The Caldwell Objects

of the field. Those living under dark skies should
try to spy the l0th-magnitude galaxy in
binoculars. I had success with 7x35s from Hawaii,
at an elevation of 4,200 feet, though it required
much time and effort — which is the key to
seeing anything dim.
As is the case with many deep-sky objects
that appear so fine in photographs, the structure
of NGC 5248 is deceptively challenging. At 23x in
the 4-inch, NGC 5248 is a small, somewhat weak
glow with a sharply condensed core surrounded
by a pale oval disk oriented
roughly east-west. As Christian Luginbuhl and
Brian Skiff also note, the galaxy lies on the eastern
side of an obvious 8'-long isosceles triangle of
stars pointing south-southeast. The view
intensifies at 72x, but not enough to bring out any
structural details. A 13th-magnitude star borders
the galaxy to the south-southwest. A possible
knot of material pops in and out of view to the
west. The galaxy's feeble surface brightness
places small telescopes at a disadvantage. Still,
the overall glow is mottled, mak-
45
ing the galaxy look like a misty bog. Increased
magnification only spreads out the galaxy's weak
outer halo to the point of invisibility.
Amateurs with larger telescopes have had
more success sighting various degrees of detail in
NGC 5248. Using an 8-inch telescope at 390x, Jere
Kahanpää of Jyväskylä, Finland, recorded a dark
patch north of the nucleus. This observation is
intriguing, since Luginbuhl and Skiff noticed a
dark patch in a 12-inch, but it was south of the
nucleus; the patch, they say, gives the galaxy a
"black-eye" appearance. Alterna-
tively, Ernst Hartung says
that through a 12-inch the
galaxy "shows only a
conspicuous diffuse haze.
. . . in a field with a few
scattered stars." The
nature of the galaxy is
undeniable in a 20-inch.
With such a telescope
Barbara Wilson saw
"beautiful" structure with
the arms revealing many
small knots.
The interesting variable
star FP Virginis lies
about 40' southwest of
NGC 5248. The star is
one of those closely monitored by participants in
the American Association of Variable Star
Observers' photoelectric photometry program.
Almost all of the stars on that program were
observed by the Hipparcos satellite during its
3½-year mission. The Hipparcos team analyzed
the satellite's extensive photometry on FP
Virginis and found that the star's brightness
variations are semiregular at best. The star varies
between magnitude 6.6 and 7.1, possibly on two
or more time scales.
The Caldwell Objects 181