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FITS Checksum Proposal

R.L. Seaman[*] - W.D. Pence[*]

24 August 1995


This paper describes a simple means for embedding a checksum within a FITS header, providing a mechanism for later verifying the integrity of the FITS file. The method uses ASCII coded 32-bit 1's complement arithmetic to force the checksum of each FITS HDU to zero. This technique requires no extension of the FITS standard to be used by any given project, in fact the technique may be used to zero the checksum of any ASCII file. The purpose of this proposal is simply to reserve keywords that will allow projects and software packages to seamlessly verify and update each other's data.