Summary (Updated - AF 11/01/2012)

MOPS has reported some peculiar magnitudes in y-band MD data offsets and larger scatter compared to predictions of asteroid y-band magnitudes while the same comparison to 3PI photometry looks reasonable (both cases are photometry from the respective diffims). Also, have found photometry from Warp-Stack (WS) difference images for two sequential MD exposures unrealistically different by >0.5 mag.

Plot of average value for (observed - predicted) magnitudes per night for 3pi and MD detections in y-band.An offset in the MD data making objects ~0.4 mag brighter is seen.

Plot of average value for (observed - predicted) magnitudes per night for 3pi and MD detections in z-band. No offset is seen.

Example: MD10 sequential exposure pair, asteroid (12891) (Peter Vereš)

o6157g0218o
o6157g0219o

ra: 353.142622 
ra: 353.142215

dec:-0.086658
dec: -0.086867

Chip/camera CAL_PSF_MAG photometry from the SMF catalogs below agree to what expected? yes, but can't be more exact because asteroid (12891) previously unstudied.

• o6157g0218o: 17.06
• o6157g0219o: 17.048

camera SMFs:

IPP_IDET  CAL_PSF_MAG  CAL_PSF_MAG_SIG  PSF_INST_MAG  PSF_INST_MAG_SIG  AP_MAG  PSF_MAJOR  PSF_QF_PERFECT  FLAGS  FLAGS2 rsep(")

2384872506.gpc1:MD10.nt:2012:08:18:o6157g0218o.512581:o6157g0218o.512581.cm.524588.smf
300 17.0643 0.116127 -12.2008  0.0112583 -12.2431 6.2846 0.999136 102760453.0 128.0 0.11619639245

2384878611.gpc1:MD10.nt:2012:08:18:o6157g0219o.512582:o6157g0219o.512582.cm.524591.smf
353 17.0482 0.119598 -12.2145 0.0109578 -12.2215 6.29196 0.999138 102760453.0 128.0 0.0714361641958

WSdiff CMFs:

IPP_IDET  CAL_PSF_MAG  CAL_PSF_MAG_SIG  PSF_INST_MAG  PSF_INST_MAG_SIG  AP_MAG  PSF_MAJOR  PSF_QF_PERFECT  FLAGS  FLAGS2  DIFF_NRATIO_BAD  rsep (")

2385003229.gpc1:MD10.nightlyscience:2012:08:18:MD10.V3:skycell.052:MD10.V3.skycell.052.WS.dif.272923.cmf
180 17.1593 0.0 -12.1058 0.0549115 -12.0586 6.91519 0.999313 35651585.0 2177.0 0.586518 0.00506595268768

2385006586.gpc1:MD10.nightlyscience:2012:08:18:MD10.V3:skycell.052:MD10.V3.skycell.052.WS.dif.272924.cmf
143 16.5429 0.0 -12.7198 0.0508926 -12.0717 10.5122 0.998732 35651585.0 129.0 0.614977 0.00257287140

Manually rerunning WSdiffims with current ipp-20121026 tag (conv + unconv refstack):

Manually rerunning WSdiffims with tag ipp-20110622 that was active when photometry looked better last year (see example mag plot for TNO145452 below):

Example: MD09, TNO145452 (Alan Fitzsimmons)

TNO 145452

• a bit faint but its' the best one I've found so far, as it stays in the field for a long long time.
• in MD09 where we can predict the y magnitude should be within 0.1 mag of ~19.3 for the below observations
• a bunch of y-band exposures in 2011 and 2012.
• columns are Exp ID, MJD, RA, Dec.

  2011:
  o5756g0570o  55756.592040       333.326857   +0.597387    
  o5756g0571o  55756.595015       333.326815   +0.597377    
  o5756g0572o  55756.597969       333.326774   +0.597368    
  o5756g0573o  55756.600918       333.326733   +0.597359    
  o5756g0574o  55756.603875       333.326692   +0.597350    
  o5756g0576o  55756.609792       333.326609   +0.597332    
  o5756g0577o  55756.612748       333.326568   +0.597323    
  o5757g0356o  55757.496424       333.314491   +0.594541    
  o5757g0357o  55757.499384       333.314449   +0.594532    
  o5757g0358o  55757.502357       333.314407   +0.594522    
  o5757g0359o  55757.505335       333.314365   +0.594513    
  o5757g0360o  55757.508292       333.314323   +0.594503    
  o5757g0361o  55757.511248       333.314281   +0.594494    
  o5757g0362o  55757.514208       333.314239   +0.594484    
  o5757g0363o  55757.517163       333.314197   +0.594475    
  o5766g0299o  55766.477073       333.180973   +0.559502    
  o5784g0173o  55784.507883       332.868350   +0.454736    
  o5784g0174o  55784.510828       332.868295   +0.454715    
  o5784g0175o  55784.513776       332.868239   +0.454695    
  o5784g0176o  55784.516717       332.868184   +0.454674    
  o5784g0177o  55784.519667       332.868128   +0.454654    
  o5784g0178o  55784.522608       332.868073   +0.454633    
  o5784g0180o  55784.528498       332.867962   +0.454592    
  (ending at 08-11-2011)
  
  2012: (starting 06-29-2012)
  o6107g0064o  56107.597172       334.910525   +0.746688    
  o6107g0065o  56107.600110       334.910498   +0.746686    
  o6107g0066o  56107.603062       334.910470   +0.746684    
  o6107g0067o  56107.606006       334.910442   +0.746681    
  o6107g0068o  56107.608993       334.910414   +0.746679    
  o6201g0056o  56201.242691       333.383584   +0.125386    
  o6201g0057o  56201.245657       333.383540   +0.125358    
  o6201g0058o  56201.248616       333.383497   +0.125330    
  
  

This is the best example in the database because of the density of measurements and the known small amplitude of any lightcurve. In warp-warp diffs the slow motion will mean that 3PI and OSS measurements would be incorrect due to self-subtraction of the flux. But this should not only occur in MD fields as MOPS is being fed warp-stack measurements, and it would make the object fainter not brighter as seen. The variation in z-band and in other filters in 2012 is also puzzling.

Plot of observed magnitudes converted to V (top), and residual of magnitude (observed - predicted), in 2011 and 2012: (Key: g=green, r=red,i=orange,z=purple,y=cyan)

Example: MD01, MBA 131130 (Alan Fitzsimmons)

This is a nice example of the offset plus large scatter in y-band for a Main Belt Asteroid seen this year.

o6169g0184o 36.353429    -4.350323    
o6169g0185o 36.353441    -4.350616    
o6170g0586o 36.360948    -4.446235    
o6170g0588o 36.360938    -4.446831    
o6170g0590o 36.360927    -4.447427    
o6170g0591o 36.360922    -4.447725    
o6170g0593o 36.360911    -4.448320    
o6171g0613o 36.362699    -4.549196    
o6171g0614o 36.362676    -4.549499    
o6171g0616o 36.362631    -4.550103    
o6171g0617o 36.362608    -4.550406    
o6171g0619o 36.362562    -4.551012    
o6172g0677o 36.358383    -4.654112    
o6172g0682o 36.358181    -4.655647    
o6172g0683o 36.358141    -4.655956    
o6172g0684o 36.358101    -4.656264    

Plot of observed magnitudes converted to V (top), and residual of magnitude (observed - predicted) in 2012. The large gap in the data was caused by telescope shutdown due to rotator problems. (Key: g=green, r=red,i=orange,z=purple,y=cyan)