IRAC Instrument Handbook - IRSA - California Institute of Technology

1 Introduction
1.1 Document Purpose and Scope
IRAC Instrument Handbook
The IRAC Instrument Handbook is one in a series of documents that explain the operations of the Spitzer
Space Telescope and its three instruments, the data received from the instruments and the processing
carried out on the data. Spitzer Space Telescope Handbook gives an overview of the entire Spitzer
mission and it explains the operations of the observatory, while the other three handbooks document the
operation of, and the data produced by the individual instruments (IRAC, IRS and MIPS). The IRAC
Instrument Handbook is intended to provide all the information necessary to understand the IRAC
standard data products, as processed by Version S18.18 of the online pipeline system, and which are
retrievable from the Spitzer Heritage Archive (SHA). Besides the detailed pipeline processing steps and
data product details, background information is provided about the IRAC instrument itself, its
observational modes and all aspects of IRAC data calibration. It should be stressed that this Handbook is
not intended to support interactive data analysis. For data analysis advice and suggested data processing
procedures, please refer to the separate documentation available at the documentation website, including
the Spitzer Data Analysis Cookbook. This Handbook serves as the reference for both the processing as
well as the correct interpretation of IRAC data as available from the Spitzer Heritage Archive.
In this document we present information on:
• the IRAC instrument and its observing modes,
• the processing steps carried out on the Level 0 (raw) data,
• the calibration of the instrument,
• the artifacts, features and uncertainties in the data,
• and the final IRAC archival data products.
An overview of the IRAC instrument is given in Chapter 2. In Chapter 3 the modes in which IRAC could
take data are presented. The calibration is described in Chapter 4. Online pipeline processing is described
in Chapter 5. The data products themselves are described in Chapter 6. Data features are presented in
Chapter 7. A brief introduction into IRAC data analysis is given in Chapter 8. Several appendices are
attached to give more detailed information on individual subjects.
1.2 Basic Definitions
This section contains a description of the most commonly used terms in this Handbook. A complete list of
acronyms can be found in Appendix E.
An Astronomical Observing Template (AOT) is the list of parameters for a distinct Spitzer observing
mode. There is one possible IRAC AOT for the cryogenic mission, and one for the warm mission. The
observing parameters and mode are described in Chapter 3. A fundamental unit of Spitzer observing is the
Introduction 1 Document Purpose and Scope