Sky and Telescope - March 2018 - 8

From Our Readers

laide, South Australia. My instrument
was an 11-cm f/8 Newtonian reﬂector
on an alt-azimuth mount. I was starhopping through faint fuzzies in and
near Sculptor using Antonín Becˇvárˇ's
Atlas Coeli 1950.0.
As I star-hopped using the ﬁnderscope, suddenly a large, bright splodge
of light moved into the ﬁeld. I was
startled. I remember thinking that this
thing would get in the way as I tried to
see the galaxy. And then it dawned -
this was the galaxy. In the eyepiece, it
took my breath away. I described it as
"Enormous, bright, narrowly elliptical;
brightening gradually to the centre and
extending to about 25′ in its long axis."
I couldn't see any internal structure.
Nowadays, a 11-cm reﬂector would
be considered a humble instrument.
An alt-azimuth mount with no drive,
star-hopping, Becˇvárˇ's charts - these
are terms familiar mainly to those with
long memories. But my excitement and
joy as I discovered the heavens back

then was as intense as it is for astronomers today.
Marilyn Hewish
Darley, Victoria, Australia

Enduring Love, Thanks to S&T
My wife, Brenda F. Branchett, passed
away on October 26, 2017, after a long
illness. Brenda founded the Ancient
City Astronomy Club of St. Augustine
in 1973, and she remained an active
observer in the 43 years that followed,
with particular interests in meteors,
deep-sky objects, and the Sun. Brenda
was also a founder of the Astronomical
League's Herschel 400 project.
I met Brenda thanks to an article by
Dennis di Cicco about the Herschel Club
in Sky & Telescope's July 1977 issue. At
the time I was observing some of these
objects from my home in England, and
in response to the article I began cor-

1968

1993

º March 1943
Active Galaxies "Dr. Carl K.
Seyfert, of Warner and Swasey
Observatory, has been studying
six of a rare class of spirals whose
nuclei exhibit high-excitation
nebular emission lines superposed
on the usual G-type absorption
spectrum. . . .
"The lines in all the objects
studied are widened, presumably
by rapid motion of the material
emitting the light - the total widths
of the lines corresponding to
speeds of [up to] 8,500 kilometers
per second. [The] composition of
the nuclei [is unknown], and further
progress of Dr. Seyfert's investigations will be awaited with considerable interest."
Seyfert's classic paper, read at
a meeting of the American Astronomical Society, launched the
close attention being paid today
to active galactic nuclei or AGNs.
Seyfert galaxies are one type, quasars another.

M A RCH 2 018 * SK Y & TELESCOPE

David Branchett
Deltona, Florida

FOR THE RECORD

* The Geminid meteor shower's radiant, at
declination +27°, is observable from all of
South America, Africa, and Australia (S&T:
Dec. 2017, p. 49).

* In the bottom panel of the illustration
showing the evolution of stellar interiors
(S&T: Jan. 2018, p. 26), the label "HeàH"
should instead be "HeàC".

SUBMISSIONS: Write to Sky & Telescope, 90 Sherman St., Cambridge, MA 02140-3264, USA or email: letters@
skyandtelescope.com. Please limit your comments to 250 words; letters may be edited for brevity and clarity.

75, 50 & 25 YEARS AGO by Roger W. Sinnott
1943

responding regularly with Brenda. We
became pen pals and married in November of 1981, soon after I had immigrated
to the United States to be with my future
bride. In 1991 she and I ﬁnally got to
meet Dennis and were able to thank him
in person for that article. It led to 35
years of adventure both in the celestial
realm as well as under the stars.

º March 1968
Star Sizes "Narrabri Observatory
in Australia has a strange-looking
instrument that is proving to be
very successful for measuring the
angular diameters of bright stars.
It consists of a circular railway 600
feet across along which can be
moved two 22-foot mosaic mirrors,
each with a photocell at its focus.
[R. Hanbury Brown's] intensity
interferometer is a considerable
advance over the Michelson phase
interferometer [used] at Mount
Wilson in the 1920's. . . .
"Detailed results for 15 stars
have just been published. . . . The
largest object on the list is Canopus
[at 0.0069 arcsecond]. The smallest,
Epsilon Orionis [0.0007 arcsecond],
appears no bigger than a large truck
tire lying on the moon!"
The best-resolution device today
(in visible light) is the Navy Precision Optical Interferometer near
Flagstaff, Arizona. It can "see" star
shapes, surface spots, and components of spectroscopic binaries.

º March 1993
Ozone Hole "Since its discovery
in 1985, the hole in the ozone layer
over Antarctica has grown, and last
fall it reached its greatest extent
yet. NASA's Total Ozone Mapping
Spectrometer (TOMS) determined
that the hole covered 23 million
square kilometers on September
23, 1992 . . .
"As measured by TOMS, the
hole typically begins to enlarge
every August and reaches its peak
extent in October. The ozone is
then slowly restored by natural
means until the cycle repeats the
following year. . . .
"The ozone molecule, O3, is an
important ingredient in our atmosphere, since it screens out harmful
ultraviolet rays. . . . Scientists have
speculated that overexposure to
ultraviolet rays may increase skin
cancer rates and weaken human
immune systems."
NASA reports that the ozone
hole totaled just 20 million square
kilometers in October 2017, its
smallest extent in three decades.

Sky and Telescope - March 2018

Table of Contents for the Digital Edition of Sky and Telescope - March 2018