Object of the Week September 2nd, 2018 – NGC 6781

[Dragan]

NGC6781
PK 41-2.1

Aquila

RA 19 18 28
DEC 06 32 19.3

Type: Planetary Nebula
Mag: 11.4
Size: 1.9’
Central Star Mag: 16.2

An often missed planetary, NGC6781 is a beautiful, nearly circular planetary located in Aquila and it definitely deserves some attention your next time out. Not only is it easily located just 4 degrees NW of Delta Aquilae, it’s bright enough to reveal itself in scopes in small as 4 inches under ideal conditions.

My last opportunity observing this object was in October of 2015 with my 30” f/4.5 OMI EVO from western Illinois skies. Seeing and transparency were both 3/5 this night. My notes state a “bright and circular, obviously green in color. brightest south. Apparent mottling in the outer ring with a dark central region. No CS visible. OIII was best view”

As a side, NGC6781 was discovered by Sir John Herschel in 1847 using his 18” f/13 speculum mirrored telescope at the Cape of Good Hope.
As always,

“Give it a go and let us know!”

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copyright Sergio Equivar

[Ivan Maly]

Great choice, Dragan.

I suspect that the historical data you cite come from J. Herschel's catalog publication but not an actual discovery. NGC 6781 is considered to be William Herschel's III.743. I suspect that J. Herschel knew of this identity. Also, 1847 is late for a Cape observation.

It seems from my notes that I haven't looked at it with anything larger than 4 and 7 inches, and briefly with another observer's 12. It's a fine object, and looks in the 12 rather exactly like a greenish (actually, pretty deep green for a sizable planetary) version of the photo in your post. No central star noted.

[lamperti]

Seen this twice: in 1987 with a 10", 45 & 86x:"Surprised I picked it up without a filter. 86x + UHC appears slightly lopsided and no ring shape. Fairly large."
1997 with a 18", 287x + UHC: "Nice, round, even solid glow. More solid on one side."
Al

[Raul Leon]

Hello , here is my observation from 8/12/2007 : large; round; dark central area seen with averted vision; central star not seen; bright knot noticed on left upper corner; UHC filter works well on this object: 14mm Meade Ultrawide eyepiece at 113x magnification with my 14.5 Starstructure Dob f/4.3 3175

[Howard B]

My latest observation of NGC 6781 is from 2008 with my 28-inch scope on the darkest and most transparent night I can remember from Steens Mountain - or anywhere else:

"N6781 is a lovely sight tonight - round, but not quite a complete circle, its perimeter is broken but still filled with some nebulosity. A faint central star is seen as are several other stars inside or just outside the planetary. 408x, 21.95 SQM."

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By the way, that 21.95 SQM reading is an average of 10 readings, and the sky lived up to them, both telescopically and naked eye. I've not seen the sky like that since.

[Uwe Glahn]

Nice and bright PN. With small aperture already a nice catch.

16", 257x, [OIII], NELM 6m0+
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[Bertrand Laville]

Hi All,

With some delay due to a journey abroad, here is my observation of this PN with a 25" Obsession.
Good conditions, SQM 21,58, NELM 6,8v, seeing good to very good, 240x with OIII 12nm.

x100 Nagler 31mm / OIII
The NP is huge, So bright enough to grow.

x240 Ethos 13mm / OIII-12
The shape is well recognized: wide center, still nebulous, L6, L8 banks. The edges of S / E / W are net but not cut with a knife.*It's almost a circle.*Blur the limit N is perfectly visible and détaillable. There is no color.

X520 Ethos 6mm sf
Peripheral stars are seen, and highlighted on the sketch-picture Capella Obs (see my report at
http://www.deepsky-drawings.com/ngc-6781/dsdlang/fr .)
CS * is seen VI4, but the three stars that compose it are not separated.
A star in the halo, partly N, VI2 view.*Several other suspects, especially in SW limit, but not drawables.
This is a beautiful nebula.

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


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