Call for SMA Science Observing Proposals
This site is not currently
open for submission of standard proposals. This previous call document
is for reference only.
The SMA Time Allocation Committee warmly welcomes submission of
proposals for the upcoming 2024A semester. We actively solicit
projects of all sizes, and we are particularly interested in
increasing the number of smaller proposals that take just a few hours
in time, projects that take advantage of the SMA ultra broad
bandwidths, continuum and spectral line polarization, and projects
that are especially time critical (such as coordinated observing
campaigns and ToO triggered event programs) and require data in the
coming several months, and in monitoring type proposals.
Information on the array and the submission process are provided
below, and we are available to answer questions or point you to any
information you may need. Please contact us at sma [hyphen] propose [at] cfa [dot] harvard [dot] edu for questions on proposal
preparation, observing techniques and strategies, observing control
scripts, and data analysis.
Contents:
Proposal Deadline
Proposal Preparation
Proposal Evaluation
Accepted Proposals and SMA In-Person Observing( info!)
The joint SAO-ASIAA SMA Time Allocation Committee (TAC) solicits
proposals for observations for the period
2024 May 16 - 2024 Nov 15. Proposals must be
submitted by:
Wednesday, 6 March 2024, 11:00 HST (Hawaii)
Wednesday, 6 March 2024, 16:00 EST (Cambridge, MA)
Wednesday, 6 March 2024, 21:00 GMT
Thursday, 7 March 2024, 05:00 CST (Taipei)
The SMA is a joint project funded by the Smithsonian Astrophysical
Observatory (SAO), one of two partners in the Center for Astrophysics
| Harvard & Smithsonian (CfA), and the Academia Sinica Institute for
Astronomy and Astrophysics (ASIAA). The SMA also includes the
Institute for Astronomy (IfA) at the University of Hawaii as a partner
institution. The time allocation ratios for the three SMA partners,
CfA:ASIAA:IfA, are 72:13:15. To promote excellence in scientific
research and cooperation in the scientific community, the CfA follows
an "open-skies" policy in allocating its share of the SMA time.
Proposals from institutions worldwide are accepted for the CfA time
and judged solely on scientific merit.
An SMA Observer Account is required prior to submission of any type of
proposal; creation is easy, and should only take a few minutes if you
do not already have one. Please see instructions on
the Log In page.
Standard Science Proposals: Beginning with the 2011B
observing semester, the CfA and the ASIAA use the same time allocation
committee (TAC). PIs from ASIAA should submit through the ASIAA queue
to take advantage of the guaranteed time share of the ASIAA.
Astronomers proposing for IfA time should submit proposals directly to
the IfA, following their independent procedures. Proposals from
outside institutions should be submitted to the CfA/SAO
queue. Collaboration between the partner institutions as well as
between the partners and other institutions is encouraged.
Large Scale Science and Key Projects: In addition to
standard proposal programs, SMA from time to time offers the
opportunity for large-scale projects needing observing time in the range of
100 to 1000 hours. As a result, if one or more large scale project
proposals is successful, the time available for standard projects will
be reduced. Proposers should refer
to Observing
Time Available for information regarding ongoing large
scale projects in the upcoming semester.
DDT Proposals:
Several nights of Director's discretionary time are
reserved for potential unforeseen or extraordinary targets of
opportunity and other use.
- An SMA Observer Account is required prior to submission of a DDT;
creation is easy, and should only take a few minutes if you do not
already have one. Please see instructions on
the Log In
page.
- To apply for a DDT, please first contact
SMA_DDT [at] cfa [dot] harvard [dot] edu for further
instructions on how to proceed.
Please note that SMA standard proposals are our
preferred method for handling ToO projects, and DDTs should be
reserved for truly unforeseen and/or extraordinary events. This is
particularly true for observations that require rapid followup. A
proposal to observe up to n events of a certain type (for
example, GRB afterglows) in the coming semester, with locations TBD
and clear triggering criteria, would be best submitted as a standard
science proposal, rather than submitting DDTs for events as they
happen. The SMA can respond much more quickly if the project is
evaluated and approved as a standard proposal for the normal calls.
On average, between five and six nights per week are allocated for
routine science observations. Weather statistics suggest that
approximately half of the useable time is suitable for observations in
the 230 GHz and the 345 GHz bands each. Taking account of time
devoted to testing, reconfigurations, and bad weather, the combined
CfA+ASIAA share of the SMA time per semester averages about 50 nights
each for the 230 GHz and the 345 GHz bands. The TAC uses these
averages to set the approximate number of A-rated tracks.
The SMA is currently supporting two SAO Large Scale
programs. Together, they may require 30-35 rise to set tracks, or up
to 1/3 of the available observing time, though the exact numbers are
not certain as one program is driven by stochastic event rates. The
other project requests significant COM configuration time in and
around the Taurus and Ophiuchus star forming regions. Additionally,
there is an active ASIAA Key Project, broadly centered in the inner
galaxy. For this reason, available time in the first six weeks as well
as the last month of the 2024A semester will be less readily available
for new standard proposals. This does not preclude standard proposals
in these times, but competition will be stronger, and the
configuration will be COM at those times.
In 2024A, the SMA will also be testing new hardware systems,
including the initial testing and rollout of the next generation cryo
systems, on at least one antenna, which may then be unavailable for
some periods of time. In addition, the SMA will begin several major
infrastructure upgrades, including expected replacement of the
correlator cooling system, and initial work toward improving the SMA's
robustness against power fluctuations. Given regular maintenance needs
for other antennas as well we expect that our effective time available
will be less than during regular semesters. However, we hope to run as
close to a normal semester as possible under these constraints.
The oversubscription rate is a function of target RA and DEC. The
figure below shows the distribution of target RA proposed in the past,
with notable peaks along the inner Galactic Plane, nearby star-forming
regions, and extragalactic fields.
For some basic information on the SMA and its capabilities, as well
as more general background information, please see
the Technical Information, Tools, and Resources
section below. There you will find links to the basic specifications,
technical information, useful tools, and several presentations on the
SMA and interferometry in general.
The SMA staff offers support for observers who are not familiar
with the SMA. We can provide support at different levels, from help
getting started to full collaboration. Please contact us at
sma [hyphen] propose [at] cfa [dot] harvard [dot] edu for
questions on proposal preparation, observing techniques and
strategies, observing control scripts, and data analysis. The SMA also
offers a first step data reduction of an observation upon request, for
PIs who are not familiar with interferometry and/or the SMA.
Following the popularity of CASA in radio astronomy, new tools are
now available allowing users to calibrate and/or image their SMA data
using CASA. This process is rapidly developing, and will soon include
pipeline calibration and correction of some SMA specific features,
such as intial Tsys calibration and a robust automatic 'despiking' at
the native resolution prior to any spectral binning. For 2024A, we are
testing export of initial passband and time dependent gain
calibrations for select programs from the pipeline as well.
SMA users can now choose to calibrate, image, and analyze their
data completely within CASA using these new tools to convert the raw
SMA data sets into CASA Measurement Sets. Our heritage data path is
also still available, allowing for calibration with MIR/IDL, and
subsequent export into a variety of formats for imaging and
analysis.
More details can be found at the
CfA Radio
Telescope Data Center, as well as in the SMA
Newsletter RTDC
Update (pdf) from July 2023, by Dr. Holly Thomas.
Under nominal conditions, 8 antennas are available for scientific
observations with the SMA. However, maintenance and operational issues
may reduce the number of active antennas available for any given
track. In order for a track to be considered passing, the project must
a) meet the weather stringency requirements for the track, and b) have
a minimum number of elements available in the array, the latter of
which is defined as follows:
- Full-polarization tracks: 7 working antennas with both an
operational LCP and RCP receiver
- Dual-polarization tracks: 14 working receivers (7 tuned to the RxA
tuning, 7 tuned to the RxB tuning)
When the array meets the above, the full observing time is charged
to the project (i.e., the track is considered "passed"), provided no
other significant technical or weather issues. When there are fewer
than the above number of elements, but the weather requirements for
the project are met, then the project is charged for time/tracks in
the following fashion:
- 6 working antennas/12 working receivers: If the weather is better
than requested (e.g., < 2.5 mm PWV during observations, when < 4 mm
PWV was requested), then a full track is charged. Otherwise, the
project is only charged half-time. I.e., 2 tracks w/ at least 6
antennas/12 receivers are combined to make a single "passing"
track).
- 5 working antennas/10 working receivers: The project is only
charged a third of the time. I.e., 3 tracks w/ at least 5 antennas/10
receivers are combined to make a single "passing" track.
- Fewer than 5 working antennas/10 working receivers: No time
charged.
There are two important caveats about the above. First, it does not
apply to triggered ToO observations, where the array is accepted
"as-is" at the time of trigger. Second, the above does not account for
differences in the synthesized beam that may arise from a limited
number of elements in the array, and thus may not be suitable for
high-SNR projects, where imaging fidelity is primarily limited
uv-coverage. PIs with projects that fall into this category may
stipulate as much in the "additional instructions" field in the
individual time requests, in which case the project will nominally not
be run with fewer than 7 antennas.
The SMA has been in operation for nearly 20 years, and has an
extensive science data archive. Proposers should query the SMA archive
prior to planning new observations to see if existing SMA data suit
their scientific goals. Data from past SMA observations are archived
by the CfA Radio
Telescope Data Center and may be searched. SMA data are publicly available
after a proprietary period of 15 months.
If older data exist, the PI should include a short statement in
their proposal discussing why new observations are warranted.
Proposals are submitted through each individual PI's SMA Project
Account. The project account contains all information about an
observer's proposals and projects, and will persist for reuse in
future proposal cycles. All SMA project activities begin at the
user's My
Projects page. Project accounts may be created from the login
page if necessary (current SMAOC account holders do not need a
separate project account).
Using the proposal submission facility, drafts may be created and
edited at any time, but may only be submitted within a few weeks prior
to the proposal deadline. Each proposal consists of an on-line cover
form and technical information forms, and an attached scientific
justification in PDF format. Proposals may be saved and edited on-line
as often as needed prior to final submission.
The scientific justification is limited to a maximum of four
US-letter sized pages including all text (11pt or larger, with
reasonable margins) figures, tables and references. The PI is now
free to design their proposal within those boundaries, such as mixing
figures within text. The PI should aim for approximately equal space
for prose (science justification+technical rationale) vs figures,
tables, etc., and text alone should not exceed 3 pages. PLEASE NOTE:
typically, a picture is truly worth many words, and proposals that are
primarily text will generally not fare well. We strongly urge the
PI to consider readability by TAC members; they are experts, but may
not be experts in your field.
***NEW*** Proposals should provide clear
statements on, and justifications for, the rms flux sensitivities,
spectral resolutions, antenna configuration(s), weather conditions,
calibration strategies, and (if applicable) any time constraints
needed to achieve their science goals. Time requests
are now required to include clear sensitivity goals for continuum and
spectral line observations, in order to allow SMA team to assess our
observational progress toward the project goals. Proposals
without clear sensitivity goals, or a clear explanation of why
sensitivity goals are not relevant (e.g. certain time domain
experiments, experiments that are systemically limited versus
sensitivity limited, etc), may be downgraded.
***NEW*** In order to help improve
proposal preparation, programs with 16 or more sources can submit
representative RA and DEC time requests for each tuning. For example,
a program to observe the mm flux of 22 sources in a survey field (say,
Cygnus) can choose to submit a single time request with a
representative RA and DEC, rather than entering 22 separate time
requests. The time request must include the total on source time for
all the sources in that group at that tuning. If there are two or more
tunings, then each tuning should have its own time request. The
representative groupings must be reasonably colocated for scheduling
purposes; if there are two fields, a group time request should be made
for each. The actual target positions must still be reported, but as a
simple table or list of "target_name RA DEC" as an additional page to
the 4 page justification. This target list will not count against your
4 page justification limit. HOWEVER, only a target list is allowed
beyond the 4 page limit for standard proposals.
SMA observations are generally executed at night when the
atmospheric phase noise is low and often continued into the early
morning. Conditions are rarely suitable for afternoon observations.
For 2024 May
- 2024 November observing,
long tracks will be feasible during at least half the semester for
sources in the range of roughly RA=16h to
4h. Sources outside this RA range will also be considered if
adequate justification is provided. However, since the array
configuration schedule is set to accommodate the most highly ranked
approved proposals, such observations may not be possible.
The SMA operates in 4 configurations with maximum baselines of 30m
(the six antennas on the inner ring of "subcompact"), 70m ("compact"),
220m ("extended"), and 508m ("very extended");
see Technical Information, Tools, and Resources
section below for more infomation. The configuration schedule is
determined after the TAC process to best fit the highest ranked
approved projects.
Many projects do not need full tracks (a full rise to set
observation)for adequate uv coverage and/or sensitivity, and the TAC
strongly encourages requests for snapshots, partial tracks, and tracks
sharing several targets in a field to enhance efficiency.
We are offering as a standard capability our expanded processed
bandwidth of 12 GHz per sideband per polarization, equal to 48 GHz of
total processed dual reciever bandwidth, all at 140 kHz
resolution. All receivers and IF chains offer full bandwidth (4-16 GHz
IF range), allowing each receiver to covering 12 GHz in each sideband.
In much of the SMA tuning range (~200 - 275 GHz and ~328 - 365 GHz),
where receivers with orthogonal polarization have overlapping
coverage, the receivers can be tuned with the same LO frequency,
providing dual polarization observations for increased line
sensitivity. In the case of equal LOs for the two selected receivers,
it is also possible to obtain full polarization observations near
1.3mm and 870 micron.
The receivers are also independently tunable. Around the regions
of tuning overlap for the dual recievers, a continuous 44 GHz coverage
is possible (with 4 GHz of 'overlap').
See Array Status and
Technical Information for more details, where up-to-date technical
information about the SMA, including antenna configurations,
correlator setups, receiver status, and new or updated SMA
capabilities are always available.
The SMA maintains several online tools for planning SMA observations,
available on the Tools page.
The Beam
Calculator / Sensitivity Estimator is a particularly useful tool
to estimate angular resolution, UV coverage and nominal sensitivities
for different configurations and weather conditions (precipitable
water vapor). Variations in weather may considerably impact actual
sensitivities.
Generally, observations at lower frequencies can be done in
atmospheric conditions of higher precipitable water vapor. Standard
values are < 4.0mm and < 2.5mm of water vapor for observations in the
frequency ranges <300 and 300-420 GHz, respectively. Proposers must
indicate and justify the atmospheric conditions required for their
scientific goals. The SMA is more oversubscribed in the weather
conditions suitable for the 350 GHz band (< 2.5mm water vapor).
The Passband
Visualizer Tool provides interactive information on spectral line
coverage and tuning.
SMA observations require calibrator sources for bandpass, gain, and
flux calibration. Quasars are generally used for bandpass and gain
calibration; however, suitable calibrators may not be available for
all parts of the sky particularly at the higher
frequencies. See The Submillimeter Calibrator List. Solar system bodies are
generally used for flux calibration but may not be available at all
times of the year. Observers should show that their proposed
observations can be adequately calibrated.
Resources:
SMA Basic
Specifications
Array
Status and Technical Information
SMA Introduction
and Proposal Information (2021A) PDF of 19 Feb 2021 presentation
SMA
Proposal Planning Tools
Presentations from the most recent SMA Interferometry School (May 2023)
Proposal selection is based on clearly demonstrated scientific
merit, alignment with SMA uniqueness and capabilities, and technical
feasibility.
The TAC assigns each proposal a numerical score and recommends an
amount of time to be allocated. The proposals are ranked and grouped
into three categories: A (best effort to execute), B (may be executed
as conditions permit), and C (will not be executed). Proposers are
notified of their proposal rating by e-mail shortly after the TAC
completes its work, typically within about 7-8 weeks of the proposal
deadline. Please see the TAC Procedures for more details of the TAC review process.
All accepted proposals are shared-risk, with no guarantee of success.
Standard proposals accepted but not observed due to time constraints
will generally not be carried over and must be resubmitted in response
to a future call for proposals.
Usually, principal investigators of successful proposals should be
prepared to provide an observer on Maunakea. Such a visit would entail
travel to Hawaii, and a stay of 3-4 nights at the summit (plus
acclimation time), paired with one of our operators. Most proposals
are queue scheduled to maximize return based on the prevailing weather
conditions and instrument status. The SMA scheduler decides which
project will be observed each night. It is unlikely that visiting
observers will execute their own project when present on Maunakea,
though the scheduler will take it under consideration if other factors
are met (weather, array, etc).
Due to awareness of health
considerations, we have for the past three years halted the practice
of hosting science visiting observers. As we transition away from
these restrictions, we will start to reimplement this observer visitor
policy. PIs of successful A ranked programs may be contacted at the
start of the semester regarding scheduling of a visiting observer to
fulfill this requirement.
Questions?
Please e-mail any questions about preparing and submitting proposals to
sma [hyphen] propose [at] cfa [dot] harvard [dot] edu.
Last updated: 2024-Feb-02 by Mark Gurwell
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