Others columns that are advertised as integers and stored as strings in LasSource are:

• SourceID
• FrameSetID
• HTMID
• Priorsec

All called bigint in the database Schema.

The likely origin of the problem is that the FITs Standard Working groups have taken a painfully long time to add support of 'double precision' Integers in the FITS standard i.e. i*8 or 64bit integers.

see http://fits.gsfc.nasa.gov/fits_news.html

which says:

Support for 64-bit integers

The issue of whether the FITS format should be expanded to support 64-bit integers (i.e, images with BITPIX = 64 and binary table columns with TFORMn = 'K') is being actively discussed by the FITS community. The 4 regional FITS committee voted on this issue in September 2005, and the IAU FITS Working Group will begin final consideration of this issue in October. See the dedicated web page for the latest status of this proposal.

http://fits.gsfc.nasa.gov/fits_64bit.html

Sadly the FITs Standard takes a painfully long time evolve. Support for 64-bit integers was originally proposed in 1998.

The good news is that various 'standard' package are already supporting the proposed standard.

Existing Software that supports 64-bit Integer FITS Files

The JavaFits library developed and supported by Tom McGlynn has supported 64-bit integer images and table columns since its inception in the year 2000.

The CFITSIO library has supported 64-bit integer images and table columns since October 2001. Support for 'Q' 64-bit array descriptor columns was added in April 2005.

The MWRFITS and RDFITS routines in IDL have supported 64-bit integer images and table columns since 2002.