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arXiv · 1406.7419

In-flight PSF calibration of the NuSTAR hard X-ray optics

Hongjun An·Kristin K. Madsen·Niels J. Westergaard·Steven E. Boggs·Finn E. Christensen·William W. Craig·Charles J. Hailey·Fiona A. Harrison·Daniel K. Stern·William W. Zhang
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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 < 3% for extraction apertures of R > 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.

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Hongjun An, Kristin K. Madsen, Niels J. Westergaard, Steven E. Boggs, Finn E. Christensen, William W. Craig, Charles J. Hailey, Fiona A. Harrison, Daniel K. Stern, William W. Zhang. 2014-06-28. In-flight PSF calibration of the NuSTAR hard X-ray optics. https://doi.org/10.1117/12.2055481

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