OF THE ROGER N. CLARK

VISUAL ASTRONOMY OF THE DEEP SKY
A VISUAL ATLAS OF DEEP-SKY OBJECTS
M77 (NGC 1068), SEYFERT GALAXY IN
CETUS
R.A. 02h 42 .7m, Dec. -000 01 ' (2 000.0)
Technical. M77 is one of a class of galaxies
with bright, very active nuclei. These are the
Seyfert galaxies, named after Carl Seyfert
who studied them in the early 1940s. The
nucleus of M77 is ej ecting clouds of gas at a
velocity of 600 kilometers per second, and
each of these clouds is estimated to contain as
much mass as 10 million suns. The nuclei of
some Seyfert galaxies vary in brightness, but
that of M77 does not.
The distance to M77 is about 75 million
light-years, and the diameter of its outermost
region is around 100 000 light-years. The total
mass is estimated to be about 100 billion
suns; the light output, 40 billion suns. Like
most Seyfert galaxies, M77 is also a strong
radio source. Radio astronomers know it as
3C 71.
Visual. M77 is magnitude 10.0 and about
2.5 by 1. 7 arc-minutes in size. Its mean surface
brightness is 20.2 magnitudes per square
arc-second. Faint spiral arms extend to a diameter
of 6 arc-minutes but have not been
reported visually. The galaxy has a bright
inner spiral pattern 40 by 20 arc-seconds in
size which is not seen in small amateur telescoes.
Some observers have reported a mottled
effect in large telescopes. A second, larger
spiral pattern extends to 2.5 by 1.7 arcminutes.
The visual impression is that of a bright
central region surrounded by a diffuse oval,
which in turn is surrounded by a larger and
fainter oval. In the 8-inch the bright inner
region did show a brighter spot southwest
the nucleus. This spot corresponds to a
part of a spiral arm, which might be re(:09ni:­
able as such in a large telescope under very
dark skies at 200x or more.
--
N GC 1 365, BARRED SPIRAL GALAXY IN
FORNAX
R . A . 03h 33.7m, Dec. _360 08' (2000.0)
Technical. NGC 1365 is a beautiful barred
spiral galaxy, probably the finest .
example of .
its class in the southern sky. It IS the third
brightest _ me b r of the FO r,:ax