sponsored by psychohistorian.org
Type: planetary nebula
Mag: B=13.4, V=14.4
Synonyms: H VI-038
Discovered in 1791 by William Herschel with an 18.7-inch f/13 speculum telescope. He classified it as a cluster, describing it as "cB, S, iF, easily resolvable. Some of the stars are visible."
This planetary is described in the NGC as "considerably bright, small, irregularly round, well resolved, clearly consisting of stars."
Terzian Y (1980) Q.J. R.astr.Soc vol 21, p82-92 [09.16.1] notes that this planetary shows multiple shell structure.
= PK 45- 4 1
The RNGC (Sulentic and Tifft 1973) notes that this is a 13.5 mag planetary nebula.
Photo Index by Jim Lucyk: Sky&Tel. 9/82 p292, Sky&Tel. 9/84 p282, Astronomy mag. 8/86 p87, Deep Sky #3 Su83 p22, Deep Sky #20 Fa87 p12.
Steve Coe, in "SACNEWS On-line for September 1996", observing with a 13-inch, notes: NGC 6804 is a planetary nebula at 19 hr 31.6 min and +09 13. I have two observations of this object which make it clear for me that it shows different shapes with direct and averted vision! The first time I observed this nebula I saw it as bright, pretty large and comet shaped at 100X. Using 200X shows a star at the tip of the comet shape and another dimmer star involved to the west. A nice object at high power. Another observation with the 13" from Dugas Rd. on a 7/10 night; pretty bright, pretty large, and round at 135X. At 220X, 4 stars are involved including a 12th magnitude star on the eastern edge. Averted vision elongates the nebula, the pretty bright star involved also makes the nebula appear comet shaped. Using direct vision it is round in shape. I observed this nebula with a 36 inch recently and I am afraid that I didn't completely solve the mystery. I saw 7 stars involved with the central star held for 20 percent of the time, central bright region is mottled and shows lots of fine detail, bright and dark regions that are small, but held steady, a unique object. There is a brighter diamond-shaped central region and then fainter outer region which makes the entire object round. So, I assume that the brighter inner section is diamond or comet shaped and the outer, faint envelope of nebulosity makes it appear round to my eye. A weird object, see for yourself.
Hartung notes that "in a field of scattered stars is an elliptical luminous haze about 40 arcsec across, pale grey and fairly even except for the diffuse edges. 15cm shows the nebula dimly."
Houston notes: "Having a total light roughly equivalent to a 13th mag star and being about a minute of arc in diameter, this object has a low surface brightness. I failed to find it on two ccassions, but was fairly certain on a third, when my magnitude limit was about 13.9. A magnification of 100 was used." He adds that it was easy in his 10-inch.
Sanford notes that this oval planetary (30" x 60") is associated with a star of about 12th magnitude on its north-eastern edge.
Steve Coe, using a 13" f/5.6, notes: "Bright, pretty large, comet shaped at 100X. Using over 200X shows a star at the tip of the comet shape and another dimmer star involved to the west. A nice object at high power. Another observation with the 13" from Dugas Rd. on a 7/10 night; Pretty bright, pretty large, round, noticed at 135X. At 220X, 4 stars involved including 12th mag on the E edge. Averted vision elongates the nebula, the pB star involved also makes the nebula appear comet shaped when with direct vision it is round."
AJ Crayon, using an 8" f/6 Newtonian, notes: "is a planetary nebula located in the center of an isoceles triangle of stars. At 100x it is seen better with a UHC filter, using averted vision during moments of good seeing. With all of this, the east side is brighter, the position angle of this slightly elongated object is east and it has a faint star involved.
DSM 3,22: br * NE edge in pa55. fntr * off W edge (pa270). no * btwn cen * and * NE.
15cm - 120x: 1' diam, even grey. * on E? HM, Roof.
- vis @ 62x, 1' diam. m12.5 * on edge in pa30. some f detail w/in. BS, 3Sep1981, Anderson Mesa.
- lg mod br neb easy to discern @ 50x. 165x/295x: m13.5-14 * exactly on NE edge, m14.5 farther NE. m14.5 cen * clr w/averted vis, and a third m14.5-15 * just off W edge. neb 1'.25 diam, seems circ, occas mottled prob due to four *s popping in & out of visibility. BS, 30Jun1989, Anderson Mesa.
25cm - vf. cen * m13 vis in center. m12.5 * on NE edge distracting. BS, Roof.
- detail from 1981 15cm obs is at least one * m13.5 off-center to E side of neb. m13.8 * on edge pa250. perhaps another * btwn `cen *' and * NE edge. BS, 3Sep1981, Anderson Mesa.
30cm - easy. cen * noted. m12 * on NE in neb. fades gradually to sky. 1' or a bit less in diam. on W is m13.5 *. CBL, Roof.
Instrument:12"Dobsonian Reflector Telescope.
Sky Conditions:The fainter parts of the Milky Way are barely visible.
Transparecy of the Sky:Haziness only visible on the horizon.
Seeing:Atmosphere stable with little interference.
First Impression:Planetary Nebula.
Chart Number:No.261(Extract taken out of "Spacewatching").
Brightness Profile:Low Surface Brightness.
Challenge Rating:Easy to observe in very dark skies in a very large aperture telescope.
Overall Shape:Oval and well defined.
Is a disk seen? Yes,a fairly medium sized disk is seen at 214*.
Is the edge sharply defined? Yes.
What colour is the nebula? Red.
Is there a central star? No.
16-inch f/10 SCT (127x 290x 462x)
This planetary was easy seen against a sea of faint stars. The shape is elongated in a north-northeast to south-southwest direction. The edges are very hazy which gives the impression of a hazy galaxy. A magnitude 12 star is situated in the north-east extreme of the nebulosity with a fainter star imbedded into the western part of the nebula.
The Messier objects
The Bennett objects
The Caldwell list
DOCdb is still in beta-release.
Known issues, feature requests, and updates on bug fixes, are here:
Found a bug? Have a comment or suggestion to improve DOCdb? Please let us know!
DOCdb is a free online resource that exists to promote deep sky observing.
You could help by sharing your observations, writing an article, digitizing and proof-reading historical material, and more.
Everything on DOCdb.net is © 2004-2010 by Auke Slotegraaf, unless stated otherwise or if you can prove you have divine permission to use it. Before using material published here, please consult the Creative Commons Attribution-Non-Commercial-Share Alike 2.5 License. Some material on DOCdb is copyright the individual authors. If in doubt, don't reproduce. And that goes for having children, too. Please note that the recommended browser for DOCdb is Firefox 3.x. You may also get good results with K-Meleon. Good luck if you're using IE. A successful experience with other browsers, including Opera and Safari, may vary.