Call for SMA Science Observing ProposalsThis 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 2024B 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:
Accepted Proposals and SMA In-Person Observing Proposal DeadlineThe joint SAO-ASIAA SMA Time Allocation Committee (TAC) solicits proposals for observations for the period 2024 Nov 16 - 2025 May 15. Proposals must be submitted by:
Thursday, 12 September 2024, 15:00 HST (Hawaii) SMA Observing TimeThe 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: Semester-based calls for observations up to 200 hrs (SAO)/100 hrs (ASIAA) on source. 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 more observing time than available in a standard proposal, up 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.
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. Number of Nights AvailableOn 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 2024B 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 2024B, 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.
General Help and Support for New UsersFor 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.
SMA Data and CalibrationFollowing 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 2024B, we are ramping up testing and 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. "Time Charged" Allocation RulesUnder 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:
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:
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. Proposal PreparationChecking for Existing SMA dataThe SMA has been in operation for over 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. Proposal Forms and SubmissionProposals 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 for all text (11pt or larger, with reasonable margins) figures, and tables (see new notes below regarding references, and also regarding programs with 16 or more targets). 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. 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; this should include the relevant bandwidths and assumptions made. 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 an effort to promote accuracy, transparency, and full crediting of previous work, references are no longer counted in the four page maximum. Instead, PIs can use a fifth page for references (e.g. no explanatory or extra text that can be used to bolster the science justification, just a standard reference list in the format of your choice). [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 the 4 page justification limit. Only references and a target list as described above are allowed beyond the 4 page limit for standard proposals. RA Coverage by Semester and UV Plane ConsiderationsSMA 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 November - 2025 May observing, long tracks will be feasible during at least half the semester for sources in the range of roughly RA=4h to 16h. 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. Technical Information, Tools, and ResourcesOur standard spectral coverage capability is a 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 345 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. Further Resources:Array Status and Technical Information SMA Introduction and Proposal Information (2021A) PDF of 19 Feb 2021 presentation
Presentations from the most recent SMA Interferometry School (May 2023)
Proposal EvaluationProposal 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. Accepted Proposals and SMA In-Person ObservingAll 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).
Questions?Please e-mail any questions about preparing and submitting proposals to sma [hyphen] propose [at] cfa [dot] harvard [dot] edu. Last updated: 2024-Aug-12 by Mark Gurwell |
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