Object of the Week October 9th, 2016 - NGC6905 The Blue Flash

NGC6905
Henize 2-466
PK 61-9.1

Delphinus

Planetary Nebula

RA 20 22 23.0
DEC 20 06 16

Mag: 10.9
CS Mag: 15.7

Size: 72.0" x 37.0"

NGC6905 or the Blue Flash Planetary, was discovered by none other than William Herschel in 1784. Located in northwestern Delphinus near the borders of Vulpecula and Sagitta, NGC6905 is a rather bright planetary visible in a plethora of apertures. Online reports indicate that scopes as small as 3.5" are capable of seeing this object but if you want to see any of its color or central star, scopes upwards of 14" is recommended.

To locate it, NGC6905 is situated in a tiny triangle asterism comprised of 10th and 12th magnitude stars approximately 6 degrees NW of Alpha Delphini. My most recent observation came nearly one year ago this month while testing out a 30" I was fortunate enough to have on loan:

NGC6905 in Delphinus 14OCT15 Dixon, Il T4S3 30" f/4 OMI EVO
Eastern and Western edges (mostly eastern) quite pronounced with northern and southern edges less defined. Overall appearance reminds me of a small M27. Mottling throughout central regions. CS direct vision. Rather light blue object but less so than 7662 i think.

So no matter the size of scope, be sure to check out NGC6905 while Delphinus is ideally placed in these October skies.

And as always,

Give it a go and let us know!

Attachment 2285
©Adam Block

Nice target, also for smaller aperture.

I have an older result with my former 16".

16", 450x, UHC, NELM 7m+
Attachment 2300

Here's an observation from last summer in the White Mountains, east of the Sierras (elevation 8500')

24" (8/14/15): the "Blue Flash" planetary was observed at 500x and 750x in excellent seeing. The main body is oval 5:4 NNW-SSE, ~48"x40" and annular. The rim is brightest along a thin strip on the east side and enhanced in a slightly brighter triangular wedge (roughly 60°-80°) extending east from the mag 15.7 central star. The opposite western rim is also brighter, but the north and south ends are not enhanced. The interior is mottled with a slightly darker, irregular central "hole", particularly on the south and west side of the central star, but not to the east. Mag 10.4 HD 352100 lies 48" N of center and a mag 12 star is 38" SSE of center, in the direction of the major axis.

An extremely faint outer halo or wing was occasionally glimpsed off the north-northwest end, tapering in the direction of the major axis and extending 10"-12" in length. The corresponding extension off the south-southeast side and ending at the mag 12 star (creating a lens-shaped outline on deep images) was not seen, although Jimi Lowrey felt it was equally visible.

Steve
What is your preferred eyepie setup to for these magnifications? Thanks

Hi,
great choice! One of the coolest PN in the skies. Here is my sketch, made with 24", 421x and UHC-filter:
Attachment 2303

best regards + CS
Daniel