Below are two sets of metadata which will be stored in the new archive in regard to Images and the Image Sets to which they belong. Included where relevant are the equivalent fields in the Virtual Observatory ObsCore Data Model, a potential source from which to obtain the data, and a comment. The images table was written specifically with the idea of spacial spatial images in mind. Other data products (spectra, time series, etc) would have different amounts of granularity in the header information available.
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- Split center_position and observing_band fields
- Retaining image size data (the VO _xel fields)
- Add fields for spectral resolution, physical data description, and spacial spatial region information
- Determination and acquisition of time-domain information.
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| Column Name | VO Equivalent | Source | Comments |
|---|---|---|---|
| sourcename | target_name | OBJECT Keyword | |
| ra (center_position) | s_ra | Center of Ra Axis | |
| dec (center_position) | s_dec | Center of Dec Axis | |
| field_of_view | s_fov | Average of NAXISn*CRDELn of the Spacial spatial Axes | |
| spacialspatial_region | s_region | Derived from Spacial spatial Data | STC-S String Defined in the TAP (Dowler, et al 2010) |
| ra_element_count | s_xel1 | Relevent NAXISn Keyword | |
| dec_element_count | s_xel2 | Relevent NAXISn Keyword | |
| spacialspatial_resolution | s_resolution | Average of CRDELn of the Spacial spatial Axes | |
| starttime | t_max | Temporal domain information for an image is dependent upon the observation(s) used in its generation. Some controlling process (Like Vlass Manager, whatever imaging pipeline we create, and any image manipulation software we use) will need to supply it. | |
| endtime | t_min | ||
| exposure_time | t_exptime | ||
| min_frequency observing_band) | em_min | Minimum of Spectral Axis | The spectral information is recoverable from the FITS header, and will identify the spectral coverage, and total bandwidth processed for the image. |
| max_frequency (observing_band) | em_max | Maximum of Spectral Axis | |
| spectral_resolution | em_res_power | Spectral CRDELn Keyword | |
| polarization_code | pol_states | Currently, there is insufficient information provided about the polarization information of the image in the quicklook FITS headers. There is a STOKES axis, but no further information is provided. Since Single Epoch images will be created in Stokes I, Q, and U, that information must be provided to distinguish the files. Adding the stokes parameter name to the CTYPEn or CUNITn header keywords would solve this issue. | |
| telescope | instrument_name | TELESCOP Keyword | This must accommodate images for multiple instruments (i.e. VLA + Single Dish) |
| file_id | automatically generated | link to information about the physical file | |
| image_id | obs_id | automatically generated | Unique Identifier for the Image |
| image_units | o_ucd | BTYPE & BUNIT Keywords | Description of the physical quantity measured in the image |
| max_intensity | These values are can be determined from the data portion of the image file in conjunction with the BSCALE & BZERO keywords. The library which is used for FITS interaction for ingestion can perform these calculations, but no information about the speed of results is yet available. | ||
| min_intensity | |||
| rms_noise | |||
| thumbnail | weblog, a PNG with identical name |
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