The Mauritius Radiotelescope

Golap, K.; Issur, Nalini H.; Somanah, Radhakhrishna; Dodson, Richard; Modgekar, Manohar; Sachdev, S.; Shankar, N. Udaya; Sastry, Ch. V.

doi:10.1007/bf00984990

Cited by 7 publications

(2 citation statements)

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“…The flux density of these three calibrators as seen by MRT is ∼ 100 Jy; strong to get reliable calibration. Further, the calibrators are unresolved and isolated from confusing sources and have well known measured positions (Golap 1998).…”

Section: Array Geometry: Hypothesis and Re-estimationmentioning

confidence: 99%

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Two-dimensional homography-based correction of positional errors in widefield MRT images

Nayak¹,

Daiboo²,

Shankar³

2010

Monthly Notices of the Royal Astronomical Society

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A steradian of the southern sky has been imaged at 151.5 MHz using the Mauritius Radio Telescope (MRT). These images show systematics in the positional errors of sources when compared to source positions in the Molonglo Reference Catalogue (MRC). We have applied two-dimensional homography to correct for systematic positional errors in the image domain and thereby avoid re-processing the visibility data. Positions of bright (above 15σ ) point sources, common to the MRT catalogue and MRC, are used to set up an over-determined system to solve for the homography matrix. After correction, the errors are found to be within 10 per cent of the beamwidth for these bright sources and the systematics are eliminated from the images. This technique will be of relevance to the new generation radio telescopes where, owing to huge data rates, only images after a certain integration would be recorded as opposed to raw visibilities. It is also interesting to note how our investigations cued to possible errors in the array geometry. The analysis of positional errors of sources showed that MRT images are stretched in declination by ∼1 part in 1000. This translates to compression of the baseline scale in the visibility domain. The array geometry was re-estimated using the astrometry principle. The estimates show an error of ∼1 mm m −1 , which results in an error of about half a wavelength at 150 MHz for a 1-km north-south baseline. The estimates also indicate that the east-west arm is inclined by an angle of ∼40 arcsec to the true east-west direction.

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Section: Array Geometry: Hypothesis and Re-estimationmentioning

confidence: 99%

“…The Mauritius Radio Telescope (MRT; Golap et al 1995; Udaya Shankar et al 2002) is a Fourier synthesis, T‐shaped non‐coplanar array operating at 151.5 MHz. The telescope was built to fill the gap in the availability of deep sky surveys at low radio frequencies in the Southern hemisphere.…”

Section: Introductionmentioning

confidence: 99%