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Object of the Week, January 3, 2021 - NGC 891
Andromeda
Edge-on galaxy
Magnitude: 10.8
Size: 14.3’ x 2.4’
RA: 02 22 33
Dec: +42 20 57
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(image by Hunter Wilson, https://en.wikipedia.org/wiki/NGC_89...nterWilson.jpg)
A somewhat ghostly but very attractive edge-on galaxy, NGC 891 comes alive in dark skies. That’s not to say that it can’t be seen and enjoyed in less-than-ideal observing conditions, but a good view is more difficult to get. Even so, it’s worth the effort of returning many times to this out of the way corner of Andromeda to enjoy this iconic object.
As were many of the OOTW objects, William Herschel discovered what we now refer to as NGC 891. Exactly edge-on from our vantage point, it sports a fairly wide and diffuse dark lane bisecting it into equally bright parts. The two halves of the galaxy look to be exactly the same apparent size.
Like the bright parts of 891, the dark lane is a subtle visual feature in a light polluted sky, even in a fairly large scope. A clean, transparent night sky gives the best chance of seeing it well. The dark lane is a much more obvious feature under a true dark sky, while still being somewhat understated – but then that’s the character of the entire galaxy.
Interestingly, 891 seems to be much the same size and luminosity as the Milky Way, and studies indicate that it may be a barred spiral, although it seems to lack the characteristic X-shaped core thought to be typical of edge-on barred spirals.
Oriented northeast to southwest, 891 is seen through a pretty spray of Milky Way stars, which to my mind adds to the overall beauty of this field of view. Approximately 27 million light years away, these foreground stars help make the point that 891 is far in the background, which might be overlooked otherwise .
I’ve found that magnifications in the 200x to 400x range work best with 891, and that a binoviewer also presents a nice view. A binoviewer doesn’t always work well on deep sky objects, but on 891 it seems to slightly boost the contrast against the sky background.
Another observing aid is Jimi Lowrey’s 48-inch scope in West Texas! Although boosting the overall brightness of 891, it doesn’t add any specific details but does make the galaxy more substantial looking. It also brings out two small galaxies on either side of the galaxy. I don’t know if they’re far in the background or satellite galaxies of 891, but it’s fun to track them down if you have a large enough scope.
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The galaxy on the east side, north of the core, is MAC 0222+4222 and is listed at magnitude 16.5. The galaxy just off the west side of the core was easier to see, although I can’t find its designation or magnitude in the literature. Both galaxies needed fairly high power to see well, and my rough sketch here was meant to only show their positions (arrows) relative to 891. I haven’t tried finding these galaxies with my 28-inch yet.
My sketch below is from 2012, and represents the view though my 28-inch scope on a good, but not great night. I had views that were quite similar with my 20-inch, and I’m curious about the smallest scope anyone has used that gave a pleasing view.
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Give it a go and let us know!
