VLSS redux: Software improvements applied to the Very Large Array Low-Frequency Sky Survey
Article first published online: 28 JUN 2012
©2012. American Geophysical Union. All Rights Reserved.
Volume 47, Issue 6, December 2012
How to Cite
2012), VLSS redux: Software improvements applied to the Very Large Array Low-Frequency Sky Survey, Radio Sci., 47, RS0K04, doi:10.1029/2011RS004941., , , and (
- Issue published online: 28 JUN 2012
- Article first published online: 28 JUN 2012
- Manuscript Accepted: 8 MAY 2012
- Manuscript Revised: 3 MAY 2012
- Manuscript Received: 1 DEC 2011
- ionospheric calibration;
- low-frequency radio astronomy;
 We present details of improvements to data processing and analysis which were recently used for a re-reduction of the Very Large Array (VLA) Low-Frequency Sky Survey (VLSS) data. Algorithms described are implemented in the data-reduction package Obit, and include smart-windowing to reduce clean bias, improved automatic radio frequency interference removal, improved bright-source peeling, and higher-order Zernike fits to model the ionospheric phase contributions. An additional, but less technical improvement was using the original VLSS catalog as a same-frequency/same-resolution reference for calculating ionospheric corrections, allowing more accuracy and a higher percentage of data for which solutions are found. We also discuss new algorithms for extracting a source catalog and analyzing ionospheric fluctuations present in the data. The improved reduction techniques led to substantial improvements including images of six previously unpublished fields (1% of the survey area) and reducing the clean bias by 50%. The largest angular size imaged has been roughly doubled, and the number of cataloged sources is increased by 35% to 95,000.