B. T. RAVISHANKAR
Articles written in Journal of Astrophysics and Astronomy
Volume 38 Issue 2 June 2017 Article ID 0032 Review Article
Early In-orbit Performance of Scanning Sky Monitor Onboard AstroSat
M. C. Ramadevi B. T. Ravishankar N. Sitaramamurthy G. Meena Brajpal Singh Anand Jain Reena Yadav Anil Agarwal V. Chandra Babu Kumar Ankur Kushwaha S. Vaishali Nirmal Kumar Iyer Anuj Nandi Girish V. Vivek Kumar Agarwal S. Seetha Dipankar Bhattacharya K. Balaji Manoj Kumar Prashanth Kulshresta
We report the in-orbit performance of Scanning Sky Monitor (SSM) onboard AstroSat. The SSM operates in the energy range 2.5 to 10 keV and scans the sky to detect and locate transient X-ray sources. This information of any interesting phenomenon in the X-ray sky as observed by SSM is provided to the astronomical community for follow-up observations. Following the launch of AstroSat on 28th September, 2015, SSM was commissioned on October 12th, 2015. The first power ON of the instrument was with the standard X-ray source, Crab in the field-of-view. The first orbit data revealed the basic expected performance of one of the detectors of SSM, SSM1. Following this in the subsequent orbits, the other detectors were also powered ON to find them perform in good health. Quick checks of the data from the first few orbits revealed that the instrument performed with the expected angular resolution of 12’ × 2.5∘ and effective area in the energy range of interest. This paper discusses the instrument aspects along with few on-board results immediately after power ON.
Volume 39 Issue 1 February 2018 Article ID 0011 Review
Study of X-ray transients with Scanning Sky Monitor (SSM) onboard AstroSat
M. C. RAMADEVI B. T. RAVISHANKAR ABHILASH R. SARWADE S. VAISHALI NIRMAL KUMAR IYER ANUJ NANDI V. GIRISH VIVEK KUMAR AGARWAL BLESSY ELIZABETH BABY MOHAMMED HASAN S. SEETHA DIPANKAR BHATTACHARYA
Scanning Sky Monitor (SSM) onboard AstroSat is an X-ray sky monitor in the energy range 2.5–10 keV. SSM scans the sky for X-ray transient sources in this energy range of interest. If an X-ray transient source is detected in outburst by SSM, the information will be provided to the astronomical community for follow-up observations to do a detailed study of the source in various other bands. SSM instrument, since its power-ON in orbit, has observed a number of X-ray sources. This paper discusses observations of few X-ray transients by SSM. The flux reported by SSM for few sources during its Performance Verification phase (PV phase) is studied and the results are discussed.
Volume 42 All articles Published: 26 June 2021 Article ID 0056 DATA PIPELINE
B. T. RAVISHANKAR S. VAISHALI D. BHATTACHARYA M. C. RAMADEVI ABHILASH SARWADE S. SEETHA
The data pipeline at the Payload Operation Centre (POC) of the Scanning Sky Monitor (SSM) onboard AstroSat involves: (i) fetching the Level-0 data from the Indian Space Science Data Centre (ISSDC), (ii) Level-0 to Level-1 data processing followed by Level-2 data generation, and (iii) transfer of theLevel-1 and Level-2 data back to ISSDC for dissemination of the re-packaged Level-2 data products. The major tasks involved in the generation of Level-1 and Level-2 data products are: (a) quality checks; time, alignment corrections, (b) temporal-HK plots generation, and, (c) image processing; light curve generation.The typical turn around time for this fully automated pipeline is about 25 min for one orbit data. In this paper, details of all the stages of this data pipeline are discussed.
Volume 42 All articles Published: 3 July 2021 Article ID 0070 PAYLOAD CALIBRATION
Calibration of Scanning Sky Monitor (SSM) onboard AstroSat
ABHILASH R. SARWADE M. C. RAMADEVI B. T. RAVISHANKAR BRAJPAL SINGH BLESSY ELIZABETH BABY DIPANKAR BHATTACHARYA S. SEETHA
SSM onboard AstroSat is designed to monitor X-ray sky in the energy range 2.5–10 keV to detect and locate X-ray sources in outburst. SSM with its three almost identical 1D-proportional counters mounted on a rotating platform, scans the sky in step and stare mode of operation. It observes the X-ray skyand generates light curves for X-ray sources detected. Here, we discuss the positional calibration to carry out imaging with SSM. Onboard calibration of SSM has been carried out with Crab, the standard X-ray source. SSM observations of Crab are compared with that of MAXI on ISS for cross calibration of the instrument.
Volume 44, 2023
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