APOD: The Big Dipper (2011 Jun 24)

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APOD: The Big Dipper (2011 Jun 24)

Post by APOD Robot » Fri Jun 24, 2011 4:11 am

Image The Big Dipper

Explanation: The best known asterism in northern skies, The Big Dipper is easy to recognize, though some might see The Plough. Either way, the star names and the familiar outlines will appear in this thoughtfully composed 24 frame mosaic when you slide your cursor over the image. Dubhe, alpha star of the dipper's parent constellation Ursa Major is at the upper right. Together with beta star Merak below, the two form a line pointing the way to Polaris and the North Celestial Pole off the top edge of the field. Notable too in skygazing lore Mizar, second star from the left in the dipper's handle, forms a vision-testing visual double star with apparently close Alcor. Also identified in the famous star field are Messier catalog objects. Download the higher resolution image to hunt for exquisite views of some of Messier's distant spiral galaxies and a more local owl.

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Re: APOD: The Big Dipper (2011 Jun 24)

Post by Beyond » Fri Jun 24, 2011 4:17 am

The Big Dipper may be Big, but it doesn't look like it could hold any water. But it is nice to get a look at owlice's homeland. :owl: :D
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Messier’s Mistake

Post by neufer » Fri Jun 24, 2011 4:56 am

http://www.theskyscrapers.org/content5817.html wrote:
Image
M40: The “Unknown” Messier Object
Glenn Chaple

<<What is the most most-observed deep-sky object in the Messier Catalog? Some might suggest the Orion Nebula (M42) or Andromeda Galaxy (M31), both cosmic showpieces. More likely, it’s the Pleiades (M45), a striking and easily observed naked eye cluster.

What about the other end of the spectrum – those Messier objects that receive scant attention? The least-observed might well be Messier 40. Arguably the oddest member of the Catalog, M40 isn’t a cluster, nebula, or galaxy. It’s a double star! We might well label M40 “Messier’s Mistake.”

Messier stumbled upon this stellar duo while searching for a nebulous object reported to be in the area. For some reason, perhaps because it might appear nebulous at low power or in an inferior instrument, he added it to his Catalog. A century later, another comet hunter, Friedrich Auguste Theodor Winnecke, rediscovered the object. He correctly catalogued it as a double star, and it bears the alternate identity Winnecke 4. As double stars go, M40 isn’t a very inspirational sight. Its magnitude 9.7 and 10.1 component stars are separated by over 52 arc-seconds. Quite likely, it’s an optical pair. It may not be one of the night sky’s spectacles, but the path to observing all of the Messier objects goes through M40.>>
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Re: APOD: The Big Dipper (2011 Jun 24)

Post by owlice » Fri Jun 24, 2011 5:01 am

What a fabulous image!
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Re: APOD: The Big Dipper (2011 Jun 24)

Post by kaigun » Fri Jun 24, 2011 7:08 am

They mentioned the pointers to the polestar, but what about "follow the arc to Arcturus?"

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Re: APOD: The Big Dipper (2011 Jun 24)

Post by Ann » Fri Jun 24, 2011 7:38 am

Fantastic imge! I got stuck identifying all those galaxies. Among the more famous ones, apart from the Messier galaxies here, are NGC 3718 and companion 3729, http://www.universetoday.com/wp-content ... -small.jpg, and NGC 3631, http://www.biblioteca-tercer-milenio.co ... GC3631.gif. I'd also like to point out NGC 3642, http://www.aanda.org/index.php?option=c ... img264.gif, and Arp 299, http://www.rochesterastronomy.org/snima ... arp299.jpg, http://www.nrao.edu/pr/2003/arp299/arp2 ... t.crop.jpg. Personally I like NGC 4605, too: http://cosmo.nyu.edu/hogg/rc3/NGC_4605_ ... g_hard.jpg. I'm kind of fascinated by NGC 3549, too, one of those bulgeless fast-rotating rather yellow galaxies that are classified as Sc galaxies even though they are rather poor in star formation: http://cosmo.nyu.edu/hogg/rc3/NGC_3549_ ... g_hard.jpg. And I want to mention NGC 3953, a handsome galaxy that can be seen below M109 in today's APOD: http://www.noao.edu/outreach/aop/observ ... ayness.jpg

I also have to mention NGC 3733, which appears to be "sticking out of a red star"! Here is a lovely image of this galaxy-star pair by R Jay GaBany:
As for the rest of the galaxies I found, I'll spare you...

Fantastic image, Rogelio!

Ann
Last edited by Ann on Fri Jun 24, 2011 11:08 pm, edited 1 time in total.
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Alessandro

Re: APOD: The Big Dipper (2011 Jun 24)

Post by Alessandro » Fri Jun 24, 2011 8:09 am

What about the object at X=6274, Y=2254 (from top left)?
an easter egg or a photographic artifact?
C°°)

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Re: APOD: The Big Dipper (2011 Jun 24)

Post by Ann » Fri Jun 24, 2011 8:28 am

Alessandro wrote:What about the object at X=6274, Y=2254 (from top left)?
an easter egg or a photographic artifact?
C°°)
I'm afraid I don't understand your coordinates, Alessandro. Can you explain a bit better? Slide your cursor over the image and you'll get several names and designations. Is your "Easter egg" close to any of the labelled objects in the picture?

By the way, thanks for the explanation about M40, Neufer! I couldn't make head or tail of it, and I absolutely couldn't remember ever reading about it, either. What's worse, when I told my software to take me to M40, I got - zilch! No, I got two faint stars, HD 238107 and HD 238108, two circa G0-type stars. They are very probably an optical pair, like you said. Sheesh! Oh, but Charles Messier did well anyway... I mean, he didn't have access to splendid images like today's APOD when he was scanning the sky.

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Re: APOD: The Big Dipper (2011 Jun 24)

Post by Alessandro » Fri Jun 24, 2011 8:46 am

Ops, sorry.. It is a small bluish circle below and left of M108, near Merak
C°°)

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Re: APOD: The Big Dipper (2011 Jun 24)

Post by Alessandro » Fri Jun 24, 2011 9:21 am

Gulp. Squared sorry, it's M97, I suppose.. (thanks to Ann for her kindness: i promise to hold back further superficial posts C°°(

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Re: APOD: The Big Dipper (2011 Jun 24)

Post by mexhunter » Fri Jun 24, 2011 10:08 am

It is an extraordinary mosaic, anyone who sees the size of the "dipper" knows the immense work involved in this picture.
Congratulations Rogelio.
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matsutoya

Re: APOD: The Big Dipper (2011 Jun 24)

Post by matsutoya » Fri Jun 24, 2011 11:08 am

This higher resolution of todays picture of the Big Dipper has what appears to be an unusual string of 28 stars or so trailing away from the star Merak. I have never seen something like this before, nor have I seen any attempt at explaining this sort of phenonema. I was wondering if M 108 and/or M 97 may have played a part in causing of this, since we see on the Owl Nebula photo what appears to be a small remnant of the same color trailing that beatiful nebula.

Jake81499

Re: APOD: The Big Dipper (2011 Jun 24)

Post by Jake81499 » Fri Jun 24, 2011 11:26 am

Im not much of a star gazer so please excuse me for not knowing the names of the stars. On the far right hand side of this photo under the bottom star of the dipper there is a streak. Does anyone know what that might be?

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Re: APOD: The Big Dipper (2011 Jun 24)

Post by neufer » Fri Jun 24, 2011 12:39 pm

Jake81499 wrote:
On the far right hand side of this photo under the bottom star of the dipper there is a streak. Does anyone know what that might be?
http://apod.nasa.gov/apod/ap101216.html
Art Neuendorffer

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Re: APOD: The Big Dipper (2011 Jun 24)

Post by orin stepanek » Fri Jun 24, 2011 1:44 pm

Very nice APOD. 8-) :)
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Re: APOD: The Big Dipper (2011 Jun 24)

Post by Chris Peterson » Fri Jun 24, 2011 2:24 pm

kaigun wrote:They mentioned the pointers to the polestar, but what about "follow the arc to Arcturus?"
And from there, "on to Antares".
Chris

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Re: APOD: The Big Dipper (2011 Jun 24)

Post by kshiarella » Fri Jun 24, 2011 4:38 pm

What a great image! My favorite APOD addiction is scanning the backgrounds of high resolution mosaic shots for background galaxies. I find that fascinating. But happening upon the Owl was the true treat here.

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Re: APOD: The Big Dipper (2011 Jun 24)

Post by luigi » Fri Jun 24, 2011 4:41 pm

This is a beautiful constellation portraits. Maybe I'm crazy but I believe constellations are nicer than people for portraits :)
Thank you to APOD and Rogelio!

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Re: APOD: The Big Dipper (2011 Jun 24)

Post by bystander » Fri Jun 24, 2011 4:57 pm

kaigun wrote:They mentioned the pointers to the polestar, but what about "follow the arc to Arcturus?"
Big Dipper Navigation
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alive to the gentle breeze of communication, and please stop being such a jerk.
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islader2

Re: APOD: The Big Dipper (2011 Jun 24)

Post by islader2 » Fri Jun 24, 2011 7:10 pm

Neufer: great post! But I wonder if nontypical Messier objects {such as M40} might not have something to do with Messier's obsession about having 100 items to list? Some of us psychometricians often dwell on stuff like that. Thanx.

graydawn

Re: APOD: The Big Dipper (2011 Jun 24)-object near M101

Post by graydawn » Fri Jun 24, 2011 7:34 pm

Hello,
Near top left corner of Big Dipper mosaic is M101. Enlarge the picture. At about 8 o'clock from M101, 2 inches away from M101, is what appears to be a transparent sphere, looking carefully, another object can barely be seen at about 1 o'clock within the spere.
What is this object?

thank you,

peter2

Re: APOD: The Big Dipper (2011 Jun 24)

Post by peter2 » Fri Jun 24, 2011 7:35 pm

In poland we call it "The big wheel-cart", as opposed to the small(er) one

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Re: APOD: The Big Dipper (2011 Jun 24)

Post by neufer » Fri Jun 24, 2011 9:54 pm

islader2 wrote:Neufer: great post! But I wonder if nontypical Messier objects {such as M40} might not have something to do with Messier's obsession about having 100 items to list? Some of us psychometricians often dwell on stuff like that. Thanx.
I don't think that Messier every had exactly 100 items in his catalogue.

However, his first catalogue containing 45 objects came out in Messier's 45th year. (Candles on the cake?)
http://en.wikipedia.org/wiki/Charles_Messier wrote:
<<Charles Messier (26 June 1730 – 12 April 1817) was a French astronomer most notable for publishing an astronomical catalogue consisting of deep sky objects such as nebulae and star clusters that came to be known as the 110 "Messier objects". The purpose of the catalogue was to help astronomical observers, in particular comet hunters such as himself, distinguish between permanent and transient objects in the sky.

The first version of Messier's catalogue contained 45 objects and was published in 1774 in the journal of the French Academy of Sciences in Paris. The final version of the catalogue was published in 1781, in Connoissance des Temps for 1784. The final list of Messier objects had grown to 103.

On several different occasions between 1921 and 1966, astronomers and historians discovered evidence of another seven deep-sky objects that were observed either by Messier or his friend and assistant, Pierre Méchain, shortly after the final version was published. These seven objects, M104 through M110, are accepted by astronomers as "official" Messier objects.

The catalogue is not organized scientifically by object type or by location, as the later New General Catalogue would be. Nonetheless, the Messier catalogue comprises nearly all the most spectacular examples of the five types of deep sky object -- diffuse nebulae, planetary nebulae, open clusters, globular clusters and galaxies -- visible from European latitudes. Because these objects could be observed with the relatively small-aperture refracting telescope (approximately four inches) used by Messier to study the sky, they are among the brightest and most attractive deep sky objects observable from earth. Furthermore, almost all of the Messier objects are among the closest to our planet in their respective classes, which makes them heavily studied with professional class instruments that today can resolve very small and visually spectacular details in them.>>
Art Neuendorffer

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Re: APOD: The Big Dipper (2011 Jun 24)

Post by Wolf Kotenberrg » Fri Jun 24, 2011 10:01 pm

I grew up where the Southern Cross pointed south. Maybe someday they will put a telescope on the Moon, or even some asteroid. With some really good batteries and a fantastic ZOOM lens.

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Re: APOD: The Big Dipper (2011 Jun 24)-object near M101

Post by Ann » Fri Jun 24, 2011 10:18 pm

graydawn wrote:Hello,
Near top left corner of Big Dipper mosaic is M101. Enlarge the picture. At about 8 o'clock from M101, 2 inches away from M101, is what appears to be a transparent sphere, looking carefully, another object can barely be seen at about 1 o'clock within the spere.
What is this object?

thank you,
That is NGC 5474, one of M101's satellite galaxies.
NGC 5474 by Adam Block. The object that seems to be inside this galaxy is actually the galaxy's bulge. The disk has been displaced to one side, probably due to interaction with M101.

Ann
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