Measurement of the vertical atmospheric density profile from the X-ray Earth occultation of the Crab Nebula with Insight-HXMT

Abstract. X-ray Earth occultation sounding (XEOS) is an emerging method for measuring the neutral density in lower thermosphere. In this paper, (XEO) of Crab Nebula investigated using Hard Modulation Telescope (Insight-HXMT). The pointing observation data on 30 September 2018 recorded by low-energy telescope (LE) Insight-HXMT are selected and analysed. extinction light curves spectra during process extracted. A forward model XEO curve established, theoretical observational signal predicted. atmospheric built with a scale factor to commonly used Mass Spectrometer Incoherent Scatter Radar Extended (MSIS) profile within certain altitude range. Bayesian analysis developed modelling retrieval. posterior probability distribution parameters derived through Markov chain–Monte Carlo (MCMC) algorithm NRLMSISE-00 NRLMSIS 2.0 as basis functions, respective best-fit profiles retrieved. It found that range 105–200 km, retrieved 88.8 % 109.7 fitting energy 1.0–2.5 keV based XEOS method. 95–125 81.0 92.3 2.5–6.0 85–110 87.7 101.4 6.0–10.0 Goodness-of-fit testing carried out validation results. measurements compared simulations previous retrieval results NASA's Rossi Timing Explorer (RXTE) satellite. For further confirmation, we also compare measured ones standard spectrum iterative inversion technique. Finally, find from models qualitatively consistent RXTE. good agreement. This research provides evaluation MSIS predictions. study demonstrates astronomical satellite can provide approach upper atmosphere. join family XEOS. other satellites orbit form space network future.