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RA: 19h 01m 54.08s
Dec: −36° 57′ 11.1″
Con: Corona Australis
Ch: MSA:1434, U2:379, SA:22
Ref: SIMBAD, [2003A&A...399..141M], Corwin (2004)
Type: reflection nebula
Mag: B=?, V=?
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Region around S Corona Austrina. Transvaal Observatory Circular, No 5, 57.
[see also NGC 6723]
The variable stars and nebulae near R Corona Australe. Union Obs. Circ. No.36, 282-284.
Catalogue of bright diffuse galactic nebulae.
The RNGC (Sulentic and Tifft 1973) notes that this is a diffuse nebula.
Ced 165c (NGC 6729)
Position (1900): RA 18 55.2, Dec - 37 5
Star: R Cor Austr (variable Mp and V, SpT=Gpe)
Spectrum of nebula: continuous and emission spectrum (observed)
Classification: Neb associated with mainly one star (which may be multiple) - star surrounded by a neb envelope with conspicuous structure (eg. IC 5146)
Notes: "165 c = NGC 6729 = GC 5937 = The variable nebula connected with R Corona Austrina = e. Disc. Schmidt 1861. (217, 271, 366, 375, 386, 429, 430, 432, 433, 450, 482, 486, 579, 690, 693, 832)."
Bernes, C. (1977) A catalogue of bright nebulosities in opaque dust clouds.
= Bernes 159
Bernes notes in his Catalogue of Bright Nebulosities in Opaque Dust Clouds that this object is also known as Cederblad 165c. He defines it as a combination emissionreflection nebula, 1' across, and part of the R CrA complex. Sanford writes: "the cometlike nebula NGC 6729 [has] the variable star R CrA in its 'nucleus' and also follows the erratic changes of brightness of the star."
= Bernes 159, N6729, GN 18.58.5, Ced 165c, Other designations: R CrA
Class: CN (cometary nebula)
by Jim Lucyk: Sky&Tel. 8/62 p69, Sky&Tel. 9/83 p277, Astronomy mag. 7/86 p94, Burnhams V2 p696.
(1992, Webb Society Quarterly Journal, 89, 1-7, 'A Visual Survey of the Complex Field Around R CrA & TY CrA') writes "Found in the same field as NGC 6726-7, this is a distinctly comet-like object with its tail extended in PA 140 degrees. It is over one minute in length with a major:minor axis ratio of about 6:1. There is a 12th mag star (T CrA) at the SE corner of the tail. The variable R CrA, which lies at the head of the comet, was not visible in either the 25cm or 53cm telescopes. The object vanishes when an O III filter is employed. ... The variable stars R CrA and T CrA are Orion-type nebular variables of irregular period; R CrA varies over the range 10.0 - 14.4 (B) and T CrA over the range 11.7-14.3 (V). As illuminating stars of the reflection nebula NGC 6729, they cause the nebula itself to vary in brightness and form, not unlike Hubble's Variable Nebula (NGC 2261) in Monoceros."
Notes: "This field lacks the faint starry background of neighbouring regions and appears to be obscured by diffuse nebulous material rendered luminous near immersed stars, as shown by this object which is a rather faint comet-like hazy ellipse about 1.5' long with the small star R CrA near the np apex . . surrounded by similar luminous haze are the two fairly bright stars preceding (NGC 6726 and NGC 6727) and about 15' sp is a fine equal pair also immersed in haze (IC 4812)."
Coe, using a 13" f/5.6, notes: "Pretty bright, pretty small, comet shaped nebula with a 12th mag star in the tip at 135X. There is a faint star on the south side. The UHC filter dims this object quite a bit, it must be a reflection nebula."
Instrument:12"Dobsonian Reflector Telescope.
Sky Conditions:The fainter parts of the Milky Way are barely visible.
Transparency of the Sky:Haziness only visible on the horizon.
Seeing:Atmosphere stable with little interference.
Chart Number:No.19(Extract taken out of "Atlas of the Night Sky").
Brightness Profile:Low Surface Brightness.
Challenge Rating:Easy to observe in dark skies in a 12-16 telescope.
Are there areas of uneven brightness? No,there are no areas of uneven brightness,but there are areas of even brightness around the two stars.Around the two stars nebulosity is discerned.It is somewhat a reflection nebula.
Are darker lanes/patches? No,there are no dark lanes.
Any structure visible? No.
The Messier objects
The Bennett objects
The Caldwell list
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