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Call for JCMT Proposals for Shared-Risks Observing with SCUBA-2

JCMT

Call for Proposals

Shared-Risks Observing with SCUBA-2

Submission Deadline:

This Special Call is for telescope time in December 2009 and January 2010.

The closing date for receipt of proposals is

Monday 09 November 2009
at
22:00 CET = 21:00 GMT = 13:00 PST = 11:00 HST

Important Notes

  • 276 hours of SCUBA-2 Shared-Risks Observing time (S2SRO) are available, of which 31 hours are available to applicants from the University of Hawaii (UH).
  • Only proposals from the three JCMT partner countries (UK, Canada and the Netherlands) and from UH will be accepted. Proposals which would normally be assigned to the International queue will not be accepted in this Call.
  • As for regular proposal rounds, the submission process for UK/CA/NL applicants is via Northstar; UH applicants should submit proposals to the UH coordinator.
  • The usual division of time between the partner nations is waived during this Call, so there is effectively just one queue - and (ironically) it will be described in Northstar as being for the 'International community'.
  • The total time requested by any proposal should not exceed 10 hours, and proposal length should not exceed one page of scientific justification plus one page for any technical comments and figures.
  • Each S2SRO proposal needs to be self-contained and not open-ended; publication of results should not be dependent on ancillary data from other instruments (or SCUBA-2), unless those data are already reduced, analysed, available and/or published.
  • Formulae from the Instrument team for calculating integration times are available below.
  • There will be only one observing mode, viz SCAN. Applicants should otherwise itemize explicitly, in the Technical section of the proposal, their inputs to their integration time calculations (viz. wavelength, airmass/elevation, opacity, desired rms noise levels), as well as their output (integration time). This is essential to allow the assigned Technical Assessor to confirm the feasibility of the proposal.
  • The science goals of the JCMT Legacy Surveys will be protected from duplication. Proposals to observe JLS targets require, and must explicitly contain, the expressed consent of the survey coordinators. A statement similar in wording to "This proposal has been approved for submission to S2SRO by the < insert survey here > coordinators." must be included in the proposal text.
    If proposed targets overlap with Legacy Survey fields, applicants should explain how the proposed observations and science differ from the survey project. See below for details on how to check for such overlap.
  • JCMT operates a 12-hour night, running from approximately 7:30pm to 7:30am HST. This table shows source transit times during semester B.
  • Your proposal should specify both the optimum weather conditions (read opacity) needed for your proposed observations, and those that it can tolerate. Scheduling during optimum conditions cannot be guaranteed.
  • The proprietary period for S2SRO data is to last up to 6 weeks after the end of S2SRO. It is expected that the first draft papers from S2SRO will start to appear by this time.

    • Contents

Shared-Risks

SCUBA-2 Shared Risks Observing being offered with this call is an opportunity for the JCMT community to obtain early science with SCUBA-2 ahead of its full commissioning. It is a chance to demonstrate the potential of the science we can expect to produce with a complete and mature system. However, due to the fact that only basic commissioning tasks will have been completed and our on-sky experience with the instrument will be limited by the time S2SRO begins, the commissioning team, the observatory and the community will be sharing the risk that observing may be inefficient, and that instrument performance and data quality may not meet expectations. The observatory reserves the right to interrupt observing in order to deal with problems and faults. Although we are not in a position to provide guarantees, together with observers from the community we will endeavour to collect data for all the projects allocated by the ITAC and to ensure that as many of those as possible are completed.

Calculating Integration Time and Overheads:

Basic parameters
   
450μm
850μm
FWHM (arcsec)
7.5
14.5
  Ωb (arcsec)2  
32
120
FoV (arcsec)
   175 x 216 = 10.5 sq arcmin     175 x 216 = 10.5 sq arcmin 
Nb
~700
~400

NEFD versus Opacity

The expected NEFD (measured at zenith) as a function of 225-GHz opacity (CSO tau) are given in the table below:

NEFD (mJy.√s)
tauCSO
  weather band  
450μm
850μm
0.040
1
100
50
0.065
2
220
55
0.100
3
550
70
0.150
4
5500
90

To calculate the NEFD for objects at lower elevations/higher air-masses (AM), one needs to multiply the NEFDs in this table by,

, where,

Overheads

At this stage, overheads are expected to be as large as 100% and these are explicitly included in the time estimate equations below for tmap. These include the time for pointing, focus, array setup and calibrations.

Calculating the required integration time

A document describing the derivation of the equations below is available by following this link.

Note that the calculations presented here are for detecting point sources and we believe are equivalent for extended structures (larger than the beam) in maps with pixels dimensions ~FWHM/2 (i.e. approx. Nyquist sampled). SCUBA-2's performance at recovering extended emission is still unknown given that at the time of this call we have not yet started the on-sky commissioning phase.

The amount of time required to integrate with a single bolometer to achieve a final noise of per beam is:

The effective surface area for the detection of a point source is:

To produce a map covering a solid angle area on the sky, we multiply the integration time by the effective number of pointings required to cover the area with the available array area. This gives the time required (including overheads):

where Nb is the number of bolometers available on the array.

Maps smaller than the field of view

The SCUBA-2 field of view with just one array at each wavelength is of the order of 10 arcmin2. The telescope will need to scan a small area in order to modulate the signal for sky removal. Using the PONG pattern, the depth achieved in the central region (3' x 3') will still match , for the same total observing time. The effective integration time will smoothly drop to zero towards the edges of the output map.

The JCMT OT

The JCMT Observing Tool (JCMTOT) will produce SCUBA-2-compatible MSBs.

JCMT Legacy Survey

In order to enable proposers to identify potential conflicts with the survey programme, a web-based Survey Clash Detector tool has been developed. The tool simply reports positional clashes for an instrument; it does not attempt to say whether the clash constitutes a conflict between your proposal and one of the surveys. If a clash is detected, you will need to check the survey descriptions to determine if there is a conflict.

Proposal Submission

The Northstar, web-based proposal submission and management system, used during recent (PATT) Calls, has been configured to receive SCUBA-2 Shared-Risks proposals. Users are advised to check and update your accounts as soon as Northstar becomes available for this round (immediately after the release of this Call). As mentioned in our Help page, you may, at first, have to accept the server certificate to gain access to Northstar. Except for the University of Hawaii, all proposals should be submitted

HERE.

If you had a (surviving) Northstar account previously you can login with your existing username and password; new users should register first.

Help regarding the submission process is available here - - - and in our Help pages !

Observing Logistics

SCUBA-2 Shared-Risk Observing (S2SRO) will be done in small-ish blocks of about 3 nights, interspersed with heterodyne observing of similar block-length for the 09B semester. This provides sufficient time for reduction of and understanding of the data, for communal learning, and for adjustment of observing techniques in order to optimize the productivity of the instrument.

The early S2SRO blocks will be done by the instrument team and local staff, after which some of the successful applicants will be invited to travel to Hawaii to execute subsequent S2SRO blocks. While not all successful applicants will travel, it is hoped that some SCUBA-2 observing experience will permeate to the communities and encourage future applicants.

The JCMT Users e-mail exploder:

From time to time, subscribers to the 'jcmt_users' email list will receive notices on the status of the JCMT, call for proposals, etc. To subscribe, please visit http://mailman.jach.hawaii.edu/mailman/listinfo/jcmt_users

And Finally:

If you've read all this and still have questions about the scheduling, the submission deadlines, the procedures, etc - please contact me.

Iain Coulson
JCMT Scheduler
Contact: Iain Coulson. Updated: Wed Nov 11 11:20:39 HST 2009

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