Title:	VLA low band project: early commissioning results and vision for a primary focus-based commensal observing system
Authors:	Kassim, Namir E. Clarke, T.E. Hicks, B. Peters, W.M. Wilson, T.L. Cutchin, S. Owen, F.N. Perley, R.A. Durand, S. Kutz, C. Harden, P. Intema, H. Brisken, W. Subrahmanyan, Ravi Taylor, G.B. Lazio, T.J.
Issue Date:	Jan-2013
Publisher:	The American Astronomical Society
Citation:	American Astronomical Society Meeting, 2103, Vol. 221
Abstract:	We present an update on the Jansky Very Large Array Low Band (VLA-LB) project, currently undergoing scientific commissioning and expected to be fully available in 2013. VLA-LB is a joint NRL and NRAO initiative to equip the VLA with broadband low frequency receivers that cover the spectrum between 66 and 470 MHz. The current system can already access the 66 to 86 MHz and 230 to 436 MHz sub-bands by working with existing 74 and 330 MHz feeds, respectively. The bandwidth at 74 MHz will increase by more than an order of magnitude while the 330 MHz bandwidth increases by approximately a factor of 6. The improved bandwidth and system temperature, coupled with the power of the WIDAR correlator, promise significantly enhanced performance compared to past VLA capabilities. Early commissioning results at “P band” (330 MHz) with a handful of antennas accessing the larger bandwidth indicate sensitivity rivaling that of the legacy 27-antenna, narrow-band old VLA capability. New feeds that can exploit a larger fraction of the available receiver bandwidth are being explored. While VLA-LB is useful as a conventional system, we are looking to enhance its power by leveraging the VLA’s capability to detect radiation at its prime and Cassegrain foci simultaneously. The ability to observe with more than one band in parallel is a powerful multiplier of a telescope’s function, and many instruments (e.g. the GMRT, WSRT and VLA) offer this. A variant is being explored for VLA-LB: observing from the prime focus during all normal Cassegrain observations. This proposed VLA-LB commensal system would piggyback normal VLA observing time to survey at low frequencies with relatively large field of views. Shared fields with other multi-beaming, dipole-based arrays that view the same sky with the VLA, e.g. the first station of the Long Wavelength Array (LWA1), would be possible. The collected data will be assembled into a database of spectra and wide-field images, suitable for studies of individual objects as well as searches for transients and high redshift spectral features (eg. HI absorption or OH mega-masers). We describe how the VLA-LB commensal system might be implemented, and explore early ideas for its scientific promise.
Description:	Restricted Access.
URI:	http://hdl.handle.net/2289/5426
Alternative Location:	http://adsabs.harvard.edu/abs/2013AAS...22132804K
Copyright:	2013 The American Astronomical Society
Appears in Collections:	Research Papers (A&A)

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