Daily Image
04-02-2009
First synthesis image Digestif & WSRT
| Submitter: | Apertif team |
| Description: | 2008 was already a very succesful year for Apertif, but it looks like that 2009 will be even better. Last december we were able to present the first fringes between Digestif and other WSRT dishes. Now, after some more effort, in particular by George Heald, we are very proud that we can show the first synthesis image based on interferometry between a WSRT dish equipped with a Focal-Plane Array and 3 other WSRT dishes that use the old MFFE frontend. In fact, these are the first synthesis images ever made using a radio dish equipped with a focal-plane array, not only here at Astron. The image shows the two `twin' radio sources 3C343 and 3C343.1, the Castor and Pollux of the radio sky1. To make this image, the outputs of 3 MFFE dishes (RT1, RT3 & RT4) were directly fed into the DIGESTIF back-end at RT52. Later, after inserting the proper delays etc, these data were correlated with the Digestif signal in software. This resulted in the measurement of the visibilities on 3 WSRT-Digestif baselines. Measurements were made at regular intervals over a period of a few hours. The dirty image obtained from the data is shown on the left, clearly showing the two radio sources. The stripes etc. are due to the fact that only 3 baselines were measured over a limited period of time. The figure on the right shows the image after correction for these effects. The spatial resolution of the image is just over 1 arcminute. The image shown is based on correlating the MFFE data with one Digestif element. However, the correlations with other Digestif elements are also available, so with the same data it possible to make a similar image based on correlations of the MFFE dishes with a compound Digestif beam. Wim van Cappellen and George Heald are working hard on this, so stay tuned. 1: for those who don't know: Castor and Pollux are the two brightest stars of the constellation Gemini (The Twins), 2: again, we would like to thank the Radio Observatory staff for their contribution in making the observations possible |
| Copyright: | Astron |
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