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The Caldwell Objects

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75<br />

ery to be unlikely, I presumed the<br />

glow to be nothing but a spurious<br />

patch of bright Milky Way. Through<br />

the 4-inch NGC 6124 appeared about<br />

⅓ times larger than this "patch,"<br />

which was contained by an obvious<br />

oval-shaped asterism of 9th-to 12thmagnitude<br />

stars. Closer inspection<br />

revealed that that single oval was<br />

comprised of two fainter ovals side<br />

by side, each scintillating with the<br />

light of fainter suns. I checked the<br />

Astronomical Journal, the Astrophysical<br />

Journal, and the Monthly Notices of<br />

the Royal Astronomical Society but<br />

did not find a reference to this<br />

"cluster." Apparently no modern<br />

research has been done<br />

on it or the surrounding field. <strong>The</strong> situation<br />

remained at a standstill until the year 2000, when<br />

Brent Archinal revised the cluster's size from 29'<br />

to 40'. When I plotted his position for the cluster's<br />

center (provided in the table below) and placed a<br />

circular 45'-diameter template around it, I was<br />

pleased to discover that the new dimensions<br />

included this curious patch of dim starlight and<br />

the bright ovals of stars. But why, then, did I see<br />

two distinct "clusters"?<br />

<strong>The</strong> answer may be simple. On National<br />

Geographic Society - Palomar Observatory Sky<br />

Survey prints I noticed an almost perfect semicircle<br />

of darkness (open to the northeast) slicing<br />

through the cluster's northeastern quadrant, just<br />

where I saw one cluster ending and the other<br />

beginning. This dark semicircle outlines the<br />

southwestern edge of the large oval of stars I<br />

detected in binoculars. Of course, the other<br />

possibility is that there really is just a random<br />

patch of Milky Way here. Check this object out<br />

and decide for yourself. <strong>The</strong> reason NGC 6124<br />

looks so large and diffuse is because it is relatively<br />

nearby (1,530 light-years). If NGC 6124<br />

298<br />

indeed spans 40', then its true physical diameter<br />

is 18 light-years.<br />

I find that NGC 6124 looks best in binoculars.<br />

At a glance it is a circular object with a dense<br />

10' core. With time, though, the core begins to<br />

break up. Soon it's a mottled haze with<br />

prominent clumps of stars to the northeast,<br />

southwest, and east. Particularly absent is any<br />

notable mottling to the west. So the cluster looks<br />

somewhat like an arrowhead pointing eastward.<br />

At 23x in the 4-inch a pair of parallel and slightly<br />

curving bands of stars (oriented northwestsoutheast)<br />

flows through the center of the<br />

cluster's densest part. Look for a tiny gang of<br />

knitted suns at the northwestern end of the core,<br />

between these two parallel streams. <strong>The</strong> streams<br />

open out into a delta of darkness at the<br />

southeastern end of the core; look for a<br />

prominent pair of lOth-magnitude suns here.<br />

Christian Luginbuhl and Brian Skiff note that the<br />

densest portion of the cluster contains about 25<br />

stars in an area 6' across. All kinds of pairs and<br />

groupings dapple the cluster. Using my<br />

imagination NGC 6124 looks like the<br />

Deep-Sky Companions: <strong>The</strong> <strong>Caldwell</strong> <strong>Objects</strong>

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