Notes for Labelling FITS files
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Fits tables, images and arrays are all compliant as they are with the PDS4 data formatting standards. Follow the guidelines below for filling in the PDS4 attribute values.
Contents
Scalar Data Types
Regardless if the data structure, the supported data types are strictly limited by the FITS standard. Here are the types you may encounter in FITS files (as specified by the BITPIX keyword), and their PDS4 equivalents:
| BITPIX Value | PDS Data Type(s) |
|---|---|
| 8 | UnsignedByte -or- 7-bit ASCII character (could be any of the ASCII_* types) |
| 16 | SignedMSB2 |
| 32 | SignedMSB4 |
| -32 | IEEE754MSBSingle |
| 64 | SignedMSB8 |
| -64 | IEEE754MSBDouble |
Headers
Use the PDS4 Header object to describe any type of FITS header.
- For <encoding_type>, use "Character"
- For <external_standard_id>, use "FITS 3.0". This is not a valid standard value, but the current value is not sufficiently specific. If you want to reference an earlier version of the FITS standard, check with your PDS consultant.
- The <object_length> must be the number of FITS blocks comprising the header * 2880 (the size of a single FITS block).
