Other photometric observations (detections)
Due to overlaps in imaging stripes, the SDSS sometimes observes the same
object more than once. In such cases, we select one observation as PRIMARY (mode=1). Each
astronomical object is assigned a thingID, and each time that "thing" is observed (detected
in SDSS imaging), it assigned a separate objID.
Information about each astronomical "thing" is stored in the
thingIndex
table; thingIndex is a thin coupling table designed only to connect repeat observations.
Information about each individual observation (detection) is in the
photoObjAll table. (Note that
photoObj contains only the primary [mode=1] and secondary [mode=2] observations of each "thing.")
The detectionIndex table connects each objID to the thingID it corresponds with.
This detected object and its associated "Thing" (Primary observation)
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