Proposals and Dispositions

Proposal 2 - For 2013B Semester

Proposal VLBA-13B-013.pdf

Disposition

--------------------------------------------------------------------------------
This email contains specific information about the subject proposal for
Semester 2013B.
--------------------------------------------------------------------------------
Proposal Id: VLBA/13B-013

Legacy Id: BB325
Proposal Title: Prompt high- and low-time resolution VLBA follow-up of GRBs

Proposal Type: Triggered

Proposal Authors: Keith Bannister, Walter Brisken, Adam Deller, Jean-Pierre Macquart, Walter
Max-Moerbeck, Steven Tingay, Randall Wayth

Science Review Panel (SRP): Energetic Transients and Pulsars

Time Allocation Summary:
   9.90 hours at 2048 Mbps.

Linear-Rank Score from the SRP: 4.51

Comments from the SRP: 
Summary: Proposed observations are to observe the directions of GRBs, with the
objective of confirming dispersed single pulses associated with prompt emission
from the GRBs. Proposal strengths: Spatial separation of VLBA antennas should
be effective discriminator of other possible explanations, such as RFI,
detection of pulses in multiple antennas. Innovative program to make use of the
VLBA when antennas are not otherwise observing. Proposal weaknesses: The
authors claim these pulses to have revolutionary capacity, but to someone
outside the field, there is nothing to back this statement up. There is no
control described, was blank sky observed for a similar length of time to
exclude the possibility that such dispersed pulses occur when the direction of
a GRB is not being observed? The observed delays and stated DMs are not
consistent. Assuming that the gamma-ray emission is at infinite frequency, and
that the Parkes 12 m observations are at 1.4 GHz, the expected delay for any
prompt radio emission would be (4.15 ms * DM/1.4**2), with DM in its standard
units. DM ~ 600 pc/cm^3 (Figure 1) implies a delay of only a few seconds, and a
DM well in excess of 10^4 pc/cm^3 is required for a 10 minute delay.
Recommended time: The SRP makes no recommendations of altering the proposed
time, though would prefer that some of the time be used for "control"
observations. Technical issues affecting ranking or recommended time: It may be
difficult to obtain the required short response time until near the end of the
requested two-semester period. The cover sheet describes 0.66 hr (40 min)
sessions, but the SRP understood that the VLBA is scheduled in 0.5 hr segments.

Comments from the NRAO Technical Reviewer:  
The observers propose to look at GRBs within minutes of a Swift trigger. The
intent is only to observe when the VLBA is otherwise idle. It is difficult to
attain the needed short response time, but may be possible by the end of the
requested two semester period of active trigger, or even earlier by stroke of
good fortune. The choice of L band is probably best, and the reliance on the
VFASTR system is a proven route.

Comments from the Time Allocation Committee (TAC): 
Approved for semesters 13B and 14A. Proposal will not be allowed to trigger
until the required capability has been demonstrated by the proposal's authors.



NRAO Student Observing Support (SOS) Funding:
You may be eligible for funding through the NRAO SOS program. See the NRAO SOS
proposal information page at https://science.nrao.edu/opportunities/student-programs/sos
for further information. The deadline for an SOS proposal associated with this
disposition letter will be June 7, 2013. Contact Jeff Mangum <mailto:jmangum@nrao.edu>
with questions. 

Comments from the NRAO:
The linear-rank score from the SRP is on a scale from 0 (a high-ranked
proposal) to 10 (a low-ranked proposal). The quartile boundaries for all
proposals considered by the TAC are 2.5, 5.0 and 7.5.

Scheduling priorities in the dynamic queue are assigned by the TAC. Possible
scheduling priorities are:

   A = the observations will almost certainly be scheduled

   B = the observations will be scheduled on a best effort basis

   C = the observations will be scheduled as filler

   N*= the observations will not be scheduled because they were
       explicitly rejected by the TAC

   N = the observations will not be scheduled because they could
       not fit in the time available

   H = not assigned because the proposal is being held for
       consideration at a future TAC meeting

For the VLBA, proposals approved for priority A time will be eligible for
scheduling during up to two semesters and proposals approved for priority B or
C time will be eligible for scheduling during only one semester, unless
explicitly stated otherwise in the Comments from the TAC. Those allocated
dynamic time should complete their key file preparation well before 2013 August
1, the start of semester 2013B.

For the VLA, proposals approved for priority A, B or C time become ineligible
when the associated configuration ends, unless explicitly stated otherwise in
the Comments from the TAC. Those allocated dynamic time should begin their
scheduling block preparation about two weeks before the planned start of the
configuration. Configuration plans are available at:

https://science.nrao.edu/facilities/vla/proposing/configpropdeadlines

Any approved time tabulated below may be divided into multiple scheduling
blocks as appropriate, considering the scheduling priority, observing
frequency, LST range suitable for the target(s), and LST pressure. For advice,
please consult the Guide to Observing with the VLA available at:

https://science.nrao.edu/facilities/vla/docs/manuals/obsguide/

Further information for proposers and observers, including statistics and
IMPORTANT telescope pressure plots, is available from the TAC report at:

http://www.aoc.nrao.edu/~schedsoc/tac2013b.shtml

Time Allocation:
+-----------------------+----------+-------------+-------------+------------+
|                       |          | Time        | CenterGST   | Scheduling |
| Session Name          | Bit Rate | (hours)     | (hours)     | Priority   |
+-----------------------+----------+-------------+-------------+------------+
| Automatic GRB Follow- | 2048     | 15 x  0.66  |   12.00     | B          |
+-----------------------+----------+-------------+-------------+------------+

Proposal 1 - For 2012B Semester

Proposal: VLBA-2012-00-009.pdf

Disposition

--------------------------------------------------------------------------------
This email contains specific information about the subject proposal for
Semester 2012B.
--------------------------------------------------------------------------------
Proposal Id: VLBA/12B-033

Legacy Id: BB317
Proposal Title: Prompt high- and low-time resolution follow-up of GRBs with the
LBA

Proposal Type: Triggered

Proposal Authors: Adam Deller, Jean-Pierre Macquart, Keith Bannister, Randall Wayth, Steven
Tingay, Walter Brisken

Time Allocation Summary:
   7.50 hours at 2048 Mbps.

Linear-Rank Score from the Science Review Panel (SRP): 1.93

Comments from the SRP: 
Summary: The proposal aims to search for radio pulses from GRBs in the first
~1/2 after discovery using unused time on VLBA with 1 antenna. Proposal
strengths: Makes good use of unused VLBA time; potential for discovery of a new
phenomenon in GRBs; provides a demonstration of TOO science with VLBA. Proposal
weaknesses: Existing claimed detections of pulses are not convincing given the
large number of >6-sigma spurious signals; it would have been useful to see the
pulses in the freq-time plane to assess their reality. Technical issues: It may
be better to use 2 antennas instead of 1 to reduce spurious signals.

Comments from the NRAO Technical Reviewer:  
The only technical issue here is the ultra-rapid response time requested.
Previous ultra-rapid proposals, on the VLA, have required a human action in the
loop, which would add a minute or two to the response time. It seems likely
that NRAO operations would impose a similar restriction on this proposal. This
does not, quite, rule out attaining the speed of response needed.

Comments from the Time Allocation Committee (TAC): 
For scheduling, at least initially, we will need to have a human in the loop.

Comments from the NRAO:
The linear-rank score from the SRP is on a scale from 0 (an outstanding
proposal) to 10 (a very poor proposal). The quartile boundaries for all
proposals considered by the TAC are 2.5, 5.0 and 7.5.

Scheduling priorities are assigned by the TAC. Possible scheduling
priorities are:

   A = the observations will almost certainly be scheduled

   B = the observations will be scheduled on a best effort basis

   C = the observations will be scheduled as filler

   N*= the observations will not be scheduled because they were
       explicitly rejected by the TAC

   N = the observations will not be scheduled because they could
       not fit in the time available

   H = not assigned because the proposal is being held for
       consideration at a future TAC meeting

For the VLBA, proposals approved for priority A time will be
eligible for scheduling during up to two semesters and proposals 
approved for priority B or C time will be eligible for scheduling 
during only one semester, unless explicitly stated otherwise in 
the Comments from the TAC. For the VLA, proposals approved 
for priority A, B or C time become ineligible when the associated 
configuration ends, unless explicitly stated otherwise in the 
Comments from the TAC.

Further information for proposers and observers, including statistics and
IMPORTANT telescope pressure plots, is available from the TAC report at
http://www.aoc.nrao.edu/~schedsoc/tac2012b.shtml

Time Allocation:
+-----------------------+----------+-------------+------------+-------------+
|                       |          | Time        | CenterGST  | Scheduling  |
| Session Name          | Bit Rate | (hours)     | (hours)    | Priority    |
+-----------------------+----------+-------------+------------+-------------+
| Automatic GRB Follow- | 2048     | 15 x  0.50  |   12.00    | A           |
+-----------------------+----------+-------------+------------+-------------+

Report sent to SCHEDSOC 15 June 2013

Dear schedsoc,

As requested, below is a report of the successful testing of the VLBA rapid response capability for the project:

2012: VLBA/12B-033 (BB317) 2013: VLBA/13B-013 (BB325)

A number of tests were conducted throughout the day on Thurs 13 Jun 2013. In summary, the tests were successful - with the final test pointing the telescopes and demonstrating we could be on source within 10 minutes of a GCN alert.

We are now ready to begin standard operations, pending approval from schedsoc.

Overall, this project has been a success. VLBA operations have been extremely helpful in finding time for us to perform these tests and in giving technical help.

More details of the tests are below.

Regards,

Keith

The first test was as follows:

Time: 2013-06-13 16:28:59 (UT) Target: PSR B0355+54 Proj code: TU002AE Chose calibrator J0346+5400 and check pulsar B0329+54 Chose t+20minute minute schedule to give us some time GRB response system found 10 available antennas, but operators chose to use only 5 This means that response created a subarray-schedule (Nant>=7). In practice, it should have created a single-array schedule, but this case (number of antennas with source above horizon => 7 and number scheduled < 7) will be rare. t+20 minute schedule was started and completed correctly, but the initial POINT command was not sent. Therefore, the antennas did not slew, but the recording was performed.

The second test was a software test of a new script to automate much of the typing and checking associated with starting the GRB observations. The observations can now be initiated by running a single (gogrb) command a following a few prompts.

The 3rd final test included actual observations. Target: B2334+61 Array: SC,HN,NL,FD,LA,PT,KP,OV,BR Proj code: TU002BB Calibrator: J2339+6010 Test pulsar: B0329+54 Time: 2013-06-14 02:58:33.299844 (UT)

The operator was Tony Sowinski. I rang him in advance to warn him an email was about to arrive. The T+5 minute schedule was chosen, but, it was 10 minutes until the antennas arrived on source. The reason for the additional delay was a 4 minute long slew, and about 1 minute delay between the schedule being ready, and the operator issuing the point command.

The data will be correlated and used to test the subarray calibration scheme.

The GCN is sending messages, and we will be online as soon as the firewall is configured to allow GCN messages. (helpdesk #36393)

-- KeithBannister - 2013-06-11