James Dunlop
Encyclopedia
Astronomer
An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...
's assistant who was hired by Sir Thomas Brisbane
Thomas Brisbane
Major-General Sir Thomas Makdougall Brisbane, 1st Baronet GCH, GCB, FRS, FRSE was a British soldier, colonial Governor and astronomer.-Early life:...
to work at his private observatory, once located at Paramatta (now named Parramatta), New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
, about twenty-three kilometres west of Sydney
Sydney
Sydney is the most populous city in Australia and the state capital of New South Wales. Sydney is located on Australia's south-east coast of the Tasman Sea. As of June 2010, the greater metropolitan area had an approximate population of 4.6 million people...
, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
during the 1820s and 1830s. Dunlop was mostly a visual observer, doing stellar astrometry
Astrometry
Astrometry is the branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. The information obtained by astrometric measurements provides information on the kinematics and physical origin of our Solar System and our Galaxy, the Milky...
work for Brisbane, and after its completion, then independently discovered and catalogued many new telescopic southern double stars and deep-sky objects. He later became the Superintendent of Paramatta Observatory when it was finally sold to the New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
Government.
Early life
James Dunlop was born in Dalry, Ayrshire, ScotlandScotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
, the son of John Dunlop, a weaver, and his wife Janet, née Boyle. Dunlop was educated at a primary school in Dalry and went to work at a thread factory in Beith
Beith
Beith is a small town situated in the Garnock Valley in North Ayrshire, Scotland approximately 20-miles south-west of Glasgow. The town is situated on the crest of a hill and was known originally as the "Hill o' Beith" after its Court Hill.-History:-Name:Beith's name is thought to emanate from...
when he was 14. He also attended a night-school in Beith kept by a man named Gardiner. He became interested in astronomy at an early age and was constructing telescopes in 1810. By fortune In 1820, he made the acquaintance of the astronomical inclined Sir Thomas Brisbane
Thomas Brisbane
Major-General Sir Thomas Makdougall Brisbane, 1st Baronet GCH, GCB, FRS, FRSE was a British soldier, colonial Governor and astronomer.-Early life:...
. In the same year, Brisbane was appointed as the new Governor of New South Wales, who then decided to set up an astronomical observatory in the new Colony. Prior to leaving Britain, Dunlop was then appointed as his second scientific assistant, and both travelled to Sydney in 1821.
Career in Australia
Soon after arriving, Brisbane almost immediately started building his observatory at Paramatta (original spelling), now named Parramatta, and it was Dunlop who was employed to do the astrometric observationsAstrometry
Astrometry is the branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. The information obtained by astrometric measurements provides information on the kinematics and physical origin of our Solar System and our Galaxy, the Milky...
for a new accurate southern star catalogue. Also employed was the German born Carl Ludwig Christian Rümker
Carl Ludwig Christian Rümker
Carl Ludwig Christian Rümker was a German astronomer. In German, his name is spelt Karl Ludwig Christian Rümker; he was also known as Charles Rümker, Charles Rumker, Charles Luis Rumker, Christian Carl Ludwig Rümker and Dr...
(or sometimes as Charles Karl Ludwig Rümker) (28 May 1788 - 21 December 1862), or simply Karl Rümker, who had been recruited by Brisbane as first astronomical assistant. Rümker soon left the observatory in protest of his treatment during 1823, leaving Dunlop in charge of the astrometric measures and general maintenance of the astronomical instruments and the Observatory. Dunlop was not a professionally trained astronomer, so he importantly lacked the necessary mathematical skills to do astrometric reductions. He had soon learned the necessary observational skills from the more able Rümker and his employer.
Between June 1823 and February 1826 Dunlop then made 40,000 observations and catalogued some 7385 stars, of which included 166 double stars and references to several bright deep-sky objects near the bright stars he catalogued. By the beginning of March, 1826, he left the Paramatta Observatory and continued working at his own home in Hunter Street, Paramatta. For there he began organising his own observations of double stars and deep-sky objects for the next 18 months, in which he constructed telescopes and other equipment for his dedicated southern sky survey.
Sir Thomas Brisbane, before finally departing Sydney for the last time in December 1825, arranged to sell all of his instruments to the Government so the observatory could continue to function. Some of the equipment he gave to Dunlop, which he used at his home, especially the useful small equatorial mounted 8.0 cm. (3¼-inch) refracting telescope
Refracting telescope
A refracting or refractor telescope is a type of optical telescope that uses a lens as its objective to form an image . The refracting telescope design was originally used in spy glasses and astronomical telescopes but is also used for long focus camera lenses...
that Rümker, and later Dunlop, both used for doing the important double stars measures as their own personal projects.
By May 1826, Rümker returned to the observatory, and seven months later he was appointed as the first New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
Government Astronomer, though this officially did not happen until a few years later, much to Rümker's disgust, due to delays from his employers in Britain.
Back to Scotland
Dunlop left Sydney for Scotland in February 1827 and was employed for four years at the observatory of Sir Thomas Brisbane. He had done very good work as an observer in New South Wales, and was associated with Rümker in the discovery of Encke's comet at Parramatta in June 1822. He was later to be the first in Great Britain to rediscover this comet on 26 October 1829. He had been awarded the Gold Medal of the Royal Astronomical SocietyGold Medal of the Royal Astronomical Society
-History:In the early years, more than one medal was often awarded in a year, but by 1833 only one medal was being awarded per year. This caused a problem when Neptune was discovered in 1846, because many felt an award should jointly be made to John Couch Adams and Urbain Le Verrier...
of London on 8 February 1828. Sir John Herschel
John Herschel
Sir John Frederick William Herschel, 1st Baronet KH, FRS ,was an English mathematician, astronomer, chemist, and experimental photographer/inventor, who in some years also did valuable botanical work...
, when making the presentation, spoke in the highest terms of the value of the work done by Dunlop in New South Wales. On arrival, he also reduced his southern double stars and deep-sky observations for publication, which was believed to have taken about one month, and these were published also in the first half of 1828.
These two detailed astronomical papers were received with many accolades from his peers, which lasted until about 1834, when his observations were able to be scrutinised by John Herschel
John Herschel
Sir John Frederick William Herschel, 1st Baronet KH, FRS ,was an English mathematician, astronomer, chemist, and experimental photographer/inventor, who in some years also did valuable botanical work...
and Thomas Maclear
Thomas Maclear
Sir Thomas Maclear was an Irish-born South African astronomer who became Her Majesty's astronomer at the Cape of Good Hope....
in South Africa. Only then were the various flaws of his observations became revealed, and the time spent in the zenith of popularly, then dwindled to fierce criticism and personal rejection especially from the British astronomical community.
Return to Australia
In April 1831, Dunlop was appointed superintendent of the Government observatory at ParramattaParramatta, New South Wales
Parramatta is a suburb of Sydney, in the state of New South Wales, Australia. It is located in Greater Western Sydney west of the Sydney central business district on the banks of the Parramatta River. Parramatta is the administrative seat of the Local Government Area of the City of Parramatta...
. He was selected mainly from his good knowledge of Colony and the observatory site, but the real reason for his selection was more because even though such an astronomical position was formally advertised, nobody applied for the astronomical tenure. Here he was to succeed Rümker with the reasonable good salary of £300 a year. He arrived at Sydney on 6 November 1831 and found the observatory in a deplorable condition; rain had entered the building, roofing plaster had fallen down, and many important records were destroyed. Dunlop succeeded in getting the building repaired and started on his work with energy, but around 1835 his health began to fail; he had no assistant, and the building, having been attacked by white ants, fell gradually into decay. In August 1847, he resigned his position, and went to live on his farm on Brisbane Waters, an arm of Broken Bay. He died on 22 September 1848. In 1816 Dunlop married his cousin Jean Service, who survived him. In addition to the medal of the Royal Astronomical Society
Royal Astronomical Society
The Royal Astronomical Society is a learned society that began as the Astronomical Society of London in 1820 to support astronomical research . It became the Royal Astronomical Society in 1831 on receiving its Royal Charter from William IV...
Dunlop was awarded medals for his work by the King of Denmark in 1833, and the Institut Royal de France
Institut de France
The Institut de France is a French learned society, grouping five académies, the most famous of which is the Académie française.The institute, located in Paris, manages approximately 1,000 foundations, as well as museums and chateaux open for visit. It also awards prizes and subsidies, which...
in 1835. He was elected a fellow of the Royal Society of Edinburgh
Royal Society of Edinburgh
The Royal Society of Edinburgh is Scotland's national academy of science and letters. It is a registered charity, operating on a wholly independent and non-party-political basis and providing public benefit throughout Scotland...
in 1832. Papers on, and references to, the work of Dunlop will be found in the Monthly Notices of the Royal Astronomical Society, in the Edinburgh Journal of Science, and in the Transactions of the Royal Society between the years 1823 and 1839.
Observations and Discoveries in Australia
Dunlop made several noteworthy discoveries in the Southern Hemisphere sky and in 1828 published A Catalogue of Nebulae and Clusters of Stars in the Southern Hemisphere observed in New South Wales, which contains 629 objects. A little more than half the objects he discovered proved to be real, most being small nebulous objects being probably artificially created from the handmade reflecting telescope he had constructed himself. His most famous discovery is likely the radio galaxy NGC 5128, though he found many new open star clusters, globular clusterGlobular cluster
A globular cluster is a spherical collection of stars that orbits a galactic core as a satellite. Globular clusters are very tightly bound by gravity, which gives them their spherical shapes and relatively high stellar densities toward their centers. The name of this category of star cluster is...
s, bright nebulae and planetary nebulae, most previously unknown to visual observers.
Dunlop's other major observational work was of 256 southern double stars or "pairs" below the declination
Declination
In astronomy, declination is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. Declination in astronomy is comparable to geographic latitude, but projected onto the celestial sphere. Declination is measured in degrees north and...
of about -30o South. These were listed in Approximate Places of Double Stars in the Southern Hemisphere, observed at Paramatta in New South Wales, published in 1829. Many of these pairs were actual new discoveries, though the most northerly of them had been earlier discoveries made by other observers. These double star observations were all made roughly between December 1827 and December 1828, being observed through his homemade 9-foot 23 cm (9-inch) speculum
Speculum
The term speculum, Latin for "mirror", and its plural specula, may refer to:* Speculum , a medical tool used for examining body cavities* Speculum , a journal of medieval studies published by the Medieval Academy of America...
Newtonian reflector, or by measuring the separated distances and position angles of selected double stars using the small 8.0 cm. (3¼-inch) equatorial mounted refracting telescope
Refracting telescope
A refracting or refractor telescope is a type of optical telescope that uses a lens as its objective to form an image . The refracting telescope design was originally used in spy glasses and astronomical telescopes but is also used for long focus camera lenses...
. Most of these pairs have proved to be uninteresting to astronomers, and many of the double stars selected were too wide for the indication of orbital motion as binary stars. It seems these observations were made when the atmospheric conditions were quite unsuitable for looking at deep sky
Deep sky
Deep-sky objects are astronomical objects other than individual stars and solar system objects . The classification is used for the most part by amateur astronomers to denote visually observed faint naked eye and telescopic objects such as star clusters, nebulae and galaxies.-Origins and...
objects, either being made under unsteady astronomical seeing
Astronomical seeing
Astronomical seeing refers to the blurring and twinkling of astronomical objects such as stars caused by turbulent mixing in the Earth's atmosphere varying the optical refractive index...
or when the sky was illuminated by the bright moon. John Herschel
John Herschel
Sir John Frederick William Herschel, 1st Baronet KH, FRS ,was an English mathematician, astronomer, chemist, and experimental photographer/inventor, who in some years also did valuable botanical work...
immediately on arrival in South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
in 1834 and 1835 re-observed all of the James Dunlop's double stars, but had troubles identifying them or finding significant differences in the measured positions of the stars . He first began with Alpha Crucis
Alpha Crucis
Acrux is the brightest star in the constellation Crux, the Southern Cross, and, at a combined visual magnitude 0.77, is the twelfth brightest star in the night sky...
/ Acrux, the brightest star in the constellation of Crux
Crux
Crux is the smallest of the 88 modern constellations, but is one of the most distinctive. Its name is Latin for cross, and it is dominated by a cross-shaped asterism that is commonly known as the Southern Cross.-Visibility:...
, also commonly known as the Southern Cross, then systematically searched for all the others. Herschel also was first to designated all the Dunlop double stars to begin with the Greek letter "Δ", which persists in many amateur observational references. Hence, bright southern doubles like p Eridani
P Eridani
p Eridani is a binary star system in the constellation of Eridanus whose distance is approximately 26 light-years. It was found to be a double star in December 1825 by James Dunlop in Australia at his home at Paramatta, now spelt Parramatta.- Naming :The name "p Eridani", according to Nature,...
is known as Δ5, Gamma Crucis
Gamma Crucis
Gamma Crucis , often called Gacrux, is a red giant star approximately 88 light-years away in the constellation of Crux. Among Portuguese-speaking peoples it is also named "Rubídea" , in reference to its color. The star is the third-brightest star in Crux and one of the brightest stars in the...
/ Gacrux is Δ124, etc. Modern double star observers have since discarded this designation and prefer the observer abbreviation "DUN", as first adopted in the Washington Double Star Catalog
Washington Double Star Catalog
The Washington Double Star Catalog, or WDS, is a catalog of double stars, maintained at the United States Naval Observatory. The catalog contains positions, magnitudes, proper motions and spectral types and has entries for 102,387 pairs of double stars. The catalog also includes multiple stars...
(WDS) as maintained by the US Naval Observatory in Washington D.C.. Hence, p Eridani is DUN 5, Gamma Crucis / Gacrux is DUN 124, etc.
James Dunlop is currently buried in St. Paul's Anglican Church in Kincumber, New South Wales
Kincumber, New South Wales
Kincumber is a south-eastern suburb of the Central Coast region of New South Wales, Australia, nested between the Kincumba Mountain Reserve and the local waterway and located north of Sydney via the Sydney-Newcastle Freeway...
.
Publications
- "A catalogue of nebulae and clusters of stars in the southern hemisphere, observed at Parramatta in New South Wales. Philosophical Transactions of the Royal SocietyPhilosophical Transactions of the Royal SocietyThe Philosophical Transactions of the Royal Society is a scientific journal published by the Royal Society of London. It was established in 1665, making it the first journal in the world exclusively devoted to science, and it has remained in continuous publication ever since, making it the world's...
, Vol. 118, p. 113--151, 1828. This catalogue with descriptions contains 629 southern deep-sky objects. - He also discovered and catalogued 256 southern double stars in "Approximate Places of Double Stars in the Southern Hemisphere, observed at Paramatta in New South Wales.", which was published in the Memoirs of the Royal Astronomical SocietyRoyal Astronomical SocietyThe Royal Astronomical Society is a learned society that began as the Astronomical Society of London in 1820 to support astronomical research . It became the Royal Astronomical Society in 1831 on receiving its Royal Charter from William IV...
Mem.Ast.Soc.London, Vol. 3, 257, 1829. - Only five other astronomical papers were published by James Dunlop between 1829 and 1839, the most significant being on comets; "Places of Encke's comet, from 30 observations. Monthly Notices of the Royal Astronomical SocietyMonthly Notices of the Royal Astronomical SocietyMonthly Notices of the Royal Astronomical Society is one of the world's leading scientific journals in astronomy and astrophysics. It has been in continuous existence since 1827 and publishes peer-reviewed letters and papers reporting original research in relevant fields...
(MNRAS)., Vol. 1, 120 (1829) and "Observation of a small comet at Paramatta. Monthly Notices of the Royal Astronomical SocietyMonthly Notices of the Royal Astronomical SocietyMonthly Notices of the Royal Astronomical Society is one of the world's leading scientific journals in astronomy and astrophysics. It has been in continuous existence since 1827 and publishes peer-reviewed letters and papers reporting original research in relevant fields...
(MNRAS)., Vol. 1, 130 (1829)
External links
- Bright Sparcs Bio at University of Melbourne
- University of Arizona SEDS
- SPACETEC (Dunlop pictures)