First image from the EVN MkIV Processor

An image of the quasar 3C380 at 6cm obtained with the EVN and the MkIV data processor at JIVE

On April 7, 1999, the EVN MkIV data processor at JIVE generated its first astronomical image. This is an important milestone in the commissioning phase and will lead to an operational correlator in the next few months.

The data is a subset of the global experiment GL034, which was also used during the demonstration of fringes at the inauguration ceremony last October. A complete 8 hour track from 8 European stations was processed: Cambridge, Effelsberg, Jodrell (Mk2), Medicina, Noto, Onsala, Torun and Westerbork. All these stations had reasonable data quality. Four 4 MHz bands in a single polarization (LCP) centred on 4987 MHz were processed in a 2 bit 1:1 mode.

Obtaining the first image exercised the data path at the JIVE processor for the first time. From the preliminary correlator output format, the data is converted into an aips++ measurement set. This is the package generally used for inspection of the data. For calibration and imaging we rely on classic AIPS. Using home-grown aips++ software, a multi-source UVFITS file was written and exported to AIPS. Calibration and mapping was done using the standard techniques. At the moment extensive editing is still required in the processing, as only limited automatic flagging in the processor is currently implemented. This (and the limited time available for processing) currently limits the image dynamic range to 200:1.

The source shows the same features as previous VLBI maps. In particular, we were happy to see the jet point in the same direction!

copyright 2022 JIVE