• N. Hari Prasad Rao

      Articles written in Journal of Astrophysics and Astronomy

    • Planning and Scheduling of Payloads of AstroSat During Initial and Normal Phase Observations

      R. Pandiyan S. V. Subbarao T. Nagamani Chaitra Rao N. Hari Prasad Rao Harish Joglekar Naresh Kumar Surya Ratna Prakash Dumpa Anshu Chauhan B. P. Dakshayani

      More Details Abstract Fulltext PDF

      On 28th September 2015, India launched its first astronomical space observatory AstroSat, successfully. AstroSat carried five astronomy payloads, namely, (i) Cadmium Zinc Telluride Imager (CZTI), (ii) Large Area X-ray Proportional Counter (LAXPC), (iii) Soft X-ray Telescope (SXT), (iv) Ultra Violet Imaging Telescope (UVIT) and (v) Scanning Sky Monitor (SSM) and therefore, has the capability to observe celestial objects in multi-wavelength. Four of the payloads are co-aligned along the positive roll axis of the spacecraft and the remaining one is placed along the positive yaw axis direction. All the payloads are sensitive to bright objects and specifically, require avoiding bright Sun within a safe zone of their bore axes in orbit. Further, there are other operational constraints both from spacecraft side and payloads side which are to be strictly enforced during operations. Even on-orbit spacecraft manoeuvres are constrained to about two of the axes in order to avoid bright Sun within this safe zone and a special constrained manoeuvre is exercised during manoeuvres. The planning and scheduling of the payloads during the Performance Verification (PV) phase was carried out in semi-autonomous/manual mode and a complete automation is exercised for normal phase/Guaranteed Time Observation (GuTO) operations. The process is found to be labour intensive and several operational software tools, encompassing spacecraft sub-systems, on-orbit, domain and environmental constraints, were built-in and interacted with the scheduling tool for appropriate decision-making and science scheduling. The procedural details of the complex scheduling of a multi-wavelength astronomy space observatory and their working in PV phase and in normal/GuTO phases are presented in this paper.

    • Special calibrations during AstroSat mission operations towards meeting observation and pointing requirements


      More Details Abstract Fulltext PDF

      AstroSat, India’s first astronomical observatory was launched on 28th September 2015 by PSLV into an orbit of altitude 650 km and 6$^{\circ}$ inclination. The simultaneous observations made by the payloads allow imaging of celestial source in various wavebands and has resulted in scientific achievements published in various fora. AstroSat is designed to carry 6 ($5+1$ auxiliary) astronomy payloads namely, UVIT, LAXPC, SXT, CZTI, CPM and SSM. The payloads are mounted such that the boresight of all the 4 main payloadsexcept SSM are along the $+$Roll direction in body frame. To meet all requirements of different payloads carried on-board AstroSat, various mission planning, analysis, and operations specific to this mission are carried out. These include post launch observations and mitigations planned and implemented onboard.

  • Journal of Astrophysics and Astronomy | News

    • Continuous Article Publication

      Posted on January 27, 2016

      Since January 2016, the Journal of Astrophysics and Astronomy has moved to Continuous Article Publishing (CAP) mode. This means that each accepted article is being published immediately online with DOI and article citation ID with starting page number 1. Articles are also visible in Web of Science immediately. All these have helped shorten the publication time and have improved the visibility of the articles.

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

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