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ASTRO: M39 Something everyone images



 
 
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  #1  
Old April 13th 14, 07:57 AM posted to alt.binaries.pictures.astro
Rick Johnson[_2_]
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Posts: 3,085
Default ASTRO: M39 Something everyone images

M39 is one of the Messier objects I hadn't captured since going digital.
It is best seen in binoculars or a small telescope. It isn't at all
suited for imaging with a 14" scope but that's all I have for digital
work right now so it will have to do. The cluster may have been
discovered recorded by Aristotle about 325 BC as a comet like object.
Modern discovery is usually credited to Charles Messier in 1764. Though
Burnham claims it was Le Gentil in 1850 that first recorded it, that
idea is not all that well accepted. It appears certain Messier's
discovery was independent of the others so I'll go with that. It is
visible naked eye so Aristotle certainly could have seen it.

The cluster is about half a degree across and triangular in shape. My
field is just wide enough to catch the base of the triangle but the top
is well out of my field at the top of the image. It is very scattered.
So much so William Herschel refused to include it saying: “Consists of
such large and straggling stars that I could not tell where it began nor
where it ended. It cannot be called a cluster.” but his son John did
saying: " “A star of 7th mag [position taken], one of a large loose
cluster of stars of 7th to 10th magnitude; very coarsely scattered, and
filling many fields." The scopes they used had very small fields of
view making seeing it as a true cluster very difficult.

The cluster consists of all main branch stars, no giants are seen. Only
stars of A0 and cooler are seen which gives it an age of about 230 to
300 million years. Sources vary but most are at or near the top figure
of 300 million years of age. It's distance is also somewhat undecided.
WEBDA says it is about 1050 light-years distant. Most other sources I
found said around 825 light-years.

There are only two galaxies in my field with known redshift. NED only
lists two others without magnitude or redshift data. The two with known
redshifts appears related. They are close together at the bottom of my
image right of center. Both very red due to being seen through a lot of
dust in the plane of our galaxy. The face on spiral is LEDA 086597 and
is classed as a face on spiral with a redshift distance of about 160
million light-years. To its right is LEDA 167495 with a redshift
putting it about 150 million light-years distant. I found no
classification for it.

As I knew clouds were a problem I took 3 10 minute shots in each color
hoping for at least 2 being usable. Nope, only one each was and the red
one I used was marginal. Still, with stars I can get away with only 10
minutes of data per color.

14" LX200R @ f/10, L=4x10' RGB=1x10', STL-11000XM, Paramount ME

Rick
--
Prefix is correct. Domain is arvig dot net

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Name:	M39L4X10RGB1X10.JPG
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Name:	M39L4X10RGB1X10-67.JPG
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ID:	5067  
  #2  
Old April 14th 14, 10:47 PM posted to alt.binaries.pictures.astro
Stefan Lilge
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Posts: 2,269
Default ASTRO: M39 Something everyone images

Rick,

I wasn't aware of the small galaxies near the lower border of your image.
Actually I have only imaged this cluster once (in 2004) because my FOV was
always a bit small for such a large cluster.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
...

M39 is one of the Messier objects I hadn't captured since going digital.
It is best seen in binoculars or a small telescope. It isn't at all
suited for imaging with a 14" scope but that's all I have for digital
work right now so it will have to do. The cluster may have been
discovered recorded by Aristotle about 325 BC as a comet like object.
Modern discovery is usually credited to Charles Messier in 1764. Though
Burnham claims it was Le Gentil in 1850 that first recorded it, that
idea is not all that well accepted. It appears certain Messier's
discovery was independent of the others so I'll go with that. It is
visible naked eye so Aristotle certainly could have seen it.

The cluster is about half a degree across and triangular in shape. My
field is just wide enough to catch the base of the triangle but the top
is well out of my field at the top of the image. It is very scattered.
So much so William Herschel refused to include it saying: “Consists of
such large and straggling stars that I could not tell where it began nor
where it ended. It cannot be called a cluster.” but his son John did
saying: " “A star of 7th mag [position taken], one of a large loose
cluster of stars of 7th to 10th magnitude; very coarsely scattered, and
filling many fields." The scopes they used had very small fields of
view making seeing it as a true cluster very difficult.

The cluster consists of all main branch stars, no giants are seen. Only
stars of A0 and cooler are seen which gives it an age of about 230 to
300 million years. Sources vary but most are at or near the top figure
of 300 million years of age. It's distance is also somewhat undecided.
WEBDA says it is about 1050 light-years distant. Most other sources I
found said around 825 light-years.

There are only two galaxies in my field with known redshift. NED only
lists two others without magnitude or redshift data. The two with known
redshifts appears related. They are close together at the bottom of my
image right of center. Both very red due to being seen through a lot of
dust in the plane of our galaxy. The face on spiral is LEDA 086597 and
is classed as a face on spiral with a redshift distance of about 160
million light-years. To its right is LEDA 167495 with a redshift
putting it about 150 million light-years distant. I found no
classification for it.

As I knew clouds were a problem I took 3 10 minute shots in each color
hoping for at least 2 being usable. Nope, only one each was and the red
one I used was marginal. Still, with stars I can get away with only 10
minutes of data per color.

14" LX200R @ f/10, L=4x10' RGB=1x10', STL-11000XM, Paramount ME

Rick
--
Prefix is correct. Domain is arvig dot net

 




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