Using the EVLA

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VLA capabilities September 2011 - January 2013

1. Obtaining Observing Time on the EVLA

Observing time on the EVLA is available to all researchers, regardless of nationality or location of institution. There are no quotas or reserved blocks of time. The allocation of observing time on the EVLA is based upon the submission of an EVLA Observing Proposal using the on-line Proposal Submission Tool available via the NRAO Interactive Service web page, at The on-line tool permits the detailed construction of a cover sheet specifying the requested observations, using a set of on-line forms, and uploading of a pdf-format scientific and technical justification to accompany the cover information.

It is also possible to obtain EVLA observing time by proposing to NASA missions, under cooperation agreements established between NRAO and those missions. Currently, such programs exist for the Chandra, Spitzer, and Fermi missions. Astronomers interested in those joint programs should consult the relevant mission proposal calls for more information.

Students planning to use the EVLA for their Ph.D. dissertation may find that such dissertations comprise pieces of several short proposals, which may not be suitable for combining into a single proposal for refereeing purposes. In this case, we shall accept, one per student, a "Plan of Dissertation Research," of no more than 1000 words, at the time of the first proposal of the series, and which can be referred to in later proposals. The plan can be submitted via the NRAO Interactive Services webpage, at This provides some assurance against a dissertation being impaired by an adverse review of one proposal when the full scope of the project is not seen. This facility is offered to students for which EVLA observations are the most important component of their planned dissertations.

Starting in 2011 time on the EVLA is scheduled on a semester basis, with each semester lasting six months. Proposal deadlines will be 5pm (1700) Eastern Time on February 1 and August 1 (if the deadline falls on a holiday or weekend, it is extended to the next working day). The February 1 proposal deadline nominally covers time to be scheduled during the following August through January, and the August 1 deadline is for time to be scheduled from February through July. Proposals for any configuration in the current DA configuration cycle (September 2011 through January 2013) may be submitted at any proposal deadline, although a proposal for a configuration that has already passed may not be held over for consideration in the next configuration cycle, since the capabilities to be offered in the future are likely to be considerably different from those described in this document.

All proposals will be reviewed by a Science Review Panel (SRP) in relevant subdisciplines (e.g., solar system, stellar, galactic, extragalactic, etc.). The SRP's comments and rating are strongly advisory to the NRAO Time Allocation Committee (TAC), and the comments of both groups are passed on to the proposers soon after each meeting of the TAC (twice yearly) and prior to the next proposal submission deadline. See for a detailed description of the time allocation process.

Because of competition, even highly rated proposals are not guaranteed to receive observing time. This is particularly true for programs that concentrate on objects in the LST ranges occupied by popular targets such as the Galactic Center or the Virgo cluster. Daytime observing will also be limited by EVLA commissioning throughout 2011 and 2012.

2. Director's Discretionary Time

The NRAO has established two categories of proposals for Director's Discretionary Time (DDT). DDT is limited to a maximum of 5% of the total observing time on the EVLA. All DDT proposals should be submitted using the standard NRAO procedures, using the on-line proposal tool. Proposals submitted by any other means (e.g., phone calls, e-mails, faxes, word-of-mouth) will be not be considered.

1. Target of Opportunity. Target of Opportunity (ToO) proposals are for unexpected or unpredicted phenomena such as supernovae in nearby galaxies or extreme X-ray or radio flares. ToO Proposals are evaluated rapidly, with scheduling done as quickly as possible and as warranted by the nature of the transient phenomenon. ToO Proposals are evaluated on the basis of scientific merit by the Chair of the relevant Science Review Panel and Observatory staff with the necessary scientific expertise. The technical feasibility of the proposed observations will be assessed by Observatory staff. The proprietary period for data obtained by ToO Proposals will be assessed on a case-by-case basis but will be no more than six months.

2. Exploratory Time. Exploratory Proposals are normally for requests of small amounts of time, typically a few hours or less, in response to a recent discovery, possibly to facilitate future submission of a larger proposal. In general, there will not be a need for immediate scheduling with these proposals, but they may need to be observed in the current EVLA configuration rather than waiting 16 months. The possibility that a proposer forgets about or misses a proposal deadline, or just discovered that he/she was granted time for a particular source on some other telescope, will not constitute sufficient justification for granting observing time by this process. Thus, Exploratory Proposals must include a clear description of why the proposal could not have been submitted for normal review at a previous NRAO proposal deadline, and why it should not wait for the next proposal deadline. Proposals for exploratory time will be evaluated on the basis of scientific merit by the relevant Science Review Panel. Observatory staff will assess their technical feasibility. Notification of the disposition of an Exploratory Proposal normally will be within three weeks of receipt of the proposal; some of these proposals may be put in a queue such that they may or may not be observed. The proprietary period for data obtained by Exploratory Proposals normally will be six months.

3. Helpdesk

Assistance with proposal submission, observation preparation, archive access, and data reduction using both CASA and AIPS is available through the NRAO Helpdesk at

4. Observation Preparation

To use the EVLA, scheduling blocks must be prepared using the "Observation Preparation Tool," or OPT. The OPT is available at:

5. Fixed Date and Dynamic Scheduling

Most of the projects on the EVLA will be observed dynamically, based on a combination of scientific priority and the expected properties of the array and the weather. Some time may continue to be scheduled as "fixed-date" observing, with the observer being given a particular sidereal date and time allocation on the EVLA, depending on the needs of the project.

Please see the scheduling officers' home page for further information, at

6. The Observations and Remote Observing

Since most VLA observations will be carried out dynamically it is in general neither necessary, nor practical, for observers to be present during their observations. However, there can be considerable benefits to observers who come to Socorro to reduce and analyze their data in terms of interactions and discussions with NRAO staff. See Reservations for the DSOC for information on coming to and staying in Socorro.

For those who choose to process their data at home, the data can be retrieved from the VLA online archive after obtaining the project key from the data analysts, or by using the NRAO Interactive Services login from the archive web page. Alternatively, the data analysts will, upon request, mail you a tape or other media containing your uncalibrated data in its original format.

7. Data Access

The online archive contains all VLA data since observing started in 1976, and will also serve the user community with EVLA data. The entire archive is now on disk, and is available via the Archive Access Tool at This interface provides a basic data retrieval tool if you know the program code of your observations. It also provides an advanced query tool which enables searches based on a large number of user-specified criteria. Data can be downloaded via standard ftp protocols. With the exception of some rapid response and large proposals, (E)VLA data associated with a given proposal normally are restricted to proprietary use by the proposing team for a period of 12 months from the date of the last observation in a proposal (Note: data taken more than 12 months previously may still be proprietary, if additional data for the same proposal have been taken within the last 12 months). Proprietary data may be downloaded by the observing team by making use of the project key (see The Observations and Remote Observing).

Data are stored in the archive in the Science Data Model (SDM) format that will be used by both the EVLA and ALMA. They are available through the Archive Access Tool in one of two formats:

- As a CASA Measurement Set.
- In UVFITS format, which can be read by either AIPS or CASA.

The raw SDM format will only be available by special request.

8. Data Processing

The primary data reduction package for the EVLA is the CASA (Common Astronomy Software Applications) package, which will also be used for ALMA. See for more information on the latest release.

NRAO will continue to support AIPS (Astronomical Image Processing System) for the foreseeable future, at least until VLBI functionality has been incorporated into CASA. See for more details.

It will be possible to reduce data obtained through the Open Shared Risk Observing program using either CASA or AIPS.

9. Travel Support for Visiting the DSOC and EVLA

For each observing program scheduled on an NRAO telescope, reimbursement may be requested for one of the investigators from a U.S. institution to travel to the NRAO to observe, and for one U.S.-based investigator to travel to the NRAO to reduce data. Reimbursement may be requested for a second U.S.-based investigator to either observe or reduce data provided the second investigator is a student, graduate or undergraduate. In addition, the NRAO will, in some cases, provide travel support to the Observatory for research on archival data. The reimbursement will be for the actual cost of economy airfare, up to a limit of $1000, originating from within the U.S. including its territories and Puerto Rico. Costs of lodging in NRAO facilities can be waived on request in advance and with the approval of the relevant site director. No reimbursement will be made for ground transportation or meals.

To qualify, the U.S. investigator must not be employed at a Federally Funded Research and Development Center (FFRDC) or its sponsoring agency. The NSF maintains a master government list of some FFRDCs at

To claim this reimbursement, obtain an expense voucher from Lori Appel in the Assistant Director's office in the DSOC.

10. Student Assistance for Data Reduction Visits to the DSOC

Students visiting the DSOC for the purposes of working on an EVLA or VLBA observing program may be eligible to have their lodging expenses in the NRAO guest house covered by NRAO. To qualify, the student must be a graduate or undergraduate enrolled at a University in the U.S., working on an approved observing program. These are the same qualifications as required for NRAO support of air travel costs described above. In addition, the duration of the visit should be between 5 and 30 days. Requests for support should be made to Claire Chandler at least 4 weeks in advance of the proposed visit. If this is a first time visit then the student should be accompanied by a collaborator on the project, or alternatively an NRAO collaborator may be requested.

11. Student Observing Support Program

In addition to travel support for individual data reduction visits NRAO maintains a program to support research by students, both graduate and undergraduate, at U.S. universities and colleges. Regular and Large proposals submitted for the EVLA, VLBA, and GBT, and any combination of these telescopes, are eligible. New applications to the program may be submitted along with new observing proposals at any proposal deadline. Details of this program can be found at

12. Computing at the DSOC

A primary goal of the computing environment at the DSOC is to allow every user full access to a workstation during his/her visit. There are 10 public workstations available at the DSOC for full-time data reduction by visitors. They are mostly four-processor, 2.0-GHz PCs running Linux.

For hardcopy, we have a number of high volume B&W laser printers, two color Postscript laser printers which can reproduce on both paper and transparencies, and one wide-bed color printer.

Visitors should reserve time on these workstations when they make their travel arrangements at (see also Reservations for the EVLA site and/or DSOC). Note that users may request remote access to the visitor machines as well, without actually visiting the DSOC. Please contact the computing helpdesk (e-mail to, extension 7213, office 262) for further information about this and any other computing assistance while at the DSOC.

For a more complete description of computing facilities at the DSOC, see

13. Reservations for the DSOC

Accommodation for visitors is no longer available at the VLA site. Observers wishing to be present for their observations should stay in the nearby towns of Magdalena or Datil.

Reservations must be made at least 1 week prior to your visit to the NRAO/NM, and 2 weeks' notice is preferred, through the online form at Computing requirements and the level of staff assistance needed must be specified through the online form.

First-time visiting students will be allowed to come to the NRAO/NM for observations or data reduction only if they are accompanied by their faculty advisor, an experienced collaborator, or if they have an NRAO staff collaborator.

14. Staying in Socorro

Visitors to Socorro can take advantage of the NRAO Guest House. This facility contains eight single, four double, and two two-bedroom apartments, plus a lounge/kitchen, and full laundry facilities. The Guest House is located on the New Mexico Tech (NMIMT) campus, a short walk from the DSOC. Reservations are made through the online registration form at

15. Help for Visitors to the DSOC

We encourage observers to come to Socorro to calibrate and image their data. This is the best way to ensure the quickest turnaround and the best results from their observing. While in Socorro, each observer will interact with members of the DSOC staff in accordance with his/her level of experience and the complexity of the observing program. If requested through the reservation form, the visiting observer will be guided through the steps of data calibration and imaging by a pre-arranged staff friend or scientific collaborator. A list of staff scientists and their interests can be found at The data analysts, computing helpdesk, and other staff are also available for consultation on AIPS and CASA procedures, and systems questions.

16. On-Line Information about the NRAO and the EVLA

NRAO-wide information is available on the World Wide Web through your favorite Web browser at URL, and information specific to astronomers using the EVLA may be found at  These pages are regularly updated by the NRAO staff.