Daily Image
28-08-2009
BBS Global Gain Solutions
| Submitter: | George Heald on behalf of the Imaging Busy Week I Team |
| Description: | In preparation for the first LOFAR Imaging Busy Week (held from 17-21 August 2009), we made a low band (30-75 MHz) observation of the 3C196 field, using the first five Dutch stations. The observation lasted for an entire weekend. During the busy week, we were able to calibrate the data and make a beautiful image (stay tuned for further radiative transfer!). Today, the daily image shows calibration results from BlackBoard Selfcal (BBS). The data points are the phase of the complex gains derived for the five LBA stations. The calibration was distributed over nine nodes of the processing cluster in Groningen, and used BBS's global solver to produce a gain solution for 17 subbands simultaneously. A separate gain solution was computed for each 5 second integration. Results for the Y polarization are shown here. The first of the series of three plots shows all of the solutions within a continuous 12-hour chunk of the data, and then two zoomed-in versions show the phase structure beautifully recovered by BBS. The dark blue rectangles illustrate the zoom ranges. We see a wealth of structure in these plots, corresponding to corrections for ionospheric and instrumental phase corruptions. The blue data points are for CS302, which functions as the "reference antenna" in these plots. The other data points are for RS307 (green), RS503 (red), RS106 (cyan), and RS208 (purple). In the RS208 solutions, phase variations corresponding to a full 360 degree rotation within 40 seconds are corrected for! The image resulting from this calibration will appear shortly. |
| Copyright: | ASTRON |
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