Sky and Telescope - March 2016 - 8

Letters
Monica Young replies: You're correct that
Type Ia supernovae require a companion -
either because the white dwarf siphons off
gas and explodes, or because the white dwarf
and its companion merge with the same
result. So "solitary" refers to the supernova's
environment - that is, whether it's part of a
galaxy or not.

CGCG
514-066
7336
7335
7340
7337

7331

PGC
69291
7326

+34° 24'

7325

Catalog Quirks
I've been getting Sky & Telescope since
1969 and have worked my way up to
observing with a 16-inch Newtonian
reflector for the last 5 years. Since most
of my recent observing is devoted to
external galaxies, Ted Forte's "favorite
things" article (S&T: Oct. 2015, p. 32)
was an excellent extension of an area
I've observed before. However, after I
cross-referenced those targets with Steve
Gottlieb's NGC and IC observations, it
appears that NGC 7325 and 7326 are actually faint double star duos.
Tom Prescher
Tolland, Connecticut

75, 50 & 25 Years Ago
March-April 1941
Skyrocket Prominence "The coronagraph has
seldom been thought of as a visual instrument, [but on] February 6, Mr. Walter Roberts,
in charge of the observational work at Climax,
was examining an interesting prominence
with a small pocket spectroscope. He had just
noticed a peculiar doubling of all of the spectral lines . . . evidently a Doppler effect, arising
from rapid motion of the gas either toward or
away from the observer. . . .
"And then, suddenly, well to the left of the
stationary prominence, he saw a small bright
patch form, rapidly growing in size and intensity. As he watched, he could see it starting
upward. . . . The left-hand prominence shot up
like a skyrocket, curving sharply to the right.
. . . The entire outburst was over in about five
minutes. . . ."
The coronagraph was
invented in France in 1931,
and Harvard's Colorado
station had one of the first
three. As told here by Donald H. Menzel, this instrument permitted real-time,
white-light views of action

8

March 2016 sky & telescope

22h 38m

22h 37m

22h 36m

Some faint objects (in yellow) near the galaxy
NGC 7331 in Pegasus are not easily identified.

Ted Forte replies: The historical record concerning NGC 7325 and NGC 7326 suggests
that a misidentification of these objects exists
in many contemporary catalogs. The objects
described in the article and identified in the
image on page 38 as NGC 7325 and NGC
7326 are, perhaps, more correctly identified as
PGC 69291 and Z514-066 (CGCG 514-066).

As shown in the revised plot at left, the "real"
NGC 7325 is an object southwest of the core of
NGC 7331, while NGC 7326 is a double star
to the galaxy's immediate west.

For the Record
✹ Mercury's perihelion precession, due to all
causes, is about 574 arcseconds per century.
The value of 43 arcseconds per century
(S&T: Dec. 2015, p. 4) refers only to the
residual, anomalous shift due to relativistic
effects. Also, the label in the illustration on
that page should state that Mercury's perihelion precesses 0.2°° (not 2°) per century.
✹ The predicted peak of the Geminid
meteor shower (S&T: Dec. 2015, p. 44) was
about 18h Universal Time on December (not
August) 14, 2015.
✹ The listed date and time of lunar perigee
(S&T: Dec. 2015, p. 49) should be December
21st at 9h UT.
✹ The long trail in a star-field image ascribed
to a Perseid meteor (S&T: Dec. 2015, p. 70)
instead resulted from a pass overhead by the
International Space Station.

Roger W. Sinnott
off the Sun's limb. A solar eclipse offers similar
views - but only for a few fleeting moments.
March 1966
Soft Landing "Two important milestones in
lunar exploration were reached in early February, as Luna 9 made the first successful soft
landing and sent back the first pictures of the
moon's surface texture as viewed from a few
feet. . . . The Moscow news agency Tass gives
the time of landing as 18:45:30 [Universal Time
on February 3rd]. . . .
"The soft landing took place near the edge
of Oceanus Procellarum. . . . The camera
recorded foreground objects as small as one or
two millimeters. . . ."
This Soviet triumph also calmed the fears of
those planning NASA's Apollo landings. Instead of
plunging into a thick bed of
Moon dust, Luna 9 gently
bounced when it hit.
March 1991
Quasar Mystery "Astronomers have long puzzled
over two stars whose
spectra are dominated by

emission lines from ionized iron. . . . Now the
mystery deepens with the recognition of a new
class of 'super strong' iron emitters among the
quasars. . . . Sebastian Lipari (Space Telescope
Science Institute) and his colleagues report the
discovery of the third such quasar, IRAS 18508
- 7815 in Octans. Its extremely strong iron lines
defy explanation.
"One of the other two 'iron quasars,' IRAS
07598 + 6508 in Camelopardalis, has similar
optical and far-infrared characteristics and
redshift. It also lies roughly on the opposite
side of the sky. Lipari and co-workers speculate that the two images might be of the same
quasar. This seeming impossibility is predicted
by Chinese astrophysicist Fang Lizhi's model of
a 'multiply connected' universe."
The idea that we could see the same object by
looking in opposite directions on the sky is a recurrent theme in cosmology,
ever since Albert Einstein
first described space-time
curvature 100 years ago
(S&T: Dec. 2015, p. 18).
But a convincing example
has yet to emerge.



Sky and Telescope - March 2016

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

Contents
Sky and Telescope - March 2016 - Cover1
Sky and Telescope - March 2016 - Cover2
Sky and Telescope - March 2016 - 1
Sky and Telescope - March 2016 - Contents
Sky and Telescope - March 2016 - 3
Sky and Telescope - March 2016 - A
Sky and Telescope - March 2016 - B
Sky and Telescope - March 2016 - 4
Sky and Telescope - March 2016 - 5
Sky and Telescope - March 2016 - 6
Sky and Telescope - March 2016 - 7
Sky and Telescope - March 2016 - 8
Sky and Telescope - March 2016 - 9
Sky and Telescope - March 2016 - 10
Sky and Telescope - March 2016 - 11
Sky and Telescope - March 2016 - 12
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Sky and Telescope - March 2016 - 84
Sky and Telescope - March 2016 - Cover3
Sky and Telescope - March 2016 - Cover4
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