NGC 6791 in Lyra - A galactic survivor

Dear friends,

Perhaps the oldest open cluster in our galaxy is NGC 6791 in Lyra which
has been estimated by Salaris (2004) to be 10.2 billion years old (ie.
about 80% the age of the universe). For an image of this galactic
survivor taken early this morning and under volatile seeing, please see
http://www.perseus.gr/Astro-DSO-NGC-6791.htm .

Clear skies!

Anthony.

Anthony Ayiomamitis wrote:
Dear friends,

Perhaps the oldest open cluster in our galaxy is NGC 6791 in Lyra which
has been estimated by Salaris (2004) to be 10.2 billion years old (ie.
about 80% the age of the universe). For an image of this galactic
survivor taken early this morning and under volatile seeing, please see
http://www.perseus.gr/Astro-DSO-NGC-6791.htm .


Anthony,

Refractors don't have diffraction spikes

Bill

William R. Mattil wrote:
Anthony Ayiomamitis wrote:

Dear friends,

Perhaps the oldest open cluster in our galaxy is NGC 6791 in Lyra
which has been estimated by Salaris (2004) to be 10.2 billion years
old (ie. about 80% the age of the universe). For an image of this
galactic survivor taken early this morning and under volatile seeing,
please see http://www.perseus.gr/Astro-DSO-NGC-6791.htm .


Anthony,

Hi Bill,


Refractors don't have diffraction spikes

They were added with the help of a pair of strings for the purposes of
this imaging project and purely for aesthetic purposes. ;-) :-)

Anthony.


Bill

On May 17, 4:29 pm, Anthony Ayiomamitis
wrote:
William R. Mattil wrote:
Anthony Ayiomamitis wrote:

Dear friends,

Perhaps the oldest open cluster in our galaxy is NGC 6791 in Lyra
which has been estimated by Salaris (2004) to be 10.2 billion years
old (ie. about 80% the age of the universe). For an image of this
galactic survivor taken early this morning and under volatile seeing,
please seehttp://www.perseus.gr/Astro-DSO-NGC-6791.htm.

Anthony,

Hi Bill,



Refractors don't have diffraction spikes

They were added with the help of a pair of strings for the purposes of
this imaging project and purely for aesthetic purposes. ;-) :-)

Anthony.





Bill- Hide quoted text -

- Show quoted text -

Antoni,

Excellent capture of my old nemesis. To date I have only resolved
one star here and that is U Lyrae and I am completely confident
that it is not part of the cluster.

I noticed on your high resolution image the foreground stars seem
to take on a light green color. You can get the same sort of effect
playing around with ALADIN images by manipulating the color
channels. This could be a potentially useful device for eliminating
the background / foreground contamination which is a problem
in many open clusters. (compare NGC 7789).

What do you think?

Ben

Ben wrote:
On May 17, 4:29 pm, Anthony Ayiomamitis
wrote:

William R. Mattil wrote:

Anthony Ayiomamitis wrote:

Dear friends,


snip




Antoni,

Hi Ben,


Excellent capture of my old nemesis. To date I have only resolved
one star here and that is U Lyrae and I am completely confident
that it is not part of the cluster.


This DSO has been on my list of targets for some time and it is now
getting into position. I must revisit it, for the result could be better.

I noticed on your high resolution image the foreground stars seem
to take on a light green color. You can get the same sort of effect
playing around with ALADIN images by manipulating the color
channels. This could be a potentially useful device for eliminating
the background / foreground contamination which is a problem
in many open clusters. (compare NGC 7789).

What do you think?

My seeing last night was volatile with differing FWHM between sets of
images. The night started out well when capturing the luminance portion
but things degraded thereafter with the blue being impacted the most.

I was debating about posting the result since it is not exactly where I
want it to be. However, it is a baseline image and which I will build
upon shortly with a follow-up image at the first opportunity.

In fact I had a slightly different problem with M92 (also from last
night) and which I purposely did not post. Anyway, since the cat is now
out of the bag, here you go:
http://www.perseus.gr/Astro-DSO-NGC-6341.htm ... this one will also
require a repeat visit.

Anthony.


Ben

snip snip snip
In fact I had a slightly different problem with M92 (also from last
night) and which I purposely did not post. Anyway, since the cat is now
out of the bag, here you go:http://www.perseus.gr/Astro-DSO-NGC-6341.htm... this one will also
require a repeat visit.

Anthony.

That's really interesting. Is it a problem on the blue channel
or are you picking up on authentic spectral information?

One used to expect a certain homogenous distribution of
spectral classes in the globulars but this has proven to
be not necessarily the case. I doubt those are "blue
stragglers". Why then the blue tint in those particular
stars? Requires repeated visits....

Ben

snip snip snip
In fact I had a slightly different problem with M92 (also from last
night) and which I purposely did not post. Anyway, since the cat is now
out of the bag, here you go:http://www.perseus.gr/Astro-DSO-NGC-6341.htm... this one will also
require a repeat visit.

Anthony.

That's really interesting. Is it a problem on the blue channel
or are you picking up on authentic spectral information?

One used to expect a certain homogenous distribution of
spectral classes in the globulars but this has proven to
be not necessarily the case. I doubt those are "blue
stragglers". Why then the blue tint in those particular
stars? Requires repeated visits....

Ben

Ben wrote:
snip snip snip

In fact I had a slightly different problem with M92 (also from last
night) and which I purposely did not post. Anyway, since the cat is now
out of the bag, here you go:http://www.perseus.gr/Astro-DSO-NGC-6341.htm... this one will also
require a repeat visit.

Anthony.


That's really interesting. Is it a problem on the blue channel
or are you picking up on authentic spectral information?

What is very odd is that the histograms are perfectly matched and, as
such, I cannot explain the blue tint. I also corrected for the
differential QE of the camera between R, G and B as well as atmospheric
extinction.


One used to expect a certain homogenous distribution of
spectral classes in the globulars but this has proven to
be not necessarily the case. I doubt those are "blue
stragglers". Why then the blue tint in those particular
stars? Requires repeated visits....

I have a second CCD camera coming (SBIG ST-10XME) and I am interested to
see if it also behaves the same.

Anthony.


Ben

On May 17, 10:29 pm, Anthony Ayiomamitis
wrote:
William R. Mattil wrote:
Anthony Ayiomamitis wrote:

Dear friends,

Perhaps the oldest open cluster in our galaxy is NGC 6791 in Lyra
which has been estimated by Salaris (2004) to be 10.2 billion years
old (ie. about 80% the age of the universe). For an image of this
galactic survivor taken early this morning and under volatile seeing,
please seehttp://www.perseus.gr/Astro-DSO-NGC-6791.htm.

Anthony,

Hi Bill,



Refractors don't have diffraction spikes

They were added with the help of a pair of strings for the purposes of
this imaging project and purely for aesthetic purposes. ;-) :-)

Anthony.





Bill- Hide quoted text -

- Show quoted text -

O.K. sunshine,now you are front and center and can openly admit to
adding aesthetic flourishes to your images.

As the only expert here on the astronomical principles behind the
creation of the 24 hour day and its application to terrestrial
longitudes I would like to see the procedure you used in creating the
analemma even though I know it is a late 17th century hoax.

If you are more comfortable explaining the procedure using the values
supplied by Huygens in the Equation tables provided below (as
opposed to 'analemmatic' tables) then be my guest -

http://www.xs4all.nl/~adcs/Huygens/06/kort-E.html

oriel36 wrote:
On May 17, 10:29 pm, Anthony Ayiomamitis
wrote:

William R. Mattil wrote:

Anthony Ayiomamitis wrote:

Dear friends,

Perhaps the oldest open cluster in our galaxy is NGC 6791 in Lyra
which has been estimated by Salaris (2004) to be 10.2 billion years
old (ie. about 80% the age of the universe). For an image of this
galactic survivor taken early this morning and under volatile seeing,
please seehttp://www.perseus.gr/Astro-DSO-NGC-6791.htm.

Anthony,

Hi Bill,




Refractors don't have diffraction spikes

They were added with the help of a pair of strings for the purposes of
this imaging project and purely for aesthetic purposes. ;-) :-)

Anthony.






Bill- Hide quoted text -

- Show quoted text -


O.K. sunshine,now you are front and center and can openly admit to
adding aesthetic flourishes to your images.

Did I ever deny or avoid such a "confession"? In fact, if you check the
archives here on s.a.a. you will find many questions (and answers!)
surrounding my open star cluster images and the spikes for the brighter
member stars.


As the only expert here on the astronomical principles behind the
creation of the 24 hour day and its application to terrestrial
longitudes I would like to see the procedure you used in creating the
analemma even though I know it is a late 17th century hoax.

Enjoy: http://www.perseus.gr/Astro-Tips-Analemma.htm .... my procedure
is described in the latter half of the page.


If you are more comfortable explaining the procedure using the values
supplied by Huygens in the Equation tables provided below (as
opposed to 'analemmatic' tables) then be my guest -

http://www.xs4all.nl/~adcs/Huygens/06/kort-E.html


The title for the above link reads "Instructions Concerning the Use of
Pendulum-Watches for finding the Longitude at Sea". What does this have
to with my photographing the sun at precisely the same time over the
course of a year?

Anthony.