An example of the OBS_ID and related keywords -
OBS_ID = 'V80600013001P0000000002101' / Programmatic observation identifier
VISIT_ID= '80600013001' / Visit identifier
PROGRAM = '80600 ' / Program number
OBSERVTN= '013 ' / Observation number
VISIT = '001 ' / Visit number
VISITGRP= '02 ' / Visit group identifier
SEQ_ID = '1 ' / Parallel sequence identifier
ACT_ID = '01 ' / Activity identifier
EXPOSURE= '1 ' / Exposure request number
visit_id = Program number + Observation number + Visit number
The OBS_ID = 'V' + visit_id + 'P' + parallel-program number + parallel-observation number + visit group identifier + parallel sequence identifier + activity_identifier.
The eight characters after the 'P' are only populated with non-zero values of the parallel program number and observation number if the exposure is a parallel. Parallel observations occur in the same visit as the prime observation, so the visit number is not needed after the 'P'. For a prime exposure with one or more exposures executing in parallel, only the prime program number and observation number will be populated. For a parallel exposure, both the prime program number / observation number and the parallel program number / observation number will be populated.
The exposure_id is not included in the OBS_ID. It is a separate field in the science image header of the ssr file.
Some of the nomenclature is confusing, especially the over use of observation in programmatic observation identifier and observation number.
| Attribute | Value |
|---|---|
| data type | string |
| enumerated Values | not defined |
| units | |
| example | V80600004001P0000000002101 |
| default value | |
| special processing | VALUE_REQUIRED |
| source | Science Image Header |
| software source | |
| calculation | |
| DB destination | ['ScienceCommon.obs_id', 'GuideStar.obs_id'] |
| data type in DB | nvarchar(26) |
| instrument | Multiple |
| mode | All |
| product level | 1a |
| FITS hdu | PRIMARY |
| FITS header section | Observation identifiers |