How frames Designates Objects

 

Each object detected during the frames analysis of a particular set of data is given a unique identifier which consists of five integers:

• run of class Segment (Table  15): A run number refers to a given uninterrupted drift-scan.
• rerun of class Segment (Table  15): Each time we analyze a run with a different set of pipeline version or calibrations we assign it a new rerun number. The same rerun number in different runs does not necessarily refer to the same version of the pipelines.
• camCol of class Segment (Table  15): This number, from 1 to 6, refers to the dewar, or column of photometric CCDs in the imaging camera, by which this object was imaged.
• fieldID of class Field (Table 16): Refers to which field (§ 3.5) the object is in.
• objID of class PhotoObj (Table 6): This is an identification number for the object that is unique within each field.

Several different versions of the pipelines were run on the imaging data for the EDR (Table  20). The rerun number for each run distinguishes a set of pipeline versions. Two rerun numbers are important for the EDR. The first rerun was used to select targets for spectroscopic observation. The second rerun used the most recent versions of the pipelines, and the results of this processing are distributed. Between reruns of frames, the run, camCol and fieldID of detected objects do not change, because frames acts on individual frames. However, the objID does change. Future data releases will most likely be made with yet another rerun which uses the most current version of our pipelines and calibrations.

In addition, data quality flags are set for each field, after we evaluate the processing from an entire run. These are discussed below in section 4.6.