Articles written in Journal of Astrophysics and Astronomy
Volume 5 Issue 2 June 1984 pp 139-148
A 4-km synthesis radio telescope has recently been commissioned at Ootacamund, India for operation at 327 MHz. It consists of the Ooty Radio Telescope (530 m × 30 m) and 7 small antennas which are distributed over an area of about 4 km × 2 km. It has a coverage of about ± 40‡ in declination δ. The beam-width is about 40 arcsec × 90 arcsec at δ = 0‡ and about 40 arcsec × 50 arcsec at δ = 40‡. The sensitivity attained for a 5:1 signal-to-noise ratio is about 15 m Jy after a 10-hour integration.
The observational programmes undertaken and some of the results obtained recently are summarized. The radio halo around the edge-on spiral NGC 4631 is found to have a larger scale-height at 327 MHz than is known at higher frequencies. Mapping of interesting radio galaxies at 327 MHz is being carried out; preliminary results for 0511-305 (∼2 Mpc) and 1333-337 (∼750 kpc) are summarized. The very-steep-spectrum radio source in the Abell cluster A85 is found to be resolved; since it has no obvious optical counterpart, it is conceivable that it is a remnant of past activity of a galaxy that has drifted away in about 109 years.
Volume 5 Issue 4 December 1984 pp 429-473
We present total-intensity and linear-polarization observations with the Very Large Array (VLA) at λ6 and 2 cm of 17 sources, almost all of which were suspected to have extended emission only on one side of the nucleus. Five of them are still one-sided, three appear unresolved, while seven have radio lobes on both sides of the nucleus. The outer components in the double-lobed sources, however, have significantly different surface brightness or are very asymmetrically located with respect to the nucleus.
Volume 5 Issue 4 December 1984 pp 475-482
We present total-intensity and linear-polarization observations made with the VLA at 5 GHz of 1400+ 162, a BL Lac object in a group of galaxies. It has a misaligned triple structure with a prominent radio jet towards the east. There is evidence of a weak counter-jet towards the western component, which also has the more prominent warm-spot.
We discuss possible explanations for some of the observed features of this source. Although interaction with the cluster medium is possibly partly responsible for the observed distortion, we suggest that the large observed misalignment could also be due to amplification of a smaller misalignment by projection effects. In the relativistic beaming model, where BL Lac objects arise when the relativistic jets are seen end-on, we suggest that 1400+ 162 is more oblique to the line of sight than most members of this class.
Volume 11 Issue 2 June 1990 pp 237-253
Observations have been conducted using the Ooty Radio Telescope in order to place constraints on the evolutionary scenario leading to the formation of the present day superclusters. The experiment attempted to detect 21 cm emission from massive neutral hydrogen condensates at a redshift of
Volume 11 Issue 4 December 1990 pp 551-551 Erratum
Volume 16 Issue 3-4 December 1995 pp 393-398
Jupiter flux at 327 MHz was monitored using the Ooty radio telescope from July 12th to July 29th during the collision of comet Shoemaker-Levi 9 with Jupiter. Flux was found to increase steadily from July 17th to July 26th by ∼ 2–5 Jy, after which it declined to its pre-event value. The comparison of 327 MHz observations with those at 840 MHz and 2240 MHz indicates that the enhancement was mainly due to the increased synchrotron emission and the contribution of thermal emission was very small at metric-decimetric frequencies. The enhancement in radio emission was found to be more at 840 MHz than at 327 or 2240 MHz. The steepening of the spectrum between 327 and 840 MHz as well as between 2240 and 840 MHz was also noted.
Volume 40 | Issue 5
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