FITS Image Requirements

Terminology
FITS Images contain a header portion and a data portion. The FITS standard allows having multiple headers and data portions using "extensions", but OLAF does not accept files with extensions. (See Requirements below.) The header consists of multiple lines (called cards) that are made up of a keyword, value, and description. The header can also contain lines that are only comments and do not contain a keyword and value.

OLAF Requirements for Directories

• OLAF recommends no more than 50 files per directory.

OLAF Requirements for Fits Images

• Files must conform to the FITS Standard as specified by the NASA/Science Office of Standards and Technology. This will be checked by running the fitsverify tool and the files must pass without any errors. Warnings are ok.
• Accepted FITS files cannot contain more than one FITS-header per file. This means files using FITS extensions such as binary tables are not accepted.
• Images are uploaded in groups. All images in the same group must have exactly the same set of keywords in the FITS header, meaning if a keyword is present for one image, it must be in the header for all images. It is ok not to have a value, but the keyword must be present.
• Images in the same data set should not have multiple keywords for the same thing. For example, it would be wrong to have a group of images with the keyword "EXPOSURE" and another group with the keyword "EXP_TIME", both meaning exposure time.
• Headers of all images in the data set must not use the same keyword to mean different things. For example, it would be wrong to have a group of images where keyword FILTER is for the filter name and another group where the keyword FILTER is for the central wavelength of the filter.
• For a given keyword, all values must all be in the same units of measurement (if applicable).