197 Years Ago
It was a clear Thursday night the 27 April 1826 in Parramatta, NSW. James Dunlop’s 9” (23cm) aperture homemade speculum reflector was aligned and pointing exactly south. It was located halfway between Marsden St and Church St about 70m south of George St. His ladder was ready for him to climb up to the eyepiece of the 9’ (274cm) long tube. An oil lamp burned dimly on a table and his pen and paper were ready to record his first night’s observations. The sunset at 5:20pm and he waited eagerly for astronomical twilight to end at 6:45pm.
Dunlop started sweeping his telescope back and forth from north to south along the meridian. At 8:35pm a large open cluster appeared in his low power 45’ field. It was not a new object. Lacaille had discovered it in 1751 and it is now called NGC 3532. He recorded the sidereal time from the pendulum clock, the object’s south polar distance (its altitude was 62 degrees) and a description, then he kept searching back and forth.
Another open cluster came into view at 8:46pm. It was a new discovery, now called IC 2714. Just 3 minutes later he discovered another cluster 46’ away, now called Mel 105. John Herschel missed these two clusters when he swept the sky from Cape Town between 1834 and 1838, and they were not included in the NGC catalogue in 1888. At 9:05pm Dunlop found the nights 4th open cluster. It was another Lacaille object, now called NGC 3766.
The 66% sunlit Moon rose at 10pm and Dunlop retired to his room at the Elder’s house, satisfied with his first night sweeping the southern sky for clusters and nebulae. James and Mary Elder were fellow Scots and their house is now part of the Woolpack Hotel. https://goo.gl/maps/VcnLmgwva6g4obaV8
The attached 1844 map shows the location of the Elder's house and a red D shows the location of Dunlop's telescope.
Sat 29th April 1826
James Dunlop catalogued 8 objects on Saturday night 29/4 with his 9” reflector, 3 open clusters (OC), 3 galaxies (Gx) and 2 globular clusters (Gb). Five were new objects and 3 were objects that had been found by Nicolas-Louis de Lacaille in 1751-52 from Cape Town.
Astronomical twilight ended at 18:42 and the 45% sunlit Moon rose at midnight.
At 19:58 he recovered NGC 3293 an OC that Lacaille had found in 1751
At 20:01 he discovered NGC 3330 a new OC
At 21:56 he discovered Harvard 6 a new OC. John Herschel missed this OC.
At 22:17 he recovered NGC 4833 a Gb that Lacaille found in 1751
At 22:23 he discovered NGC 4945 an amazing, large new Gx
At 22:44 he discovered NGC 5128 an amazing new Gx also called Cen A.
At 22:55 he recovered M83 a Gx that Lacaille found in 1751 with a 0.5” aperture refractor!
At 23:04 he discovered NGC 5286 a new Gb next to M Cen an orange mag 4.6 star.
He didn’t know it but he discovered two bright galaxies that night!
Astronomers realised they were galaxies, not nebulae, after 1920.
The attached files are his descriptions of M83 (D628), NGC 4945 (D411) and NGC 5128 (D482) and his drawings of them, Fig 17 and Fig 20.
The descriptions give the Dunlop number, RA, SPD and number of observations.
Glen,
Excellent piece of history about an often forgotten astronomer.
To me Dunlop never received the accolades he deserved
A pioneer of astronomy in our Country
One question though , I’m assuming this location D is another observing spot ( Elders house ) as his timber Observatory in Parramatta Park was a fare distance from this location near the Woolpack hotel.
Did Dunlop have various observing locations ? I assumed he only used the Observatory in the Park ?
I’ve had a beer at the Woolpack with my son , he lived in Dunlop st Parramatta for 5 years
Thanks for posting
Cheers
Martin
Between 11 March 1822 and 16 June 1823 Rumker and Dunlop observed between 2000 and 2300 stars for Brisbane’s star catalogue. Rumker then left the observatory after some disputes with Brisbane, and Dunlop carried on alone.
Governor Brisbane left Sydney on 1 December 1825 and returned to Scotland on the ship Mary Hope via Cape Horn and Rio. Dunlop finished observing for a catalogue of 7385 stars on 2 March 1826.
Dunlop wrote “On the 7th March 1826 I removed from the (Parramatta) observatory to (James and Mary) Elders house” in Marsden St. He made two catalogues there. The first catalogue contained 629 clusters and nebulae and the second 253 double stars.
What an amazing experience it must have been, knowing that he was (potentially) cataloguing objects never discovered before. It's enjoyable enough viewing objects from catalogues these days, but to make significant contributions to them would have been incredible, if he was aware of it at the time. Thanks for sharing Glen.
Astronomical twilight ended at 18:40 on Sunday night at Parramatta and the 34% sunlit Moon rose at 1am on 1/5. Dunlop catalogued 8 new objects that night and revisited 6 that he had seen on previous nights.
The 8 new objects were
At 20:03 NGC 3372 the eta Carinae nebula that Lacaille found in 1751
At 20:14 Collinder 236 an OC
At 21:07 NGC 3960 an OC
At 21:22 NGC 4103 an OC
At 21:39 NGC 4349 an OC
At 21:40 NGC 4372 a faint Gb, his longest description was for this globular cluster
At 21:43 NGC 4439 an OC
At 22:14 NGC 4852 an OC
The 6 that he revisited were
OC NGC 3532 a Lacaille cluster
OC IC 2714
OC Melotte 105
Gb NGC 4833 a Lacaille globular
Gx NGC 4945 and
Gx NGC 5128
His descriptions of NGC 3372 (D309) and NGC 4372 (D67) are attached.
Dunlop’s drawing of eta Carinae is also attached, Fig 14.
His catalogue was arranged by south polar distance from south to north (SPD)
Wed 3 May 1826
Dunlop re-observed 6 objects and discovered one new cluster on Wed night.
The objects he revisited were NGCs 3766, 4349, 4945, 5128, 5286 and Harvard 6.
The new object was the open cluster Trumpler 17.
He swept the sky from 20:02 to 22:48.
Sunday 7 May 1826
Dunlop saw 12 objects on Sunday night; 3 OC, 3 Gb and 6 Gx.
Three of these galaxies were discovered by William Herschel; NGCs 2997, 3621 and 5253.
The other 3 were NGC 4696 (a new discovery) plus NGCs 4945 and 5128 which he saw again.
He discovered three new open clusters that night; NGCs 3680, 5460 and 5749.
Dunlop also discovered the Gb NGC 2808 at 18:06, 30 mins before twilight ended.
He observed the Gb NGC 3201 again and wrote the first good description of the globular cluster omega Centauri, NGC 5139. Halley was the first to realise that omg Cen was not a star. Lacaille saw omg Cen on 17 Feb 1752 and wrote “… it appears to the naked eye like a 3rd magnitude star seen through a thin mist and in the telescope, like a large, ill-defined comet.”
Attached is Dunlop’s description of omega Centauri (D440). Dunlop finished by observing NGC 5749 at 23:33.
Thoroughly enjoying reading these posts about Dunlops' observations and discoveries . Having spent most of my childhood and adolescence in the Parramatta region adds to the gravity of his work, to me.
Monday 8 May 1826
Dunlop saw 19 objects on Monday night, 17 OC and 2 Gb
Twilight ended at 18:34 and he discovered the large bright OC NGC 3114 at 18:50. At 0:12 he discovered the Gb NGC 5927 and the nearby Gb NGC 5946 at 0:19. He finished the night by discovering the rich OC NGC 6067 at 0:56 and the OC NGC 6087 at 1:01.
The other OCs seen that night were NGCs 3766, 4103, 5606, 5617, 5715, 5749, 5823, 5999, 6005, 6025, Trumpler 17, IC 2714, Melotte 105 and Ruprecht 164.
Tuesday 9 May 1826
At 18:24 Dunlop saw his first object, the OC NGC 2972.
He saw 18 OC that night, the best one was NGC 3293 at 19:19.
He also revisited three Gb; NGCs 3201, 4372 and 5286 and the Gx M83.
The last object that night was the OC NGC 5823 at 23:41.
