deepskytraveler
June 3rd, 2024, 03:32 AM
Cannon (Cn) 3-1, PK 038+12.1, PN G038.2+12.0, VV 171
Constellation: Ophiuchus
Type: Planetary Nebula
RA: 18h 18m 41s
Dec: +10°09’44”
Mag: 13.5(v)
Size: 0.1' x 0.1'
Cannon (Cn) 2-1, PK 356-04.1, PN G356.2-04.4, VV 126
Constellation: Scorpius
Type: Planetary Nebula
RA: 17h 55m 0s
Dec: -34°22’30”
Mag: 12.2(v)
Size: 2”x3”
My original plan for this week’s OOTW was to document one of the many fine planetary nebulae found throughout the constellation Ophiuchus. As I began my research little did I know I would soon find myself going down a rabbit-hole and discovering the Cannon catalog. Here’s my story.
The expanse of sky containing the constellation Ophiuchus is a bountiful hunting ground for every type of deep-sky object. So too is my long-forgotten collection of DEEP SKY magazines from the late 80s and early 90s which I had recently came across. While browsing through the Summer 1988 Volume 6, Number 2 (issue #23) for planetary nebulae candidates in Ophiuchus I found two articles, each by a different author and each focused on a different constellation, however both referencing a planetary nebulae from the Cannon catalog, which I had never heard until now. Multiple Google searches failed to turn up anything on the Cannon objects or the Cannon catalog (with one minor exception). Not surprisingly that one minor exception was a reference by our own Steve Gottlieb in an August 28, 2021 Deep Sky Forum S&T Editors post (https://www.deepskyforum.com/showthread.php?1525-S-amp-T-editors-(Steve)) replying to a member’s query about H-beta targets. Steve’s reply included this short notation on Cn 2-1: “Dims with an OIII filter - best with UHC or H-beta.” It was apparent to me that Steve had at one time observed this planetary nebula.
With the Google searches failing me, on a whim, I searched for these two planetary nebula in SkySafari 7 Pro. Lo and behold not only were these two listed, but so were 5 other Cannon planetary nebulae, which I will list at the end of this article.
Returning to the DEEP SKY magazine, in an article by Jack Marling he wrote the following about Cannon 2-1: “This 12th magnitude planetary on the northeast edge of M7 is readily visible in most backyard telescopes. Photometric measurements yield a true visual magnitude of 12.2 for Cannon 2-1; the object is certainly brighter than its photographic magnitude of 13.8. Cannon 2-1 consists of a small disk surrounding a bright central star.” Jack continues by referencing a June 14, 1985 observation by Pierre Schwaar and his 20-inch telescope at 291x who described it as: “very small, about 2” in diameter. The object has a bright central star and blinks (averted vision shows the nebula, direct vision the star). Cannon 2-1 appears stellar at 138x. I estimate its brightness at 10th magnitude, including the star.”
Returning once again the DEEP SKY magazine, in an article by Phil Harrington, he wrote the following about Cannon 3-1: “About 4° to the northwest of the planetary nebula NGC 6572 in Ophiuchus is another planetary, unlabeled on the Sky Atlas 2000.0. Cannon 3-1 is a 12th magnitude planetary measuring about 6” across, which makes it readily identifiable with 6- to 8-inch instruments at high power. There is little additional information on Cannon 3-1 in any of the popular literature for observers.”
Unfortunately the story stops here, at least temporarily. I trust that the members of Deep Sky Forum will be able to fill in the blanks, so I can tell the rest of story. I had a hunch that Cannon might be Annie Jump Cannon, one of Harvard Computers hired by Edward Pickering in the early 20th century. Her story (https://www.aps.org/archives/publications/apsnews/202004/history.cfm) is fascinating so be sure to check it out. However after digging through many articles about her life and work I’ve been unable to find any evidence that this was her planetary nebulae catalog. Do you know who compiled the Cannon catalog of planetary nebulae?
More than most other OOTW objects we really need your observation reports and sketches of Cn 2-1 and Cn 3-1. As always, give it a go and let us know.
Cannon 1-1 mag 12.89 PN in the constellation Norma
Cannon 1-3 mag 11.89 PN in the constellation Scorpius
Cannon 1-4 mag 12.89 PN in the constellation Ara
Cannon 1-5 mag 11.89 PN in the constellation Sagittarius
Cannon 1-6 mag 11.89 PN in the constellation Sagittarius
Author’s note: the magnitude of these 5 Cannon planetary nebulae seem suspect
Constellation: Ophiuchus
Type: Planetary Nebula
RA: 18h 18m 41s
Dec: +10°09’44”
Mag: 13.5(v)
Size: 0.1' x 0.1'
Cannon (Cn) 2-1, PK 356-04.1, PN G356.2-04.4, VV 126
Constellation: Scorpius
Type: Planetary Nebula
RA: 17h 55m 0s
Dec: -34°22’30”
Mag: 12.2(v)
Size: 2”x3”
My original plan for this week’s OOTW was to document one of the many fine planetary nebulae found throughout the constellation Ophiuchus. As I began my research little did I know I would soon find myself going down a rabbit-hole and discovering the Cannon catalog. Here’s my story.
The expanse of sky containing the constellation Ophiuchus is a bountiful hunting ground for every type of deep-sky object. So too is my long-forgotten collection of DEEP SKY magazines from the late 80s and early 90s which I had recently came across. While browsing through the Summer 1988 Volume 6, Number 2 (issue #23) for planetary nebulae candidates in Ophiuchus I found two articles, each by a different author and each focused on a different constellation, however both referencing a planetary nebulae from the Cannon catalog, which I had never heard until now. Multiple Google searches failed to turn up anything on the Cannon objects or the Cannon catalog (with one minor exception). Not surprisingly that one minor exception was a reference by our own Steve Gottlieb in an August 28, 2021 Deep Sky Forum S&T Editors post (https://www.deepskyforum.com/showthread.php?1525-S-amp-T-editors-(Steve)) replying to a member’s query about H-beta targets. Steve’s reply included this short notation on Cn 2-1: “Dims with an OIII filter - best with UHC or H-beta.” It was apparent to me that Steve had at one time observed this planetary nebula.
With the Google searches failing me, on a whim, I searched for these two planetary nebula in SkySafari 7 Pro. Lo and behold not only were these two listed, but so were 5 other Cannon planetary nebulae, which I will list at the end of this article.
Returning to the DEEP SKY magazine, in an article by Jack Marling he wrote the following about Cannon 2-1: “This 12th magnitude planetary on the northeast edge of M7 is readily visible in most backyard telescopes. Photometric measurements yield a true visual magnitude of 12.2 for Cannon 2-1; the object is certainly brighter than its photographic magnitude of 13.8. Cannon 2-1 consists of a small disk surrounding a bright central star.” Jack continues by referencing a June 14, 1985 observation by Pierre Schwaar and his 20-inch telescope at 291x who described it as: “very small, about 2” in diameter. The object has a bright central star and blinks (averted vision shows the nebula, direct vision the star). Cannon 2-1 appears stellar at 138x. I estimate its brightness at 10th magnitude, including the star.”
Returning once again the DEEP SKY magazine, in an article by Phil Harrington, he wrote the following about Cannon 3-1: “About 4° to the northwest of the planetary nebula NGC 6572 in Ophiuchus is another planetary, unlabeled on the Sky Atlas 2000.0. Cannon 3-1 is a 12th magnitude planetary measuring about 6” across, which makes it readily identifiable with 6- to 8-inch instruments at high power. There is little additional information on Cannon 3-1 in any of the popular literature for observers.”
Unfortunately the story stops here, at least temporarily. I trust that the members of Deep Sky Forum will be able to fill in the blanks, so I can tell the rest of story. I had a hunch that Cannon might be Annie Jump Cannon, one of Harvard Computers hired by Edward Pickering in the early 20th century. Her story (https://www.aps.org/archives/publications/apsnews/202004/history.cfm) is fascinating so be sure to check it out. However after digging through many articles about her life and work I’ve been unable to find any evidence that this was her planetary nebulae catalog. Do you know who compiled the Cannon catalog of planetary nebulae?
More than most other OOTW objects we really need your observation reports and sketches of Cn 2-1 and Cn 3-1. As always, give it a go and let us know.
Cannon 1-1 mag 12.89 PN in the constellation Norma
Cannon 1-3 mag 11.89 PN in the constellation Scorpius
Cannon 1-4 mag 12.89 PN in the constellation Ara
Cannon 1-5 mag 11.89 PN in the constellation Sagittarius
Cannon 1-6 mag 11.89 PN in the constellation Sagittarius
Author’s note: the magnitude of these 5 Cannon planetary nebulae seem suspect