2012/05/16 by W. M. Lane, W. D. Cotton, J. F. Helmboldt +1 · 1 citation
Engineering · Physics and Astronomy · #Data processing #Data reduction #GNSS positioning and interference #Interference (communication) #Ionosphere #Ionosphere and magnetosphere dynamics #Radio Astronomy Observations and Technology #Sky #Software #Software package #astro-ph.IM
paper · pdf · doi:10.1029/2011rs004941
12 pages, 4 figures, accepted for publication in the "Low Frequency Arrays and the Ionosphere" special edition of Radio Science
openalex publication_date 2012/05/16 · crossref created 2012/05/16 · arxiv created 2012/05/21 · arxiv updated 2012/05/22 · crossref issued 2012/06/28 · crossref published 2012/06/28 · crossref published-online 2012/06/28 · crossref published-print 2012/12/01 · openalex created_date 2019/12/13 · crossref deposited 2023/10/30 · crossref indexed 2026/08/03 · openalex updated_date 2026/08/05
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 The improved reduction techniques led to substantial improvements including images of six previously unpublished fields (1% of the survey area) and reducing the clean bias by 50%.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.