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The Armagh Observatory and Planetarium
Annual Report and Accounts for 2008/2009 Year Ended 31 March 2009


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The Armagh Observatory and Planetarium Annual Report and Accounts for 2008/2009, Year Ended 31 March 2009

Laid before the Northern Ireland Assembly by the Department of Culture, Arts and Leisure under clause 8 of the Armagh Observatory and Planetarium (Northern Ireland) Order 1995 as amended by Schedule 1, clause 6 of the Audit and Accountability (Northern Ireland) Order 2003 10 December 2009


The Armagh Observatory and Planetarium Annual Report and Accounts for 2008/2009, Year Ended 31 March 2009
Pages Management Commentary Remuneration Reports Statement of the Responsibilities of the Governors and Accounting Officers Statement of Disclosure of Information to the Auditors Statement on Internal Control ­ Armagh Observatory Statement on Internal Control ­ Armagh Planetarium The Certificate and Report of the Comptroller and Auditor General to The Northern Ireland Assembly 1 18 20 20 21 22 23 ­ 24

ARMAGH OBSERVATORY Statement of financial activities Statement of total recognised gains and losses Balance sheet Cash flow statement Notes to the financial statements 25 25 26 27 28 ­ 40

ARMAGH PLANETARIUM Statement of financial activities Statement of total recognised gains and losses Balance sheet Cash flow statement Notes to the financial statements Shop and mail order trading account 41 41 42 43 44 ­ 54 54


Management Commentary
Background
The Armagh Observatory and the Armagh Planetarium are distinct institutions, part of a single statutory corporation and arms-length body `The Governors of the Armagh Observatory and Planetarium' described in the Armagh Observatory and Planetarium (Northern Ireland) Order 1995. This superseded the original 1791 Act of the Irish Parliament entitled `An Act for Settling and Preserving a Public Observatory and Museum in the City of Armagh For Ever', and an Amendment of 1938 (`The University and Collegiate and Scientific Institutions Act [Northern Ireland], 1938'). The Northern Ireland Order 1995 has since been amended by the Audit and Accountability (Northern Ireland) Order 2003, the Insolvency (Disqualification from Office: General) Order (Northern Ireland) 2008 and a number of other amendments. The Armagh Observatory is also a recognized charity, having been granted charitable status for tax purposes by Her Majesty's Revenue and Customs (HMRC) under Section 505 of the Income and Corporation Taxes Act 1988; the HMRC reference number is XN 46022. The principal function of the Observatory, founded in 1789 as part of Archbishop Richard Robinson's dream to see the creation of a university in the City of Armagh, is to undertake original research of a world-class academic standard that broadens and expands our understanding of astronomy and related sciences. The Armagh Planetarium, which is also a recognized charity (HMRC reference number XN 48022), was founded by Dr Eric Mervyn Lindsay, the seventh director of the Armagh Observatory, and was officially opened on 1st May 1968. The Planetarium's primary function is to disseminate knowledge of a wide range of science and to promote public understanding of astronomy and science through its programme of educational services for schools and the wider public. The two institutions operate under two directors and receive core funding from the Northern Ireland Department of Culture, Arts and Leisure. There is a total population of around 50 staff, approximately 40 in the Observatory and 10 in the Planetarium.

Aims and Objectives
The aim of the corporation is to advance the knowledge and understanding of astronomy and related sciences through the execution, promotion and dissemination of astronomical research nationally and internationally in order to enrich the intellectual, economic, social and cultural life of the community.

Principal Activities
The principal function of the Armagh Observatory is to undertake original research of a world-class academic standard that broadens and expands our understanding of astronomy and related sciences. The Observatory carries out front-line astronomical research in three key areas of astrophysics, namely: Solar-System Science, Solar Physics, and Stellar and Galactic Astrophysics. These fields encompass the dynamical structure, evolution and origin of objects in the inner and outer solar system; comparative planetology and meteor physics; the use of spacecraft such as SoHO, TRACE and Hinode, to study fundamental questions such as how the Sun's outer atmosphere is heated, what drives the solar wind and the Sun's variable magnetic activity (and its effect on climate); and a very wide range of detailed investigations into the formation and evolution of stars, taking into account factors such as mass loss through stellar winds, stellar oscillations, stellar magnetic fields, extreme chemical abundances, and the impact of binarity (two stars orbiting closely around one another) on our understanding of the evolution of stars and galaxies. In particular, our multi-strand multi-wavelength approach to the discovery of ultra-compact binaries will provide crucial input for understanding the first detected gravitational wave events. The Observatory also undertakes an active programme of Science in the Community, for example providing guided tours of the Observatory and its Grounds, Astropark and Human Orrery, holding occasional open days and exhibitions, organizing and delivering public lectures, supervising school children and undergraduates on work-experience programmes and summer research projects, and maintaining and improving the resource of the Grounds and Astropark as a unique inner-city parkland to enrich the lives of visitors to Armagh and residents alike. The Observatory attracts a high level of media interest (e.g. more than 300 mass-media citations to its work per year); its web-sites attract typically around a million distinct e-visitors annually from around the world; and more than 40,000 people visit the landscaped Observatory Grounds, Astropark and Human Orrery every year. In addition to this primary research role the Observatory maintains a unique nearly 215-year long meteorological record and databank (http://climate.arm.ac.uk/), the longest in the UK and Ireland from a single site. Calibration of these data has enabled researchers and government agencies to use the Armagh series for reports and research into global warming, a subject of strategic importance for Northern Ireland as we move into an era of rapid climate change. The Armagh Observatory's climate record provides a long historical baseline against which to judge how Northern Ireland's climate is responding to climate change world-wide. The Observatory also has an important responsibility to maintain and preserve the fabric of the historic buildings, the library, historic books and archives, and the collection of scientific instruments and other artefacts built up over 220 years of continuous astronomical activity in Armagh. The main historic buildings of the Observatory have unique architectural features and house a valuable library, archives and museum collection that contains a growing collection of historic books and manuscripts and a wide range of astronomical images and photographic plates, scientific instruments, clocks and other artefacts concerning the development of astronomy in the UK and Ireland over more than two hundred years.

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The Armagh Planetarium is a leading educational establishment whose primary function is to disseminate knowledge of a wide range of science and to promote the public understanding of astronomy and science through its programme of educational services for schools and the wider public. Staff deliver interactive presentations using the latest projection and information technology to all age groups and abilities on a wide range of astronomical and scientific topics, including meteorite impacts, the planets, current astronomical phenomena and Earth sciences. The Planetarium, also through the large number of visitors coming through its doors, plays an important role in promoting and enhancing tourism within Armagh City and District.

Equal Opportunities Policy
The corporation is an equal opportunities employer, committed to ensuring that the talents and resources of all members of the corporation are utilised to the full. The corporation does not discriminate directly or indirectly on the grounds of religious belief, political opinion, trade union membership, gender, marital status, sexual orientation, age, disability, race, colour or ethnic origin, against any member of staff, full-time or part-time, or job applicant, actual or potential, in any aspect of the corporation's activities, including matters of recruitment, training, promotion, appointment, nomination or selection for any position, job transfer or redundancy.

Policy on Payment of Suppliers
The corporation is committed to the payment of all invoices not in dispute within agreed contractual terms or within 30 days of the presentation of a valid invoice, or delivery if later. In the year ended 31 March 2009, all of the corporation's invoices were paid within these limits.

Auditors
Under the Audit and Accountability (Northern Ireland) Order 2003, responsibility for the audit of the accounts of the Armagh Observatory and Planetarium has been vested in the Comptroller and Auditor General for Northern Ireland.

Employee Information and Consultation
The corporation takes every opportunity to inform and consult with all members of the organisation on the corporation's activities and plans for the future through the dissemination of annual reports and operational plans, the provision of the latest information on research, educational and other activities through the web-sites, regular formal and informal briefing and discussion meetings, and consultations with staff representatives on employment-related and operational policies and procedures. Further information on the Observatory is available at http://star.arm.ac.uk/ and http://climate.arm.ac.uk/, and on the Planetarium at http://www.armaghplanet.com.

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Corporate Governance
Board of Governors
The Board of Governors comprises the Church of Ireland Archbishop of Armagh (Chairman), the Dean and Chapter of the Church of Ireland Cathedral of Armagh (9 persons), 1 DCAL nominee, 1 Queen's University Belfast (QUB) nominee, and up to 3 additional members nominated by the Board of Governors. Nominees normally serve for an initial period of 5 years with the possibility of extension. Chairman: His Grace, The Most Reverend A.E.T. Harper, The Archbishop of Armagh and Primate of All Ireland The Dean: The Very Reverend Dean P.W. Rooke, St. Patrick's Cathedral, Armagh The Precentor: The Reverend Canon H.J.W. Moore, also Rector of Ballinderry, Tamlaght and Arboe1 The Precentor: The Reverend Canon T. Scott, also Rector of Magherafelt The Chancellor: The Reverend Canon J.M. Barton, also Bishop's Curate of Acton and Drumbanagher2 The Chancellor: The Reverend Canon C.F. Moore, also Rector of Newtownhamilton, Ballymoyer and Belleek The Treasurer: The Reverend Canon J.W. McKegney, also Rector of St. Mark's Parish, Armagh The Archdeacon: The Venerable R.G. Hoey, also Rector of Camlough and Mullaglass The Prebendary of Mullabrack: The Reverend Canon R.J.N. Porteus, also Rector of Derryloran Parish (Cookstown) The Prebendary of Ballymore: The Reverend Canon W.J.A. Dawson, also Bishop's Curate of Pomeroy The Prebendary of Loughgall: The Reverend Canon J.N.T. Campbell, also Rector of St. Mark's Parish, Portadown3 The Prebendary of Tynan: The Reverend Canon W.M. Adair, also Rector of St. Columba's Parish, Portadown4 Councillor W. Gardiner-Watson (DCAL Nominee) Professor A. Hibbert, Queens University Belfast (QUB Nominee) The Right Honourable the Lord Ballyedmond, Ballyedmond Castle, Rostrevor (Board of Governors Nominee) Professor J.E. Dyson, University of Leeds (Board of Governors Nominee)5 Dr R.D. Oudmaijer, University of Leeds (Board of Governors Nominee)6

Management Committee
The Management Committee comprises the Church of Ireland Archbishop of Armagh or his nominee (Chairman), 3 Nominees from the Board of Governors, 6 DCAL nominees, 1 QUB nominee, 1 Science and Technology Facilities Council (STFC) nominee, 1 Dublin Institute for Advanced Studies (DIAS) nominee, and up to 4 additional members co-opted by the Board of Governors. Nominees and those co-opted by the Governors normally serve for an initial period of 3­5 years with the possibility of extension. Chairman: His Grace, The Most Reverend A.E.T. Harper, The Archbishop of Armagh and Primate of All Ireland Deputy Chairman: Dr F.N. Byrne (Co-opted, Board of Governors) The Venerable Archdeacon R.G. Hoey, Camlough and Mullaglass (Board of Governors Nominee) Professor J.E. Dyson, University of Leeds (Board of Governors Nominee)7 Dr R.D. Oudmaijer, University of Leeds (Board of Governors Nominee)8 Professor A. Hibbert, Queens University Belfast (Board of Governors Nominee) Mr E.P. Donnelly (DCAL Nominee)9 Dr E.M. (à.) Downey (DCAL Nominee) Mrs S. Hogg (DCAL Nominee) Mr A. Peoples (DCAL Nominee)10 Mr J.I. Shields (DCAL Nominee)11 Mrs P.E. Wilson (DCAL Nominee)12 Professor P.L. Dufton, Queens University Belfast (QUB Nominee) Professor M.R. Merrifield, University of Nottingham (STFC Nominee) Professor E.J.A. Meurs, Dublin Institute for Advanced Studies (DIAS Nominee) 13 Professor T.P. Ray, Dublin Institute for Advanced Studies (DIAS Nominee)14

Internal Audit Committee
The Internal Audit Committee, a sub-committee of the Management Committee, comprises Dr F.N. Byrne (Chairman), Dr E.M. (à.) Downey, Professor P.L. Dufton and Mr A Peoples.

Directors and Secretary
Professor M.E. Bailey MBE -- Director, Armagh Observatory Dr T.R. Mason MBE -- Director, Armagh Planetarium Mr L.F. Young -- Secretary
1 2 3 4 5

To 2008 August 31 To 2009 February 22 From 2009 February 23 From 2008 September 1 To 2008 November 20

6 7 8 9 10

From 2008 November To 2008 November 20 From 2008 November From 2008 November From 2008 November

20 20 1 1

11 12 13 14

From 2008 November 1 From 2008 November 1 To 2009 February 27 From 2009 March 4

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The Armagh Observatory -- Operating Review 2008/2009
The following research highlights, performance indicators for 2008/2009, and objectives for 2009/2010 are extracted from the Armagh Observatory Annual Report for Calendar Year 2008 (Financial Year 2008/2009), which contains an extensive summary of the whole of the Observatory's principal research and other activities during 2008. The full report is available at http://star.arm.ac.uk/annrep/ or by contacting the Administrator at the Armagh Observatory, College Hill, Armagh, BT61 9DG, tel. +44-28-3752-2928; e-mail: info@arm.ac.uk.

Alignment with Northern Ireland Government Objectives
Shared Heritage There is a very significant level of public interest in astronomy, space science and related fields. This is mirrored by the Observatory's academic focus and addressed by its very active programmes of public outreach and public understanding of science. Astronomical research makes a fundamental contribution to knowledge, and helps to attract people -- both young and old -- towards science and into a more scientific way of thinking. Science, in Carl Sagan's phrase, is "a candle in the dark"; and astronomy -- foremost amongst sciences -- helps people to make sense of the world and the wider world around us. Astronomy is part of world heritage and an important part of the shared heritage of people living on the island of Ireland. The Armagh Observatory is Northern Ireland's oldest scientific institution, and Northern Ireland government support for astronomy at Armagh is central to the mission of the Department of Culture, Arts and Leisure (DCAL) "to protect, nurture and grow Northern Ireland's Cultural Capital for today and tomorrow." In return, astronomers at Armagh make distinctive contributions to major strands of government policy and project a key part of Northern Ireland's cultural and scientific heritage to millions of people world-wide. Research Staff at the Armagh Observatory have maintained a high level of research activity and other outputs during the year, producing 53 publications in refereed scientific journals during 2008 as well as many other scientific papers and attracting a record 413 identified mass-media citations to the Armagh Observatory, its staff and their work. Electronic access to the Armagh Observatory has remained at a very high level: during 2008 there were approximately a million Distinct e-Visitors (DEVs) to the Observatory's principal web-sites (http://star.arm.ac.uk/, http://climate.arm.ac.uk/ and http://arpc65.arm.ac.uk~spm/), 13.6 million `hits', and a record 7.0 TB (1 TB = 1 million Megabytes) of data were exported from the Armagh Observatory to users of astronomical information elsewhere. During calendar year 2008, Armagh Observatory staff delivered more than 94 scientific papers and general public talks at meetings both locally and abroad, and maintained an active programme of in-house training including some 28 internal seminars and colloquia, many of which were delivered by external visiting speakers. In addition, Stefano Bagnulo organized an international workshop "Spectroscopy and Spectropolarimetry of A and B-type Stars: Research Tools, Techniques, and Goals", which was held at the Armagh Observatory from 2008 February 18 to February 22. Total external grant receipts and other income during 2008/2009 amounted to ¸254.3k (cf. ¸219.4k for 2007/2008), of which ¸242.8k was attributable to external grant receipts (cf. ¸200.0k for 2007/2008). This figure, which significantly exceeded the anticipated figure in the 2008/2009 Business Plan (¸219.1k), highlights the success of Armagh Observatory staff in proactively obtaining externally funded, peer-reviewed research grants in a very difficult financial climate. Presenting Northern Ireland on the International Stage The Armagh Observatory presents a strong, positive image of Northern Ireland on the international stage. Members of staff play a full role in the international astronomical community: reviewing grant and research proposals on behalf of external funding agencies; reviewing scientific papers; editing international academic journals; and serving on the committees of bodies such as the Science and Technology Facilities Council (STFC), the Royal Astronomical Society and the Royal Irish Academy. During 2008, staff at the Armagh Observatory significantly expanded the Observatory's programme of Science in the Community by providing additional guided tours of the Observatory and Astropark, holding occasional exhibitions, organizing and delivering public lectures, supervising school children and undergraduates on work-experience programmes and summer research projects, and maintaining and improving the resource of the Observatory Grounds, Astropark and Human Orrery as a unique facility to enrich the lives of visitors to Armagh and residents alike. In recent years, the number of people visiting the Astropark has grown significantly, reaching approximately 45,000 in each of the last two years.

Principal Achievements During 2008 and 2008/2009
Advances in Astronomy and Astrophysics Magnetic Fields of Massive Stars Stefano Bagnulo, Jorick Vink and Colin Folsom are co-Investigators of a large programme at the Canada-France-Hawaii Telescope (CFHT), a 3.6m telescope on Mauna Kea, Hawaii, which was granted 650 hours for spectropolarimetry of massive stars with the ESPaDONs polarimeter over the next five years to study magnetic fields. A newly recruited STFC PhD student (Bridget Kendrick) will be working full time on this project in association with colleagues at the University of Hertfordshire. Bagnulo and Folsom attended a conference in Kingston, Canada, at the end of June and early July 2008 to discuss the organizational details of this programme, as well as to present scientific papers. Mass Loss from Hot Massive Stars Jorick Vink and colleagues (Joachim Puls and Paco Najarro) have reviewed various aspects of radiation-driven mass loss, encompassing both theoretical and observational perspectives. Their extensive review (116 pages) will be published in the Astronomy and Astrophysics Review series (Puls, Vink & Najarro, 2009, in press).

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Jorick Vink and his former PDRA at Keele University, Patrick MÝller, report that they have made significant progress in solving the problem of the wind hydrodynamics for a massive O-star stellar wind. Their new theoretical framework together with the iteration method developed by MÝller &Vink (2009) supersedes the 35-year old method of Castor, Abbott & Klein (1975). The new method will allow Vink and collaborators to study mass loss in regions of the Universe for which empirical constraints on individual O stars are not readily available, for example massive stars in the early Universe. Rapid Temporal Survey (RATS) and the Search for Gravitational Wave Progenitors Gavin Ramsay reports that, in collaboration with Paul Callanan's group at University College Cork, he and Paul Callanan obtained ESO Director's discretionary time to observe SAX 1808.4-3658. This is a binary system containing an accreting millisecond pulsar. It went into outburst in 2008 September, and the group was successful in obtaining separate sets of spectroscopic data using two of the Very Large Telescopes (VLTs) at Paranal, in Chile. He further notes that using the Isaac Newton Telescope (INT) on La Palma, observations of a target object discovered as a result of the RATS project indicated the presence of an unusual source varying in brightness with a period of 20 minutes. Follow-up observations using the Nordic Optical Telescope (NOT) in 2008 September showed that the object had brightened by 4 magnitudes (i.e. by a factor of about 40). This indicates that the object is probably a dwarf nova, only the third known dwarf nova to show quasiperiodic oscillations during quiescence. The amplitude of these quasi-periodic oscillations is the largest yet seen in any dwarf nova. Gavin Ramsay also reports that with colleagues he has been successful in obtaining Cycle 17 time on the Hubble Space Telescope. Subluminous B Stars Subluminous B stars are hot, low-mass stars evolving between their major hydrogen-burning phase of evolution and their final white-dwarf end-state. Simon Jeffery reports that a recent investigation of the distribution of these hot subdwarf B stars versus surface temperature, surface gravity and hydrogen abundance, with colleagues Christopher Winter (a former PhD student) and Simon Hall (a TCD undergraduate, working on a final-year project at Armagh), has shown a correlation between the hydrogen abundance of the sdB star and its luminosity. The correlation is such that in the overall population there is a higher fraction of very rare helium stars (hydrogen-deficient or helium-rich He-sdB stars) at higher luminosity. This result suggests a new and potentially efficient way to discover helium stars. Ultracool Dwarfs: The `Runts' of the Main Sequence Gerry Doyle and colleagues have reported the discovery of a completely new category of radio emitting object which has immense implications for our understanding of stellar magnetic activity. The observations concerned the detection of periodic pulses of 100% circularly polarized radio emission, which appear to be produced at the poles of a large-scale magnetic field by the electron cyclotron maser instability, the same mechanism known to be responsible for the radio emission from the magnetized planets in our solar system. These observations show that ultracool dwarfs have kilo gauss (kG) fields and that they have active upper atmospheric conditions. Furthermore, they question the interpretation of radio emission from active stars over the last 20 years. Many questions remain about these objects, and in an effort to look into the short-term variability of the emission the group was awarded three 2.5 hour shifts at the Arecibo Observatory in late 2008 May. These were consecutive shifts, scheduled to observe the ultracool dwarf TVLM 513, which has a 1.96 hour rotation period, with 1-second time resolution. On successive nights it was observed that the pulses as seen with the lower time resolution VLA data have a lot of substructure, implying structures in the stellar atmosphere with dimensions no more than 600 km. They also showed a factor of five variability in flux over a 24 hour interval. Polarimetry of Outer Solar-System Objects Stefano Bagnulo reports that, using the ESO VLT, he and co-authors have performed the first-ever polarimetric survey of trans-Neptunian objects (TNOs). These are small solar system bodies orbiting on the fringes of the planetary system beyond Neptune which are believed to contain the most primitive and thermally least-processed material from the early accretional phase of the solar system. Their study allows us to investigate the interrelationships between the various classes of small solar-system body, and their origin and evolution. The results of this work have shown that there are two different polarimetric behaviours for these kinds of body, possibly associated with different evolutionary stages of the objects. Aurigid Meteor Outburst A very rare outburst of the Aurigid meteor shower was predicted to occur at 11:36 ±20 min UT on 2007 September 1, due to Earth's encounter with dust from long-period comet C/1911 N1 (Kiess), ejected from the cometary nucleus some 2000 years ago. Outbursts of this type provide unique scientific opportunities to study long-period comets which, by their very nature, are very unlikely to come under the scrutiny of in situ spacecraft missions either now or in the foreseeable future. Three members of the Armagh Observatory (Apostolos Christou, Prakash Atreya, Martin Murphy) travelled to San-Francisco, California, USA, where the shower was anticipated to be best seen. They coordinated their efforts with a US-group led by Dr Peter Jenniskens of the SETI Institute. The outburst did occur as predicted, with meteors as bright as the planet Jupiter appearing at a peak rate of about 100/hr for a period of about 90 min, and several gigabytes of data on this outburst were recorded by the Armagh Observatory group. In 2008, these have been analyzed by software developed in-house by Atreya to yield information on the physical nature of the meteoroids and the structure of the dust stream of this long-period comet. Partial external financial support for this trip was obtained by the N3 activity of the European Planetology Network (EuroPlaNet) funded through the 6th Framework Programme of the European Union. New Temporary Satellite Capture Comet David Asher and colleagues (Ohtsuka, Ito, Yoshi-kawa, and Arakida) have discovered that a comet first found in 1993 is a member of the rare class of comets known as temporary satellite captures (TSCs). These are objects that have been temporarily captured by the giant planet Jupiter and which orbit the planet as if they were another Jovian satellite. They show that comet 147P/Kushida-Muramatsu represents both the third longest temporary satellite capture event and the third longest orbiter around Jupiter, behind 111P/Helin-Roman-Crockett and D/1993 F2 (Shoemaker-Levy 9), the latter whose fragments collided with Jupiter in 1994 July. The present study explores the dynamical link, exemplified by 147P/KushidaMuramatsu, between the Hilda region of the main asteroid belt and Jovian satellite capture orbits.

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Observational and Theoretical Studies of Comets Stefano Bagnulo and colleagues (BÆhnhardt, Tozzi, Muinonen, Nathues, and Kolokolova) have used the VLT in Chile to determine the linear polarimetric phase function for the short-period comet 2P/Encke, the first ever measured for a cometary nucleus. Threat of Dark Comets David Asher reports that during 2008 he and Bill Napier (Cardiff University), a former senior research fellow at the Armagh Observatory, completed a major invited review article on the Tunguska impact event (1908 June 30). This was published in the 2009 February issue of Astronomy and Geophysics, the journal of the Royal Astronomical Society, and focused on the nature of the impactor and the importance or otherwise of a cometary component to the extraterrestrial impact hazard. The paper attracted a significant amount of media attention. One hundred years ago an incoming object from space exploded above the Tunguska region of Siberia and devastated two thousand square kilometres of forest. The article reviews the question of an asteroidal (rocky and/or metallic) versus cometary (icy, or once icy and now substantially devolatilised) nature for the Tunguska impactor. The issue has been intensively debated for many years and its solution, by informing the more general question whether comets or asteroids dominate the variable influx of extraterrestrial debris on to Earth, will help to clarify the nature of the threat posed by so-called near-Earth objects (NEOs) -- comets and asteroids -- to civilization. The new work assesses the evidence for the importance of cometary populations, and presents evidence for the effect of the solar system's Galactic environment on the Oort comet cloud through the variable frequency versus time over many millions of years of extraterrestrial impact craters on Earth. The importance of comets has significant implications for hazard mitigation: cometary bodies, or cometary fragments generally, have much higher impact speeds and shorter warning times than their asteroidal co