National RadioAstronomy Observatory
National RadioAstronomy Observatory
National Radio
News for VLA/VLBA/HSA/VLBI Proposers, September 15, 2009This "News" posting contains the following sections
News for VLBA/HSA/VLBI proposers
1. General newsa. Support for PhD dissertations using NRAO facilitiesStudents planning to use an NRAO telescope for their PhD dissertation (particularly if more than one proposal will be required) must submit a "Plan of Dissertation Research" of no more than 1000 words with their first proposal. This plan can be referred to in later proposals. At a minimum it should contain a thesis time line and an estimate of the level of NRAO telescope resources needed. The plan provides some assurance against a dissertation being impaired by adverse referee comments on one proposal, when the referees do not see the full scope of the project. The plan can be submitted via the NRAO Interactive Services. Proposers are reminded to prepare the plan comfortably in advance of the proposal deadline. This requirement applies to all three of the NRAO major instruments: VLA, VLBA and GBT. b. Large proposalsLarge proposals to use NRAO instruments will be considered at the 2009 October 1 proposal deadline, and at all subsequent proposal deadlines, as part of the normal proposal selection and time allocation process. There is no longer a separate call for large proposals. Please see the Large Proposal Policy for further details. c. Key Science ProjectsBeginning with the October 1, 2009 deadline, proposals for time on the VLBA and the GBT will be considered for designation as "Key Science Projects." This is part of the NRAO plan to call for "Key Science Projects" for all NRAO facilities, including EVLA and ALMA as they come into full science operation in the next few years. Key Science Projects should be those that have high science impact, addressing fundamental and forefront issues in astronomy and astrophysics. Key Science Project status will be based on scientific ranking, recommendation by the NRAO Proposal Selection Committee (PSC) and approval by the NRAO Director. Please see the September 2009 NRAO eNews for further details on the Key Science Project policy. 2. News for VLA proposersa. General observing capabilities for the 2009 October 1 proposal deadline: EVLA Early ScienceThe 2009 October 1 deadline is for the first trimester of EVLA Early Science. The VLA correlator will be turned off in January 2010. Following the transfer of hardware from the VLA correlator to the new EVLA correlator, the array will return as the EVLA in March 2010. The October 1 deadline is for proposals to use the first EVLA D-configuration (currently scheduled between 2010 March 1 and 2010 May 24) and DnC-configuration (from 2010 May 28 to 2010 June 14), along with proposals to use the reconfiguration time from the D configuration to DnC (May 24-28, 2010). The number of EVLA antennas continues to increase at a rate of one every two months. At the beginning of the EVLA D-configuration we will have 25 EVLA antennas in the array. EVLA Early Science will be provided by two programs for the user community: the Open Shared Risk Observing (OSRO) program and the Resident Shared Risk Observing (RSRO) program. These programs have been announced previously in the NRAO eNews. Details of the correlator capabilities expected to be available through these programs are described at the OSRO and RSRO web pages, available from the EVLA Information for Astronomers web page. We remind users that access to the EVLA is on a shared-risk basis, and that the EVLA is a telescope undergoing commissioning through the end of 2012. Nevertheless, NRAO will make every effort to ensure the quality of data obtained from the EVLA. For the trimester under consideration we will be offering extended EVLA tuning ranges at L, C, K, Ka, and Q bands. Some of these systems are "interim", which means they use old VLA polarizers. At C-band the EVLA antennas with receivers containing the old polarizers are able to tune from 4.2 to 7.7 GHz. The ranges outside the nominal VLA frequencies for C and L bands have poor sensitivity and polarization performance for the interim receivers, as compared with the nominal VLA frequencies. Further details of the sensitivity as function of frequency is available in the new EVLA Observational Status Summary. The numbers of receiver systems available at the beginning of the EVLA D configuration are approximately as follows:
Along with the extended tuning range systems above, all antennas will have the VLA X-band (8.0-8.8 GHz) receivers available as well. For those EVLA antennas whose receivers support the wide bandwidths it is now possible to separate the two IF pairs by 10 GHz. There are some limitations on the tuning of the IFs for the Ka-band receiver. Please consult the EVLA Observational Status Summary for more details. New EVLA antennas will not be outfitted with 12-18 GHz (U-band) receivers until the end of the construction project. Proposals to use U-band will not be considered at the 2009 October 1 proposal deadline. Similarly, users are reminded that no proposals for 327 MHz will be considered until we find a way to solve the problem of the incompatibility of the 327 MHz receivers with the wideband EVLA electronics, announced in the January 15 edition of the News for Proposers. The installation and testing of S-band (2-4 GHz) receivers has begun on the EVLA. S-band receivers will be available for shared-risk observing when at least 5 have been commissioned, currently expected in late 2009. Subarrays and VLBI observing modes will not be available initially with the EVLA correlator. Users will be notified when these observing modes have been commissioned. All EVLA observations will be set up using the new Observation Preparation Tool (OPT), available at http://e2e.nrao.edu/opt/. Use of the OPT requires registration in the NRAO User Database, and accessing the above link will redirect users to NRAO Interactive Services for authentication automatically. The OPT is already being used for Ka-band observations and will be ready for use with OSRO correlator configurations after January 1, 2010. Initially it is expected that all projects will be observed dynamically, so users should submit scheduling blocks early in the configuration to maximize the opportunity of being observed. Further information about the OPT can be found at http://www.vla.nrao.edu/astro/opt/. Proposal preparation and submission are via the Proposal Submission Tool at NRAO Interactive Services. Several modifications to the PST have been made and will be in place starting 12:00 EDT (noon) Monday, 14 September 2009. (See the PST Release Notes (01 October 2009) for details of recent changes.) The different capabilities available for the OSRO and RSRO programs may be selected in the "resources" section of VLA proposals. The PST will continue to serve as the mechanism by which Rapid Response Science proposals are submitted. Until January 2010, when the VLA correlator is turned off, selecting "Rapid Response" as the proposal type will continue to display VLA correlator capabilities. Therefore, for this proposal deadline only, RRS proposals to use the EVLA correlator submitted in response to this call for proposals (i.e., for observations beginning in March 2010 or later) should be marked as "Regular" in order to see the EVLA correlator capabilities under "resources." b. EVLA impact and availabilityi. Short term (January 2010 - June 2010)With the shutdown of the VLA correlator in January 2010 many of the issues that have plagued observations during the VLA to EVLA transition phase, such as aliasing for narrow bandwidth modes on the EVLA antennas, will go away. Any remaining VLA antennas will be decommissioned at the same time that the VLA correlator is turned off, and will no longer be used for astronomy until they have been converted to the EVLA design. The primary antenna conversions will be complete by July 2010, although not all the frequency bands will be installed on all antennas. ii. Medium term (Mid 2010 - Mid 2011)The wide-band Q, Ka, K, and C band receiver systems are expected to be completed by the end of 2010. New capabilities will continue to be commissioned throughout this period, with the goal of being able to offer up to 2 GHz bandwidth for Open Shared Risk Observing by the next D-configuration in 2011. The fast samplers needed to access the full 8 GHz of bandwidth at high frequencies will be installed in all antennas through the end of 2010 and into 2011. iii. Long term (2011 - 2012)The fast samplers will be commissioned throughout 2011 and 2012, and access to wide bandwidths for general use is expected in 2012. The remaining receiver bands will be completed by Q4, 2012. c. EVLA Observational Status Summary availableA new EVLA Observational Status Summary is available that summarizes the OSRO capabilities and expected sensitivities of the EVLA for the upcoming October 1 proposal deadline. Users are reminded, however, that until the VLA correlator it turned off in January 2010 it is not possible for us to test the EVLA correlator with a full complement of antennas. Thus the information in this document gives a guide to expected capabilities that have not yet been commissioned, and performance expectations should be regarded with a degree of caution. 3. News for VLBA/HSA/VLBI proposersa. Proposal deadline is 2009 October 1 for trimester 2010-AThis deadline applies to regular observing proposals requesting
This deadline also applies to large observing proposals requesting the VLBA, alone or with other NRAO resources. The observing period is 2010 mid-January through 2010 mid-May. b. New Science Enabled by Microarcsecond AstrometryAn aim of this workskop, held 2009 Jul 21-23 at the Pete V. Domenici Science Operations Center in Socorro, was to foster development of major observing projects for the VLBA. The presentations from the workshop are now available online. c. VLBA to begin using DiFX software correlator for trimester 2010-ANRAO's implementation of the DiFX software correlator is the first element of the VLBA Sensitivity Upgrade project to be completed - and fortunately, it is one that can be put into operation, with scientific benefits to VLBA users, before the other elements are in place. DiFX was developed at Swinburne University in Melbourne, Australia, (Deller et al. 2007, PASP, 119, 318), and adapted to the VLBA operational environment by NRAO staff. Ongoing point-by-point comparisons between DiFX and the original VLBA hardware correlator have yielded excellent results thus far. Amplitudes agree at better than (0.4 +/- 1.7) percent, and phases to (0.1 +/- 1.0) degrees, across a wide range of observing modes. Figures presenting a few test results are shown in the September 2009 NRAO eNews. We therefore expect that all VLBA observations proposed at the 2009 October 1 deadline will be correlated using DiFX. In the near future, we also expect to announce opportunities for rapid response "exploratory" proposals to use DiFX later in trimester 2009-C, and for requesting DiFX correlation of projects already granted observing time but not yet correlated. An updated version of the VLBA Observational Status Summary provides current information on NRAO's implementation of DiFX. The principal new capabilities and other advantages DiFX offers at this time are summarized below.
The maxima specified above are flexible, and can be waived on the basis of a sufficiently compelling scientific justification. Please consult the updated VLBA Observational Status Summary for detailed information. Most aspects of DiFX are discussed in Section 7, while the new pulsar gating options are presented in Section 16 on pulsar observations. Up-to-date information on the VLBA's DiFX correlator will be maintained on a "DiFX Arrives" web page. d. SCHEDThe VLBI scheduling program SCHED will be changing significantly over the next year, first to support the new DiFX software correlator and then to support the new digital backend systems and recording hardware that are part of the bandwidth upgrades occurring on the VLBA and EVN. These equipment changes will bring additional flexibilities and constraints to the the way observations are configured. The changes make it especially important that users obtain the latest version of SCHED before producing observing schedules. SCHED releases, and information about configuration issues that users will need to be aware of, will be announced on the VLBI email exploder as they become available. If you wish to receive these announcements and are not on that list, please sign up. Note that the exploder is moderated and typically has low traffic, usually a couple of messages per month. e. VLBA Observational Status SummaryNRAO has produced an updated version of its comprehensive document "VLBA Observational Status Summary", with the primary changes all related to bringing the DiFX software correlator into routine operation (see item 3c above). The updated document can be found in html, pdf, or ps formats. f. VLBI at the EVLAThe VLA will no longer be available for VLBI observations beginning in 2010 Jan, when installation of the new EVLA correlator will begin. Although it is expected that EVLA commissioning will eventually include VLBI capabilities, no definite timescale for implementing this has yet been set. 
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