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MSSS-HBA 6-field mosaic

Submitter: George Heald
Description: Over the past year, the MSSS Team has developed a set of automatic procedures to calibrate and image interferometric LOFAR data obtained through observations of arbitrary locations on the sky. These steps have been incorporated by ASTRON's software group into the LOFAR Standard Imaging Pipeline. The MSSS processing chain was designed on the basis of systematic testing of LBA data, but in the more recent past some HBA data have been obtained in preparation for the beginning of large scale MSSS-HBA observations. After a couple of very small modifications, the same procedures have been found to work extremely well for the HBA data.

One of the recent HBA datasets is shown in today's image. MSSS observations now use the 8-bit mode, enabling about 96 MHz of bandwidth. For MSSS, this bandwidth is distributed over 6 simultaneous fields. Each of the six fields is observed using eight bands, and each band has 2 MHz of contiguous bandwidth. For the HBA survey, each set of six fields is observed twice, for seven minutes each.

The image above therefore represents just 14 minutes of observing time (although 2 additional minutes of primary flux calibrator observations were also used). The image was produced after the pre-defined automatic sequence of processing steps were followed. It is a mosaicked image of all 6 fields together, and combines all 16 MHz of survey bandwidth (irregularly spanning the range 119 to 158 MHz). This particular image was made using only baselines shorter than 4 km, and therefore has an angular resolution of about 2 arcminutes. The noise is approximately 10 mJy/beam (the dynamic range is over 2000) and is probably confusion limited. Longer baselines are included in MSSS observations and can be utilized to obtain images with higher angular resolution.

You can look forward to seeing more of these images being produced by MSSS in the coming months!
Copyright: LOFAR / MSSS Team
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