Starlink Project
Starlink User Note 236.5

Paul Hirst
Brad Cavanagh
Joint Astronomy Centre, Hilo, Hawaii

October 2005

Copyright © 2005 Particle Physics and Astronomy Research Council

ORAC-DR – spectroscopy data reduction


User Guide


ORAC-DR is a general-purpose automatic data-reduction pipeline environment. This document describes its use to reduce spectroscopy data collected at the United Kingdom Infrared Telescope (UKIRT) with the CGS4, UIST and Michelle instruments, at the Anglo-Australian Telescope (AAT) with the IRIS2 instrument, and from the Very Large Telescope with ISAAC. It outlines the algorithms used and how to make minor modifications of them, and how to correct for errors made at the telescope.


1 Introduction
2 Using the pipeline
 2.1 Setting up Orac-dr
 2.2 Raw Data Formats and Conversions
  2.2.1 ISAAC Preliminary Conversion
 2.3 Running the pipeline
 2.4 Graphical initialisation and operation
 2.5 Display
 2.6 Calibration Information
  2.6.1 Available calibration methods
 2.7 Log files
3 Features of the Primitives
 3.1 Preparation of Single Frames
  3.1.1 Manipulation of Raw Data
  3.1.2 Preliminaries
  3.1.3 Bad pixels
  3.1.4 Readnoise Variance
  3.1.5 Bias Subtraction
  3.1.6 Poisson Variance
  3.1.7 Chopping
  3.1.8 Flat Fielding
  3.1.9 Interleave and Coadd
  3.1.10 Orient Image Normally
  3.1.11 Wavelength Calibrate
 3.2 Group Formation
  3.2.1 Sky Subtraction
  3.2.2 Group Coaddition
 3.3 Spectrum Extraction
  3.3.1 Counting Beams
  3.3.2 Finding Beams
  3.3.3 Beam Extraction
  3.3.4 Derippling
  3.3.5 Beam Cross Correlation
  3.3.6 Extracted Beam Coaddition
 3.4 Signal-To-Noise Calculation
 3.5 Division By Standard Star
 3.6 Flux Calibration
4 Science Target Recipe Details
5 Calibration Recipe Details