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M-44 and ST80

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#1 JIMZ7

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Posted 23 April 2019 - 10:43 PM

I haven't been on this section of CN in few years since I had a Discovery 12.5" f/5 split-tube Dob. Now I have downsized to a Orion ST80 due to health issues. But had a chance to see the "Beehive" tonight in my light polluted skies. With a Orion 17mm Sirius Plossl at 23x it was kinda stunning. I don't know how many stars in that cluster, but I'm sure I saw 3 dozen or so. 

I remember when I had the 12.5" scope I wheeled it out of the garage and put a Celestron 30mm Ultima in the focuser. It was still twilight and really not expecting anything until I just took a quick look see. Yikes I was looking at M-44 in twilight. Looked like diamonds in a pale blue sky. Not expecting that. What a lucky find without even trying!

Now I have a very portable ST80 and only one eyepiece. It's actually very sharp for a f/5 scope. I never use a finder scope so the ST80 is the finder. I took a wild guess where M-44 was tonight and was immediately rewarded. Wow that made my night.

Jim


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#2 vkhastro1

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Posted 24 April 2019 - 06:37 AM

The larger open clusters like M44 need larger FOV to give them a proper "perspective". 

Ditto for M45 and the Coathanger and M31.

The ST80 (especially in 2" mode) is a great RFT option.

 

I also enjoy even lower power binocular views (6.5° - 8.1° with my APM 10x50 ED and 8x42 Legend M binoculars respectively).

Great targets include - Coma Cluster, alpha Perseus moving Cluster (Mel 22), Double Cluster/Stock 2, NGC 7000

(NA Nebula), among others.


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#3 Inkswitch

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Posted 24 April 2019 - 07:53 AM

In my own mind I call M44 the "triangle cluster".  All I can see are triangles every time I look at it.


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#4 Dave Mitsky

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Posted 25 April 2019 - 01:03 PM

It's getting a bit late in the year for it but M41 is known by some as the Little Beehive Cluster.  M41 is about half the apparent size of M44 and is almost a magnitude fainter. 

 

http://www.messier.s...org/m/m041.html

http://www.messier.s...org/m/m044.html

I've attached an image of M41 that I captured in 2010.

BTW, the Alpha Persei Moving Cluster is Melotte 20.

 

http://www.messier.s...c/alphaper.html

 

Dave Mitsky

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  • M41 BRT 2010-12-24.jpg


#5 REC

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Posted 25 April 2019 - 01:35 PM

It's getting a bit late in the year for it but M41 is known by some as the Little Beehive Cluster.  M41 is about half the apparent size of M44 and is almost a magnitude fainter. 

 

http://www.messier.s...org/m/m041.html

http://www.messier.s...org/m/m044.html

I've attached an image of M41 that I captured in 2010.

BTW, the Alpha Persei Moving Cluster is Melotte 20.

 

http://www.messier.s...c/alphaper.html

 

Dave Mitsky

I was out the other night with my ST-80 just cruising around. Went to M41 first as it's sinking fast, but still high enough to view right after it gets dark out. I was using my 19mm Pan and it was nicely framed. FYI for the OP. Might want to look around for a used 8-24mm zoom for that scope. Meade or Celestron run around $50 used. Good fit for the ST-80.



#6 tchandler

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Posted 26 April 2019 - 07:36 AM

Kinda stunning. That’s an unusual turn of phrase. I’ll chalk it up to your eyes maybe being in a state of disbelief! Note, I say this very much tongue in cheek!

 

This week I made it up to my Darkest Sky Site, and the beehive was easily naked eye as a nebulous patch. It’s been such a long time since seeing it this way. That alone was stunning. 

 

For kicks, I aimed my 11 dob at this little cloud and popped in a 26 mm NAG with a FOV of 1.6 degrees and magnification of 48X. Holy flipping Hannah. I imagined that it was like looking at the centre of M 22 from a distance of a couple of hundred light years.

 

Stunning! 


Edited by tchandler, 26 April 2019 - 07:38 AM.


#7 Organic Astrochemist

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Posted 26 April 2019 - 09:22 AM

Kinda stunning. That’s an unusual turn of phrase. I’ll chalk it up to your eyes maybe being in a state of disbelief! Note, I say this very much tongue in cheek!

This week I made it up to my Darkest Sky Site, and the beehive was easily naked eye as a nebulous patch. It’s been such a long time since seeing it this way. That alone was stunning.

For kicks, I aimed my 11 dob at this little cloud and popped in a 26 mm NAG with a FOV of 1.6 degrees and magnification of 48X. Holy flipping Hannah. I imagined that it was like looking at the centre of M 22 from a distance of a couple of hundred light years.


Stunning!

That sounds like a great view. What do you think was your limiting magnitude?

Most of the brightest members of M44 are concentrated in a 1.6 degree diameter (35 Cnc excepted). To see all the members of M44 down to mag 9, you would need about twice the FOV (~3.2 degrees). Fainter than that the members are scattered even further out and are mixed with many field stars.
Here’s a chart I made plotting members down to mag 9.0.
0D3EEEB8-81D6-4BB5-AEFA-BA2624F55FA6.jpeg

Edited by Organic Astrochemist, 26 April 2019 - 01:55 PM.

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#8 tchandler

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Posted 26 April 2019 - 09:31 AM

That’s a good question. The sky meter indicated 21.54. Someone else was taking this reading and I’m not entirely sure what it means. Apart from being reasonably dark.

 

i was dazzled by so many bright stars squeezed in one small space that I scarcely noticed the faintest in the crowd.



#9 Organic Astrochemist

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Posted 26 April 2019 - 11:05 AM

i was dazzled by so many bright stars squeezed in one small space that I scarcely noticed the faintest in the crowd.

Precisely.

In general I wonder what range of magnitudes the eye can see at once. I’m sure it depends on sky background and star brightness and star density. I’m guessing six magnitudes.

I think that for clusters roughly older than 100,000,000 years the bright stars really shine. There are more evolved stars, more blue stragglers and more equally matched binaries. There are also lots of stars with B-V 0-0.5 where the slope of the main sequence isn’t as steep. With cluster age the bright stars will concentrate in the center and dimmer stars will be thrown further out.
See figure 2.
https://arxiv.org/pdf/1804.09378.pdf

Edited by Organic Astrochemist, 26 April 2019 - 11:40 AM.


#10 Dave Mitsky

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Posted 26 April 2019 - 11:43 AM

This week I made it up to my Darkest Sky Site, and the beehive was easily naked eye as a nebulous patch. It’s been such a long time since seeing it this way. That alone was stunning.

One of the naked-eye views that I really enjoy from a dark site in the spring is seeing M44 and Melotte 111 simultaneously.



#11 Dave Mitsky

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Posted 26 April 2019 - 12:22 PM

A number of galaxies that are visible with larger apertures lie "within" M44.  They include NGC 2624, NGC 2625, NGC 2647, NGC 2643. IC 2388, and CGCG 89-56 and are discussed in the Deep-Sky Wonders column in the March 2009 issue of Sky & Telescope and as challenge #157 in Phil Harrington's Cosmic Challenge: The Ultimate Observing List for Amateurs.  

https://www.cloudyni...he-beehive-m44/

 

https://www.cloudyni...ve-cluster-m44/

 

Dave Mitsky



#12 RussL

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Posted 26 April 2019 - 01:55 PM

M44 is one of my favorite bright objects, being that I live in a red zone. I don't see as many background stars due to such a bright sky, but, to be honest, I like it that way on M44. Normally, I can see only about 30-40 stars in the cluster, but that helps it stand out, almost constellation-like. I feel the same way about the Auriga clusters, M36, 37 and 38. Also, M7 in Scorpius. I once caught M7 when it was low in the soup, and the cluster's stars were all twinkling. I just loved that, aesthetically.

#13 Tony Flanders

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Posted 27 April 2019 - 06:22 AM

In general I wonder what range of magnitudes the eye can see at once. I’m sure it depends on sky background and star brightness and star density. I’m guessing six magnitudes.

At least ten magnitudes; probably much more.

 

Granted a planet isn't the same as a star. But Saturn usually clocks in around zero magnitude, and it's easy to see its 12th-magnitude moons through my 12.5-inch Dob as long as they're not hard up against either the rings or the planet's disk.

 

Likewise, even binoculars show most of the stars of the Pleiades when the full Moon passes through that cluster.



#14 tchandler

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Posted 27 April 2019 - 07:51 AM

One of the naked-eye views that I really enjoy from a dark site in the spring is seeing M44 and Melotte 111 simultaneously.

 

A fellow in our club joined me the other night. He is an avid astrophotographer and I was not aware that he didn't do much in the way of visual. He'd never seen Mel 111 before. It was amusing to hear his reaction when seeing it for the first time. And when he pointed 10X50 binoculars at it. 



#15 Organic Astrochemist

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Posted 27 April 2019 - 09:31 AM

At least ten magnitudes; probably much more.

Granted a planet isn't the same as a star. But Saturn usually clocks in around zero magnitude, and it's easy to see its 12th-magnitude moons through my 12.5-inch Dob as long as they're not hard up against either the rings or the planet's disk.

Likewise, even binoculars show most of the stars of the Pleiades when the full Moon passes through that cluster.

Thanks for that useful data.

I think the term for what we’re talking about is contrast sensitivity and from what I’ve seen not only does it depend on background brightness and the apparent size of the object, it also depends spatial frequency of the contrast variation or how closely spaced are the variations in contrast.

Contrast sensitivity is greatest in the photopic regime, so its interesting that the examples you chose to illustrate maximum contrast sensitivity involved very bright objects suggesting photopic conditions.

As the brightness of the objects decreases and one enters purely scotopic vision contrast sensitivity will decrease. The angular separation required to perceive that contrast will increase.

When observing the whole beehive cluster, what are the faintest stars you can see?

Ten magnitudes? From mag 6 to mag 16?


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