# Copied verbatim from
# http://www.sdss.org/dr3/products/catalogs/flags_detail.html


   Flags associated with moving objects

A main-belt asteroid will show a parallax of a few arcseconds between 
the r and g exposure in the SDSS camera. The photometric pipeline, and 
in particular, the deblending algorithm, explicitly tests for this, and
measures the motion as appropriate. There are quite a few flags associated 
with this process. For most purposes, the only flag you need to examine is 
DEBLENDED_AS_MOVING, whose name should be self-explanatory. If one wants a 
catalog of moving objects, for example, cut on this flag, as well as the 
derived motion (rowv, colv) and associated errors. It is possible that 
objects with small enough motion will have a statistically significant 
proper motion, but not trigger this flag; this requires further exploration. 
There are no doubt a number of Kuiper Belt objects to be discovered in 
the SDSS data!

The flags related to moving objects (other than DEBLENDED_AS_MOVING) 
are mostly informational in nature, but are useful in understanding why 
a specific object was not deblended as moving:

    * MOVED indicates that the object is a candidate to be deblended as 
      moving. This is not a terribly useful flag. In particular, despite 
      its name, it does not mean that the object is actually determined to 
      be moving!
    * NODEBLEND_MOVING Objects flagged MOVED that are not deblended as 
      moving. Not terribly useful.
    * Objects with detections in only a few bands will not be able to be 
      tested for motion; they are flagged TOO_FEW_DETECTIONS. Even if the 
      object passes this threshold, it may turn out that the centroids are 
      not good in a few of the bands, in which case the flag 
      TOO_FEW_GOOD_DETECTIONS is also set.
    * BAD_MOVING_FIT the motion of the object is inconsistent with a 
      straight line and it is not deblended as moving. A related flag is
    * BAD_MOVING_FIT_CHILD, which states that in a complicated deblend 
      putatively involving both a moving and stationary object, a child's 
      velocity fit is too poor, so the parent wasn't deblended as moving.
    * STATIONARY the moving object's velocity is consistent with zero
    * CENTER_OFF_AIMAGE the nominal motion moves the object right off the 
      edge of the atlas image in some band.

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SUMMARY: if any of the moving object-specific flags such as STATIONARY, 
TOO_FEW_GOOD_DETECTIONS, BAD_MOVING_FIT, BAD_MOVING_FIT_CHILD, as well as 
"other" flags EDGE, NOTCHECKED, BINNED2, BINNED4, NODEBLEND, MAYBE_CR,
DEBLEND_DEGENERATE, PEAKS_TOO_CLOSE is set, one should be careful when
searching for objects with peculiar colors (in such cases, visual inspection
of images would be prudent). 
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