2021/10/21 by Kristin K. Madsen, Madsen, Kristin K., Karl Forster +9
Physics and Astronomy · #Advanced X-ray Imaging Techniques #Astrophysical Phenomena and Observations #Astrophysics #Calibration #Crab Nebula #Detector #FOS: Physical sciences #Gamma ray #Gamma-ray bursts and supernovae #High Energy Astrophysical Phenomena (astro-ph.HE) #Instrumentation and Methods for Astrophysics (astro-ph.IM) #Lens (geology) #Optics #Physics #Telescope #Vignetting #astro-ph.HE #astro-ph.IM
paper · pdf · doi:10.48550/arxiv.2110.11522
26 pages, 18 figures
arxiv created 2021/10/21 · openalex publication_date 2021/10/21 · arxiv updated 2021/10/25 · openalex created_date 2021/11/08 · openalex updated_date 2026/07/28
We present here the updated calibration of The Nuclear Spectroscopic Telescope ARray NuSTAR, which was performed using data on the Crab accumulated over the last 9 years in orbit. The basis for this new calibration contains over 250ks of focused Crab (imaged through the optics) and over 500ks of stray-light Crab (not imaged through optics). We measured an epoch averaged Crab spectrum of the stray-light Crab data and define a canonical Crab spectrum of Gamma = 2.103 +- 0.001 and N = 9.69 +- 0.02 keV-1 cm-2 s-1 at 1 keV, which we use as our calibration standard. The new calibration, released in the CALDB update 20211020, provides significant updates to: 1) the detector absorption component, 2) the detector response function, and 3) the effective area vignetting function. The calibration improves agreement between FPMA and FPMB across detectors with a standard deviation of 1.7% for repeat observations between off-axis angles of 1-4 arcmin, and the measured flux has increased by 5-15%, with 5% below 1 arcmin off-axis angle, 10% between 1-2 arcmin, and 15 above 4arcmin.