Summary of MD01.refstack.20120803

Similar to the MD01.GR0 (MD.GR0#MD01.GR0) refstacks for the 2011/2012 season, these include recent improvement and input cuts to help constrain the convolved stacks as well. Because the refstack is made with reprocessed pixels, the refstack pixels will now have the ubercalibration.

MD01 observations started in August (last season started mid-August and ended mid-January).

Filter N total N FWHM<8 pixels N (FWHM<8 pixels for 2011
g 520 421 144
r 489 430 136
i 555 505 187
z 659 602 243
y 365 337 179

MD01.V3 Processing (chip->warp + refstack)

Exposure reprocessing was done for only a limited number (~150) of the best images from 2010+2011 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: MD01.refstack.20120803 --> once set as active refstack for diffims, stack label will change to MD01.refstack, chip/cam/warp label will remain the same
  • data_group: MD01.refstack.20120803

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.20120803 (top blue) and used for refstack.2011 (bottom blue) in grizy order

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

  • label: MD01.reftest.20120803
  • data_group:
    • MD01.reftest.20120803.c#f<FWHM cut> where #=comparison run, <FWHM cut>=cut <fwhm_major from camProcessedExp x10>
    • MD01.reftest.20120803.all.<FWHM cut> where all means 2009+2010+2011 data possible, <FWHM cut>=cut <fwhm_major from camProcessedExp x10>
    • MD01.reftest.20120803.2011.<FWHM cut> where 2011 means 2011 data only, <FWHM cut>=cut <fwhm_major from camProcessedExp x10>

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.

version data_group (stack_id) filter center skycell input warps (rej) center skycell FWHM (major, pixels)
new MD01.refstack.20120803 g 96(29) 5.28
MD01.reftest.20120803.all.50 g 68(22)
MD01.reftest.20120803.2011.50 g 54(16)
MD01.reftest.20120803.c1f49 g 36(10) 5.11
MD01.reftest.20120803.c1f51 g 66(16) 5.18
MD01.reftest.20120803.c1f53 g 95(29) 4.91
MD01.reftest.20120803.c1f55 g 108(46) 4.89
old MD01.refstack.20110820 g 65(7) 4.80
new MD01.refstack.20120803 r 84(20) 4.60
MD01.reftest.20120803.all.45 r 74(21)
MD01.reftest.20120803.2011.45 r 52(20)
MD01.reftest.20120803.c1f42 r 36(5) 4.58
MD01.reftest.20120803.c1f44 r 56(10) 4.62
MD01.reftest.20120803.c1f46 r 84(21) 4.72
MD01.reftest.20120803.c1f48 r 114(28) 4.76
old MD01.refstack.20110820 r 54(7) 4.40
new MD01.refstack.20120803 i 88(15) 3.58
MD01.reftest.20120803.all.41 i 74(24)
MD01.reftest.20120803.2011.41 i 49(11)
MD01.reftest.20120803.c1f39 i 30(7) 3.34
MD01.reftest.20120803.c1f41 i 57(16) 3.46
MD01.reftest.20120803.c1f43 i 88(15) 3.58
MD01.reftest.20120803.c1f46 i 121(23) 3.63
old MD01.refstack.20110820 i 74(3) 4.00
new MD01.refstack.20120803 z 88(18) 3.59
MD01.reftest.20120803.all.39 z 72(19) 3.50
MD01.reftest.20120803.2011.39 z 46(10) 3.39
MD01.reftest.20120803.c1f37 z 37(9) 3.39
MD01.reftest.20120803.c1f40 z 66(22) 3.52
MD01.reftest.20120803.c1f42 z 88(20) 3.61
MD01.reftest.20120803.c1f45 z 114(22) 3.67
old MD01.refstack.20110820 z 58(3) 3.48
new MD01.refstack.20120803 y 90(28) 3.53
MD01.reftest.20120803.all.40 y 83(21) 3.48
MD01.reftest.20120803.2011.40 y 42(12) 3.65
MD01.reftest.20120803.c1f37 y 38(11) 3.47
MD01.reftest.20120803.c1f39 y 63(21) 3.49
MD01.reftest.20120803.c1f43 y 90(29) 3.54
MD01.reftest.20120803.c1f47 y 118(37) 3.61
old MD01.refstack.20110820 y 52(1) 3.36

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.


  • generally edge skycells have issues, need better containment of those still.
  • some convolved stacks have strange PSF -- reprocessed using DEEP_STACK config with lighter input restrictions so may not have best FWHM, but 99% on the edge of field so won't anyways.
    • g: 024, 056
    • r: 031
    • i: ---
    • z: 013, 053, 062, 063
    • y:
  • bad cell arc in primarily skycell.036,033,024,025,026,047 y-band from ota14, cell 31 -- doesn't appear to be problem in raw image: neb://ipp058.0/gpc1/20120831/o6170g0590o/o6170g0590o.ota14.fits

  • poor/bad cell arc in primarily skycell.054 g-band (and less so in other filters) from ota43, cell 54? see MD10.refstack.20120705
  • misc ghosts in g-band

Refstack Summary

Refstacks run through the staticsky (full 5 filter mode with deteff measurements) and skycal stage on the unconvolved stacks:

  • label: MD01.refstack.20120803, MD01.refstack.20120803
  • data_group: MD01.refstack.20120803.5x20120805, MD01.refstack.20120803.5x20120805.cal20120805

Rerun through 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: MD01.refstack.20120803, MD01.refstack.20120803
  • data_group: MD01.refstack.20120803.1x20121006, MD01.refstack.20120803.1x20121006.cal20121006

Source photometry psf_major,_minor maps (grizy):

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

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

Stack photometry comparisons -- looks like a possible problem even in recent x20130115, cal20130128:

skycell overlap match mag comparison
refcat match mag comparison example: appears 0.03-0.05 mag error in pixels (staticsky)
refcat match mag comparison example: appears 0.03-0.05 mag error still in photometry recalibration (skycal)