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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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 less than or similar to 3 for extraction apertures of R greater than or similar to 60" with no significant energy dependence. We also show that the PSF of the NubSTAR optics has been stable over a period of similar to 300 days during its in-orbit operation.
Original languageEnglish
Title of host publicationProceedings of the SPIE Astronomical Telescopes + Instrumentation 2014: Ultraviolet to Gamma Ray
EditorsTadayuki Takahashi, Jan-Willem A. den Herder, Mark Bautz
Number of pages10
PublisherSPIE - International Society for Optical Engineering
Publication date2014
Article number 91441Q
Publication statusPublished - 2014
EventSPIE 2014: Astronomical Telescopes + Instrumentation - Palais des congrés de Montréal Montréal, Quebec, Canada, Montreal, Canada
Duration: 22 Jun 201427 Jun 2014


ConferenceSPIE 2014
LocationPalais des congrés de Montréal Montréal, Quebec, Canada
SeriesProceedings of S P I E - International Society for Optical Engineering

Bibliographical note

Copyright 2015 Society of Photo Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic electronic or print reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.


  • NuSTAR
  • X-ray optics
  • Point Spread Function (PSF)
  • Half Power Diameter (HPD)
  • Calibration


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