In-flight PSF calibration of the NuSTAR hard X-ray optics
Abstract
We present results of the point spread function (PSF) calibration of the hard X-ray optics of the Nuclear Spectroscopic Telescope Array (NuSTAR). Immediately post-launch, NuSTAR has observed bright point sources such as Cyg X-1, Vela X-1, and Her X-1 for the PSF calibration. We use the point source observations taken at several off-axis angles together with a ray-trace model to characterize the in-orbit angular response, and find that the ray-trace model alone does not fit the observed event distributions and applying empirical corrections to the ray-trace model improves the fit significantly. We describe the corrections applied to the ray-trace model and show that the uncertainties in the enclosed energy fraction (EEF) of the new PSF model is (approximately less than) 3% for extraction apertures of R (approximately greater than) 60'' with no significant energy dependence. We also show that the PSF of the NuSTAR optics has been stable over a period of ~300 days during its in-orbit operation.
- Publication:
-
Space Telescopes and Instrumentation 2014: Ultraviolet to Gamma Ray
- Pub Date:
- July 2014
- DOI:
- 10.1117/12.2055481
- arXiv:
- arXiv:1406.7419
- Bibcode:
- 2014SPIE.9144E..1QA
- Keywords:
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- Astrophysics - Instrumentation and Methods for Astrophysics;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 10 pages, 6 figures. Presented at the SPIE conference Astronomical Telescopes + Instrumentation 2014