
notation:

object : an astronomical source, may be observed multiple times
measurement : a single observation of an object (one per object per exposure) 
m_inst : instrumental magnitude measurement
m_cat  : catalog magnitude measurement (m_inst + 25.0)
m_sys  : nominal internal system magnitude measurement (m_inst + ZP(CCD,FILTER)
m_rel  : transparency adjusted magnitude measurement (m_sys + offset)

M_ave  : average (object) magnitude in internal system
M_ref  : average (object) magnitude in reference system

test for photometric consistency:

for the output from dither.corr:

M_ave - m_rel(ccd) vs x_ccd, y_ccd
M_ave - m_rel vs x_mosaic, y_mosaic
M_ave - m_rel vs airmass?



  MEGACAM.g.00 Minst - MEGACAM.g.01 Mcal : time

  MEGACAM.g.00 - g : time

  MEGACAM.g.00,Mrel - MEGACAM.g.01,Mcal : MEGACAM.g.00 - MEGACAM.r.00

- use relphot to flag stars in poor locations, etc

- we can choose for entry if it is Minst, Mcat, Msys, Mvrel, Mcal, Mave, or Mref

int GetMagnitudeType (char *name, PhotCode *code, int *MagMode);

- should return photcode & value MEAS_MREL, AVE_MREF, or what ever
- should provide an appropriate default for measures, etc
- should check for consistency with photcode type:
  PRI/SEC : AVE_MREF, AVE_MAVE
  DEP     : MEAS_ETC
