IRS-TR 11001: Temporal Responsivity Variations on the Red Peak-Up Sub-Array

TL;DR

This paper investigates the temporal responsivity variations of the Red Peak-Up sub-array on the IRS of the Spitzer Space Telescope during its cryogenic mission, revealing a ~2% fluctuation over time.

Contribution

It provides the first detailed analysis of responsivity changes over the mission duration, quantifying the variations and their uncertainties.

Findings

Responsivity varied by approximately 2% during the mission.

Sensitivity decreased by 1.7% after initial campaigns and recovered by 1.0%.

Measurement uncertainties are better than 0.3%.

Abstract

Over the course of the cryogenic mission of the Spitzer Space Telescope, the responsivity of the Red Peak-Up sub-array on the Infrared Spectograph (IRS) varied by ~2%, based on an analysis of five standard stars. The sensitivity dropped 1.7% after the first 14 IRS campaigns, then climbed back up 1.0% later in the mission. The uncertainty in these measurements is better than ~0.3%. The random variations in the Peak-Up photometry of the standard stars has a gaussian distribution of width ~2%, similar to the magnitude of the systematic temporal variations.