This page is a summary the basics of IFS data reduction together with an introduction to some of the more advanced or complex aspects. Here we define "data-reduction" as anything that needs to be done to remove the effects imposed by the instrument and atmosphere on the science. Tasks to analyse the science data are covered in the data analysis section.
Note that while the basics of reducing IFS do not vary from science target to target, the additional reduction (and analysis) tasks one can do can be quite different if you are looking at point sources or extended targets. When reading (and writing for) this wiki, do bear that in mind.
It is assumed that the reader already has a basic knowledge of the steps involved in reducing standard long-slit spectra.
We begin with a summary of the steps required to extract and standardise spectra taken with fibre-fed IFSs, image-slicers, and Fabry-Pérots (although currently the image-slicer section is empty and the FP a bit short). This includes finding, extracting and calibrating the spectra, and converting between different data formats.
We then discuss some standard subsequent tasks such as mosaicking and combining cubes, and DAR and PSF corrections.
Finally we have some links to "Extras" pages where we hope details about reducing data from individual instruments will be posted: pipeline manual links, tips on what to do that the pipelines do not include, how to deal with any unique quirks the instrument may have.
Reducing the data
- The Starlink IFU Data-Product Cookbook
- See reference list for further, more detailed work on aspects of IFU reduction
Reducing data from fibre-fed (+lenslets) IFUs
- General Outline
- Aperture Tracing
- Throughput Correction
- Sky Subtraction
- Cosmic Rays
- Flux Calibration
- A general data reduction package
- IDL: Adam S. Bolton (IfA) and Scott Burles (MIT) have written kungifu, a set of IDL software routines designed for the calibration and reduction of fiber-fed integral-field unit (IFU) astronomical spectroscopy.
- p3d: A general data-reduction tool that is intended to be used with data of fiber-fed integral field spectrographs
Reducing data from image-slicer IFUs
Has anyone does this, and can they contribute please to this section?
Reducing data from Fabry-Pérot Spectrographs
If anyone has personal experience with FPs, could you consider adding your "tips and tricks" to this page?
Further Reduction Tasks
- General Outline
- RSS or Cube format
- Combining Cubes
- DAR Correction
- Thoughts on PSF Variations
Instrument-specific data reduction pages
One of the most frustrating things about IFS data reduction is the little idiosyncrasies and unresolved problems that inevitably exist for each instrument (or even specific set-up). The following pages (will) contain a list of points to watch out for together with hints, tips and work-arounds particular to the individual instrument.
If you have any experience IFS data reduction, we encourage you to contribute to these pages. A specialist with e.g. GMOS data could easily feel as 'at sea' with e.g. VIMOS data as will a complete novice!
- DensePak/SparsePak (WIYN)
- FaNTOmM (Observatoire du mont Mégantic 1.6-m)
- FISICA (KPNO 4m)
- Giraffe+ARGUS/IFU (VLT)
- GMOS (Gemini)
- GriF (CFHT)
- Integral (WHT)
- NIFS (Gemini)
- OSIRIS (Keck)
- PIFS (Palomar)
- PMAS/PPAK (Calar Alto)
- SAURON/OASIS (WHT)
- SINFONI (VLT)
- VIMOS (VLT)
- WIROspec (WIRO)
- Imacs (Magellan)
- Pacs (Herschel)
- Spire (Herschel)
We could use contributions for many of these instruments, and would be grateful for all and any information you can add. Add your comments here ("Comments" just below) or join to add more.