Data Reduction FAQ

If your question is not found below, please email your query to salthelp@salt.ac.za.

  1. Where can I find line lists for SALT spectra?
  2. Are filters curves available for the instruments?
  3. Where can I find an extinction curve for Sutherland?
  4. What are those extra lines in my arc spectra?
  5. I used scisoft for my installation of pyraf. Can I install pysalt?
  6. How do I flat-field my data?
  7. What are those weird faint emission lines at unidentifiable wavelengths in my spectra?

1. Where can I find line lists for SALT spectra?

An arc atlas has been compiled here.

An alternative/additional atlas put together by Brent Miszalski is also available here. (Note that you have to replace the extension “.tar_” with “tar” in the downloaded file.)

2. Are filters curves available for the instruments?

Yes, filters curves are available as part of the PySALT package in the data/ directory.  They are also available online: SALTICAM filter curves are available here and RSS filter curves are available here.

3. Where can I find an extinction curve for Sutherland?

An extinction curve is available as part of the PySALT package and is also available here.

4. What are those extra lines in my arc spectra?

We have had a range of issues with the lamps and the power supplies and have had to swamp lamps at times.   Some of the lamps show contamination and depending on the lamp you are using there may be additional lines.   For example, the Neon lamp shows contamination from Argon and the NeAr lines may provide a better fit.

5. I used scisoft for my installation of pyraf. Can I install pysalt?

We suggest that you visit the PySALT User Package page and install PySALT as recommended.

6. How do I flat-field my data?

Please see this page on the SALT science wiki.

7. What are those weird faint emission lines at unidentifiable wavelengths in my spectra?

If you have bright stars on the slit you may be more prone to Littrow Ghost reflections. According to this paper on the issue, these are usually at a fixed position and around 1E-4 fainter than the star causing them. While most common on RSS longslit spectra, they can also appear in RSS MOS observations, so special care should be taken not to confuse them with real emission line objects!