Towards a BRICS Optical Transient Network

1. David BuckleyDarraghO’DonoghueAstronomerSALT Global AmbassadorSouth African LSST PI Affiliate South African Astronomical Observatory Towards a BRICS Optical Transient Network

2. BRICS Astronomy Goals SALT (near Sutherland) MeerKAT (near Carnarvon) • Common aspirations for scientific and technological development • Enhancing human capital development • Leveraging facilities within BRICS For South Africa: • SALT: the largest optical telescope in the southern hemisphere (2005) • MeerKAT: will be the most sensitive radio telescope array (2018) • HESS: the Cherenkov TeV gamma ray array (2004)

3. BRICS Astronomy Goals SKA artist’s concept (late 2020s) • Synergies with other astronomical facilities in BRICS countries • Brazil: access to 4.0-m SOAR optical telescope and European Southern Observatory • Russia: access to many optical telescopes (1 to 6-m) and RATAN radio telescope • India: 3.5-m ARIES and smaller optical telescope; GMRT radio array • China: FAST radio dish (largest in the world) plus 1 & 2-m optical telescope • South Africa: future host of the Square Kilometer Array (SKA) • Telescopes distributed in longitude and latitude • Allow access to a wide area of sky continuously

4. The Transient Universe • Time domain and transient astronomy is new frontier of discovery space • “things that go bump in the night” • Allows studies of variability over timescales of milliseconds to years • Observations of transient behaviour for a wide range of objects and timescales • From the closest (Solar System) to the furthest • Some of the most energetic objects in the Universe • Opening the frontiers of time domain multi-messenger astronomy

5. SALT Transient Program GW170817 spectrum from SALT 1.2 d after event • Covering wide range in luminosity (& distance) • Variability on wide range of timescales • Sub-seconds domain a new frontier • Covering many object classes • X-ray transients • Cataclysmic Variables • Novae • Intermediate luminosity transients • Tidal Disruption Events (TDEs) • From Gaia, OG • Black Hole microlensing events • Flaring Blazars • Unusual supernovae (e.g. Super Luminous Supernovae) • Gamma-Ray Bursts (GRBs) • Multi-messenger (Gravitational Wave & Neutrino) events • Radio transients with MeerKAT (ThunderKATprogramme; see Patrick Woudt’s talk)

6. The Transient Universe: Detections MeerLICHT (2018) MASTER-SAAO (2015) Swift (UV/X-ray) • Increasing number of facilities and surveys leading to discoveries of transients of all classes • Some dedicated to specific classes of objects (e.g. supernovae) • Others finding many different classes of transients as a by-product of wide-field surveys (e.g. Gaia, OGLE, PanSTARRS, ZTF, TESS) • Both ground-based and space-based facilities are sources of alerts • South Africa has developed its own ground-based optical detection facilities • A SALT large science programme on transient followup has been running since 2016 and is highly productive (27 refereed publications to date) • Paving the way for the next big transient discovery machine: the Large Synoptic Survey Telescope • Need for machine learning tools based on current experiences

7. The SALT/SAAO Transient Programme • SALT Large Program on transients began in May 2016 • 200-300 ksec per semester • 60% allocated in highest priority (override) class (P0) • allows for rapid response to alerts • Basic pipeline reduced data available in < 12 h (raw data immediately) • Extended for 3 more years (at least) to 30 Apr 2021. • Multi-institutional/multi-partner program • 5 South African institutions (SAAO, UCT, UFS, NWU, UJ) • 4 other SALT partners (Poland, IUCAA, UKSC, USA) • 32 investigators (incl. many graduate students) • Now being expanded to include BRICS participation • Led to South African BRICS astronomy project • Involving Russia, India & China • Focus on highly energetic phenomena • Leveraging national facilities

8. Highlighted Example of Science: • GW170817: the first electromagnetic counterpart to a GW event (a kilonova) involving South African facility follow-up • Observations done with 4 telescopes at SAAO: • SALT spectroscopy (on 18 & 19 Aug) • Optical photometry (MASTER-SAAO and 1-m) • Infrared photometry (Japanese IRSF telescope) SALT MASTER-SAAO IRSF

9. SALT & SAAO results appeared in 9 refereed papers (including Nature and Science) • SALT spectra featured in a massive (3,677 author) “multi-messenger” paper • SALT/SAAO led paper helped to build a consistent model for neutron star mergers and resulting kilonova SALT/SAAO GW170817 results

10. The Next Big Thing for Transients: The Large Synoptic Survey Telescope (LSST) US-ledproject to continuously survey ~20,000 deg2 of Southern sky over 10 year with an 8.4-m telescope equipped with ~10 deg2 wide field 3.2 gigapixelcamera, beginning 2023 Multi-filter (ugriz); few day cadence (higher for some min-survey fields) Under construction now in Chile (commissioning during 2021-2022) International participation, including BRICS (Brazil, China, South Africa) Great opportunity for followup science

11. Future BRICS Opportunities for Co-ordinated Transient Science Background • Adoption at Sep 2017 BAWG in Pune of a call for BRICS “flagship” astronomy projects • Should be compelling and competitive science • Ideally involve most BRICS countries • Call announced in early 2018 for proposals • Review of the 18 “concept note” proposals received at the Oct 2018 BAWG in Durban • Thomas Auf derHeyde (BRICS AWG chair) appointed a Task Team with membership from all BRICS countries to review and short-list proposals (Bisikalo, Buckley (chair), Muthri, Shen, Taylor, Wuensche) • A set of criteria were defined for the Task Team • Task Team were asked to identify potential proposals of similar themes which potentially could be combined synergistically • Three proposals had the themes of transient science • Buckley, RSA (Transient Universe; followup) • Liu, China (The Sitian project; detection & followup) • Shustov, Russia (PHOBOS project; NEO detection & followup)

12. Future BRICS Opportunities for Co-ordinated Transient Science Criteria for selection of viable proposals Appropriateness in terms of a flagship project rather than one which could be funded through the existing ~3yr STI Framework Programme Science impact, international competitiveness and uniqueness Potential for participation amongst most/all of the BRICS countries Socioeconomic benefits, particularly in terms of human capacity development Alignment with developments within 4th industrial revolution paradigm Potential for private sector involvement Potential to leverage existing and planned national facilities Alignment with national priorities Ability for the projects to be developed in a phased approach appropriate to funding cycles Three obvious themes, somewhat expanding the scope of the concept notes: 1. An optical transient network (3 concept notes) -> Buckley et al. 2. Big data infrastructure in era of large surveys like SKA & LSST (4 concept notes) -> Taylor et al. 3. Neutral hydrogen (21 cm) cosmology (3 concept notes) -> Ma et al.

13. BRICS-Optical Transient Network Encapsulates all 3 of the concept notes on transient detection and follow-up studies: BRICS Optical Transient Network (OTN) Aims: To develop a network of ground-based optical telescopes for an all-sky survey to detect short lived optical transients and to allow follow-up of multi-wavelength and multi-messenger transient objects. Enhance levels of collaboration within the BRICS group on multi-wavelength astronomy, focusing on astrophysical transients and time domain studies. Will make the best use of the diverse expertise and facilities in different BRICS countries and support capacity development. BRICS-OTN will be a ground-breaking tool to search for electromagnetic counterparts of multi-messenger transient detected with LIGO/Virgo (gravitational waves) and Ice-CUBE (neutrinos). Will leverage existing and new facilities within the BRICS countries and will also draw on the opportunities presented by other multi-wavelength space- and ground-based facilities that exist within the BRICS group.

14. BRICS-Optical Transient Network • Significant participation by all BRICS countries through over 60 investigators: Brazil: 10 Russia: 11 India: 13 China: 11 South Africa: 16 • Various topics of investigation: • radio transients; FRBs • extreme cosmic explosions (GRBs, GW events/kilonovae) • supernovae, TDEs, nuclear transients • X-ray transients (Low and High Mass X-ray binaries) • novae and binary star transients • microlensingevent, unusual stellar transients • transient event followup from LSST and other alert streams • Near Earth Objects, Potentially Hazardous Objects • outreach, education and development • networking software for telescopes for automated followup • data processing pipelines

15. BRICS-Optical Transient Network • Huge opportunity for young researchers & students • 6 postdoc fellowships • 12 postgraduate scholarships • Co-supervision with other BRICS partners • annual meetings • Phased approach with potential to expand as funding allows • Utilize exiting telescope facilities within BRICS • Spend initial effort on networking telescopes to allow for more efficient response to alerts • Automated scheduling through event brokers (as with LSST) and marshalls that decide on appropriate followup(as with Growth/ZTF) e.g. Imaging, spectroscopy...) • Quite a challenge for heterogeneous collection of telescopes, but tractable • Initial effort will be quite software intensive, hence the requirement for funding SW engineers • Approach will closely follow the SAAO’s Intelligent Observatory initiative (just starting; see Steve Potter’s talk at the end of today)

16. SAAO Sutherland plateau:An Intelligent Observatory • Future aspirations at SAAO: make the whole Sutherland site an integrated intelligent machine for transient follow-up • This work is beginning now with several recent initiatives: • resources being provided to allow development of SW target selection and scheduling tools for automated follow-up of transient alerts (in collaboration with other groups (e.g. LCO) • Synergy with South African participation in LSST • Potential to involve ~11 telescopes (incl. LCO)

17. Triggering Transient Followup Outside Alerts Local Alerts W Swift IRSF LCO Lesedi Followup MASTER MeerLICHT Followup Followup Trigger automated requests for followup observations from alert triggers Will allow for the automated selection of telescopes, instruments & modes and appropriate observation setup and scheduling GCN socket, VOEvents, APIs for robotic & queue-scheduled telescopes

18. SAAO FollowupFacilities • Follow-up selected objects with robotic facilities and SALT • LCOGT 1.0-m (+ other longitudes) • MONET 1.2m • new SAAO 1.0 m robotic telescope (Lesedi) • instruments including CCD and high speed • EM-CCD cameras and spectrograph(s) New 1-m robotic telescope (Lesedi) MONET-South

19. SAAO Followup Facilities • MeerLICHT(0.65 m; 2 sq ° FoV) • Joint Dutch-UK-SA venture • Optical monitoring of MeerKAT fields • Correlate with radio transients to identify optical counterparts • Potential source of followup alerts • (see Patrick Woudt’s talk later) MeerKAT: 64 x 13.5-m dishes MeerKAT: 64 x MeerLICHT

20. BRICS-Optical Transient Network Second Phase: Development of a network of new 1-m class telescopes Aims: Develop an automated global network (distributed in latitude and longitude) of many (72) wide field (25 sq °) 1-m optical telescopes, which will map the whole sky 20-60 min in 3 filters (g, r, i) to a limit of g > 21. This will enable an unprecedented high time resolution view of the sky (e.g. compared to LSST’s few night cadence). Will enable research in many areas of time-domain multi-wavelength astronomy: • Fundamental knowledge of physical laws and astrophysical processes in the Universe • Neutron star - neutron star mergers (GW events) • Core-Collapse and Super-Luminous Supernovae • Long γ-ray Bursts & Fast Transients • Optical and ultraviolet flares in galactic nuclei • Optical counterpart of Fast Radio Bursts • Reverberation mapping: black hole masses in AGN • Outbursts and state transitions in X-ray binaries • Detecting hazardous near-Earth objects • Detection of Chelyabinsk-type events (~10-m size asteroids) • ~4h before impact

21. BRICS-Optical Transient Network Second Phase: Development of a network of new 1-m class telescopes New discovery space:

22. BRICS-Optical Transient Network Second Phase: Development of a network of new 1-m class telescopes Top Level Requirements: • A survey rate of >5000 deg2/ hr to achieve an ultimate aim for 0.5-1 h cadence. • Distributed in latitude & longitude, including (but not limited) within BRICS countries (e.g. Chile, Australia, La Palma (or Iran?) as additional sites) • 24h operation time. This requirement is important to ensure that the system will be able to respond to any alert and any given time on night sky. • Limiting magnitude of at least AB ~ 21 • g, r, ifilters (dedicated to specific telescopes) • Fast readout cameras (also use for high time resolution photometry • Angular resolution better that 2 arcsec is required (ideally match to seeing) Start with building of proto-types to test performance. Eventually install groups of 3 telescopes at different sites.

23. BRICS-Optical Transient Network Proposed Chinese (left; see Roberto Soria talk on Tues) and Russian (right; modifiedHamilton; see Dmitry Bisikaloet al. poster) designs Second Phase: Development of a network of new 1-m class telescopes Telescope design: • Already initial design work done as part of Chinese (Sitian; Liu et al.) and Russian (PHOBOS; Shustov et al.) studies • These will be taken forward in an initial design trade-off study

24. BRICS-Optical Transient Network Camera: • sCMOS (fast) cameras under consideration Control: • Potentially based on Sitian • Large project (e.g. ZTF)

25. BRICS-Optical Transient Network Benefits to BRICS • Promotes collaboration and development amongst BRICS countries and their existing partners in science and engineering • Large potential for human capacity development • Focuses on the enormous scientific potential of multi-wavelength studies of astronomical transients for decades to come • Will be ideal tool for supporting multi-messenger astronomy (e.g. E-M counterparts of GW events) • Internationally competitive and unique – a flagship • Utilizes existing and future multi-wavelength facilities (optical, IR, radio, X-ray, γ-ray, UV) • Can start with relatively modest investment and grow as funding allows • Ticks all the boxes for the criteria of a flagship program

26. The End