Institute of Astronomy  

 Bob Carswell's page


Bob Carswell
Institute of Astronomy

Madingley Road
Cambridge   CB3 0HA
Office: Hoyle 16

Phone:            +44.1223.337514
Switchboard: +44.1223.337548
FAX:               +44.1223.337523
Email:  rfc (at

The main use for this page is to provide links various versions of a Voigt profile fitting program. The code is now fairly stable, though there are probably bugs in the more obscure corners of it. The downloadable gzipped tarfile also includes another program, rdgen, which may be used to set up files for vpfit, and generally looking at spectroscopic data.

A stable version VPFIT10.4 (here as a gzipped tarfile) has passed the standard tests so should generally be OK. The October 5, 2016 version was not quite - there was a bug which precluded fitting with linear column densities. Log column densites were fine. This bug has now been fixed (2 November 2016). The documentation is included in the tarfile but is also available separately.

A more recent version which has a better Voigt profile interpolator is VPFIT11.0. This version was posted here 9 Nov 2017. It is largely similar to 10.4 otherwise. This is now the version which gets looked at if somebody reports a possible bug, or ambiguity in the documentation.

If you want older versions (vpfit10.3, 10, 10. 9.5) then these still exist. Please ask, or, for now, look at vpfit.html.

A somewhat dated collection of data showing the redshift evolution of the Lyman alpha forest, covering redshifts up to z=6.3.

Other links

Last update: 9 November 2017
by rfc