Visual Challenge Object - August 2021

Original article appears in GuideStar August, 2021.

by Stephen Jones

Barnard 86 – Dark Nebula in Sagittarius

B86 – Dark Nebula in Sagitarius

RA 18h02m58.6s Dec -27deg 52’00”

Size 5.0’ Vmag n/a


NGC 6520  – Open Cluster in Sagittarius

RA 18h03m24.9s Dec -27deg 52’56”

Size 6.0’ Vmag 7.6

With the summer Milky Way prominently in view this month, our skies are full of some of the brightest and most lovely objects in the sky.  This month’s object, on the other hand, belongs to a class of objects neglected by a lot of visual observers because they are quite the opposite of bright: the dark nebulae.  Indeed, dark nebulae were simply thought of as “holes” in the Milky Way until the advent of astrophotography in the 19th century revealed them to be dark clouds of gas and dust passing in front of the Milky Way.  Still, from a dark site, the bright backdrop of the Milky Way can help make these dark dust clouds stand out.

One of my favorite dark nebulae to observe, and also one of the easier ones, is Barnard 86, located in a very busy part of the Milky Way right near the galactic center.  It is located right next to the bright open cluster NGC 6520, which is a lovely object itself.  My notes are as follows:

7/14/2018 11:14 pm – 16” f/4.5 Dobsonian 131x

Same field as NGC 6520; large triangular black spot against the sky; clearly darker than the empty space, Opacity about 9; not much structure, just a big "ink blot" pretty bright orange star at the northern end;

To locate B 86, first look for NGC 6520 as it will be easier to spot at first glance.  It can be easily located next to the spout of the Sagittarius teapot, forming a right triangle with γ and δ Sagittarii. 

The HAS VSIG would love to hear about your own visual observations of B 86 and NGC 6520.  Send them to the VSIG list server.  To get on the VSIG email list server, contact me at [email protected]

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