Volume 6, Issue 7
July 8, 2013
NRAO Call for Proposals: Semester 2014A
NRAO eNews Volume 6, Issue 7 July 8, 2013
The NRAO announces the Call for Proposals for the 1 August deadline for Semester 2014A. The call is open now and will close on Thursday, 1 August 2013, at 17:00 EDT (21:00 UTC).
Proposal preparation and submission are via the NRAO Proposal Submission Tool (PST) available through the NRAO Interactive Services. Important modifications to the PST have been made and will be in place starting 17:00 EDT (21:00 UTC) Monday, 8 July 2013. All proposal authors must be registered users. On the registration form you will be asked for contact information that will be used for notification about proposal disposition, telescope scheduling, etc. We encourage all proposers to register early.
New Technical Justification Section
Starting with this Call for Proposals, the Technical Justification Section has been broken out into a series of text boxes as part of the proposal cover sheet within the PST. All boxes must be completed for a proposal to validate, but for some boxes an "NA" (not applicable) may be all that is needed. The new Technical Justification Section ensures that sufficient information is provided for the proposal to undergo technical review, and also frees extra space within the page limit of the Scientific Justification for the science case. Since this is the first semester involving the observatory-provided template for the Technical Justification Section, we strongly recommend that proposers start preparing their proposals early. Links to relevant online documentation are provided for all parts of the Technical Justification Section, but any questions may be directed to the NRAO Helpdesk.
NRAO telescopes and backends are sufficiently flexible in many cases to allow two experiments to run commensally. To the degree that this enhances science return from the telescopes, NRAO wishes to support commensal projects subject to resource and scheduling constraints. Groups wishing to carry out commensal observations should submit independent science cases as separate primary and secondary proposals. A primary proposal will be submitted that controls the telescope pointings and requests the full amount of telescope hours required. Secondary proposals(s) will be submitted that run commensally with the primary pointings but request 0 hours of telescope time. Each proposal must contain estimates of the full resources needed (correlator setup, data rates, etc.) to carry out their specific part of the project. During the proposal review and time allocation process it will be determined if the combination of the observing set-up and the positions by the primary or secondary proposals conflict with any approved projects. In the case of a conflict, some data restrictions may be applied to the primary and/or the secondary commensal proposal. If the primary and secondary proposals use the same back-end resources (VLA-WIDAR, GBT-VEGAS, etc.) it may be necessary for technical reasons to require that the investigators on both primary and commensal projects be given full access to all data.
Proposal Finder Tool
The Proposal Finder Tool (PFT) may be used to search cover sheets of proposals approved for time on NRAO telescopes. The PFT returns the proposal's authors, title, abstract, and, if available, approved hours.
The NRAO now requires proposers to specify their source lists in full. This enables the Observatory to identify potential conflicts between observing programs and to better understand scheduling pressure on the instruments it operates. It may be the case that the final target list has not been selected at the time a proposal is submitted. In such cases, all potential targets and fields should be listed. The only exceptions to this requirement are for Triggered proposals to observe targets that are unknown a priori. Proposal source lists are not made public by the Observatory.
In recent Calls for Proposals, the NRAO announced plans to perform service observations of Sgr A* in support of the anticipated encounter of a gas cloud with the super-massive black hole lying at the center of the Milky Way. The details of the service observations were described in the October 2012 eNews. The observations will take the form of: (1) baseline measurements in advance of the encounter with the VLA and VLBA; and (2) multi-band monitoring of Sgr A* for an extended period of time with the VLA. These data are available to the community on a non-proprietary basis. The first photometric and imaging observations are available here. The page will be updated on a regular basis.
In addition to the service observing described above, we encourage proposals from the community on the announced proposal deadlines for scientifically compelling observing programs of this event using the GBT, the VLA, and/or the VLBA. These proposals will undergo the normal peer review and time allocation process.
GBT and VLBA Partnerships
In consultation with NSF, NRAO/AUI has entered into several domestic and international partnerships to provide telescope time on GBT and VLBA for scientific investigations. As a result, fewer hours are available on these telescopes to the wider community, and the proposal pressure for available time may be correspondingly higher. The effect is not large at present, amounting to less than 10% of science observing time on each telescope, but we anticipate additional agreements in the near future. These agreements are in addition to those for the joint observing programs with Chandra and Fermi (see below).
NRAO Semester-Based Proposal Cycle
Proposal submission deadlines are on 1 February and 1 August each year. At each deadline, proposers may request time on the Karl G. Jansky Very Large Array (VLA), the Very Long Baseline Array (VLBA) and/or the Robert C. Byrd Green Bank Telescope (GBT). The 1 February deadline applies to requests for time from 1 August through 31 January, and the 1 August deadline applies to requests for time from 1 February through 31 July. Further details about proposal submission, proposal evaluation, and time allocation are available here.
Tips for Proposers
The NRAO proposal evaluation and time allocation process is panel based. That is, members of the scientific community are responsible for reviewing proposals based on their scientific merit through eight Science Review Panels (SRPs). As a means of broadening the scientific perspective of its reviewers, and of increasing the participation of the wider astronomy and astrophysics community in the science program of NRAO facilities, SRP membership deliberately includes some colleagues who are not necessarily experts in radio observational techniques. This being the case, we encourage proposers to consider the following when preparing their proposals.
- Avoid the use of radio astronomy jargon.
- Do not assume the reader is familiar with a particular observing technique - explain it briefly.
- Do not assume the reader is familiar with an earlier rationale for a developing line of research - provide adequate historical context and connect the dots as necessary.
- Describe previous observations and publications relevant to the proposed observations.
- If a particular point source or brightness temperature sensitivity is required, justify it.
The Observatory would like to point out that there are opportunities for so-called "filler" programs on all of its telescopes. Observing programs that exploit frequencies below 10 GHz, do not have strong scheduling constraints, and could benefit from short scheduling blocks are encouraged to propose for such opportunities. The proposal should make clear in the abstract and early in the science justification that "filler" time (scheduling priority C) is being requested, not time at scheduling priority A or B.
Those who are planning to submit a Triggered proposal are reminded that they must include well-defined trigger criteria and state applicable semesters in their request for telescope time. Furthermore, a Triggered proposal must ask for the full amount of time needed to achieve the science goals, including both initial and follow-up observations. Proposers should not be using Director's Discretionary Time to request follow-up of an event initially observed under a Triggered proposal.
High Risk Proposals
As a means of maximizing its scientific impact through cutting edge observations, the Observatory also encourages the submission of high-risk/high-reward proposals. Such proposals may involve unusual targets, nonstandard observing techniques, new post-observing data reduction and analysis, or supplementary hardware or new back ends. Please contact Science Support & Research prior to submitting such proposals to discuss anticipated resource requirements. Observers contemplating such proposals may also wish to consider submitting an Exploratory Proposal to request Director's Discretionary Time as a means of demonstrating a proof of concept.
Opportunities for Joint Observations with Fermi or Chandra
We remind the community that it is possible to propose for observing time on NRAO facilities through the Fermi Gamma-ray Space Telescope Joint Proposal Opportunity or the Cooperative Proposal Opportunity. For Fermi, which is primarily in sky-survey mode, potential observers may propose for NRAO observations that make use of the Fermi survey data even without re-pointing of the Fermi satellite. The actual amount of NRAO observing time allocated via the Joint Fermi Process depends on the amount of proposal pressure and the scientific quality of the proposals. A maximum of 10% of the NRAO scientific observing time is made available on the VLA, the VLBA and the GBT, or up to 400-650 hours per year on each telescope. Details about joint observations with Fermi and the VLA, the VLBA or the GBT may be found here. The next Fermi proposal deadline is in January 2014. Similarly, the community may propose for observing time on NRAO facilities through a joint program with the Chandra X-ray Observatory. For Chandra, proposals must be for observations that require both Chandra pointing and NRAO observations to carry out a scientific investigation. The NRAO has allocated up to 3% of the observing time on the VLA, the VLBA and the GBT for Chandra joint proposals. Section 4.5.5 of the Chandra call for proposals gives specifics of the joint NRAO/Chandra program. The next Chandra proposal deadline is in March 2014.
PhD Dissertations using NRAO Facilities
Students planning to use one or more NRAO telescopes for their PhD dissertation 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 the plan should contain a thesis timeline, an estimate of the level of NRAO telescope resources needed and, clear statements about the importance of each proposal to the thesis as a whole. The plan provides some assurance against a dissertation being impaired by an adverse review of a proposal when the full scope of the thesis is not seen. The plan can be submitted via NRAO Interactive Services. Students are reminded to submit their plan comfortably in advance of the proposal deadline. New thesis plans must be in pdf format so science reviewers can easily access the plans. Students who have not yet graduated but have active plans on file should update those plans to a pdf format if they are not already in that form.
Observing Capabilities for Semester 2014A
The 1 August 2013 deadline covers the observing period 14 February 2014 through 8 September 2014 (Semester 2014A), corresponding to the A and D configurations. Multi-configuration proposals that include A and/or D configurations may also be submitted. In addition, proposals only for configurations that will fall in semester 2014B or later may be submitted, if the Principal Investigator is a graduate student. NRAO offers this service to provide scientific and technical feedback for students, and to provide them with an opportunity to re-submit their proposals for their principal semester with this information in hand. Students should ensure that their status is up-to-date and correct in the NRAO User Database. All other proposals for configurations not included in semester 2014A will be held over for review in the appropriate semester. See the VLA Configuration Plans for further information, including plots of the estimated available observing hours as a function of LST for all configurations in the upcoming semester.
This call offers several capabilities in excess of those offered for 2013B. Both the 8-bit sampler system (up to 2 GHz bandwidth) and the 3-bit samplers (up to 8 GHz bandwidth) will be available. New for semester 2014A will be flexible tuning of the 3-bit system, use of the 3-bit system at C/X/Ku bands, and higher data rates. Details of the general capabilities are given in the VLA Observational Status Summary (OSS), and are summarized below:
|Phased array for VLBI||
Both single pointing and mosaics with discrete, multiple, field centers will be supported. Data rates of up to 60 MB/s (216 GB/hour) will be available to all users, combined with correlator integration time limits per band and per configuration, as described in the OSS. Data rates in excess of 25 MB/s (90 GB/hour) require additional justification. The data rate and total data volume required by a proposal will be a consideration in its evaluation.
There are some limitations on frequency settings and tuning ranges, please consult the OSS for further details. In addition, special tools are available to assist users with the development of correlator set-ups for the proposal deadline (see VLA Proposal Preparation and Submission), and the Exposure Calculator has been updated. All antennas employ electronics and receiver systems that provide continuous frequency coverage from 1-50 GHz in the following observing bands: 1-2 GHz (L-band); 2-4 GHz (S-band); 4-8 GHz (C); 8-12 GHz (X); 12-18 GHz (Ku); 18-26.5 GHz (K); 26.5-40 GHz (Ka); and 40-50 GHz (Q).
We will continue to offer shared risk programs to our user community for those who would like to push the capabilities of the VLA beyond those offered for general use:
- Shared Risk Observing: This program allows users access to capabilities that can be set up via the OPT and run through the dynamic scheduler (without intervention), but are not well tested. The following capabilities are offered under the Shared Risk Observing program: correlator dump times as short as 50 ms; mixed 3-bit and 8-bit set-ups; use of the new low frequency system in the frequency range 230 to 470 MHz for Stokes I continuum imaging. Please refer to the VLA Proposal Preparation and Submission web page for information about tools and other advice on proposing for Shared Risk observing capabilities.
- Resident Shared Risk Observing (RSRO): This program provides access to extended capabilities of the VLA that require additional testing, in exchange for a period of residence to help commission those capabilities. Capabilities that would fall under the RSRO program include, e.g. , correlator dump times shorter than 50 ms; data rates above 60 MB/s; use of recirculation in the correlator; use of the P-band system for polarimetry or spectroscopy; more than 3 sub-arrays or sub-arrays with the 3-bit system; on-the-fly (OTF) interferometric mosaicing; complex phased array observations (e.g. , pulsar and complex VLBI observing modes). A detailed description of the VLA RSRO program for semester 2014A and beyond is available at the VLA Proposal Preparation and Submission web page.
Low Frequency Observing for Semester 2014A
A new low frequency system has been developed in collaboration with the Naval Research Laboratory, and all 27 antennas will be outfitted by the start of the A configuration. Use of the low frequency system for Stokes I continuum observations at P-band (230 to 470 MHz) will be through the Shared Risk Observing program for semester 2014A. Use of the P-band system for polarimetry and/or spectroscopy will be through the Resident Shared Risk Observing Program. The new receivers also work at 4-band (58 to 84 MHz), but this part of the system is not yet commissioned. However, members of the community interested in helping to commission the 4-band system in return for peer-reviewed telescope time should apply through the RSRO program described above.
Proposal and Observation Preparation
Proposal preparation and submission are via the Proposal Submission Tool (PST) at NRAO Interactive Services. Use of the PST requires registration in the NRAO User Database. There are various tools and documentation to help users in this process. Descriptions of all updated documentation and tools along with an outline of the steps required to write a proposal are available at the VLA Proposal Preparation and Submission web page.
All approved VLA observations are set up using the Observation Preparation Tool (OPT). Most, if not all, projects will be observed dynamically so users should submit scheduling blocks early in the configuration to maximize the opportunity of them being observed. Advice on the optimal length of scheduling blocks and other useful information may be found at the Observing FAQ web page.
Information about VLA capabilities, observing strategies, and calibration overhead can be found in the VLA Observational Status Summary, at the Guide to Observing with the VLA, and at the Observing FAQ web page. Questions may also be directed to the NRAO Helpdesk.
The 1 August 2013 deadline is for the Semester 2014A observing period: 1 February 2014 through 31 July 2014. Proposals will be considered for the following receivers: 290-920 MHz (PF1), 910-1230 MHz (PF2), 1.15-1.73 GHz (L), 1.73-2.60 GHz (S), shared-risk 3.8-8 GHz (C), 8.0-12.0 GHz (X), 12.0-15.4 GHz (Ku), 18.0-26.0 (KFPA), 26.0-39.5 GHz (Ka), 38.2-49.8 GHz (Q) receivers, shared-risk MUSTANG1.5 (80-100 GHz Bolometer Array) and 67-93.3 GHz (W).
Available observing modes include spectral line (including cross-polarization), continuum, pulsar, and VLBI/VLBA. The VLBA back end with Mark5A disk recorder may be used as a high-time resolution (> 2 ns) backend for single-dish observing.
Details of all GBT observing modes are in the GBT Proposer's Guide. Proposers should also consult the more general document "The Performance of the GBT: A Guide for Planning Observations." Proposers should make sure that they are familiar with the latest versions of these documents before writing their proposal.
VErsatile GBT Astronomical Spectrometer (VEGAS): The first mode for VEGAS has been released and all observing modes should be delivered by the end of 2013. Shared-risk proposals to use VEGAS will be considered for the 14A semester. Please see the GBT Proposer's Guide for more information on VEGAS.
Mustang1.5: The Mustang bolometer array will undergo an upgrade. The receiver cryogenics will be redesigned such that the receiver can be kept cool at all elevations and will allow observations below 30 degrees elevation.We will accept shared-risk proposals to help commission the upgraded Mustang bolometer array in the 14A semester.
450 and 600 MHz feeds: Digital TV transmissions above 470 MHz will make observing very difficult with these two feeds of the PF1 receiver. Available radio frequency interference (RFI) plots do not show the strength of these signals as they overpower the system - they are too low by a factor of 10 to 50 at minimum. Observers should consult the GBT support scientists before submitting a proposal for these feeds.
VLBI Observing: Beginning with the 13B semester the GBT will no longer provide setup and overhead time prior to the beginning of the VLBI observations. All VLBI proposals requesting the GBT should include any needed setup and overhead time in the time request of their proposals.
C-band Receiver: The C-band receiver will be upgraded to cover the 3.8-8 GHz frequency range. We will consider shared-risk proposals for the 1 August 2013 deadline for observations with this receiver.
New Sensitivity Calculator: All proposers, including pulsar proposers,should use the GBT Sensitivity Calculator. Please see the GBT Sensitivity Calculator User's Guide for further instructions. The new Sensitivity Calculator results can be cut and pasted into the Technical Justification section of the proposal. This will streamline the creation of your Technical Justification and will increase your chances of getting a positive technical review.
Proposers requesting GBT participation in High Sensitivity Array (HSA), Very Long Baseline Array (VLBA), or global Very Long Baseline Interferometry (VLBI) observations should consult the VLBA, HSA, and VLBI section below.
The GBT is scheduled by the Dynamic Scheduling System (DSS). The DSS system is fully described in the GBT Proposer's Guide and the GBT Observer's Guide. The GBT observing policies describe the remote observing restrictions.
Technical questions, questions about the proposal process or about the PST should be sent to the NRAO helpdesk.
The 1 August 2013 deadline applies to all types of Very Long Baseline Array (VLBA) and High Sensitivity Array (HSA) proposals requesting time in semester 2014A (2014 February 1 through 2014 July 31), or multi-semester proposals. It also applies to global mm VLBI proposals for the May 2014, or later, sessions. Please see the instructions for submitting VLBA, HSA, and global VLBI proposals.
VLBA General Observing Capabilities for Semester 2014A
Details of the following capabilities may be found in the VLBA Observational Status Summary. In what follows, a "channel" refers to a single contiguous frequency range (of any bandwidth), observed in a single polarization, that is sampled, filtered, and recorded as a separate entity.
- Observing Systems: Two separate observing systems are available within the Roach Digital Backend (RDBE) units, and can be requested in the NRAO Proposal Submission Tool's "Resources" section via the drop-down menu at the top of the "Observing Parameters" column.
- The Polyphase Filterbank (PFB) observing system provides sixteen 32-MHz channels, with a fixed 2048-Mbps recording rate, the maximum rate supported by the Mark 5C recorder. The channels can be selected flexibly between two VLBA IFs; typically these are different polarizations, but less common modes, including use of different frequency ranges in the new C-band receiver, are also possible. Channel placement is restricted to 32-MHz steps along the frequency axis.
- The Digital Downconverter (DDC) observing system is considerably more flexible than the PFB. Within a single RDBE unit, as many as four channels can be selected arbitrarily from two input IFs, and placed at 15.625-kHz steps on the frequency axis with bandwidths ranging from 1 MHz to 128 MHz by factors of 2. Extremely narrow bands can be accommodated by observing at 1 MHz bandwidth, and selecting a narrower range using the DiFX correlator's spectral zoom mode. Two RDBE units are available at each station, so that as many as eight channels are supported. All bandwidths must be identical, and channels cannot span either of two IF zone boundaries, at 640 and 896 MHz. Use of 128 MHz bandwidth is restricted to 4 (or fewer) channels to keep within the 2048 Mbps rate limitation of the Mark 5C recording system.
- Wideband C-band receivers: The use of two RDBEs (using the DDC observing system) will support two dual-polarization IF pairs on the new wideband, EVLA-style, C-band receivers, which can be placed arbitrarily along the entire 4-8 GHz range. This is similar to the existing S/X capability, although requiring only a single receiver. The new C-band receivers also open the possibility of observing the excited OH line at 6.0 GHz, and the methanol line at 6.7 GHz.
High Sensitivity Array (HSA)
The phased VLA ("Y27") will be available for semester 2014A. The VLA will primarily be in the A and D configurations at this time (see the VLA Configuration Plans). HSA proposals can request the phased VLA in conjunction with the VLBA and other HSA telescopes, subject to availability of matching observing systems (see below). Phased-VLA observing is limited to two independently-tunable VLA subband pairs, one polarization pair (RCP+LCP) in the A0/C0 baseband pair, and the other (RCP+LCP) in the B0/D0 baseband pair. Any matching bandwidths available on the VLA as well as the VLBA DDC data system described above can be used. Bandwidths must be uniform at each station, across the entire VLBI array, and throughout the entire duration of the observation. In particular, VLA phasing and VLBI observing must be carried out at the same bandwidth. Bandwidths of 16 MHz and wider are available as a general capability. Bandwidths narrower than 16 MHz may work if the source is strong enough, but have not been tested at this time. Such narrow bandwidths are expected to be of limited use, but are available through a Shared Risk Observing program similar to that for the VLA. Under this program, observers may propose for capabilities that can be set up using our standard tools and run through the dynamic scheduler, but may not be well tested. Such observations come with no guarantee of success. Further details are available in the VLA section of this Call for Proposals, in the document VLBI at the VLA, and in the VLBA Observational Status Summary.
Observing with a single VLA antenna ("Y1") in conjunction with the VLBA will only be available through the VLBA Resident Shared Risk Observing program.
Proposals to use the GBT as part of the HSA will be considered for semester 2014A. The GBT is equipped with the full VLBA Sensitivity Upgrade instrumentation, and is able to support all the observing configurations described in the VLBA Observing Capabilities section above. A table of Available Receivers and Bands compares the frequency ranges of GBT receivers with their VLBA counterparts, and includes sensitivity data and special capabilities. Note that all proposals to use the GBT as part VLBI must include time to set up the telescope (pointing, focus, etc. ) prior to the start of the observation. This can take 0.5-1 hr depending on the frequency (see Chapter 6 of the GBT Proposer's Guide).
The Effelsberg and Arecibo HSA stations have also installed the same wideband equipment, but their implementation is not yet complete. An observing mode to match the PFB system works well for continuum science, but there is currently no mode to match the DDC for spectroscopy that has been fully commissioned. The following table summarizes the availability of the various observing systems for HSA stations for 2014A:
|HSA station||Observing system|
where DDC-4 refers to a 4-channel mode with the DDC, and DDC-8 refers to use of 8 channels with the DDC. Combinations marked "RSRO" are only available through the Resident Shared Risk Observing program (below). The observing system MUST be identical for all stations in an observation.
Global 3mm VLBI Array (GMVA)
VLBI proposals for observing at 3mm wavelength using the VLBA, GBT, Effelsberg, Pico Veleta, Plateau de Bure, Onsala, Yebes and Metsaehovi telescopes should be submitted by 1 August 2013 through the NRAO Proposal Submission Tool. Successful proposals will be considered for scheduling in May 2014 or in a later session. In order to maximize the sensitivity for continuum observations the GMVA will record at the highest bit rate which telescope instrumentation and resources permit. All telescopes will record at 2 Gbps (the only exception being Plateau de Bure which will record in a compatible 1 Gbps mode).
For further details on proposing please consult the relevant administrative and technical information hosted at Bonn.
VLBA Scheduling Considerations for Semester 2014A
Dynamic scheduling from a finite queue of observing blocks, combined with occasional poor weather and/or antenna downtime, can sometimes make it difficult to completely fill the schedule with fixed LST observing blocks. Proposals for projects that can tolerate less than the full array or that can observe in poor weather, or especially projects that can be scheduled flexibly in segments of one to a few hours with arbitrary start times and lengths, are strongly encouraged. Flexibly scheduled blocks should be based on a script, provided by the PI, that can be run by VLBA Operations shortly before observe time, without the need to consult the observers.
VLBA Resident Shared Risk Observing Program
The VLBA Resident Shared Risk Observing (RSRO) program provides users with early access to new capabilities in exchange for a period of residency in Socorro to help commission those capabilities. The phased-VLA system was developed through RSRO programs, and NRAO encourages additional RSRO proposals to expand the phased-VLA capabilities. A number of additional areas are suggested at the VLBA RSRO program webpage, including the development of Y1 with the VLBA. We encourage other innovative ideas for new VLBA observing modes from the community as well.
Proposal preparation and submission for the VLBA, HSA, and GMVA are via the Proposal Submission Tool (PST) at NRAO Interactive Services. Use of the PST requires registration in the NRAO User Database.