Sky and Telescope - July 2016 - 56

OBSERVING

Deep-Sky Wonders

Starry Swarms
Tour the great star cities of southern Ophiuchus.
There is a certain attraction in these far-away glimpses of
starry swarms, for they give us some perception of the awful
profundity of space. When the mind is rightly attuned for
these revelations of the telescope, there are no words that can
express its impressions of the overwhelming perspective of the
universe.
- Garret P. Serviss, Pleasures of the Telescope, 1901
Serviss penned these words of awe in his discussion
of the globular clusters that grace our sky at this time of
the year. Among them he included four clusters arrayed
in the shape of a backward L in the far southern reaches
of Ophiuchus.
The quartet's brightest cluster is Messier 19, the only
one to unveil stars through the scopes piloted by Serviss.
M19 is quite simple to find because it lies due east of
Antares. If your telescope has an equatorial mount,
you can simply sweep eastward from Antares until you
bump into it. If not, Earth can find it for you. Center
Antares in a low-power field of view, and 33 minutes
later the world will have turned far enough around its
axis to point your scope toward the cluster.
M19 is rather alluring in my 105-mm refractor. At

17h 40m

17h 30m

17h 20m

17h 10m

87× the tenuous 6′ halo encloses a bright 3½′ core that's
distinctly oval north-south. Several stars spatter the cluster, including a 12th-magnitude foreground star slightly
northeast of the core. At 127× a generous dusting of
stars emerges, and the core enfolds a tiny, blazing heart.
Through my 10-inch reflector at 213×, numerous suns
adorn the 8′ halo and 3½′ × 2½′ core.
Dropping the magnification of the 105-mm scope to
17×, I can fit M19 in the same field with two of the other
clusters in the backward L. NGC 6293 sits at the end
of the L's short bar, and NGC 6284 is at the middle of
its long bar, each much fainter than M19 and about 2′
across with a brighter center. At 127× NGC 6284 exhibits
slight mottling. The core is about one-third the cluster's
diameter, and its brightest region is elongated, tipped
north-northeast, and punctuated by a tiny, intense
nucleus. A few faint field stars sparkle just beyond the
borders of the halo.
In the 10-inch scope at 115×, NGC 6293 displays
quite a few very faint stars down to its vivid and coarsely
mottled ½′ hub. The cluster remains fairly bright out
to a diameter of 1½′, and the surrounding halo reaches
about 2½′ before fading into the background sky. NGC

17h 00m

16h 50m

16h 40m

16h 30m

16h 20m

t

j
6235

52

-22°

6287
24

B72

6369

15

22

6325

OPHIUCHUS

6401
51

k

44

Star magnitudes

2

-24°

18

31

k

26

6284

e

3
4
5
6
7
8

25

28

M19
36

SCORPIUS
Antares

6293

o

56

July 2016 sky & telescope

m
-26°
M4

43

45

l

-28°

M62
-30°



Sky and Telescope - July 2016

Table of Contents for the Digital Edition of Sky and Telescope - July 2016

Contents
Sky and Telescope - July 2016 - Cover1
Sky and Telescope - July 2016 - Cover2
Sky and Telescope - July 2016 - 1
Sky and Telescope - July 2016 - Contents
Sky and Telescope - July 2016 - 3
Sky and Telescope - July 2016 - A
Sky and Telescope - July 2016 - B
Sky and Telescope - July 2016 - 4
Sky and Telescope - July 2016 - 5
Sky and Telescope - July 2016 - 6
Sky and Telescope - July 2016 - 7
Sky and Telescope - July 2016 - 8
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Sky and Telescope - July 2016 - 10
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