The EVLA’s WIDAR correlator will be extremely powerful. With just a small fraction of its boards in place, its capabilities will exceed those of the VLA correlator for both spectral line and continuum observations. The delivery of WIDAR production boards to NRAO from our Canadian partner is underway and will continue throughout 2009. Science Commissioning of the EVLA, which will include commissioning the WIDAR correlator’s full suite of capabilities, will occupy the remainder of the EVLA construction phase that ends in 2012. As part of this commissioning process the VLA correlator will be turned off in January 2010 and will be replaced by WIDAR. At the same time the direction of the configuration cycles will also change, from A→B→C→D→A… to D→C→B→A→D…, in order to facilitate the WIDAR correlator commissioning and to limit initial EVLA data rates. The transition from the VLA correlator to WIDAR, and the reversal of the configuration cycle, marks the beginning of EVLA Early Science.
At the end of this year the VLA/EVLA will spend two trimesters in D configuration, starting with the VLA correlator (October 2009 through mid-January 2010) and followed by the commissioning of some basic observing modes using the WIDAR correlator. The EVLA Early Science Phase, which includes both an Open Shared Risk Observing (OSRO) program for the general user community and the Resident Shared Risk Observing (RSRO) program described below, is expected to begin in March 2010 in the D configuration. This article describes the enhanced scientific opportunities that will be offered to users during the EVLA Early Science Phase as a result of the upcoming correlator transition, under these two different programs.
The Open Shared Risk Observing (OSRO) program continues the shared risk observing access to the EVLA that has been offered to all users of the VLA since the EVLA construction project began. Under the OSRO program the general user community will be offered early access to a number of WIDAR capabilities and observing modes that represent a significant improvement over those of the VLA correlator. The initial WIDAR configurations to be offered to all users for OSRO are described in more detail at the EVLA Information for Astronomers web page. Time will be allocated for OSRO via the normal NRAO peer-review process. It will be possible to reduce simple OSRO datasets using AIPS, although users are encouraged to use CASA, which will also be available. The capabilities of the WIDAR correlator available for OSRO will be expanded as soon as they can be supported for general use. The OSRO program will run from March 2010 through the end of the EVLA construction phase.
Along with the OSRO program described above, NRAO also announces a Resident Shared Risk Observing (RSRO) program during the EVLA Early Science Phase. This program offers participants full access to the growing capabilities of the WIDAR correlator for peer-reviewed science projects, in exchange for a period of residence in Socorro to assist with the Science Commissioning of the EVLA.
The RSRO program is intended to accelerate the development of the EVLA’s full scientific capabilities by gaining enhanced commissioning resources and expertise through community participation. It will at the same time help quickly optimize the scientific productivity of the EVLA. The EVLA capabilities currently expected to be available under the RSRO program as a function of time are described at the EVLA Information for Astronomers web page. The RSRO program will run for approximately two years (from March 2010 through the end of 2011), with up to 25% of the EVLA time available for astronomical observations allocated to the RSRO program, depending on demand and quality of science proposed. At the end of this period all access to the EVLA will be through the OSRO program, until full operations begin in 2013.
The primary requirement of the RSRO program is that there be at least one expert from each participating group in residence in Socorro. These experts must be able to contribute effectively to the Science Commissioning of the EVLA. Some NRAO support for salaries or accommodation may be available. Further details of the RSRO program are available at the EVLA Information for Astronomers web page.
In order to assess community interest in the RSRO program, and to inform whether a special workshop for potential resident shared risk observers on EVLA capabilities should be held later this spring, we request that Letters of Interest be sent directly to the Assistant Director for NM Operations (firstname.lastname@example.org). A list of potential commissioning tasks that would benefit from RSRO participation can be found in the description of the RSRO program, available at the EVLA Information for Astronomers web page.
Questions regarding the EVLA early science opportunities should be directed to Claire Chandler (email@example.com).