UK Involvement in LSST: Phase A

Lead Research Organisation: Queen's University of Belfast
Department Name: Sch of Mathematics and Physics

Abstract

We propose a programme of work to enable UK participation in the Large Synoptic Survey Telescope (LSST), one of the most ambitious science projects planned for the next decade, and a key part of the astronomical landscape in the 2020s. LSST will have both a large collecting area and a wide field of view, giving it an etendue more than an order of magnitude larger than any current or planned facility. This will enable it to survey the whole visible sky every few days, leading to both a stacked sky survey of great depth, and the ability to find moving, variable, and transient objects. It will make advances over a large range of science, from Potentially Hazardous Asteroids, through the structure of the Milky Way, to the most distant quasars, and the nature of dark matter and dark energy - all areas where UK astronomers stand poised to make leading contributions.

LSST originated as a US project but is now transforming into an international one. This mostly requires operational support rather than capital construction, which makes engagement in LSST tremendous value for money. Rather than simply being an old-fashioned sky-atlas resource, the best LSST science will come through organised, massive, and systematic exploitation of its vast dataset in international teams. For UK astronomers to play a strong role it is therefore crucial to engage early and fully - in science working group planning, in development of specialised analysis software (the so-called "Level 3") and to have a framework to implement and run that Level 3 code.

The LSST:UK consortium aims to meet these goals through a four-phase programme. The immediate request is only for Phase A (April 2015 - March 2019) but PPRP will need to understand the lifetime implications. There are three elements to the lifetime costs:
1. To allow full data access, LSST requires a contribution to operations. These funds will only be required in later phases, but we intend to complete our MoU before Phase A commences.
2. LSST requires that we make provision for the added cost of UK community access. Rather than hand over more cash, our proposal is to construct a UK Data Access Centre (DAC). This will enable us to fully engage immediately with LSST both scientifically and technically, will allow much more control for UK astronomers, and has a potential for industry involvement. Here we request initial Phase A study and development funding for the DAC. For longer term DAC construction and operations, we intend to target BIS-level funding as well as STFC.
3. To maximise UK scientific return, we further propose a community development programme for Level 3 algorithms and data products, working closely in conjunction with the UK DAC. Phase A funding will focus on assessing the project-provided Level 1 and 2 products to determine where we will need to target subsequent Level 3 funding to meet our science goals.

Planned Impact

Support for UK involvement in LSST, through funding the LSST:UK Science Centre (LUSC), can generate societal and economic impact under the following five headings:


1. Enhancing the research capacity, knowledge and skills of enterprises working on "Big Data" issues being incubated within the Higgs Centre for Innovation.

The Phase A LUSC Data Access Centre workpackage is co-located on the Royal Observatory Edinburgh campus with the Higgs Centre for Innovation, which is being funded to improve interaction between academia and industry in Space and Big Data, and to enhance economic impact in those two domains. We shall exploit that co-location to ensure that Big Data innovations within the LSST project in the US filter through to UK SMEs and that the challenging requirements of LSST inspire the development of novel Big Data techniques and technologies within the UK, as has been the case in the US.


2. Increasing public engagement with research through Citizen Science initiatives.

LUSC will develop a Citizen Science platform based on the pioneering Zooniverse project, which currently has more than one million users doing real science online. Computational advances between now and the start of LSST operations will enable Citizen Science activities that greatly exceed what is currently possible, and perhaps most exciting is the prospect of involving Citizen Scientists in the classification of the million or more transient alerts that LSST will generate per night, placing the public at the heart of LSST's pioneering exploration of time-domain astronomy.


3. Enhancing cultural enrichment and quality of life through education & outreach activities.

The LSST:UK Consortium institutions have a wealth of experience in education and public outreach (EPO) activities, from running Open Days and exhibitions to CPD courses for school teachers to Massive Online Open Courses (MOOCs). During Phase A we will develop an EPO plan, in conjunction with the very active LSST EPO team in the US, for implementation during the later phases of the programme.


4. Enhancing the research capacity, knowledge and skills of organisations through the employment of researchers with high-level expertise derived from working on LSST.

Over the 18-year lifetime of the LUSC programme, many students and postdocs who have developed high-level expertise from working on LSST will pass from astronomy to the commercial sector, taking their valuable knowledge and skills with them. Particularly valuable will be the computational and statistical skills that will be readily applicable to the Big Data challenges prevalent in the public and private sector, and the expertise in thick CCDs developed through UK involvement in the LSST camera team.


5. Wealth creation, through the placing of construction contracts with UK companies.

The detector characterisation work to be undertaken during LUSC Phase A will also be helpful for securing a larger role for UK research institutions in the LSST construction project after the vendor selection for production CCD sensors is made, should that be determined by the LSST project in the US to be desirable. A number of UK companies possess the expertise needed to secure LSST construction contracts, and the technical and scientific involvement of the UK in the LSST through the LUSC Phase A programme would greatly aid that process.

Publications

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Chambers K. C. (2018) Pan-STARRS1 Transient Discovery Report for 2018-02-14 in Transient Name Server Discovery Report

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Chambers K. C. (2018) Pan-STARRS1 Transient Discovery Report for 2018-02-14 in Transient Name Server Discovery Report

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Chambers K. C. (2018) Pan-STARRS1 Transient Discovery Report for 2018-02-04 in Transient Name Server Discovery Report

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Chambers K. C. (2018) Pan-STARRS1 Transient Discovery Report for 2018-02-14 in Transient Name Server Discovery Report

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Chambers K. C. (2018) Pan-STARRS1 Transient Discovery Report for 2018-02-03 in Transient Name Server Discovery Report

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Chambers K. C. (2018) Pan-STARRS1 Transient Discovery Report for 2018-02-10 in Transient Name Server Discovery Report

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Chambers K. C. (2018) Pan-STARRS1 Transient Discovery Report for 2018-02-02 in Transient Name Server Discovery Report

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Chambers K. C. (2018) Pan-STARRS1 Transient Discovery Report for 2018-02-14 in Transient Name Server Discovery Report

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Chambers K. C. (2018) Pan-STARRS1 Transient Discovery Report for 2018-02-04 in Transient Name Server Discovery Report

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Chambers K. C. (2018) Pan-STARRS1 Transient Discovery Report for 2018-02-12 in Transient Name Server Discovery Report

 
Description The SOXS consortium : Data Flow Architecture Work Package
Amount £239,079 (GBP)
Funding ID ST/S002693/1 
Organisation Science and Technologies Facilities Council (STFC) 
Sector Public
Country United Kingdom
Start 04/2018 
End 03/2021
 
Title Broker software for LSST 
Description Lasair is a broker for astronomers studying transient and variable astrophysical sources. It is being developed as a collaboration between the University of Edinburgh and Queen's University, Belfast to build a broker service for alerts generated by the Large Synoptic Survey Telescope (LSST). We are planning to serve LSST transient alerts to the LSST user community and combine these data with value-added cross-matches against existing catalogues and analysis tools. 
Type Of Material Improvements to research infrastructure 
Year Produced 2018 
Provided To Others? Yes  
Impact Current and next-generation time-domain surveys will produce more data than ever before. The Zwicky Transient Facility (ZTF; Kulkarni 2018; Bellm et al. 2019) generates up to ~106 alerts3 (individual photometric data points of time-variable sources) per night (Patterson et al. 2019), while the Large Synoptic Survey Telescope (LSST; LSST Science Collaboration et al. 2009) is expected to produce up to ~107 alerts per night. However there are significant computational challenges in processing these data into a digestible format, in near real-time, in order to identify interesting transients and trigger follow-up such as spectroscopy and observations in other wavelength regimes. To this end, we present Lasair,4 the transient alerts broker for the LSST:UK collaboration. In preparation for LSST's data stream, Lasair ingests the ZTF public alert stream into a relational database, assimilates the alerts into objects, and produces lightcurves and reliable cross-matches to star and galaxy catalogs. Lasair can be viewed and queried through a web browser5 and we provide simple example streams of interesting objects, as well as access to a full SQL search engine. Registration to the website is optional, free, and open to all. 
URL https://lasair.roe.ac.uk/
 
Title Lasair: The Transient Alert Broker for LSST:UK 
Description Lasair provides a user-friendly interface to access public ZTF transient alerts. The alerts are transmitted by ZTF typically within 13 minutes of the exposure, in Avro/Kafka format. They are ingested into the Lasair database (on hardware in Edinburgh) within 20 minutes. 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes  
Impact Lasair is the transient alerts broker for the LSST:UK collaboration. In preparation for LSST's data stream, Lasair ingests the ZTF public alert stream into a relational database, assimilates the alerts into objects, and produces lightcurves and reliable cross-matches to star and galaxy catalogs. Lasair can be viewed and queried through a web browser5 and we provide simple example streams of interesting objects, as well as access to a full SQL search engine. Registration to the website is optional, free, and open to all. 
URL https://lasair.roe.ac.uk/
 
Title Public database of transient discoveries 
Description As a pathfinder for LSST - we run the The Pan-STARRS Survey for Transients. This refines our techniques for searching the sky and the algorithms we will use for LSST. The Pan-STARRS1 telescope carried out the 3Pi survey of the whole sky north of -30 degrees between 2010-2014 in grizy (PS1 specific filters). This was run by the PS1 Science Consortium. Each region on the sky was typically visited four times a year in each filter. As described in Magnier et al. (2013, ApJS, 205, 20) and Inserra et al. (2013, ApJ, 770, 128) the four epochs were typically split into two pairs called Transient Time Interval (TTI) pairs which are single observations separated by 20-30 minutes to allow for the discovery of moving objects. The exposure times at each epoch (i.e. in each of the TTI exposures) were 43 s, 40 s, 45 s, 30 s, and 30 s in grizy(PS1). An all sky image of these stacked frames between 2010-2012 has been created in each band (internally called Processing Version 1) and all individual exposures since mid-June 2013 were differenced with respect to this static sky and transient sources have been catalogued. We typically reached high confidence transients (greater than 5-sigma) at depths of approximately 21.0, 20.6, 20.7, 20.4, and 18.3 (AB mags) in the grizy PS1 filters. The Pan-STARRS1 Science Consortium finished this sky survey and since mid-2014 the PS1 telescope has been running a wide-field survey for near earth objects, funded by NASA through the NEO Observation Program. This survey takes data in w-band in dark time, and combinations of i, z and y during bright moon time. We are now processing these data through the PS1 IPP difference imaging pipeline and recovering stationary transients. Effectively the 3Pi survey for transients that started during the PS1 Science Consortium is being continued under the new NEO optimised operations mode. The observing procedure in this case is to take a quad of exposures, typically 30-45s separated by 10-20mins each. This cadence may be repeated on subsequent nights.In ATel 5850, we announced the public release of the first 880 transients from the PS1 3Pi survey, during the search period September 2013 - January 2014. These are mostly supernova candidates, but the list also contained some variable stars, AGN, and nuclear transients (defined below). The lightcurves are too sparsely sampled to be of standalone use, but they may be of use to the community in combining with existing data (e.g. Fraser et al. 2013, ApJ, 779, L8), constraining explosion and rise times (e.g. Nicholl et al. 2013, Nature, 502, 346) as well as many being new discoveries. 
Type Of Material Database/Collection of data 
Year Produced 2017 
Provided To Others? Yes  
Impact We have discovered the most supernovae candidates ever and are the world leading survey - see the Official IAU statistics here https://wis-tns.weizmann.ac.il/stats-maps 
URL https://star.pst.qub.ac.uk/ps1threepi/psdb/