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ASTRO: Common object uncommonly processed



 
 
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  #1  
Old June 17th 07, 09:00 PM posted to alt.binaries.pictures.astro
Rick Johnson[_2_]
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Posts: 3,085
Default ASTRO: Common object uncommonly processed

Seeing was very bad when I took this one. So bad I never processed it,
about 6". None of the detail usually seen in this object was visible at
such seeing. But I did notice an odd galaxy on the left side so decided
to process it anyway for that galaxy. Then I found the object I was
taking had a lot more to it than was normally seen in photos of it that
showed just the burned out center. The center is burned out mainly
because seeing didn't allow any of the fine detail there to be seen so I
just said the heck with it and let it burn out to better expose the much
larger outer region. The bright blue cloud right of center carries its
own IC number. I'm not sure if that red chevron is part of the object or
just a bit of unrelated gas that is being hit by the shock front from
the object. It has no catalog ID I could find. In any case both the
emission object and the very weird barred spiral turned out worth
processing after all. Can anyone figure out what the commonly
photographed object in the center is? Hubble took a very famous shot of
it.

The blue oval at the bottom is a 9.6 mag star that hit the very edge of
the CCD. The exposure time was cut short by clouds. Happening all too
often this spring. If I ever get seeing like I did for NGC 4517 posted
a couple days ago, I'll try again to get the core detail.

14" LX200R @ f/10, L=3x10' RGB=1x10' all binned 2x2, STL-11000XM,
Paramount ME

Rick

--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".

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  #2  
Old June 17th 07, 10:04 PM posted to alt.binaries.pictures.astro
Richard Crisp[_1_]
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Posts: 985
Default ASTRO: Common object uncommonly processed

nice one Rick

I like the target

now the trick is to capture and process it so that you can see the outer
part and the inner part and not do a cut and paste

that's what I was doing he

http://www.narrowbandimaging.com/ngc...ge.htmunli ke you I never finished my color version.you remind me that I should :-)"Rick Johnson" wrote in ... Seeing was very bad when I took this one. So bad I never processed it, about 6". None of the detail usually seen in this object was visible at such seeing. But I did notice an odd galaxy on the left side so decided to process it anyway for that galaxy. Then I found the object I was taking had a lot more to it than was normally seen in photos of it that showed just the burned out center. The center is burned out mainly because seeing didn't allow any of the fine detail there to be seen so I just said the heck with it and let it burn out to better expose the much larger outer region. The bright blue cloud right of center carries its own IC number. I'm not sure if that red chevron is part of the object or just a bit of unrelated gas that is being hit by the shock front from the object. It has no catalog ID I could find. In any case both the emission object and the very weird barred spiral turned out worth processing after all. Can anyone figure out what the commonly photographed object in the center is? Hubble took a very famous shot of it. The blue oval at the bottom is a 9.6 mag star that hit the very edge of the CCD. The exposure time was cut short by clouds. Happening all too often this spring. If I ever get seeing like I did for NGC 4517 posted a couple days ago, I'll try again to get the core detail. 14" LX200R @ f/10, L=3x10' RGB=1x10' all binned 2x2, STL-11000XM, Paramount ME Rick -- Correct domain name is arvig and it is net not com. Prefix is correct. Third character is a zero rather than a capital "Oh".

  #3  
Old June 18th 07, 08:56 PM posted to alt.binaries.pictures.astro
Stefan Lilge
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Posts: 2,269
Default ASTRO: Common object uncommonly processed

Ahh jep, that's NGC 6543. I have a similar picture with a burned in core,
only less deep and less detail.
Your picture makes me want to revisit it at f/10.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
...
Seeing was very bad when I took this one. So bad I never processed it,
about 6". None of the detail usually seen in this object was visible at
such seeing. But I did notice an odd galaxy on the left side so decided
to process it anyway for that galaxy. Then I found the object I was
taking had a lot more to it than was normally seen in photos of it that
showed just the burned out center. The center is burned out mainly
because seeing didn't allow any of the fine detail there to be seen so I
just said the heck with it and let it burn out to better expose the much
larger outer region. The bright blue cloud right of center carries its
own IC number. I'm not sure if that red chevron is part of the object or
just a bit of unrelated gas that is being hit by the shock front from
the object. It has no catalog ID I could find. In any case both the
emission object and the very weird barred spiral turned out worth
processing after all. Can anyone figure out what the commonly
photographed object in the center is? Hubble took a very famous shot of
it.

The blue oval at the bottom is a 9.6 mag star that hit the very edge of
the CCD. The exposure time was cut short by clouds. Happening all too
often this spring. If I ever get seeing like I did for NGC 4517 posted
a couple days ago, I'll try again to get the core detail.

14" LX200R @ f/10, L=3x10' RGB=1x10' all binned 2x2, STL-11000XM,
Paramount ME

Rick

--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".


  #4  
Old June 18th 07, 11:52 PM posted to alt.binaries.pictures.astro
Rick Johnson[_2_]
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Posts: 3,085
Default ASTRO: Common object uncommonly processed

As Stefan and Richard mention this is the Cat's Eye Nebula NGC 6543.
The bright blue part of it to the right is IC 4677. The Cat's Eye
nebula is about 3000 light years away. There are two famous Hubble
shots of it:
http://antwrp.gsfc.nasa.gov/apod/ap061112.html
http://apod.nasa.gov/apod/ap070513.html

A composite of the eye and the distant faint shell I shot, as Richard
wants to avoid, taken by earth based scopes is at:
http://apod.nasa.gov/apod/ap020904.html

If I ever get super seeing, I'll try a similar compost. To do it in one
shot isn't possible with an ABG camera like mine. With a long enough
exposure to capture the outer shell the inner part is reduced to a
handful of intensity levels by the ABG gate. In my shot the core was
57126 to 57214 ADU units showing no useful detail.

The galaxy is NGC 6552 and is some 325 to 350 million light years
distant. For it to appear this large at that distance it is a giant galaxy!

Rick

  #5  
Old June 19th 07, 02:14 AM posted to alt.binaries.pictures.astro
Richard Crisp[_1_]
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Posts: 985
Default ASTRO: Common object uncommonly processed

it says composite but composite can mean different things to different
people

it can be a composite made from different filters....

the abg camera makes is far more doable than an NABG in my opinion

deeper wells help too.

my sensor used was the KAF6303E.... 100K wells NABG


"Rick Johnson" wrote in message
...
As Stefan and Richard mention this is the Cat's Eye Nebula NGC 6543. The
bright blue part of it to the right is IC 4677. The Cat's Eye nebula is
about 3000 light years away. There are two famous Hubble shots of it:
http://antwrp.gsfc.nasa.gov/apod/ap061112.html
http://apod.nasa.gov/apod/ap070513.html

A composite of the eye and the distant faint shell I shot, as Richard
wants to avoid, taken by earth based scopes is at:
http://apod.nasa.gov/apod/ap020904.html

If I ever get super seeing, I'll try a similar compost. To do it in one
shot isn't possible with an ABG camera like mine. With a long enough
exposure to capture the outer shell the inner part is reduced to a handful
of intensity levels by the ABG gate. In my shot the core was 57126 to
57214 ADU units showing no useful detail.

The galaxy is NGC 6552 and is some 325 to 350 million light years distant.
For it to appear this large at that distance it is a giant galaxy!

Rick



  #6  
Old June 19th 07, 03:52 AM posted to alt.binaries.pictures.astro
Rick Johnson[_2_]
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Posts: 3,085
Default ASTRO: Common object uncommonly processed

I'm sure the ADU counts I listed for the core are more reflective of the
efficiency of the AB gate on that pixel than of the actually photon
count. By 50k the count is completely unreliable. I try and limit the
brightest parts of the object I'm taking to less than 30k for this
reason. It is quite linear below 30k but above that the individual ab
gates seem to start adding noise. It's so small as to be meaningless to
the photo, not photometry however, until you hit about 45k. Above that
all bets are off. Most of the time only stars reach that level so its
not a problem but the core of the Cat's Eye is so bright it hits that
level in about 2 minutes at 2x2 binning even through a color filter (not
narrow band). At that time the outer shell would be barely out of the
noise. It could be done in one shot but I doubt it would look as good
as it would with separate short shots for the core. Your type of chip
would be far superior for this, even the ST-7's chip being non abg would
do better though it would barely fit the FOV. I'll go the two exposure
route.

Rick


Richard Crisp wrote:
it says composite but composite can mean different things to different
people

it can be a composite made from different filters....

the abg camera makes is far more doable than an NABG in my opinion

deeper wells help too.

my sensor used was the KAF6303E.... 100K wells NABG


"Rick Johnson" wrote in message
...

As Stefan and Richard mention this is the Cat's Eye Nebula NGC 6543. The
bright blue part of it to the right is IC 4677. The Cat's Eye nebula is
about 3000 light years away. There are two famous Hubble shots of it:
http://antwrp.gsfc.nasa.gov/apod/ap061112.html
http://apod.nasa.gov/apod/ap070513.html

A composite of the eye and the distant faint shell I shot, as Richard
wants to avoid, taken by earth based scopes is at:
http://apod.nasa.gov/apod/ap020904.html

If I ever get super seeing, I'll try a similar compost. To do it in one
shot isn't possible with an ABG camera like mine. With a long enough
exposure to capture the outer shell the inner part is reduced to a handful
of intensity levels by the ABG gate. In my shot the core was 57126 to
57214 ADU units showing no useful detail.

The galaxy is NGC 6552 and is some 325 to 350 million light years distant.
For it to appear this large at that distance it is a giant galaxy!

Rick


  #7  
Old June 19th 07, 04:06 AM posted to alt.binaries.pictures.astro
Richard Crisp[_1_]
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Posts: 985
Default ASTRO: Common object uncommonly processed

here's my point;

you actually want dynamic range compression and that's what you get with an
ABG: the more signal the less "gain" you have in the system.

effectively that increases the dynamic range of the system, but the
nonlinearity can be an issue in at least one non-photometric scenario:.

in a linear ccd, there can be a very small signal "swing" (low contrast
image) sitting atop a tall "pedestal" (bright background: a spicule on the
surface of the sun shot through a tight Ha filter for example)

since the response is linear: 100ADU difference in the signal at the top of
the Pedestal is the same as 100ADU difference at the lower end of the
sensor's dynamic range.

in the case of an ABG sensor, what can happen is that a 100ADU signal at the
lower end of the range may compress to a 25ADU signal sitting atop a tall
pedestal.

that's really the only issue I see.

in the case of the Cat's Eye, the core is reasonably high contrast; but the
darn thing is just bright compared to the outer halo

my way of thinking is that you use an ABG to advantage by:

1) use [OIII] and Ha filters and or [SII]
2) take longish unbinned exposures (see how long you can go without
saturating a 2x2 binned and then multiply that by four) that don't saturate
the core
3) forget binning and luminance, do it straight up eline (except maybe Blue
in lieu of [SII] which isn't blue anyway). The ESO shot you showed used
[NII] and [OIII]. You could accomplish nearly the same thing by using Ha and
[OIII]

you can do that shooting even in a full moon which is pretty nice



"Rick Johnson" wrote in message
...
I'm sure the ADU counts I listed for the core are more reflective of the
efficiency of the AB gate on that pixel than of the actually photon count.
By 50k the count is completely unreliable. I try and limit the brightest
parts of the object I'm taking to less than 30k for this reason. It is
quite linear below 30k but above that the individual ab gates seem to
start adding noise. It's so small as to be meaningless to the photo, not
photometry however, until you hit about 45k. Above that all bets are off.
Most of the time only stars reach that level so its not a problem but the
core of the Cat's Eye is so bright it hits that level in about 2 minutes
at 2x2 binning even through a color filter (not narrow band). At that
time the outer shell would be barely out of the noise. It could be done
in one shot but I doubt it would look as good as it would with separate
short shots for the core. Your type of chip would be far superior for
this, even the ST-7's chip being non abg would do better though it would
barely fit the FOV. I'll go the two exposure route.

Rick


Richard Crisp wrote:
it says composite but composite can mean different things to different
people

it can be a composite made from different filters....

the abg camera makes is far more doable than an NABG in my opinion

deeper wells help too.

my sensor used was the KAF6303E.... 100K wells NABG


"Rick Johnson" wrote in message
...

As Stefan and Richard mention this is the Cat's Eye Nebula NGC 6543. The
bright blue part of it to the right is IC 4677. The Cat's Eye nebula is
about 3000 light years away. There are two famous Hubble shots of it:
http://antwrp.gsfc.nasa.gov/apod/ap061112.html
http://apod.nasa.gov/apod/ap070513.html

A composite of the eye and the distant faint shell I shot, as Richard
wants to avoid, taken by earth based scopes is at:
http://apod.nasa.gov/apod/ap020904.html






If I ever get super seeing, I'll try a similar compost. To do it in one
shot isn't possible with an ABG camera like mine. With a long enough
exposure to capture the outer shell the inner part is reduced to a
handful of intensity levels by the ABG gate. In my shot the core was
57126 to 57214 ADU units showing no useful detail.

The galaxy is NGC 6552 and is some 325 to 350 million light years
distant. For it to appear this large at that distance it is a giant
galaxy!

Rick




 




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