Pointing the SOFIA Telescope

TL;DR

This paper details the algorithms and systems enabling the SOFIA airborne telescope to maintain accurate pointing and coordinate referencing despite its dynamic flight conditions.

Contribution

It introduces novel methods for coordinate transformation, tracking, and image stabilization tailored for an airborne infrared telescope.

Findings

Successful implementation of coordinate referencing algorithms

Effective management of field rotation and tracking

Enhanced pointing accuracy during flight

Abstract

SOFIA is an airborne, gyroscopically stabilized 2.5m infrared telescope, mounted to a spherical bearing. Unlike its predecessors, SOFIA will work in absolute coordinates, despite its continually changing position and attitude. In order to manage this, SOFIA must relate equatorial and telescope coordinates using a combination of avionics data and star identification, manage field rotation and track sky images. We describe the algorithms and systems required to acquire and maintain the equatorial reference frame, relate it to tracking imagers and the science instrument, set up the oscillating secondary mirror, and aggregate pointings into relocatable nods and dithers.