PySALT is the python/PyRAF-based data reduction and analysis pipeline for the Southern African Large Telescope
(SALT), a modern 10m class telescope with a large user community consisting of 13 partner institutions. The two first
generation instruments on SALT are SALTICAM, a wide-field imager, and the Robert Stobie Spectrograph (RSS). Along
with traditional imaging and spectroscopy modes, these instruments provide a wide range of observing modes, including
Fabry-Perot imaging, polarimetric observations, and high-speed observations. Due to the large user community, resources
available, and unique observational modes of SALT, the development of reduction and analysis software is key to
maximizing the scientific return of the telescope. PySALT is developed in the Python/PyRAF environment and takes
advantage of a large library of open-source astronomical software. The goals in the development of PySALT are: (1)
Provide science quality reductions for the major operational modes of SALT, (2) Create analysis tools for the unique
modes of SALT, and (3) Create a framework for the archiving and distribution of SALT data. The data reduction software
currently provides support for the reduction and analysis of regular imaging, high-speed imaging, and long slit
spectroscopy with planned support for multi-object spectroscopy, high-speed spectroscopy, Fabry-Perot imaging, and
polarimetric data sets. We will describe the development and current status of PySALT and highlight its benefits through
early scientific results from SALT.
Construction of the Southern African Large Telescope (SALT) was largely completed by the end of 2005 and since then
it has been in intensive commissioning. This has now almost been completed except for the telescope's image quality
which shows optical aberrations, chiefly a focus gradient across the focal plane, along with astigmatism and other less
significant aberrations. This paper describes the optical systems engineering investigation that has been conducted since
early 2006 to diagnose the problem. A rigorous approach has been followed which has entailed breaking down the
system into the major sub-systems and subjecting them to testing on an individual basis. Significant progress has been
achieved with many components of the optical system shown to be operating correctly. The fault has been isolated to a
major optical sub-system. We present the results obtained so far, and discuss what remains to be done.
This paper presents details of the instrument calibration system employed on the SALT. It is designed to inject light into
the Spherical Aberration Corrector at about the position of the primary mirror caustic, thereby simulating the same
degree of vignetting as experienced by celestial objects. A light-shaping diffuser screen, coupled with Fresnel lenses,
modifies the beam to increase efficiency and attempt to illuminate the detectors in the same manner as a uniform sky.
Light is conveyed by means of liquid light guides from either QTH flat field lamps or a choice of hollow cathode
(CuAr, ThAr) and penray (Ar, Hg, Xe, Ne) lamps, used for wavelength calibration. Changing entrance pupil effects are
accounted for by employing a moving exit pupil baffle, which can simulate the pupil geometry of a specific track.