Articles written in Journal of Astrophysics and Astronomy
Volume 22 Issue 1 March 2001 pp 131-144
Development of a three channel photometer for UPSO, Naini Tal
B. N. Ashoka Kumar V. C. Babu S. Seetha V. Girish S. K. Gupta Ram Sagar S. Joshi P. Narang
The design and performance of a portable three channel photometer installed at the Uttar Pradesh State Observatory (UPSO), Naini Tal is described. The photometer is modular and the whole unit can be disassembled as individual channels such that the system can also be used as a single channel or two channel photometer. The system also has provision to monitor a guide star. The instrument was put into operation since November 1999 on the 1m Sampurnanand telescope at UPSO, Naini Tal. Since then, it is used extensively for the ‘Survey of rapidly oscillating Ap (roAp) stars in the northern sky’ from UPSO. Observational results using this new photometer in its initial phase of operation are discussed. The advantage of having continuous sky measurement is demonstrated.
Volume 26 Issue 2-3 June 2005 pp 203-211
HD 12098 and other results from Nainital-Cape Survey
Nainital-Cape Survey was started with an aim to search for new rapidly oscillating Ap stars in the northern hemisphere. We discovered one new mono-periodic roAp star HD 12098. The frequency separation of HD 12098 suggests a rotation period of 5.5 days for the star. We summarize here the observations of HD 12098 and briefly discuss the results of the multi-site observation campaign organized to resolve the ambiguity in the determination of the rotation period of HD 12098. Other interesting results like non-oscillating Ap stars discovered and two candidate stars in which roAp periodicity is seen but not confirmed are also discussed.
Volume 38 Issue 2 June 2017 Article ID 0028 Review Article
In-orbit Performance of UVIT and First Results
S. N. Tandon J. B. Hutchings S. K. Ghosh A. Subramaniam G. Koshy V. Girish P. U. Kamath S. Kathiravan A. Kumar J. P. Lancelot P. K. Mahesh R. Mohan J. Murthy S. Nagabhushana A. K. Pati J. Postma N. Kameswara Rao K. Sankarasubramanian P. Sreekumar S. Sriram C. S. Stalin F. Sutaria Y. H. Sreedhar I. V. Barve C. Mondal S. Sahu
The performance of the ultraviolet telescope (UVIT) on-board AstroSat is reported. The performance in orbit is also compared with estimates made from the calibrations done on the ground. The sensitivity is found to be within ∼15% of the estimates, and the spatial resolution in the NUV is found to exceed significantly the design value of 1.8′′ and it is marginally better in the FUV. Images obtained from UVIT are presented to illustrate the details revealed by the high spatial resolution. The potential of multi-band observations in the ultraviolet with high spatial resolution is illustrated by some results.
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 May 2021 Article ID 0020 PAYLOAD REVIEW
In-orbit performance of UVIT over the past 5 years
S. K. GHOSH P. JOSEPH A. KUMAR J. POSTMA C. S. STALIN A. SUBRAMANIAM S. N. TANDON I. V. BARVE A. DEVARAJ K. GEORGE V. GIRISH J. B. HUTCHINGS P. U. KAMATH S. KATHIRAVAN J. P. LANCELOT D. LEAHY P. K. MAHESH R. MOHAN S. NAGABHUSHANA A. K. PATI N. KAMESWARA RAO K. SANKARASUBRAMANIAN P. SREEKUMAR S. SRIRAM
Over the last 5 years, UVIT has completed observations of more than 500 proposals with $\sim$800 unique pointings. In addition, regular planned monitoring observations have been made and from their analysis various key parameters related to in orbit performance of UVIT have been quantified. The sensitivities of the UV channels have remained steady indicating no effect of potential molecular contamination confirming the adequacy of all the protocols implemented for avoiding contamination. The quality of the PSF through the years confirms adequacy of thermal control measures. The early calibrations obtained during the Performance Verification (PV) phase have been further revised for more subtle effects. These include flat fields and detector distortions with greater precision. The operations of UVIT have also evolved through inorbit experience, e.g. tweaking of operational sequencing, protocol for recovery from bright object detection (BOD) shutdowns, parameters for BOD thresholds, etc. Finally, some effects of charged particle hits on electronics led to optimised strategy for regular resetting. The Near-UV channel was lost in one of suchoperations. All the above in-orbit experiences are presented here.
Volume 42 All articles Published: 12 June 2021 Article ID 0045 MISSION
AstroSat science operations and userbase
V. GIRISH LEO JACKSON JOHN C. BALAMURUGAN K. R. SANGAMESH
AstroSat, India’s first observatory class satellite, operates as a proposal based observatory. AstroSat carries five science payloads capable of simultaneous observations in a broad energy band. In this article, we will summarize the science operations of AstroSat, AstroSat user distribution, user support available for AstroSat users and publications related to AstroSat and AstroSat data.
Volume 42 All articles Published: 24 July 2021 Article ID 0083 SCIENCE RESULTS
Observations of AR Sco with
K. P. SINGH V. GIRISH J. TIWARI P. E. BARRETT D. A. H. BUCKLEY S. B. POTTER E. SCHLEGEL V. RANA G. STEWART
We present our
Volume 44, 2023
Continuous Article Publishing mode
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.
Click here for Editorial Note on CAP Mode