OF THE ROGER N. CLARK
OF THE ROGER N. CLARK
OF THE ROGER N. CLARK
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MI09 (NGe 3992), GALAXY IN URSA<br />
MAJOR<br />
R.A. J1h 57.6m, Dec. 53° 22 ' (2 000.0)<br />
Technical. NGC 3992 was added to Messier's<br />
catalog as "M109" as recently as 1953,<br />
by Owen Gingerich. It is a barred spiral<br />
galaxy of type SBb. A short bar extends<br />
through the central hub. At its ends are long,<br />
thin spiral arms that can be traced for about<br />
three-quarters of a turn.<br />
VISUAL ASTRONOMY <strong>OF</strong> <strong>THE</strong> DEEP SKY<br />
. . '<br />
3 5<br />
h<br />
Y<br />
. arc-mmutes m Size; t e mean surfac<br />
brightness comes to 22.9 magntudes pe<br />
square arc-second. Through the 8-mch unde<br />
moderate skies, M109 appeared as a diffus:<br />
round glow. The central region appeared<br />
stellar. There was no hint of spiral structure.<br />
Visual. ML09 is magnitude 10.9 and 6.;;-<br />
A VISUAL ATLAS <strong>OF</strong> DEEP-SKY OBJECTS<br />
------- -- ---- -- ---- -- ---- -------------<br />
Photograph of MI09. South is up. (Courtesy Evered<br />
Krezmer, The Messier Album.)<br />
o<br />
---5'---<br />
Drawing of MI09.<br />
Scale: 1.2 arc-min/cm<br />
8-inch f/ 11.5 Cassegrain<br />
20mm Erfle (117x)<br />
12.4mm Erfle (188X,<br />
best view)<br />
Viewing Distance (cm)<br />
25X :115 200X:14<br />
50X :57 300X: 10<br />
100x:29 400X:7<br />
air mass: 1.32, faintest star: 13.8 at zenith 188X'<br />
no tracking<br />
5/ 1 5/83 9:05-9: 16 UT at Barbers Point Hawaii'<br />
R. Clark<br />
"<br />
'<br />
,<br />
138<br />
139
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