Summary (in process of updating)

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.

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 photometry from the SMF catalogs below agree to that expected -- yes, but can't be more exact because asteroid (12891) previously unstudied.

o6157g0218o: 17.06 o6157g0219o: 17.048

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 and positions on two separate dates:

  o6107g0064o  334.194813  +0.274227  
  o6107g0065o  334.199167  +0.283357  
  o6107g0066o  334.194763  +0.292497  
  o6107g0067o  334.184892  +0.294695  
  o6107g0068o  334.176975  +0.288368  
  o6201g0056o  334.176975  +0.288387
  o6201g0057o  334.176992  +0.278257
  o6201g0058o  334.184921  +0.271952
  

Although this is the best example in the database because of the density of measurements and the known small amplitude of any lightcurve, we may be misled because of the slow motion of the object causing problems in brightness measurements. But this will only occur if MOPS is being fed warp-warp measurements instead of warp-stack, and it should 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)