 (pixels)
+-------------------------------+---------+----------+----------+-----------+
--> 2013 refstack

--> reftest comparisons					

	
--> previous 2012 refstack				

As before, the FWHM_MAJOR with the central skycell can be variable and more so with largely different input sets. Comparison with the psf_major/minor maps are more useful between refstack versions.

Problems

• as with all past refstacks, generally edge skycells have issues -- need better containment of those still. (see core coverage below).
• like others, greater % of inputs rejected (20-30%) so per pixel input is less, but still of order 30 inputs per pixel
• some convolved stacks have poorer FWHM PSF but not significant enough to be likely improved by reprocessing using DEEP_STACK config as in earlier MD fields
• g,i in particular seems to vaguely show the arc of shallower depth but no where close to what last year's refstack had?
• skycell details:
  • y:
  • z:
  • i:
  • r:
  • g:

Core coverage -- one of the larger shifted pointings so very different from normal distribution of skycells (also see detection efficiency maps below)

• skycells with fewer inputs: ; ~50% or less

Refstack Summary

Refstacks run through the staticsky (single filter mode so basic psphot with deteff measurements) and skycal stage on the unconvolved stacks to make the map plots (full 5 filter version still having occasional faults to work through):

• label: MD09.refstack.20130613, MD09.refstack.20130613
• data_group: MD09.refstack.20130613.1x20130615, MD09.refstack.20130613.1x20130615.cal20130615

Source photometry psf_major,_minor maps (grizy):

Magnitude of sources@5-sigma maps (grizy):

Detection efficiency magnitude @50% recovery (500 fakes, grizy):