SALT Longslit Line Atlas

The here presented line data are based on arc-lamp observations (longslit) obtained between September 2011 and March 2012. The wavelength coverage (in particular of the high-resolution gratings) is not complete but fair except for the bluest and reddest regions. The plots show typical exposures for all gratings and representative grating angles. Also given are lists of the presented example files and their grating characteristics.

The lines were mainly selected from early line data available for SALT (October 2011) and the NIST web-pages. The lines were preferentially selected for high-resolution gratings, and faint lines and the blending of close-by lines in low resolution exposures may still confuse the automatic line detector in specidentify at this stage (May 2012). Therefore there are two line data files available for the Argon lamp, that is, the low-resolution line data excludes many of the problem cases while sufficient lines are left to be identified in areas where many lines appear. No such separation has been made for the other arc-lamp data.

Details on the various arc lamp lines and plots for different gratings (as of July 2009) can also be found in the SALT document Atlas of Reference Spectra for RSS Observations by A. Kniazev.   

Arc Lamp Line Atlas

The line data files are in ascii format with wavelength in Ångstrøm, a relative intensity (only as rough estimates in the present case since specidentify as of yet does not make use of intensities) and a comment column. Please note that these files are not a final version but at this stage (May 2012) serve mainly to identify lines in all parts of the spectrum except for the most extreme parts where lines are sparse. Furthermore, there are a few unidentified strong lines, probably from contamination by other elements.

Arc Lamp Plots

The plots are one pdf-file per arc-lamp, with the line identification done by specidentify. They are sorted by grating (PG3000 comes first, PG0900 or PG0300 comes last) and grating angle (see figure captions). The list of exposures and their characteristics is given in an ascii file. In some cases where there are very bright as well as faint lines to be identified, there are two plots, where the second is a zoom-in of the first plot.

Sky Lines

In addition to the arc lamp data, here is a first iteration of a sky line atlas and plot by Curtis McCully. He fitted the sky spectrum with mpfit in IDL with a number of Gaussians at the central wavelength from Iraf's identify task. The strength of a line was taken from the height of the Gaussian (as opposed to the area), while the width of all of the Gaussians was fixed so they should be equivalent. The weaker lines are a little suspect because they might be enhanced by the continuum.

SALT HRS Line Atlas

For the High Resolution Spectrograph (HRS) only the ThAr lamp is used. The following line lists are based on the draft Line Atlas (Sep 2015). They were compared with two observations made on 08 Feb 2016 and 26 Feb 2016. From all arc lamp data obtained in January and February, these were deemed to be the deepest (though they all have the same exposure time, that is, 300s, there are small variations between exposures). New bias, flat and order frames were produced for the LR (based on the 26 Feb observations).

For every resolution HR, MR, and LR the draft Lines Atlas was compared with actual observations, and lines not appearing in the spectra were removed. Since the sensitivity (and possible blending) varies between the three resolutions, a new line list per resolution was made. In addition, a new flag was introduced in the line list to mark lines useful for automated identification (that is, high signal-to-noise lines) and fainter lines that can be used manually to improve a fit where necessary (note that the use of these flags is not implemented yet in the pysalt scripts so both line list versions are listed below).