Reconstruction of the NuSTAR point spread function using single-laser metrology

Abstract

We describe a method by which the metrology system of the Nuclear Spectroscopic Telescope Array (NuSTAR) X-ray space observatory, which uses two lasers to characterize the relative motion of the optics and focal plane benches, can be approximated should one laser fail. The two benches are separated by a 10-m-long rigid mast that undergoes small amounts of thermal flexing that needs to be compensated for to produce a nonblurred image. We analyze the trends of mast motion by archival observation parameters to discover whether the mast motion in future observations can be predicted. We find that, using the solar aspect angle, observation date, and orbital phase, we can simulate the motion of one laser by translating the track produced by the other and applying modifications to the resulting mast aspect solution, allowing for the reconstruction of a minimally distorted point spread function in most cases. We will implement the generation of simulated mast files along with the usual NuSTAR data reduction pipeline for contingency purposes. This work has implications for reducing the risk of implementing laser metrology systems on future missions that use deployable masts to achieve the long focal lengths required in high-energy astronomy by mitigating the impact of a metrology laser failure in the extended phase of a mission. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

The extendable boom and laser metrology design for the high energy x-ray probe (HEX-P)

“…For example, over a ten-year lifetime, the NuSTAR lasers have lost up to 50% of their initial power for reasons that are not known. 9 A lens is used to focus the laser beam on the detector to an elliptical spot with major axis of 3.7 mm. The lasers to be used are already identified as the space-qualified spares for the Planetary Instrument for X-Ray Lithochemistry (PIXL) † instrument, currently is storage.…”