|
NGC 6726
Ced 165b, Bernes 160
RA 19:01:39
Dec -36°53.5'
Bright
nebula |
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 6.7 mag in
faint, pretty large nebulosity.”
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.
For Hartung’s comments, see NGC 6729.
Bernie 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.”
William P. Clarke (San Diego, California, USA)
writes in the The Webb Society Nebulae and Clusters Section Report No. 10, July
1992: “NGC 6726-7 appears as a conspicuous haze around a close pair of
stars, the brightest of which is TY Cra. Some contrast enhancement was found
using an O III filter. NGC 6729, a reflection nebula, is found in the same field
as NGC 6726-7; this is faint and highly elongated in PA 170-350 degrees: rather
comet-like. Faint star (R CrA) at south end. NGC 6729 disappeared when then O
III filter was introduced. The general field is fairly devoid of stars. (21-inch
f/20, x140 & 10-inch, x48).” In (1992, Webb Society Quarterly Journal,
89, 1-7, 'A Visual Survey of the Complex Field Around R CrA & TY CrA') he
also 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: “13M; Double-lobed complex
nebular region surrounds TY and R CRA; includes comet-like N6729 just 4' to SSW”
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.” |
