Articles written in Journal of Astrophysics and Astronomy
Volume 41 All articles Published: 25 September 2020 Article ID 0022
Quasars are ideal targets to use for astrometric calibration of large scale astronomical surveys as they have negligible proper motion and parallax. The forthcoming 4-m International Liquid Mirror Telescope (ILMT) will survey the sky that covers a width of about 27$'$. To carry out astrometric calibration of theILMT observations, we aimed to compile a list of quasars with accurate equatorial coordinates and falling in the ILMT stripe. Towards this, we cross-correlated all the quasars that are known till the present date with the sources in the
Volume 42 All articles Published: 28 May 2021 Article ID 0021 MISSION
AstroSat is India’s first dedicated astronomical observatory in space with multi-wavelength payload on a single platform. It enables simultaneous observations in the desired wavebands. The increase in the number of payloads has also led to an increase in the complexity in space segment design, groundsegment design, and mission operation management. Each payload instrument and mainframe has its own constraint for the operation, which needs to be satisfied to ensure the safety of the systems. In this paper, we explain the challenges in ground operations for mission management with various constraints. Also, we list the various constraints, both geometric and otherwise, with respect to the mainframe systems and payload instruments of AstroSat.
Volume 42 All articles Published: 11 June 2021 Article ID 0041 MISSION
Ultra Violet Imaging Telescope (UVIT) is one of the 5 instruments on AstroSat satellite, which was launched on September 28, 2015. UVIT was designed to make images with a resolution of <1:8$''$, simultaneously in two ultraviolet channels: Far Ultraviolet (130–180 nm) and Near Ultraviolet (200–300 nm). Images are also made in visible region (320–550 nm) for tracking drifts in pointing. The shortest wavelengths to be observed with UVIT can be heavily absorbed by mono-molecular deposits/contamination on the optical surfaces.Keeping contamination under control in UVIT was a major challenge and it required a variety of actions: (i) strict control of the payload materials and process, (ii) mechanical configuration, (iii) baking of all the parts to release all the adsorbed molecules etc., (iv) assembly in ultra cleanrooms, (v) pre-inspection and auditing of all the areas, in which UVIT was placed, for any potential for contamination, (vi) continuous purging, with ultrapure nitrogen gas, till a few days before the launch, etc. In order to minimise any possible cross contaminationsfrom the other payloads/satellite, the doors of UVIT were opened 2 months after the launch. The high performance in the orbit and high stability of the sensitivity over 4 years in the orbit shows that the contamination was negligible. This paper presents the processes and protocols followed during the integration and testingphase to minimise the contamination in order to prevent any performance degradation.
Volume 42, 2021
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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.
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