|NGC 7640: Spiral Galaxy (Andromeda) RA: 23h 22.1m / DEC: +40° 50'.7|
Instrument: 10-inch Starfinder
This delicate edge-on spiral is screened from view by the thick disk of our own Milky Way galaxy. NGC 7640 resides in Andromeda, about 2.5 degrees northwest of 5.2 magnitude 14 Andromedae. My sketch portrays a high power (129X) view in the 10-inch Starfinder Newtonian. NGC 7640 appears initially as a slender stroke of light, 4'x1' in size, and aligned very roughly north-to-south. But the most intersting feature of this SBc-type galaxy is its tilde-shape form. I spent more than 20-minutes at the eyepiece trying to figure this one out. Eventually, I decided to trust what my eye was telling me: Beginning at the northern tip near 11.1 magnitude Tycho 3234:471:1, NGC 7640 extends south for a distance of some 2', veers slightly to the east, then continues the journey southward. Nearly 40 stars are included in my sketch. Three 11th magnitude stars form a triangular frame around the NGC 7640, which itself shines with an 11.4 visual magnitude. NGC 7640 has a surface brightness of just 23.4 magnitude per square arc second, which makes it a challenging object. While in the area, stop and visit NGC 7662, about 2 degrees to the north.
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Revised: October 24, 2003 [WDF]