wvreeven
August 20th, 2018, 08:56 AM
Sh2-84, LBN 131, LBN 055.73-03.64
Emission Nebula
Constellation: Sagitta
RA: 19 49 07.7
Dec: +18 23 05
When we point our telescopes towards the constellation Sagitta usually it is to observe the globular cluster M 71 or to move on to M 27 in Vulpecula. But there are several other treasures in this constellation, among which Sh2-84. As many of us undoubtedly are aware, Sh2 stands for the 2nd catalog published by Stewart Sharpless. When you search for his last name on this forum you'll find more than 25 threads mentioning his name but who was he?
Stewart Sharpless was an astronomer who helped identify the structure of the Milky Way. As an undergraduate at Yerkes Observatory he helped Johnson and Morgan, then Sharpless' supervisor, with calculations that helped define the UBV photometric system. In 1952 Sharpless and fellow student Osterbrock published estimates of the distances to HII regions which demonstrated the spiral structure of the Milky Way. In 1953 he moved to Flagstaff where he joined the staff of the US Naval Observatory. Here he published his catalog of HII regions, the first edition in 1953 with 142 nebulae and the second and final in 1959 with 313 nebulae. This is the now famous Sh2 catalog.
There are many bright and famous nebulae in the Sh2 catalog though Sh2-84 is not among them. Here is an image taken by Ron Brecher. For the original, see http://astrodoc.ca/sh2-84/:
http://astrodoc.ca/wp-content/uploads/2016/07/Sh2-84-12hr05m-HaRGB-July-2016.jpg
I got interested in this nebula recently because it nicely fits in the same FOV of my 71 mm refractor in combination with my DSLR camera as M 71. If you look closely you can see some red glow just left of the bright red star (Delta Sagittae) to the lower right of my image:
3161
When I imaged it a few weeks ago I got curious to see if it would be visible in my 20" telescope visually. It was! My notes read:
At 83x with UHC and better with OIII visible as an arced patch of light next to the star TYC 1619-0647-1. Other much fainter hazes are visible around HD 350683 and due north of the first and brightest bit. At 151x the brightest part has a sharp edge to the east and an absorption hole is visible. The nebula is dolphin shaped.
As always,
"Give it a go and let us know!
Good luck and great viewing!"
Emission Nebula
Constellation: Sagitta
RA: 19 49 07.7
Dec: +18 23 05
When we point our telescopes towards the constellation Sagitta usually it is to observe the globular cluster M 71 or to move on to M 27 in Vulpecula. But there are several other treasures in this constellation, among which Sh2-84. As many of us undoubtedly are aware, Sh2 stands for the 2nd catalog published by Stewart Sharpless. When you search for his last name on this forum you'll find more than 25 threads mentioning his name but who was he?
Stewart Sharpless was an astronomer who helped identify the structure of the Milky Way. As an undergraduate at Yerkes Observatory he helped Johnson and Morgan, then Sharpless' supervisor, with calculations that helped define the UBV photometric system. In 1952 Sharpless and fellow student Osterbrock published estimates of the distances to HII regions which demonstrated the spiral structure of the Milky Way. In 1953 he moved to Flagstaff where he joined the staff of the US Naval Observatory. Here he published his catalog of HII regions, the first edition in 1953 with 142 nebulae and the second and final in 1959 with 313 nebulae. This is the now famous Sh2 catalog.
There are many bright and famous nebulae in the Sh2 catalog though Sh2-84 is not among them. Here is an image taken by Ron Brecher. For the original, see http://astrodoc.ca/sh2-84/:
http://astrodoc.ca/wp-content/uploads/2016/07/Sh2-84-12hr05m-HaRGB-July-2016.jpg
I got interested in this nebula recently because it nicely fits in the same FOV of my 71 mm refractor in combination with my DSLR camera as M 71. If you look closely you can see some red glow just left of the bright red star (Delta Sagittae) to the lower right of my image:
3161
When I imaged it a few weeks ago I got curious to see if it would be visible in my 20" telescope visually. It was! My notes read:
At 83x with UHC and better with OIII visible as an arced patch of light next to the star TYC 1619-0647-1. Other much fainter hazes are visible around HD 350683 and due north of the first and brightest bit. At 151x the brightest part has a sharp edge to the east and an absorption hole is visible. The nebula is dolphin shaped.
As always,
"Give it a go and let us know!
Good luck and great viewing!"