Le Gentil 3 Dark Nebula (Cygnus) in LHaRGB
Planewave CDK12.5; AP 1100GTO AE
ASI6200MM, - Antlia Pro RGB & 3.5nm NB filters
Ha: (25 x 360s exposures, Bin 1x1, Gain 200)
R,G,B: (25,23,18 x 240s, Bin 1x1, Gain 100)
L:(29 x 210s, Bin 1x1, Gain 100)
Total Integration Time = 8.6 hours
“Ou est Le Gentil?” is the question on many minds in Paris late in the year 1761. Le Gentil was a very accomplished astronomer, discoverer of several nebulae (including M32, M36, M3, M8, and, of course, Le Gentil 3), and member of the French Royal Academy of Sciences. He is likely most famous for his unsuccessful expedition to India to observe the transit of Venus as one of hundreds of astronomers who travelled the globe to help determine the distance between the Earth and the Sun.
In any event, Le Gentil did not return with his data after the transit which he had missed due to a war, several travel itinerary problems, his being particular about his observatory location and ending up at sea during the actual transit.
Even geniuses can make questionable choices however, and Le Gentil’s choice was to stay away from Paris to have a second chance at the Venus transit eight years later. In the end, this was thwarted by cloud cover. Honestly, his expedition reads like a comic-tragedy and was even immortalized in song.
Meanwhile back in Paris, having received no answer to their question Le Gentil was declared dead, his seat on the Royal Academy assigned to someone else, his wife remarried, and his relatives plundered his estate. While all was eventually rectified, he never did supply his transit data but that is OK too because we all now know that the Sun’s distance is precisely 1 AU away.
The other reason for this title, is that I am not convinced that this image is indeed “Le Gentil 3” – the precise coordinates of this dark nebula were somewhat elusive to me. This image was my best guess – plate solving says it is definitely on LDN984 and surrounds. I thought was a very nice dark nebula vista with some nice looking reflections and various star colours. Of particular note is the arc reflection around the star v1331-Cyg – a variable star seemingly buried in the molecular cloud. I am not sure what caused the spurious reflection/flare in the upper left (likely my guider), but I left it in, rather than crop or clumsily try and fix.
No matter my equipment or weather frustrations, I now know to relax – it could be worse and don’t compound the problem by making poor choices.