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RA: 19h 01m 40.6s
Dec: −36° 52′ 36″
Con: Corona Australis
Ch: MSA:1434, U2:379, SA:22
Ref: Corwin (2004)
Type: bright nebula
Mag: B=?, V=?
Size: 2′ x 2′
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This object, along with NGC 6727, is a reflection nebulae, also known as Bernes 160. It lies on the border of Sag-CrA, between the globular cluster NGC 6723 and Gamma CrA.
It was discovered by Marth, observing from Malta. He recorded it in the NGC as a "Star of 8th mag in faint, pretty large nebulosity."
[see also NGC 6723]
Variable Nebulous Star CPD –37°8450. Bulletin of the Harvard College Observatory, 780.
".. announced by Innes in Circular No 33 of the Union Obs. in 1916."
Ced 165b (NGC 6726/7)
Position (1900): RA 18 54.9, Dec - 37 2
Star: -37 13023/4 (Mp=7.1, V=7.1, SpT=B9)
Spectrum of nebula: continuous spectrum (observed)
Classification: Neb associated with mainly one star (which may be multiple) - star surrounded by a neb envelope without conspicuous structure (eg. lambda Scorpii)
Size: (not given)
Notes: "165 b = NGC 6726 + NGC 6727. NGC 6726 = GC 5935. NGC 6727 = GC 5936. Disc. Schmidt 1860. (375). FA 40. FA 63. (366, 376, 385, 386, 486, 560, 832, 856). R. -37 13023 = HD 176386 = Boss 26118. The star -37 13024 and the nebula NGC 6727 are variable."
Bernes, C. (1977) A catalogue of bright nebulosities in opaque dust clouds.
Bernes 160 = NGC 6726 / NGC 6727
Bernes notes in his Catalogue of Bright Nebulosities in Opaque Dust Clouds that these objects are also known as Cederblad 165b. He gives it a diameter of 4' and classifies it as a reflection nebula. He notes that it is part of the R CrA complex.
The RNGC (Sulentic and Tifft 1973) notes that this is a diffuse nebula.
Photo Index by Jim Lucyk: Sky&Tel. 8/62 p69, Sky&Tel. 9/83 p277, Astronomy mag. 7/86 p94, Burnhams V2 p696.
Sanden notes there are two sets of double stars, one with nebulosity glowing faintly around its southernmost component, to the southeast of the globular. Between the two doubles, slightly to the east, is a 12th magnitude star with a wisp of nebulosity extending away from the globular. The nebulosity is fan-shaped, giving this object a comet-like appearance similar to Hubble's Variable in Mon. With direct vision the fan is small and rectangular, but with averted vision it grows to twice the length. With a little imagination, the 'comet' appears to be in orbit around the globular!" (Deepsky magazine, 24, 1988).
Sanford notes "the figure-8 shape of the nebulae NGC 6726 and 6727 surrounds two stars, one of which is a variable, TY CrA. This variable star changes magnitude erratically from 8.8 to about 12.5 and the nebula generally follows."
comments, see NGC 6729.
(1992, Webb Society Quarterly Journal, 89, 1-7, 'A Visual Survey of the Complex Field Around R CrA & TY CrA') writes about NGC 6726-6727: "this nebular complex was found as a bright, hazy envelope around 2 stars, the brightest of mag. 7.2, and the other a variable - TY CrA - about one minute of arc away at PA 60-65 degrees; at the time of the observation, TY CrA was of about 8th magnitude. Some contrast enhancement is evident when using an O III filter with x48 on the 25-cm telscope. The size of the nebulosity was about 2'."
Tom Lorenzin, in the e-version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "13M; Double-lobed complex nebular region surrounds TY and R CRA; includes comet-like N6729 just 4' to SSW; 30' ESE of GLOB N6723."
Steve Coe, using a 13" f/5.6, notes: "Pretty bright, pretty large, round, with two blue-white stars involved at 135X. The UHC filter enhances the contrast of this nebula somewhat. It is difficult to tell where NGC 6726 starts and 6727 ends, however in moments of good seeing there is a hint of a dark lane through the nebula."
variable nebula lit by R CrA.
8cm - much higher sfcbr than -23, brtr overall, yet smlr. cen * consp
15cm - sm but pretty br. NE of m7 *. R CrB m~10.
25cm - 3'-4' diam w/indef border. R CrB seems bluish. best @ 90x.
The Messier objects
The Bennett objects
The Caldwell list
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