International Coordination of Multi-Messenger
Transient Observations in the 2020s and
Beyond
K
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v
l
i
-
I
A
U
W
h
i
t
e
P
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p
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r
S. Bradley Cenko
(co-chair), Patricia A. Whitelock
(co-chair),
Laura Cadonati
,
1
2
3
Valerie Connaughton
, Roger Davies
, Rob Fender
5
, Paul J. Groot
, Mansi M.
4
5
6
Kasliwal
, Tara Murphy
, Samaya Nissanke
, Alberto Sesana
, Shigeru Yoshida
7
8
9
10
11
and Binbin Zhang
12
1
Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD
20771, USA; Joint Space-Science Institute, University of Maryland, College Park, MD 20742, USA
2
South African Astronomical Observatory, P.O. Box 9, Observatory, 7935 Cape Town, South Africa;
Department of Astronomy, University of Cape Town, 7701 Rondebosch, South Africa
3
Georgia Institute of Technology, USA
4
SMD - Astrophysics Division, NASA HQ, 300 E St SW, Washington, DC 20546, USA
5
Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Rd., Oxford, OX1 3RH,
UK
6
Department of Astrophysics, IMAPP, Radboud University Nijmegen, PO Box 9010, 6500 GL
Nijmegen, the Netherlands;
Department of Astronomy and Inter-University Institute for Data Intensive
Astronomy, University of Cape Town, 7701 Rondebosch, South Africa; South African Astronomical
Observatory, P.O. Box 9, Observatory, 7935 Cape Town, South Africa
7
Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA
91125, USA
8
Sydney Institute for Astronomy, School of Physics,
University of Sydney, NSW, 2006, Australia
9
GRAPPA, Anton Pannekoek Institute for Astronomy and Institute of High-Energy Physics, University
of Amsterdam, Science Park 904, 1098 XH Amsterdam & Nikhef, Science Park 105, 1098 XG
Amsterdam, The Netherlands
10
Department of Physics G. Occhialini, University of Milano - Bicocca, Piazza della Scienza 3, 20126
Milano, Italy
11
Department of Physics, Graduate School of Science and International Center for Hadron
Astrophysics Chiba University, Japan
12
School of Astronomy and Space Science
Nanjing University, China
Summary
This
White
Paper
summarizes
the
discussions
from
a
five-day
workshop,
involving
50
people
from
18
countries,
held
in
Cape
Town,
South
Africa
in
February
2020.
Convened
by
the
International
Astronomical
Union’s
Executive
Committee
Working
Group
on
Global
Coordination
of
Ground
and
Space
Astrophysics
and
sponsored
by
the
Kavli
Foundation,
we
discussed
existing
and
potential
bottlenecks
for
transient
and
multi-messenger
astronomy,
identifying
eight
broad
areas
of
concern.
Some
of
these
are
very
similar
to
the
challenges
faced
by
many
astronomers
engaging
in
international
collaboration,
for
example,
data
access
policies,
funding,
theoretical
and
computational
resources
and
workforce
equity.
Others,
including,
alerts,
telescope
coordination
and
target-of-opportunity
implementation,
are
strongly
linked
to
the
time
domain
and
are
particularly
challenging
as
we
respond
to
transients.
To
address
these
bottlenecks
we
offer
thirty-five
specific
recommendations,
some
of
which
are
simply
starting
points
and
require
development.
These
recommendations
are
not
only
aimed
at
collaborative
groups
and
individuals,
but
also
at
the
various
organizations
who
are
essential
to
making
transient
collaborations
efficient
and
effective:
including
the
International
Astronomical
Union,
observatories,
projects,
scientific
journals
and
funding
agencies.
We
hope
those
involved
in
transient
research
will
find
them
constructive
and
use
them
to
develop
collaborations
with
greater
impact
and
more
inclusive
teams.
Table of Contents
1.
Motivation and Objectives
2.
Bottleneck Overview
3.
B1 Transient Alerts and Communication
4.
B2 Data Policies
5.
B3 Follow-up Spectroscopy
6.
B4 Telescope Coordination
7.
B5 International Funding and Collaboration
8.
B6 Target-of-Opportunity Implementation
9.
B7 Theoretical and Computational Resources
10.
B8 Diversity, Equity, Inclusion and Workforce Development
11.
Conclusions and General Recommendations
12.
Acknowledgments
2
13.
Appendix 1
Workshop Program (with links to most presentations)
14.
Appendix 2
Members of the Local Organizing Committee
15.
Appendix 3
Organizations Represented at the Workshop
16.
Appendix 4
Participants in the Workshop
17.
Appendix 5
Table of Acronyms (with links)
Motivation and Objectives
With the recent discoveries of an electromagnetic counterpart to the binary neutron star
merger gravitational-wave source GW170817 (
Abbott et al. 2017
), as well as the association
between a flaring high-energy blazar TXS 0506+056 and a high-energy neutrino event
(
Aartsen at al. 2018
), a new era of multi-messenger astrophysics is upon us. Observations of
multi-messenger and transient sources in the coming decade promise to address some of
the most pressing questions in (astro)physics, including testing General Relativity, the origin
of the heavy elements, the equation of state of dense matter, and the source(s) of
ultra-high energy cosmic rays.
Fully capitalizing on the opportunities offered as new facilities come online (e.g., Vera C.
Rubin Observatory, the Extremely Large Telescopes and the Square Kilometre Array) and
current facilities are upgraded (e.g., Advanced LIGO+, Advanced Virgo+, and the planned
IceCube-Gen2) will require international coordination at a scale not currently practiced.
Recognizing this, the IAU Executive Committee Working Group on Coordination of Ground
and Space Astrophysics, with financial support from the Kavli Foundation, organized a
workshop at the South African Astronomical Observatory (SAAO) in Cape Town, South
Africa, from 2 to 7 February, 2020.
Fifty representatives of the major observatories, projects, and scientific interests [see
Appendix 3 for a list of the projects and observatories represented and Appendix 4 for the
full list of Participants] involved in transient and multi-messenger astronomy gathered to
discuss how to take this exciting and rapidly developing field forward in a strategic and
inclusive manner. To capture the results of this workshop, we have produced this White
Paper that includes both recommendations and best practices for the community. It is not
intended to be the final word on this complex subject, but instead as one contribution to an
evolving conversation about how to optimize the scientific return from this exciting new era
in astronomy.
3
Most of the recommendations below have been associated with one or more
IAU Division
,
Commision
and/or
Working Group
, which we ask to consider whether drafting an
IAU
Resolution
, involving one or more of the recommendations, is desirable. If it is, they should,
in liaison with other stakeholders, draft the appropriate wording, for consideration by the
next
IAU General Assembly
(to be held in Busan in the Republic of Korea in August 2021).
Note that (assuming the resolution has no budgetary implications for the IAU) these drafts
should be submitted to the General Secretary six months before the General Assembly.
Bottleneck Overview
Prior to the workshop, the Scientific Organizing Committee [authors of this White Paper]
met and held a number of sessions to structure the workshop. In addition to solicited talks
on the lessons learned from the major projects working in transient/multi-messenger
astronomy and on the scientific opportunities in the coming decade, the SOC identified a
series of “bottlenecks” that are currently limiting scientific progress in these areas [see
Appendix 1 for the full Workshop Program]. While there was clear overlap between topics
and common themes that emerged throughout, we have structured this document
following the bottleneck areas discussed in extended sessions at the workshop.
B1 - Transient Alerts and Communication
Timely notification of newly discovered transients (or, for that matter, interesting behavior
of known sources) is critical to our understanding of these events. Well-designed systems
enable an efficient marshaling of observational resources larger than could be provided by
any single individual or collaboration, resulting in greatly improved scientific understanding.
Much like peer-reviewed publications, effective transient notification systems also provide
motivation to observers by assigning scientific “credit” to those enabling discovery by
others (e.g., precisely localizing gamma-ray burst afterglows, which can then subsequently
be observed with sensitive, narrow-field facilities).
The most well-known example was the development 28 years ago of the Gamma-Ray
Coordinates Network (GCN). Born of necessity due to the failure of an on-board recording
device on the Compton Gamma-Ray Observatory, the GCN system currently provides
prompt notifications of transient discoveries from 13 distinct “streams”, including both
4
high-energy satellites (e.g.,
Swift, Fermi, INTEGRAL
) and ground-based observatories
(Advanced LIGO-Virgo, IceCube, HAWC). In addition to these machine-readable Notices,
human-written Circulars describing observing results are published by the community at a
rate of several hundred per month.
A more recent highly successful example is the Transient Name Server (TNS), which on 1
January 2016 became the official IAU mechanism for reporting astronomical transients, and
in particular designating names for supernovae. TNS can receive both manual (e.g., from
amateurs, who still discover a number of nearby supernovae each year) and fully
automated (e.g., from large professional surveys such as ATLAS, Pan-STARRS, and ZTF)
transient discoveries, automatically associating observations of objects imaged by different
surveys. Upon spectroscopic classification and confirmation of a supernova origin (as
opposed to, say, a previously unknown flare star), sources are provided an official
supernova designation (e.g., SN2020A, SN2020B, ...). Currently approximately 3000 optical
transients are reported each month to TNS, compared to less than 500 total
reported to
13
the Central Bureau for Astronomical Telegrams for the entire year of 2011.
Impending event rate increases in transient and multi-messenger discoveries outside the
(current) purview of TNS require new and/or updated systems with similar capabilities:
name service, machine-readable communication, etc. Given the widely varying needs of
different communities within transient/multi-messenger astronomy, a single “one-size fits
all” solution is unlikely to be optimal. We therefore make the following recommendations:
Alerts/Communication Recommendation 1:
Despite its role as a pioneer in automated event
notification, there is a clear need for upgrades to the GCN system to accommodate the new
multi-messenger era. This includes (but is not limited to): an automated name server to
correlate events found by different facilities and/or at different wavelengths; increased
machine-readability for GCN Circulars (e.g., standardize formats, tagging specific events,
flux measurements / upper limits); and a means to query results based on source, position,
and/or time. A number of ongoing efforts include GCN upgrades/augmentation as one (of
many) goals, including the Time-Domain Astronomy Coordinate Hub (TACH) and the
Scalable Cyberinfrastructure for Multi-Messenger Astrophysics (SCiMMA). Coordination
amongst these efforts is critical going forward; the IAU should consider the formal adoption
13
Including both spectroscopically confirmed supernovae and unconfirmed optical transients.
5
of a naming convention for such sources and endorsing a centralized clearing house similar
to TNS.
[DivD WG:SNe DivB]
Alerts/Communication Recommendation 2
: In the near future, similar notification capabilities
will be necessary for X-ray (e.g., SRG/eROSITA, Einstein Probe) and radio (e.g., MeerKAT,
ASKAP, SKA) transients. Under the auspices of major projects in these areas, we
recommend that the relevant major projects work with their communities to develop
desired approaches, utilizing lessons learned from e.g., the optical and gamma-ray
communities. An example is an effort in the fast radio burst community, where public alerts
(utilizing IVOA standards,
Petroff et al. 2017
) will be incorporated into TNS. These proposals
can then be brought to the IAU
[DivB Com B2, B4; DivD ]
for official endorsement.
Alerts/Communication Recommendation 3:
Standards are critical to ensuring that
heterogeneous nodes in the transient/multi-messenger ecosystem can communicate
efficiently and effectively. We strongly recommend that the transient/multi-messenger
community work with the International Virtual Observatory Alliance (IVOA) to build its
standards. IVOA standards should follow the procedure described in the IVOA Document
Standards
(Genova et al. 2017)
, with
at least two reference implementations and available
validation tools. In this process it is critical to have involvement and support of the
community, which can be accomplished in a variety of ways (technical/scientific
interchanges, training schools, etc.).
[DivB ComB2, DivD ComD1 WG:SN]
Alerts/Communication Recommendation 4:
The ultimate arbiter of scientific analysis is the
peer review process. As such, scientific journals have a unique opportunity to play a critical
role in ensuring that published data is broadly accessible. We strongly recommend the IAU
work with relevant journals to establish uniform standards for data reporting on transient
and multi-messenger sources (as well as static sources, for that matter). This will facilitate
large astronomical databases (CDS, NED, etc.) in being able to ingest such measurements,
making them broadly available to astronomers across the world.
[DivB ComB2,
WG:Information Professionals].
6
B2 - Data Policies
While an issue for the astronomy community as a whole, data availability and accessibility is
particularly important in the transient/multi-messenger world, where time-critical
observations cannot be repeated. Widely available and accessible data products greatly
enhance the scientific return of any project. Furthermore, in a
recent survey
of those
utilizing NASA missions for multi-messenger science, a strong preference was expressed for
“open” data policies (corresponding to proprietary periods less than or equal to 1 month).
Lowering barriers to data access is particularly critical for astronomers from developing
countries (
Peek at al. 2019
).
At the same time, multiple complex factors often compete with the desire for broadly
“open” data policies, in some cases for good reasons. All projects have a legitimate interest
in ensuring that those responsible for funding a facility reap the benefit of its scientific
return, whether this be individual scientists, institutions, or even taxpayers of a given
nation. There also can be a cultural disconnect between the high-energy physics community
and the astronomy community, possibly in part due to the distinction sometimes found in
astronomy between those operating a facility and those performing scientific analysis (e.g.,
HST). To balance these competing interests, we recommend the following:
Data Policies Recommendation 1:
we recommend the IAU build on their
Resolution on Open
Access
, made in Sydney in 2003, making specific reference to the importance of limited data
proprietary periods for the effective follow-up of transients and other time-critical
observations.
[DivB ComB2]
Data Policies Recommendation 2:
Towards this end, data availability is not sufficient: data
should be FAIR (findable, accessible, interoperable, and reusable). Good archives and
supporting software are thus essential. As a result, even data policies with modest
proprietary periods can contribute to the broad goals of open data. For example, by
releasing not only raw data but high-level data products in a queryable database, the Sloan
Digital Sky Survey has distinguished itself as one of the most scientifically productive
projects in astronomy in the last several decades. Organizations such as ESCAPE, working
7
with all the major astronomy infrastructures in a region, will have an increasingly important
role to play.
[DivB ComB2]
Data Policies Recommendation 3:
Large projects in the USA and Europe should pay particular
care towards supporting open data policies. Other countries including China and India are
rapidly developing observational capabilities in astronomy, some are already using current
and next generation flagship facilities in the USA and Europe as models for their data
policies. Long proprietary periods based on country of origin, e.g. SKA, and/or specific
subscription models, such as is planned for Rubin Observatory,
and a lack of funding for
worldwide data distribution will set a deleterious precedent at this critical time.
Open-access to data associated with follow-up observations is just as important, but it is
the major projects that set the tone and expectation of others.
[DivB ECWG:Global
Coordination]
B3 - Follow-Up Spectroscopy
At optical wavelengths (which currently dominate transient discoveries), discovery is largely
done via broadband imaging, with no, or extremely limited, information about the source
spectrum. Yet with some notable exceptions (e.g., cosmology with photometric
supernovae), most scientific analyses require optical (or ultraviolet/near-infrared) spectra in
order to obtain any physical understanding of their nature. From redshift measurement
and classification to ejecta composition and velocity, the power of spectra is readily
apparent to all practicing astronomers.
Yet even with the current generations of discovery facilities, the community’s capacity to
discover new sources is greatly outpacing our ability to understand them - even for
relatively bright supernovae (V< 19 mag), only ~ 10% obtain a spectroscopic classification
(
Kulkarni 2020
). This situation will only be exacerbated as more sensitive facilities like Rubin
Observatory come online in the coming years. While this issue is not as acute for other
wavelengths (e.g., X-rays and radio), that also may change in the not too distant future (e.g.,
SKA).
Lack of access to (in particular) optical spectroscopy is a clear bottleneck towards the
scientific understanding of transients and multi-messenger sources. To address this, we
recommend the following:
8
Follow-up Spectroscopy Recommendation 1:
A concerted effort be made around the globe,
enlisting philanthropic and public funding opportunities, to increase the capacity for
spectroscopic follow-up. For current generation facilities, this does not require particularly
large telescopes: currently the 1.5m Palomar telescope equipped with a very low-resolution
(R~100) integral-field spectrograph (SED Machine) leads the world in supernova
classification. Dedicated instruments on modest-aperture facilities can have a very large
impact here, particularly if economies of scale could be harvested (e.g., instrument copies
on multiple telescopes).
[DivB ECWG:Global Coordination]
Follow-up Spectroscopy Recommendation 2:
In a similar vein, lack of spectroscopic follow-up
offers an opportunity for developing countries to make major contributions to transient
and multi-messenger science. Our experience has shown that integration into a larger
network of observational facilities has proved a successful strategy for long-term
engagement (e.g., the GRANDMA and GROWTH collaborations). Major investments in the
development of “Observatory-level” capabilities, as is being done in South Africa, is also an
effective strategy for some nations (though may be less feasible for many).
[ECWG:Global
Coordination]
Follow-up Spectroscopy Recommendation 3:
Despite lacking sufficient global capacity in this
area, there is still some degree of inefficiency in that duplicative observations of the same
source may be obtained. While this is inevitable and in some cases desirable (e.g., to
cross-check results), improved communication protocols (see
Alerts/Communication
and
Global Coordination Recommendations
) would nonetheless result in a more efficient usage of
limited resources.
[DivB ECWG:Global Coordination]
Follow-up Spectroscopy Recommendation 4:
The limiting magnitude of current optical surveys
such as ASAS-SN, Pan-STARRS, ATLAS, and ZTF is well-matched to obtaining classification
spectra with moderate-aperture telescopes. While it is still possible, we recommend
astronomers undertake (and facilities support) spectroscopic measurements on large,
unbiased samples (e.g., well-defined flux- and/or magnitude-limited samples), which can be
used to train machine-learning models, to improve our understanding of transient
demographics and improve the performance of machine-learning classifiers. Such results
will be critical to guide the usage of more limited follow-up with large-aperture facilities in
9
the era of Rubin Observatory - hence the time critical nature of such endeavors.
[DivB
ECWG:Global Coordination]
B4 - Telescope Coordination
Transient and multi-messenger science inherently requires complex observational data,
spanning a diverse range of wavelengths, time scales, and (of course) cosmic messengers.
Combined with the ephemeral nature of most sources, this presents the community with a
unique set of challenges in acquiring datasets that span across observing technique,
funding agency, ground vs. space, etc. The success of recent visualization packages such as
the
Treasure Map
suggest that such a need remains to be filled by the community.
To simplify the acquisition of the observational datasets necessary to make
ground-breaking progress in these areas, we make the following recommendations:
Telescope Coordination Recommendation 1:
We recommend the IAU endorse a common
format for all observatories to report previous and planned observations, namely the
standard developed by the IVOA (
ObsLocTAP
,
Salgado et al. 2020
). A number of
space-based facilities have begun to implement this protocol already (e.g.,
Chandra,
NuSTAR
); broad-based buy-in from current and future facilities would make the protocol
even more useful to the broader transient and multi-messenger community. When existing
standards are found limiting or inadequate, collaborative efforts should be made to
improve or replace them, perhaps through the IVOA, to ensure interoperability.
[DivB,
ComB2]
Telescope Coordination Recommendation 2:
Multi-observatory datasets can be particularly
difficult to acquire, as proposals face not only the issue of “double jeopardy” but also the
logistical challenge of coordinating different dates for each observatory (e.g., semester vs.
year cycles, offset cycle starting dates, etc.). A number of facilities offer joint proposal
opportunities to mitigate this issue (e.g.,
Chandra+HST
,
VLA+XMM,
etc.). We strongly
recommend that all projects, particularly large facilities, pursue joint proposal opportunities
aggressively and early in their life cycle. As an example, in the USA, the Las Cumbres
Observatory is partnering with NOIRLab facilities (Gemini Observatory, SOAR Observatory,
and the CSDC) to form AEON, the Astronomical Event Observatory Network. AEON will
provide rapid, flexible, programmable access to multiple telescope follow-up facilities. The
1
0
AEON partners are working to form a single time allocation process which could be
expanded to include other facilities. For timely follow-up, intercontinental collaboration
would be especially beneficial, e.g. between the telescopes in South Africa and/or Australia
and various facilities in Chile.
[DivB ECWG:Global Coordination]
B5 - International Funding and Collaboration
The scope of the scientific questions addressed currently by the transient and
multi-messenger communities is remarkably broad - ranging from fundamental physics
(the expansion history of the Universe; the equation of state of dense matter) to some of
the most long-standing questions in astronomy (the origin of cosmic rays, heavy elements,
and relativistic jets). It is not surprising, then, that the facilities required to address many of
these questions are inherently large, often requiring multi-national collaborations to
support them.
Furthermore, given the rapid evolution of many transient and multi-messenger sources of
interest (in particular those on sub-day time scales), observing facilities distributed around
the globe are essential. Thus our community is more dependent on the ease and availability
of international collaborations than many other astronomical disciplines.
Spinning up new collaborations, ranging from two individual researchers to the largest
multinational observing facilities, across international boundaries presents a unique set of
challenges. From language and cultural barriers to funding and legal issues, difficulties
abound. There are often not easy solutions to these issues; however, we recommend the
following as positive steps towards enabling international collaboration in this area:
International Collaboration Recommendation 1:
We recommend the IAU endorse and support
international networks of people with common science goals to exploit existing facilities
and/or propose new ones, facilitated for example through their Working Group on
Coordination of Ground and Space Astrophysics. With improved capabilities for remote
collaboration, such networks can be particularly powerful in transient studies by capitalizing
on time-zone differences (e.g., responding to time-critical alerts during local day time).
Often funding agencies are more receptive to funding people rather than hardware
(particularly when that hardware funding may be spent abroad). These are also natural
1
1
projects to develop capacity in areas lacking such infrastructure (e.g., African VLBI).
International efforts such as the PIRE program and the Newton Fund should be strongly
encouraged to continue (and/or be expanded).
[ECWG:Global Coordination]
International Collaboration Recommendation 2:
Training early-career scientists and engineers
is critical towards a self-sustaining global community of astronomy. The IAU International
Schools for Young Astronomers (ISYA) have been highly successful in this area; we
encourage the IAU to work in partnership with other organizations and facilities (e.g., ESO
and NASA) so as to increase cross-fertilization across the major communities, but also to
facilitate the involvement of young people from less developed nations.
[DivC OYA]
International Collaboration Recommendation 3:
An additional major challenge towards
scientific advancement is the difficulty in establishing large, international projects. Even
once such efforts have passed the proposal stage, creating an appropriate legal entity with
an acceptable management structure can often delay projects more than hardware
difficulties. There are several intergovernmental treaty level organisations that can play this
role, but not all countries are prepared to subscribe to such organisations. There are a
number of other models, besides treaty level organisations, that have been shown to work
e.g. ERICs for CTA, umbrella entities such as AUI or AURA that join with a treaty level
organisation (ESO), e.g. ALMA (but note that SKA needed to create its own IGO). We
therefore recommend that the IAU commission a separate group to study this issue and
generate a report on best practices for scientists and funding agencies, as the full scope of
this issue was beyond what could be addressed at our workshop.
[ECWG:Global
Coordination]
International Collaboration Recommendation 4:
We encourage scientists to pursue
alternatives to standard (i.e., governmental) funding routes to enable future projects of
modest scale. Philanthropic funders are playing an increasing role in supporting scientific
endeavors, and often do not suffer from the same limitations on international cooperation
as governmental organizations. Similarly, in some cases corporations may be valuable
partners for projects, as data generated by our facilities is in some cases of interest beyond
the astronomical community (e.g., BlackGEM data is being archived by Google for no
charge, due to the perceived educational and public relations value of the BlackGEM
dataset).
[not suitable for IAU Resolution]
1
2
International Collaboration Recommendation 5:
Satellite access to low-Earth orbit (LEO) has
decreased in cost dramatically in recent years, enabling novel possibilities for transient
astronomy (e.g., CubeSat constellations). However, increased LEO usage, particularly by
industry, also presents challenges: streaked images for ground-based telescopes, radio
frequency interference, increased risk of collision, etc. We commend the IAU for taking a
proactive approach to
address
satellite constellations. Continued IAU engagement with all
stakeholders (industry, science, and military) will be necessary to ensure all parties continue
to function as stewards of both LEO and the night sky, in addressing these important
challenges. In particular, to minimize the likelihood of unforeseen satellite collisions, we
encourage the IAU to explore the possibility of a separate group to coordinate civil
information gathering and dissemination of satellite orbit data.
[DivBC ComB7, Executive
Committee]
B6 - Target-of-Opportunity Implementation
For many (though not all) science topics in transient and multi-messenger astronomy, rapid
response observations are required. Examples range from the most distant gamma-ray
burst afterglows from the epoch of reionization, to newly discovered comets in our solar
system. Such observations are by definition not possible to schedule in advance,
necessitating the implementation of “target-of-opportunity” (ToO) interrupt schemes.
Given that each observing facility presents a unique set of challenges in implementing a
ToO program, no “one-size-fits-all” solution will be applicable for all projects. Nonetheless,
based on our collective experience in the field we highlight the properties we find in
common amongst the most successful ToO programs at facilities across the globe. Rather
than a series of recommendations, we consider this a list of best practices for facilities to
draw from when considering their unique circumstances in implementing
transient/multi-messenger science:
ToO Implementation Best Practice 1:
For new / planned facilities, ToO programs function
most effectively when treated as part of the requirements definition process in the early
stages of formulation. Attempts to implement ToO programs in existing facilities inevitably
encounter fundamental limits in e.g., response time, data latency, etc. that may well have
1
3
been circumvented with little to no change in project cost, if addressed at an earlier stage.
[DivB]
ToO Implementation Best Practice 2:
The broad properties of the ToO program, including the
total amount of time available, the allowed response time, etc., should be driven by the
science (and not, e.g., programmatic considerations) whenever feasible. Thus, “artificial”
caps (both upper and lower limits) on ToO time are not placed on observers as part of a
proposal call (even if ultimately they are not strictly adhered to).
[DivB]
ToO Implementation Best Practice 3:
The time allocation policy for ToO observations (both
through regular peer-reviewed proposals and via Director’s Discretionary opportunities) is
transparent, to ensure that everyone is aware of how choices are made.
[DivB]
ToO Implementation Best Practice 4:
Proprietary periods are limited so that data may be used
by as broad a section of the community as possible (see
Data Policies Recommendation 1)
[DivB]
ToO Implementation Best Practice 5:
ToO policies are constructed to encourage groups to
pool resources, work together (where sensible), and maximize the science possible from
any given dataset. For example, the capability to propose as “Co-PIs” with
HST
allows early
career scientists, who might otherwise struggle to compete, to be able to collaborate, while
still demonstrating scientific leadership (e.g., for promotion or in tenure packets).
[DivB]
ToO Implementation Best Practice 6:
Data products are available promptly, and software
tools are in place to rapidly produce publication-quality results (see also
Data Policies
Recommendation 2).
[DivB]
B7 - Theoretical and Computational Resources
Theoretical advances have always been critical in the development of transient and
multi-messenger astronomy. For example, the development in the last several decades of
catalogs of waveforms generated by numerical simulations of merging compact objects is a
fundamental ingredient of the most sensitive template-based searches employed by
ground-based gravitational wave detectors. More recently, both analytic and numerical
calculations of the predicted electromagnetic emission from kilonovae - the transient event
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powered by r-process nucleosynthesis accompanying the merger of two neutron stars -
played a key role in guiding the observational campaigns that discovered and characterized
the UV/optical/NIR counterpart to GW170817.
Theory will continue to play a key role in multi-messenger astronomy as we look forward to
the launch of the Laser Interferometer Space Antenna (LISA) mission in approximately 10
years. Much like high-frequency GW detectors, refinements in numerical simulations of
merging supermassive black holes will be necessary to identify electromagnetic
counterparts in the large localizations error regions.
Towards supporting a robust and sustainable theory program in transient and
multi-messenger astrophysics, we make the following recommendations:
Theory/Computation Recommendation 1:
A robust investment in theoretical research, ideally
some significant fraction of that provided to observational facilities (e.g.,
Kollmeier et al.
2020
), is necessary for the long-term success of transient and multi-messenger
astrophysics. We encourage the IAU to endorse such an investment in theory from relevant
funding agencies.
[DivBDGHJ - but much broader than transients]
Theory/Computation Recommendation 2:
Modelling of binary mergers, in particular the
supermassive black holes relevant for the LISA mission, is extremely complex, involving a
wide range of time and size scales and a diverse set of underlying (astro)physics. As a
result, state-of-the-art simulations require increasingly large computational allocations. The
current PI-funded model is not well-suited to such a problem, where major resources are
necessary from many institutions. We encourage the IAU to endorse new models for
relevant funding agencies suitable for the large scale of the problem.
[DivB Exec Comm]
Theory/Computation Recommendation 3:
Training and workforce retention of numericists is a
major issue for the future of this field. To encourage as broad and international a
workforce as possible, we recommend current practitioners work to develop online courses
with regular updates (given the fast-evolving nature of the field).
[DivBC OYA OAD]
Theory/Computation Recommendation 4:
Infrastructure, in particular internet bandwidth, is a
fundamental limitation towards the full harnessing of talent in developing countries. Efforts
to expand internet access around the globe should be strongly encouraged. It may be
possible to use new observational facilities in developing countries as leverage for such
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investments, as they are critical to the success of such projects. Every effort must also be
made to ensure that doing so does not degrade sky access and therefore negatively impact
astronomy (see also
International Collaboration Recommendation 5)
.
[DivB OAD
ECWG:Global Coordination]
B8 - Diversity, Equity, Inclusion and Workforce Development
Even aside from moral considerations, a diverse and inclusive working environment has
been repeatedly demonstrated to foster more effective teams (
Hunt at al. 2015
). To tackle
the major questions posed in the transient / multi-messenger worlds, developing and then
tapping into the skill set of the broad population of historically under-represented groups
will be required. However, there is growing evidence of bias, detrimentally affecting
members of these groups, in the allocation of resources, including telescope time (e.g.
Reid
& Strolger 2019
,
Johnson & Kirk 2020
).
Transient and multi-messenger science poses a unique set of challenges in this area. While
the astronomy community is still on a long path towards broadly establishing more
equitable and inclusive collaborations, the high-energy physics community, where many
key multi-messenger facilities have been historically located, lags behind even this
standard. The international nature of many collaborations, stretching across diverse
cultural norms, makes these issues particularly acute.
Nonetheless, we see reason for some optimism. In the United States, the Decadal Survey
process has for the first time solicited white papers in the area of the “State of the
Profession and Societal Impacts”, with a goal to assess the health of the community,
including topics such as demographics, diversity and inclusion, workplace climate,
workforce development, education, and public engagement. New flagship facilities, such as
Rubin Observatory, have invested significantly in both creating a diverse and inclusive
collaboration. Countries such as South Africa that have invested heavily in astronomy and
transformation and have seen this investment pay off, both in terms of world-class facilities,
but more importantly in training a diverse set of citizens with technical skills that translate
beyond the astronomy world.
Entire workshops could be (and have been!) devoted to the topics above. Here we highlight
some of the recommendations arrived at during our week-long workshop:
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DEI Recommendation 1:
Sharing of best practices is critical. Even well-intentioned leadership
may be unaware of what needs to be done (and why). The Multi-Messenger Diversity
Network (MDN) was funded in the USA by the National Science Foundation to perform this
task for USA-based collaborations, and has been quite successful in this endeavor. An
international analog, formed with the support of (or under the auspices of) the IAU would
play an important (and missing) role for international collaborations.
[Exec Comm on
Astronomy for Equity and Inclusion, Exec Comm on Women in Astronomy]
DEI Recommendation 2:
In a similar vein, the IAU may serve as a repository for best practice
documents adopted by effective collaborations, with input from the
IAU Executive Working
Group on Equity and Inclusion
, as well as from the collaborations. A template code of
conduct and collaboration framework agreement could be officially endorsed by the IAU,
and used as a starting point by future collaborations.
[Exec Comm on Astronomy for Equity
and Inclusion, Exec Comm on Women in Astronomy]
DEI Recommendation 3:
Workforce and Leadership training should be an integral part of all
transient and multi-messenger collaborations, across a broad agenda. This should include
skills beyond those simply necessary for day-to-day activities, as many early career
scientists will ultimately pursue opportunities outside astronomy. Leadership skills are
particularly important for under-represented groups, where the fractional representation in
leadership positions is even lower than the overall fraction.
[Exec Comm on Astronomy for
Equity and Inclusion, OYA]
DEI Recommendation 4:
In order to deal with issues of bias in the allocation of telescope
time and other resources, we recommend a combination of training reviewers to deal with
unconscious bias and, where practical, the use of dual-anonymization to eliminate even the
possibility of bias.
[Exec Comm on Astronomy for Equity and Inclusion, Exec Comm on
Women in Astronomy]
DEI Recommendation 5:
The transient and multi-messenger community (as well as the
astronomy community more broadly) needs to improve recognition for contributions
outside published manuscripts. Examples include instrumentation work, software
development/maintenance, and also public education and outreach activities. From society
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