Maximizing Science in the Era of LSST: Study Report Posted

The Large Synoptic Survey Telescope (LSST) will be a discovery machine for the astronomy and physics communities, revealing astrophysical phenomena from the Solar System to the outer reaches of the observable Universe. While many discoveries will be made using LSST data alone, taking full scientific advantage of LSST will require ground-based optical-infrared (OIR) supporting capabilities, e.g., observing time on telescopes, instrumentation, computing resources, and other infrastructure.

A recent community-based study identifies, from a science-driven perspective, capabilities that are needed to maximize LSST science. Expanding on the initial steps taken in the 2015 OIR System Report (Optimizing the U.S. Optical and Infrared System in the Era of LSST, Elmegreen et al. 2015), the study takes a detailed, quantitative look at the capabilities needed to accomplish six representative LSST-enabled science programs that connect closely with scientific priorities from the 2010 decadal surveys (New Worlds, New Horizons and Vision and Voyages for Planetary Sciences in the Decade 2013–2022). The study, led by NOAO and LSST, is funded by the Kavli Foundation and the study concept endorsed by NSF/AST.

The study report [6.9 MB PDF], recently published on arXiv and at the study website, (1) quantifies and prioritizes the resources needed to accomplish the science programs and (2) highlights ways that existing, planned, and future resources could be positioned to accomplish the science goals. The results overlap closely with and expand on those of the OIR System Report. The study recommendations, reproduced below, relate to the capabilities that were found to have particularly high priority and high demand from multiple communities.

Study Recommendations:

Develop or obtain access to a highly multiplexed, wide-field optical multi-object spectroscopic capability on an 8m-class telescope, preferably in the Southern Hemisphere. This high priority, high-demand capability is not currently available to the broad US community. Given the long lead time to develop any new capability, there is an urgent need to investigate possible development pathways now, so that the needed capabilities can be available in the LSST era. Possibilities include implementing a new wide-field, massively multiplexed optical spectrograph on a Southern Hemisphere 6-8m telescope, e.g., as in the Southern Spectroscopic Survey Instrument, a project recommended for consideration by the DOE’s Cosmic Visions panel (arxiv.org/abs/1604.07626 and arxiv.org/abs/1604.07821); open access to the PFS instrument on the Subaru telescope in order to propose and execute new large surveys; and alternatively, joining an international effort to implement a wide-field spectroscopic survey telescope (e.g., the Maunakea Spectroscopic Explorer at CFHT or a future ESO wide-field spectroscopic facility) if the facility will deliver data well before the end of the LSST survey.

Deploy a broad wavelength coverage, moderate-resolution (R = 2000 or larger) OIR spectrograph on Gemini South. The Gen 4#3 instrument is an ideal opportunity. It is critical that development plans for these capabilities proceed in a timely way so that the capabilities are available when LSST operations begin. A basic, workhorse instrument, deployed early in the LSST mission, is greatly preferred to a multi-mode instrument that arrives later in the mission. A wavelength range of at least 0.36–2.5 microns would provide the highest scientific impact.

Ensure the development and early deployment of an alert broker, scalable to LSST. Public broker(s), and supporting community data and filtering resources, are essential to select priority targets for follow-up. The development of an alert broker that can process the LSST alert stream has challenges beyond the field of astronomy alone. The key questions can be best addressed by computer scientists working with astronomers on this multi-disciplinary problem, and support is needed to enable effective collaboration across the relevant fields.

Support into the LSST era high-priority capabilities that are currently available. Wide-field optical imaging (e.g., DECam on the Blanco 4m at CTIO) is one valuable, but relatively uncommon, capability, as is AO-fed diffraction limited imaging (e.g., NIFS on the 8m Gemini telescope). Other important capabilities are standard on many facilities. Those called out in this report include

• single-object, multi-color imaging on < 5m facilities
• single-object R = 100–5000 spectroscopy on 3–5m facilities

Support costs for these capabilities include those associated with routine operations as well as timely repair and refurbishment.

Support OIR system infrastructure developments that enable efficient follow-up programs. Two of LSST’s strengths are the large statistical samples it will produce and LSST’s ability to provide rapid alerts for a wide variety of time domain phenomena. An efficient OIR system can capitalize on these strengths by (i) developing target and observation management software and increasing the availability of (ii) follow-up telescopes accessible in queue-scheduled modes, as well as (iii) data reduction pipelines that provide rapid access to data products. Following up large samples will be time and cost prohibitive if on-site observing is required and/or large programs and triage observations are not part of the time allocation infrastructure. To develop and prioritize community needs along these lines, we recommend a study aimed at developing a follow-up system for real-time, large-volume, time domain observations. As part of this study, discussions with the operators of observing facilities (e.g., through targeted workshops) are important in developing workable, cost-efficient procedures.

Study and prioritize needs for computing, software, and data resources. LSST is the most data-intensive project in the history of optical astronomy. To maximize the science from LSST, support is needed for (i) the development and deployment of data analysis and exploration tools that work at the scale of LSST; (ii) training for scientists at all career stages in LSST-related analysis techniques and computing technologies; (iii) cross-disciplinary workshops that facilitate the cross-pollination of ideas and tools between astronomy and other fields. We recommend a follow-on systematic study to prioritize community needs for computing, software, and data resources. The study should account for the capabilities that will be delivered by the LSST project and other efforts, the demands of forefront LSST-enabled research, and the opportunities presented by new technology.

Continue community planning and development. It is critical to continue the community-wide planning process, begun here, to motivate and review the development of the ground-based OIR System capabilities that will be needed to maximize LSST science. The current study focused primarily on instrumentation. Further work is needed to define the needs for observing infrastructure and computing, as described above. Regular review of progress (and lack thereof) in all of these areas is important to ensure the development of an OIR System that does maximize LSST science. Studies like these form the basis for a development roadmap and take a step in the direction envisioned by the Elmegreen committee that “a system organizing committee, chosen to represent all segments of the community … would produce the prioritized plan. NSF would then solicit, review, and select proposals to meet those capabilities, within available funding.”