This page is intended to provide a starting point for those interested in getting involved in the Rubin LSST and LSST:UK. It assumes no prior knowledge of either, although most people reading it will know some of this material, so please use the table of contents below to skip to the bits that are new to you.

The Vera C. Rubin Observatory

The main component of the Vera C. Rubin Observatory is the Summit Facility currently under construction on Cerro Pachón in Chile. It comprises the 8.4-metre Simonyi Survey Telescope, on which will be mounted the 3.2-gigapixel LSST Camera, together with the Auxiliary Telescope (AuxTel, used for spectrophotometric calibration observations) and various ancillary services. The telescope has a novel, compact design, providing good image quality across a 3.5-degree field of view, plus the ability to move across the sky quickly and take relatively short (~30 second) exposures efficiently, with little time lost to prior stabilisation. Data from the camera will travel from Cerro Pachón to the Base Facility at La Serena, and then on to the US Data Facility (USDF) at SLAC National Accelerator Laboratory. The Observatory has been designed as an end-to-end system, encompassing that journey from the summit all the way to the tools on the astronomer’s laptop with which they will analyse the final data products.

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(Credit: Rubin Obs/NSF/AURA)

The Legacy Survey of Space and Time

For the first decade of its operational lifetime, the Rubin Observatory will conduct the Legacy Survey of Space and Time (LSST). The survey has four main science themes:

• Probing data energy and dark matter

• Taking an inventory of the solar system

• Exploring the transient optical sky

• Mapping the Milky Way

Those high-level goals drove the development of a design for the Observatory and the ten-year survey it will undertake, as described in the LSST overview paper by Ivezic et al (2008, arxiv:0805.2366). While some details of the survey specification remain to be optimised, its basic plan remains as outlined in that paper, notably:

• ~90% of the observing time will be devoted to the Wide-Fast-Deep (WFD) Survey, covering ~18,000 square degrees of the southern sky, with each field receiving ~800 visits (back-to-back pairs of 15 second exposures) distributed over the u, g, r, i, z and y bands. The predicted 5 sigma point source depths of the WFD data in each band is as follows:

  • single visit depth: u = 23.9, g = 25.0, r = 24.7, i = 24.0, z = 23.3 and y = 22.1

  • 10-year stacked depth: u = 26.1, g = 27.4, r = 27.5, i = 26.8, z = 26.1 and y = 24.9

• The remaining ~10% of the observing time will be divided amongst smaller programmes requiring different observing strategies, such as the Deep Drilling Field (DDF) programme, where selected fields will be observed much more frequently than in the WFD survey, to produce greater integrated depths and finer temporal sampling. The first four DDFs have already been selected, with more still to be agreed.

One aspect of the LSST design that is still being optimised is the observing strategy, which will determine how the ~800 visits in each field will be distributed across the ten years of the survey. Different temporal sampling distributions favour different science goals, so detailed analysis of a wide range of simulated survey strategies is being performed, to inform a decision as to how best to trade-off these conflicting preferences. This activity is being coordinated by the Survey Cadence Optimisation Committee, with input from Rubin Observatory staff and the scientific community.

LSST Data Products

There are three broad categories of LSST data product:

• Prompt products. These are generated by a Difference Image Analysis pipeline that is run as soon as the images from each visit reaches the USDF. Each image is compared with a reference image of that field in the same band, and alerts are issued to record all celestial objects in that field that are significantly detected to have moved or changed brightness. Alerts will be issued from the USDF within a minute of the closing of the shutter in Chile at the end of the exposure from which they originate, allowing rapid follow-up observations of transient phenomena.

• Data Release products. A range of static-sky data products - e.g. calibrated single visit and stacked images, together with object catalogues derived from them - will be released in a series of Data Releases. Two data releases are planned from the first year of survey operations, with annual releases thereafter. Each data release will reduce all extant data with the same set of software, so that each comprises a homogeneous dataset.

• User-Generated products. The data release products will not be optimal for all possible science analyses, so the Observatory will accept, and publish alongside the data releases, some additional datasets generated by the community. These may include data from other instruments, as well as bespoke products generated by optimised re-reduction, or further analysis, of LSST data and intended for particular science analyses.

The Rubin LSST dataset will be huge. About 20 TB of image data will emerge from the camera every night, yielding several million alerts per night The final data release catalogue database is expected to exceed 15 PB in size, and to contain information on ~20 billion galaxies, ~ 17 billion resolved stars and ~6 million solar system objects. Researchers will access this dataset through Data Access Centres (DACs) with the computational resources needed to support the storage and analysis of this vast volume of data. The alert stream will be world-public immediately, while each data release will become public after a proprietary period of two years, during which time it will only be accessible to data rights holders.

Rubin LSST Funding and Data Rights

The Rubin LSST is a billion-dollar project. Rubin construction is primarily being funded by the US, with the National Science Foundation (NSF) providing $437M for the construction of the telescope and site facilities, development of the data management system and of the Education and Public Outreach programme, while the Department of Energy (DOE) is funding the camera and associated systems to the tune of $168M. Additional contributions to camera construction have come from IN2P3, the French particle physics agency, while Brazil is providing the network from the summit to the USDF and, of course, Chile has provided the site.

In return for these contributions, all professional astronomers in the US and Chile will have data rights, while other international participants will earn rights to the proprietary data through contributions to Rubin LSST operations. Initially, this was expected to follow a subscription model - and, indeed, in 2015 STFC signed a Memorandum of Agreement (MoA) to secure data rights for a set of UK astronomers that way - but, more recently, the US funding agencies decided that these should be in-kind contributions, which can either help offset the $70M per year Rubin operating costs or add value to the US community’s exploitation of the Rubin LSST dataset through enhancing the range of user-generated products. Potential international participants submitted in-kind proposals in the autumn of 2020, and they are currently under review, with the expectation that data rights agreements resulting from them will be signed by late summer 2021.

Rubin LSST Organisation

The complicated picture to the right show the various bodies currently involved in running the Rubin LSST, as construction draws to a close and before the start of operations. NSF construction funds are routed through AURA, while SLAC National Accelerator Laboratory receives the DOE funds. Crucial early construction funding from private donors came through the LSST Corporation (LSSTC), a not-for-profit organisation supporting LSST science. The construction project team receives scientific advice from the Science Advisory Committee (SAC) and from eight Science Collaborations, which are described in more detail below. Steve Kahn is the Rubin Observatory Director and Zeljko Ivezic is the Deputy Director and Project Scientist.

During survey operations, the two Operations Partners will be NSF’s NOIRLab and SLAC, with Brazil, Chile and France (IN2P3) as Affiliate Partners, and the SAC and Science Collaboration likely to retain their advisory roles. The Rubin Director will be based at NOIRLab in Tucson, with a Deputy Director each there and at SLAC: Bob Blum is the Operations Director (Acting), with Amanda Bauer and Phil Marshall set to fill the deputy roles at NOIRLab and SLAC, respectively.

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(Credit: Rubin Observatory/NSF/AURA)

Rubin LSST Science

Membership of any Science Collaboration is open to any data rights holder, with some Science Collaborations having a higher level of membership that must be earned and that they conveys some level of authorship rights on papers produced by the Science Collaboration. The Rubin data rights policy is currently under being updated, to take account of the forthcoming signing of in-kind contribution agreements with international contributors, but a key principle that it is expected to retain is that any data rights holder may do any science with proprietary LSST data; the Science Collaborations are coordinating research in particular science areas, but they do not “own” that area of LSST science.

A lot of further information about Rubin LSST science can be found on the For Scientists page on the Rubin website, which includes an FAQ for scientists and a link to a page of Key Numbers summarising the project.

LSST:UK

The Consortium Board comprises a representative of each member institution and acts as a proxy for the UK astronomical community, providing strategic guidance to ensure that the community derives the greatest possible benefit from UK participation in the Rubin LSST. Mike Watson is currently the Consortium Board Chair and Alastair Edge the Deputy Chair.

Further details about the LSST:UK Consortium can be found in the Home space of the LSST:UK wiki and on the LSST:UK website.

UK Data Rights

One of the duties of the Consortium Board is to administer the UK data rights agreement. Until a new agreement, resulting from the UK’s in-kind contribution, takes effect, UK data rights is governed by the Memorandum of Agreement (MoA) signed on the Consortium’s behalf by STFC in 2015. The MoA secured data rights for 100 Affiliate PIs (i.e. faculty members) and 400 Junior Associates (postdocs and PhD students), and, following the policy set by the Board, these slots are awarded through a competitive process, with one round per years for Affiliate PIs (APs) and two for Junior Associates (JAs). AP and JA status is usually awarded in three-year terms and the current list of APs and JAs is available on the LSST:UK wiki: N.B. there is currently a JA selection round open, with closing date of 4pm BST on Friday 21st May 2021.

LSST:UK Executive Group

The Consortium Board typically meets twice a year, so it delegates many of its responsibilities to an Executive Group that meets monthly. The Exec Group is chaired by the LSST:UK Project Leader (Bob Mann) and comprises the LSST:UK Project Scientist (Stephen Smartt) and five members elected by the Board. Currently they are: Adam Amara, Catherine Heymans, Richard McMahon, John Stott and Aprajita Verma. Exec Groups meetings are also attended by the LUSC Project Managers (George Beckett and Terry Sloan), the Consortium Board Chair (Mike Watson) and the Commissioning Coordinator (Graham Smith).

LSST:UK Science Centre

A second tranche of funding - for LUSC Phase B - enabled continuation of these activities from July 2019 to March 2023. With the advent of the in-kind mechanism for securing data rights, the LUSC programme has become part of the UK’s proposed in-kind package, and will continue to do so once survey operations has begun: a call will be issued later in 2021 for further DEV projects, to run from April 2023.

As they reach maturity the outputs from the LUSC programme will become available to the community. The first substantial such output is the Lasair alert broker, which is currently processing alerts from the Zwicky Transient Facility, as is the UK’s candidate to be a Community Broker, to receive the full Rubin LSST alert stream.

Further details of current LUSC activities (including a number of Technical Reports) can be found in the LUSC space in the LSST:UK wiki, which requires wiki login credentials.

LSST:UK Science Working Group

The LSST:UK Project Scientist, Stephen Smartt, chairs the LSST:UK Science Working Group, which provides scientific advice to the Board and the Exec Group, and acts as a bridge between LSST:UK, the broader Rubin LSST science community and other facilities for which there are clear synergies with the Rubin LSST. The Science Working Group comprises Points of Contact (PoCs) for each of the Science Collaborations

• Galaxies: Brooke Simmons

• Stars, Milky Way and Local Volume: Phil Lucas (Milky Way stars) and Annette Ferguson (Local Group and near-field cosmology)

• Solar System Science: Meg Schwamb

• Dark Energy: Benjamin Joachimi and Catherine Heymans

• Active Galactic Nuclei: Sebastian Hoenig

• Transients and Variable Stars: Sarah Casewell (variable stars) and Cosimo Inserra (transients)

• Strong Lensing: Aprajita Verma

• Informatics and Statistics: Jason McEwen

together with additional Science Liaisons contributing expertise in specific areas or relating to complementary facilities

• Square Kilometre Array: David Bacon

• Euclid: Bob Nichol

• Stars, Milky Way, Astrometry: Tim Naylor

Further information about the Science Working Group can be found in the SWG space in the LSST:UK wiki, which requires wiki login credentials.

Getting Involved

The following are some suggestions for how to get involved in the Rubin LSST and in LSST:UK, respectively. Specific questions about getting involved can also be emailed to the LSST:UK Project Leader (Bob Mann, for organisational issues) or the LSST:UK Project Scientist (Stephen Smartt, for scientific matters).

Getting involved in the Rubin LSST

The Rubin Observatory maintains a How to get involved page, which includes the following:

• Sign up to the scientists mailing list by emailing science-join@lists.lsst.org. That list is used project announcements

• Visit the Community forum: this is main way that the Observatory staff interacts with the user community, so posting a question on http://community.lsst.org is the best way to get a technical question answered, and will remain so during survey operations.

• Subscribe the Project Digest(by emailing lsst-weekly-join@lists.lsst.org) to receive regular news updates

Getting involved in LSST:UK

• Subscribe to the lusc-announce email list: this is a low-traffic list, used to provide the LSST:UK community with announcements and news (including the monthly LSST:UK Newsletters). In particular, this list will be used to circulate further information about the expansion of data rights expected to follow from agreement of the UK’s in-kind contribution to Rubin operations, and further calls resulting from that, such as:

  • Proposing a LUSC Phase C DEV Work Package: we will be circulating information in the latter half of 2021 on how to seek funding to develop user-generated products as part of the LUSC Phase C programme; and

  • Participating in Rubin LSST Commissioning: the LSST:UK Commissioning Coordinator, Graham Smith, is currently liaising with the Rubin commissioning team, so see how UK researchers can contribute to the Rubin LSST commissioning programme. This is likely to include the chance to participate in analysis of commissioning data to characterise instrumental behaviour, which will also provide a very valuable early look at LSST data.

• Apply for an account for the LSST:UK wiki: if you have a serious interest in the Rubin LSST and LSST:UK you probably want to have access to the wiki, as some material (e.g. scientific content in the SWG space) is available only to registered users.

• Sign up to the LSST:UK Code of Conduct: all LSST:UK meetings are conducted according to this code, so attendees must have registered their adherence to it.

• Talk to the Point of Contact in the science area in which you work to learn more about plans of the relevant Science Collaboration. If you have secured data rights you may then join one (or more) of the Science Collaborations.

• Look at the Lasair alert broker and test its capabilities on the alert stream from the Zwicky Transient Facility.

• Keep an eye out for relevant meetings and, if necessary, apply for financial support from the LSST:UK Pool Travel Fund to enable attendance.