Instrumental Signature Analyses¶

Instrumental Signature FNAL meeting info

Star flat¶

• u and VR star flats created 29 May 2015 by Gary Bernstein
• Comments by Jim Annis on Photometricity versus Calibration, Gary Bernstein's comments on SV Calibration Plan, and Paul Martini's Data Processing Overview
• Starflat comparisons
• Photometric stability - Gary's analysis of time variation of dome flats and star flats from Nov-Feb of SV.
• Year 1 star flats - Star flats and dome flats at start of Year 1 observations compared to SV.

Crosstalk¶

• Non-linear crosstalk - Kerstin Paech's results on crosstalk.
• Kerstin's update at LBL collaboration meeting Apr 2013 here

Low-light-level Nonlinearities¶

• AB Ratio Variation
• u-Band Star Flats

High-light-level nonlinearity¶

• Photometric tests of high-ADU nonlinearities - Gary Bernstein & Christina Krawiec examination of February on-sky linearity tests
• Non-linearity at large ADU - has Huan Lin's analyses of PTC sequences.
• Huan Lin's update at LBL collaboration meeting Apr 2013 and Juan Estrada slides on SiDet testing

Flux-dependent PSF, a.k.a. brighter-fatter¶

• Flux-dependent PSF work plan
• Non-linearity at large ADU - has Vinu Vikraman's measures of PSF size vs flux and vs position on focal plane.
• Flux-dependent PSF results from on-sky analysis
• New Gain and Read Noise Values derived with b/f-aware reduction March 2014 by Gruen & Bernstein
• Session at the OSU WL workshop: https://cdcvs.fnal.gov/redmine/projects/deswlwg/wiki/BrighterFatter

PSF wings¶

• Mapping of the PSF to large radii

Astrometry¶

• Astrometry - some early fitting results and pictures of bad exposures' behavior
• Astrometric solution variation - changes in SCAMP WCS solutions over SV and Y1

Bad pixels¶

• Bad pixel mask - report on some odd bad-pixel behavior from SNWG.
• Funky columns
• The death of N30

Flat-field and fringe frames¶

• Flat-field periodic structure - sawtooth pattern along x axis seen in DECam flats
• Flat-field Structure - overall structure and time changes to flat fields (incl. tape bumps)
• Flat Fields - Paul Martini's Nov 2012 comparison of domes to twilights and night-to-night dome variation
• Fringing - Paul Martini's Nov/Dec 2012 examination of fringe frames - also docdb #6830
• Time dependence of dome flats - Changes in dome flats over 2013-2014

Ghosts¶

• Ghosting Analyses - Steve Kent's ghost-hunting.

Dome offsets and flat fields¶

• Dome offsets and flat fields - DJJ and WCW study of flat fields and small offsets in the dome alignment. Thought to be a problem pre-March 2013

u-band LED flat field degredation¶

• u-band LED flat field degredation - It has been noticed that throughout Year 1, the LED illumination in u-band LED flat fields has degraded where the levels recorded in mid-Jan 2014 are only about 20% of the values of the beginning of Sept 2013. The file OneLEDataTime.pdf shows the results of a study where a special run by DJJ et al (see elog 156461, for instance). In short, the degradation appears to be due to the individual degradation of especially two of the four stations, but all stations have degraded as well.