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Processing data within a repository generally requires specifying an identifier to select the specific data to process. The identifiers that apply to a given repository of raw or single-frame calibrated data depend upon particular camera from which the data were obtained. Alternatively, if the calibrated images have been transformed to an output all-sky tesselation, the organization will reflect that mapping. The identifiers map to the directory hierarchy of the files on disk. 

Data Identifiers are supplied to command-line processing tasks with the --id option, which may appear multiple times on the command line, or may be specified in an include file. The arguments to the identifier are specified with keyword/value pairs; giving a partial specification implicitly includes every bit of data that matches the remaining elements of the specification.

There is a special syntax for specifying multiple values and ranges for an argument: 

Comma-separated sequenceccd=1,21 and 2
Union of specific valuesfilter=r^ir and i

Inclusive range of numerical arguments,

with an optional stride

visit=12345..12349:212345, 12347, 12349

As with all command-line options for tasks, they may optionally be specified in a separate file and referenced with the @ symbol. 


A complete identifier for the SDSS camera (obs_sdss) consists of the runrerun, camcol, field, and filter

--id run=5765 rerun=40 camcol=3 field=29 filter=r      # Single field
--id run=5765 rerun=40 camcol=3 field=29               # Single field, all filters
--id run=5765 rerun=40 camcol=3 field=29^30 filter=r   # Two fields


A complete identifier for the LSST camera (simulation) consists of the visit, raft, and sensor (a filter identifier may optionally be given, but LSST will only observe with one filter in a visit):

--id visit=201409090 raft=1,1 sensor=1,1  # One sensor on one raft of a snap
--id visit=201409090 raft=1,1^1,2         # All sensors on each of two rafts
--id visit=201409090                      # All sensors on all rafts for a single visit


Identifiers for the Subaru HSC camera (obs_hsc) consist of the visitccd, filter, and field: 

--id visit=902086 ccd=0^41..50^103  # CCDs 0, 41 through 50, and 103 for one visit
--id visit=902122..902128:2         # All CCDs for visits 902122, 902124,...,902128
--id field=SDSS1115 filter=W        # All CCDs in filter W for SDSS field 1115 


A complete identifier for the DECam camera (obs_decam) consists of the visitside, and ccd

Sky Patch

Identifiers for portions of an all-sky tesselation (i.e., image co-adds) would include a tract, sky patch, and possibly a filter

--id tract=1 patch=2,3 filter=r
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