IRAC Instrument Handbook - IRSA - California Institute of Technology

2 Instrument Description
2.1 Overview
Instrument Description 4 Overview
IRAC Instrument Handbook
The InfraRed Array Camera (IRAC) was built by the NASA Goddard Space Flight Center (GSFC) with
management and scientific leadership by the Smithsonian Astrophysical Observatory (SAO) under
principal investigator Giovanni Fazio. The information in this Handbook is based on the design
requirements and on the characterization of the flight instrument in pre-flight ground tests and on in-flight
performance, including the In-Orbit Checkout (IOC)/Science Verification (SV) period in
August−November 2003.
Figure 2.1. IRAC Cryogenic Assembly model, with the top cover removed to show the inner components.
A brief, high-level summary of IRAC for astronomers appeared in the ApJS Spitzer Special Issue,
specifically the paper by Fazio et al. (2004, ApJS, 154, 10, [9]) entitled “The Infrared Array Camera
(IRAC) for the Spitzer Space Telescope” and in the paper by Hora et al. (2004, SPIE, 5487, 244, [15])
entitled “In-flight performance and calibration of the Infrared Array Camera (IRAC) for the Spitzer
Space Telescope.” Copies of these papers are available on the Spitzer documentation website.
IRAC is a four-channel camera that provides simultaneous 5.2’ × 5.2’ images at 3.6, 4.5, 5.8, and 8 µm.
Two adjacent fields of view are imaged in pairs (3.6 and 5.8 µm; 4.5 and 8.0 µm) using dichroic
beamsplitters. All four detector arrays in the camera are 256 × 256 pixels in size, with a pixel size of