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.
We warmly welcome submission of proposals for the upcoming
2021A 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 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. SAO has access to 72% of the observing
time on the SMA, which is allocated using an 'open skies' policy,
while ASIAA (13%) and the University of Hawaii (15%) allocate to PIs
eligible under their programs.
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. You may also view a PDF of an overview
presentation given by TAC Chair Mark Gurwell on 19 February, 2021
SMA Introduction and
Proposal Information (2021A) (PDF)
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.
SMA Observing Time
Support for New Users
Number of Nights Available
Accepted Proposals and SMA Observing
The joint CfA-ASIAA SMA Time Allocation Committee (TAC) solicits
proposals for observations for the period
2021 Jun 01 - 2021 Nov 15. Proposals must be
Thursday, 4 March 2021, 11:00 HST (Hawaii)
Thursday, 4 March 2021, 16:00 EST (Cambridge, MA)
Thursday, 4 March 2021, 21:00 GMT
Friday, 5 March 2021, 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) and 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.
In addition to regular proposal programs, SMA offers opportunity
for large-scale projects needing observing time in the range of
100 to 1000 hours. As a result, if a large-scale project proposal is
successful, the time available for regular projects will be reduced.
Proposers should refer
Time Available for information regarding current ongoing large
scale projects in the upcoming semester. The SMA is again offering as
a shared-risk capability our expanded processed bandwidth. We have
fully vetted our 50% bandwdith increase, to 12 GHz per
sideband per polarization, equal to 48 GHz of total processed receiver
bandwidth (24 GHz from each of two orthogonally polarized
receivers), which we now offer as a standard capability.
Please see the Array Status and Technical Information for more details. The
full polarization mode, recently under shared-risk mode, has been
upgraded to a standard SMA capability in
As of 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.
Several nights of Director's discretionary time are reserved for
potential targets of opportunity and other use. Please contact the TAC
chair, Mark Gurwell, and the director, Ray Blundell at
SMA_DDT [at] cfa [dot] harvard [dot] edu to apply for
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. Starting this semester, 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.
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, overhead, and lost to bad weather, the combined
CfA+ASIAA share of the SMA time per semester averages about 40 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.
In 2021A, the fraction of time available may be somewhat
reduced, depending on safety protocols in place as a response to the
coronavirus pandemic. 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. The Figure below
shows the distribution of target RA proposed in the past few semesters
with notable peaks in the inner Galactic Plane.
Existing SMA data
Proposers should query the SMA archive before planning 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.
RA range and UV coverage
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 2021 May
- 2021 November observing,
long tracks will be feasible during at least half the semester for
sources in the range of roughly RA=17h 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 rangked
approved proposals, such observations might 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"). The configuration
schedule is determined after the TAC process to best fit the highest
ranked approved projects.
Many projects do not need full tracks 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.
Technical Information and Tools
2021A 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. The correlator in this case will also allow 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 is 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
Generally, observations at lower frequencies can be done in
atmospheric conditions of higher precipitable water vapor. Standard
values are < 4.0 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).
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.
Proposals should provide clear justifications for the rms flux
sensitivities, spectral resolutions, antenna configuration(s), weather
conditions, and calibration strategies needed to achieve their science
Proposal Forms and Proposal Submission
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
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 reasonble 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.
Proposal selection is based on clearly demonstrated scientific merit and technical
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 Mauna Kea. 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 Mauna
Kea. Due to the ongoing pandemic, we are currently not hosting any
visitors, including SMA staff not stationed in Hawaii, and it is
uncertain when this will change. Therefore, at this time we do not
know if observing support by PIs will be required for successful 2021A
Data from SMA observations may be retrieved from the
CfA's Radio Telescope
Data Center archive for reduction. Due to the larger bandwidth
and finer resolution of the new correlator, the data sizes are
significantly larger. Raw data from a typical 12 GHz BW dual receiver track
will take up to 100 GB on disk and a full polarization track will
require twice that. A software tool, SMARechunker, can be used to
rebin the data - a factor of 8 rebinning (to 1.117 MHz resolution)
should be adequate for many spectral line observations. The data can
also be retrieved at a lower spectral resolution from the archive if
desired. These sizes are for 30s scan times and 12 hr tracks and will
be larger if smaller scan sizes are used for finer visibility
sampling, e.g., in the very extended configuration. Please see the
Radio Telescope Data Center webpages for more details on data
processing and hardware requirements.
Please e-mail any questions about preparing and submitting proposals to
sma [hyphen] propose [at] cfa [dot] harvard [dot] edu.
Last updated: 2021-Jan-30 by Mark Gurwell