Science Operations

Data Reduction Pipelines

There are no observatory based and supported pipelines for the reduction of data from the 3 pairs of facility instruments: LBCB+LBCR, LUCI1+2 and MODS1+2. However, frequent users have developed some data reduction software which they have made publicly available, and this page aims to collect links to their contributions. If you know of any software packages missing from this page, or have any suggestions regarding reduction of data from these instruments, please let us know, at scienceops at lbto dot org.

The MODS team have provided both a set of scripts (modsCCDRed) to remove instrumental signatures from MODS images and an IDL-based MODS data reduction pipeline which was updated on 19-Feb-2019 to work with both MODS1 and MODS2 grating modes. These are also linked here, although they are discussed in more detail on dedicated web pages.

LBC Data Reduction Tools

  • LBC-reduction (a script to reduce LBC data, written by Benjamin Weiner, UA, and using IRAF, IDL, scamp and swarp. Most recently updated in 2013.)
  • LBC_Redux (similar to LBC-reduction but written by Neil Crighton, then at MPIA, and using python instead of IDL. Most recently updated in 2014.)

     

If you choose to reduce your data with standard packages, keep in mind that the LBC bias level varies, therefore the correct way to remove the bias offset is to use the overscan region. Bias frames are used to remove remaining bias structure, which is stable. See the LBC Calibrations page for more details.

MODS Data Reduction Tools

mods_quickreduce — An onsite quick reduce tool is discussed in the observing section.

modsCCDRed — modsCCDRed is a collection of python scripts which process the MODS 2D full-frame CCD images. While they perform basic tasks such as bias- (actually prescan-) subtraction, flat-fielding, they effectively deal with features that are unique to MODS, for example, the “even-odd” effect.

The modsCCDRed suite of scripts generates color-normalized flats and then bias-subtracts, flat-fields and corrects for bad pixels and columns in the full-frame spectroscopic images.

The scripts, along with installation instructions and a User Manual, are available at: http://www.astronomy.ohio-state.edu/MODS/Software/modsCCDRed and they are now (as of 02-02-2019) also distributed on GitHub:https://github.com/rwpogge/modsCCDRed

modsIDL — modsIDL is a suite of programs written in IDL for the reduction of MODS long-slit and multi-slit spectroscopy. Until recently, it worked only for MODS1 spectra, both grating and prism, however a new release issued on 02-19-2019 extends it to MODS2 grating spectra.

The full modsIDL distribution is available for download, along with a User’s Manual, from http://www.astronomy.ohio-state.edu/MODS/Software/modsIDL/

For users with earlier versions, an incremental release can be downloaded from the OSU MODS website linked above or from GitHub: https://github.com/rwpogge/modsIDL
When publishing results which made use of modsIDL, please include an acknowledgement following the guidelines given in the links above.

LUCI Data Reduction Tools

FLAME is an IDL-based data reduction pipeline for LUCI, written by Sirio Belli (MPE).
For an overview, see his Users’ Meeting presentation about FLAME. The paper by Belli, Contursi and Davies (2017) describes the pipeline more thoroughly and should be cited in works that make use of it.

For telluric corrections, two tools which may be helpful are the IDL-based xtellcorr, (Vacca, W., Cushing, M. and Rayner, J. 2003, PASP, 115, 389) which determines the telluric absorption by fitting the spectrum of an A0V star that is observed close in time and airmass to the target with a high-resolution model of Vega and ESO’s molecfit. By request, molecfit has been installed on the mountain computers. xtellcorr_general is part of the IRTF’s Spextool package, but can be run as a standalone procedure in IDL.