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Entire DOCdb database of 18,816 objects.



NGC 7635 (17,776 of 18,816)


oc gc pln bn dn gx gxcl ast aka lost




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Bubble Nebula

NGC 7635, Ced 210, LBN 548, Sh 2-162, PN Hb 11, Caldwell 11, Hubble 11, Bubble Nebula, IV 52, h 2235, GC 4947

RA: 23h 20m 48.3s
Dec: +61° 12′ 6″

Con: Cassiopeia
Ch: MSA:1070, U2:34, SA:3


(reference key)

Type: bright nebula (HII region)

Mag: B=?, V=?

Size: ?
PA: ?

Image gallery

Photos  (3)

Select a photo and click the button to view

Historical observations

William Herschel (c.1784)

Synonyms: H IV-052

Discovered in 1787 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "a star 9th mag with vF nebulosity of small extent about it."

NGC/IC Dreyer (1888, 1895, 1908)

This bright nebula, which covers an area of 90 square arc minutes, is described in the NGC as "very faint, star of 8th magnitude involved in excentric nebulosity."

Published comments

Mount Wilson Observatory Annual Reports (1920-1921)

p.254: "NGC 7635 appears to be a planetary involved in an extended nebula. There is some suggestion that this is a case of actual collision."

Doig, P. (1926)

"A Catalogue of Estimated Parallaxes of 112 Nebulae, Open clusters and Star Groups", Vol 36 (4), p 107-115.

"nebulous star, 8th magnitude."

Cederblad, S. (1946) [VII/231]

Ced 210 (NGC 7635)

Position (1900): RA 23 16.3, Dec + 60 39

Star: +60 2522 (Mp=8.5, V=8.7, SpT=O7)

Spectrum of nebula: emission spectrum (observed)

Classification: Neb associated with mainly one star (which may be multiple) - Quasi-planetary, representing a transitional type between real planetaries and bright diffuse nebulae (eg. NGC 1514)

Size: 15.5'x7.5'

Notes: "NGC 7635 = GC 4947 = h 2235 = H IV 52. Disc. 1787. (88 Pl 86, 103, 114, 364, 366, 482, 486, 578, 630 Pl 20 Pl 24, 715, 761, 762, 821). R. Has also been classified as a planetary."

Sharpless (1959)

A catalogue of H-II regions. Astrophys.J.Suppl.Ser., 4, 257-279.

Sh 2-162: "NGC 7635. Peculiar elliptical structure near center; similar to No. 298."

Lynds, B.T. (1962)

Lynds, B.T. (1962) Catalogue of dark nebulae. Astrophys.J.Suppl.Ser. 7, 1-52. [also: computer datafile: VII/7A]

Lynds, B.T. (1965)

(Astrophysical Journal Supplement, No 105, 1965) in her Catalogue of Bright Nebulae notes that this nebula is very bright, more prominent on the red POSS plate and has a maximum size of 15' x 8'.

Sulentic & Tifft (1973)

The RNGC (Sulentic and Tifft 1973) notes that this is a diffuse nebula.

Photo index

by Jim Lucyk: Sky&Tel. 7/61 p7, Sky&Tel. 5/81 p463, Sky&Tel. 12/88 p712, Astronomy mag. 11/79 p79, Deep Sky #7 Su84 p29, Deep Sky #23 Su88 p19, Burnhams V1 p522, Vehrenberg's Atlas of DS Splendors (3ed) p237, Astronomy mag. 7/76 p77, The Astrograph 6-7/88 p86,87, Vehrenberg's Atlas of Galactic Neb-2 p153.

[amastro] Hubble's Planetaries

I received an email from a gentleman who is researching the 12 'planetaries' discovered by Edwin Hubble and which were referenced in an early PASP paper. This gentleman, whom I shall call Tom, has run into a stone wall in regards to Hb 11. He says that he has obtained information on all the other Hb objects, but can find nothing about Hb 11. The paper in which Hubble announced his discoveries was 'Twelve NEW Planetary Nebulae', PASP 33, 175 (1921). Tom was wondering if I had a copy of this or how to go about obtaining one, as his university's PASP publications don't go back that far. I don't have a copy of this, and nothing that I have accessed on the net has led me any closer to any information on Hb 11. It's not in SIMBAD nor catalogued as a planetary. It is not included in the Megastar database. Can anyone shed any light on this object and/or PASP paper? Evidently it has turned out to be a non-existant object, or re-classified and the Hb designation dropped (which doesn't sound likely). No where (so far) have I been able to obtain any coordinates for this object. Hb 8, a PN is at 19h 06 -33 11, Hb 9 is NGC7048 at 21h 14, +46 16, and Hb 12, another PN, is at 23h 26 +58 10.

Thanks for any help on this. This is a great and very interesting resource, guys!



The first place I looked was at the ADS article service to see if they'd scanned-in the old PASPs yet---nope. Well, the library is maybe 150 away....

source: 1921PASP...33..174H


Publ. Astron. Soc. Pac., 33, 174-176 (1921)

Twelve new planetary nebulae.

Hubble Modern name, comments

1 IC 289

2 NGC 2818

3 NGC 6072

4 PN G003.1+02.9? SIMBAD sez "not Hubble 4"! position matches at least

5 PN G359.3-00.9 = HD 316340

6 IC 4670

7 PN G003.9-14.9 = HD 175194

8 PN G003.8-17.1

9 NGC 7048

10 IC 1470 (not PN)

11 NGC 7635 (not PN)

12 PN G111.8-02.8

It is worth noting that Hubble gives relative line strengths for the green [OIII] doublet (still called "nebulium" in 1921), H-beta and other Balmer lines, HeI 4686A, and [OIII] 3727A. This is the sort of data needed to decide ahead of time whether a UHC or [OIII] filter is better for visual detection.



Thanks again Brian!

Yes, I had also looked at the ADS service too, and saw that the PASP articles only go back a few years.

So all that searching for Hb 11, and it turns out to be the 'Bubble Nebula' in Cassiopeia! Now's that's got to be good for a bit of star party trivia. I recall observing the Bubble with a UHC on a 20" from Fremont Peak, and it was pretty striking. Don't have notes on it with a OIII though. BTW, Hb 5 in Sagittarius was imaged by the HST, and was dubbed 'Hubble's Double Bubble'; so Hb 11, re NGC 7635, although not a PN, could still claim the name 'Hubble's Bubble'.

I forwarded your information on to Tom in San Diego, and I'm sure he'll appreciate it, as I do.


Modern observations

Sanford (1989) Observing the Constellations

writes: "Some 36 arcminutes to the southwest [of NGC 7654, M52], is the Bubble Nebula, NGC 7635. This object shows a complete spherical shell of gas in large instrument photographs, but only the diffuse area near the bright star was apparent in a 22-inch f/8 reflector."

Neilson, David (1992)

Neilson (Oakland, California, USA), writes in the The Webb Society Nebulae and Clusters Section Report No. 10, July 1992: "Very large and incredibly thin and faint. Overlooked several times before being spotted. Appears oval in shape with eccentrically located star, to the west of which a concentration is seen. Faint striations to the south (12.8-inch)."

Tom Lorenzin

Lorenzin, in the e-version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "7M; emission nebula associated with 8M star; 8' x 15' extent; larger aperture and N-filter shows detail; just 30' SW of M-52."

Gross, Todd (IAAC)

Your skill: Intermediate ; Date and UT of observation: 08/01/97 0750 GMT; Location & latitude: 22 miles west of Boston, Ma. 42.3N; Site classification: Suburban; Limiting magnitude (visual): 5 (estimated) 5(est) in vicinity of object; Seeing (1 to 10 - worst-best): 5; Moon up (phase?): Yes, thin crescent; Instrument: 16" Dob, 96%, 99% coatings; Magnifications: 61,122,263; Filters used: UHC

In scanning the sky near M52, I was able to pick up a very weak, round nebulous area surrounding a moderately bright, approximately 9th magnitude star. However, at highest power I began to see evidence of detail, although not exactly a "bubble". The round glow was much more evident at higher power in my suburban skies. A somewhat comma shaped appearance began to become evident, with a tail-like extension coming down on one side of the circular glow.

Gramer, Lew (IAAC)

Your skills: Intermediate; Date and UT of Observation: 1997-07-31/08-01, 06:40 UT; Location: Savoy, MA, USA (42N, elev 700m); Site classification: rural; Limiting magnitude: 7.2 (zenith); Seeing: 7 of 10 - pretty good, intermittent haze; Moon up: no; Instrument: 20" f/5 Tectron truss-tube dob Newtonian reflector; Magnification: 170x, 290x, 360x; Filters used: None, UHC; Object: ngc7635 (Bubble Nebula); Category: Emission nebula (with planetary features); Description:

This famous but faint enigma was easily found 30' or so SW of M52, just NE of mag. 7 star HD 220057. The brightest region surrounds a pretty double of mags 10 and 11, wth a third star mag 14 involved to the NW. Diffusely visible to direct vision, with some mottling apparent, especially to W and SW. To averted vision, a distinct long arc of nebulosity stretches N, curving gracefully around to the E, toward a mag. 11 star 15' away. Three distinct hazes were also visible to the S and SW of the main nebulosity, all needing averted vision (and usually field motion), and all showing little detail other than an irregular outline. Yet another "hook" of neb- ulosity was faintly visible to averted vision, arcing S and then SW of the main nebula. Quite a sight, when viewed with patience!

Brian Skiff

15cm - cen * seen. vindef neb. some haze seen but difficult to estimate size.

HM/BS, 28Jun1971, FtL.

- only vf haze mostly N of the fntr of two br *s in fld. BS, 12Jul1988,

Anderson Mesa.

- fairly f diffuse neb mostly N of m9.5 * (sl fntr than br * in M52). 2'.5

diam, sl enhanced by DS filter, best w/UHC, [OIII] def worse than UHC,

which reveals br knot immed W of br *. BS, 12Oct1990, Anderson Mesa.

25cm - not much. among *s, neb is a few arcmin N of m7.5 *.

30cm - little neb seen, 1' diam, NW of cen *, which is on edge of neb. m14 *

assoc. a little brtr in the middle.

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