Object of the Week – Aug 26, 2018 – NGC 7094, PN in Pegasus

[Steve Gottlieb]

NGC 7094 = PK 66-28.1 = PN G066.7-28.2 = K 1-19
RA: 21h 36m 52.9s
DEC: +12° 47' 19"
Type: Planetary Nebula (class IV - ring)
Size: 99" x 91"
Distance: ~5900 light years
Mag: V ≈ 13.7

American comet-hunter and prolific nebula-hunter Lewis Swift discovered NGC 7094 (Swift II-88) on 10 Oct 1884 using his Clark 16-inch refractor in Rochester, New York. He recorded "nebulous star; Bright *; in eeF nebulosity; v difficult; nearly pointed to by 3 st. in a line." He added in a footnote, "This is a prototype of GC 4634 [NGC 7023] and several others, and of No. 7 of my Catalogue No. 1 [NGC 2247], which differs from most nebulous stars by being exactly in the center of circular nebulous atmospheres of uniform brightness." Wolfgang Steinicke mentions that Swift also called this object "the most wonderful of all [nebulous stars] - in fact it is the only instance known to me - for instead of the central star being single, it is double." The second star is line-of-sight on the northeast side.

This beautiful planetary is located just 1.8° NE of M15 and 7' south of 10th magnitude SAO 107277. Images show a complex of interior filaments, an irregular multi-rim structure, and a darker center. On deep images, faint galactic nebulosity (IFN) suffuses the surrounding field in a misty haze and a few distant galaxies are visible. The central star is a relatively bright mag 13.5.

NGC 7094.jpg

The planetary is visible in an 8-inch scope using a filter and unfiltered in a slightly larger scope. My first observation was 33 years ago in a 13.1-inch f/4.5, which easily showed the central star and a low surface brightness halo unfiltered, but even with a UHC filter there was no structure. Here's my last observation in 2016 through my 24-inch.

Excellent view at 200x using a NPB filter. The 90" disc is fairly crisply defined and contains a bright central star (mag 13.5), even with a filter. Unfiltered, a mag 14.5-15 star is at the NE edge. The planetary is weakly annular and brighter in a 90° arc along the west side. There appears to be a knot or local brightening right at the west edge of the rim.

As a challenge, the compact galaxy II Zw 141 = PGC 67044 lies 6' WNW. It was logged as "faint, very small, round, 12" diameter." On the DSS a mag 15.2 star is at the southwest edge (6" separation from the center of II Zw 141) and probably the galaxy + star were merged visually.

Give it a go and let us know!

[Steve Gottlieb]

This close-up image by Adam Block/NOAO/AURA/NSF shows the slightly brighter western side and enhanced point --

NGC 7094-1.jpg

[Raul Leon]

Hello, here is my observation from 9/9/2010 with my 15 inch Dob: ngc 7094 ,very faint, round; central star observed; DeepSky filter works well on this object; 10mm Radian at 158x magnification ngc 7094.jpg

[Bertrand Laville]

Hi All,

Here is my observation with 25*» Obsession, in rather bad conditions*: NLEM 6,5v, SQM 21,26
Detailed report here*: http://www.deepsky-drawings.com/ngc-7094/dsdlang/fr


NGC 7094 T635 BL 2009 09 23.jpg


x240 Ethos 13mm / Oiii
This is a very PN "transparent", very fine.
Practically round.*I see that this is not a perfect round, but I can draw the shape irregularities.
The color is very saturated, and azure: C140 / S20.*The CS C140 / S40.
The central hole, L2, occupies almost the whole space;*in fact, there is a single circumferential reinforcement, L3.*A slightly thicker reinforcement, L3.5 to L4, is noticeable NW S.

Nagler 3.5mm x890
Central star is very light, m ​​~ 13v.
A Star in the halo, obviously, m ~ 14.5V, but nothing else, neither above nor around the halo.

But the most interesting is following.
Some months later, 2010 December 27: to set the proper design, I discovered that I perfectly positioned but stellar, and taken to a star of the 15th or 16th, the small galaxy 2MASSX J21364460 + 1247588, m14.25J, and m16,894B according to GLADE v2/3.
NGC 7094 is a very NP "light", very transparent, and ultimately unspectacular.

Clear skies
Bertrand
http://www.deepsky-drawings.com/

[Howard B]

I observed 7094 at the OSP a couple weeks ago with my 28-inch through fairly thick wildfire smoke. My sketch looks identical to Bertrand's above but here are my notes:

"Larger and fainter than I expected but the OIII popped it out at 155x, and the NPB at 253x. The southern rim is the brightest part of this planetary."

Curiously, I also have an observation - but no sketch - from September 1999 with my old 20-inch Obsession:

"I tracked down the faint planetary NGC 7094 in Pegasus just 1.5 degrees east of M15. Looked best with the OIII at 323x - a broken ring with shreds of wisps littered about the relatively bright central star."

Looks like I saw a lot more 19 years ago with a smaller scope!

[Uwe Glahn]

Very nice object Steve.

I found an old sketch with my 16-inch. Under not perfect transparency of a normal sky I noted a brighter rim and a stellar knot at the western side.
sketch: 16", 180x, [OIII], Seeing III
NGC7094.jpg

Additional I found an observing note with the 27-inch. Under very good transparency (NELM 7m0+), 326x and UHC filter I wrote:
no sign of the inner structure, to faint at all; second star northeast of the bright CS easy to see; three ring segments visible - brighter western side with a stellar peak to the southwest and a longer rim from west to northwest, fainter rim to the southeast; PN seems to be brighter inside the north filling