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ASTRO: Sh2-116



 
 
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  #1  
Old April 7th 10, 07:01 PM posted to alt.binaries.pictures.astro
Rick Johnson[_2_]
external usenet poster
 
Posts: 3,085
Default ASTRO: Sh2-116

Sh2-116 is also known as Abell 71. The latter is a mistake as it isn't
a planetary nebula but an HII region. It is "embedded" in the much
larger SH2-115 which is centered well southeast of my image. Sh2-115
really needs to be shot in H alpha with a wide angle telescope. So its
outskirts show up poorly in my image. I can't find much on this object,
not even a distance estimate. It is located in Cygnus not far from
Deneb which cast a nasty gradient across the image. Removing it without
removing nebula covering the entire image wasn't easy nor done all that
well. Another reason for H alpha data. Since the distance to Sh2-116
is unknown there's no way of knowing how it relates to Sh2-115 that is
also in my image. It may be in front, in it or beyond it. No way to
know. So the appearance of Sh2-116 being in Sh2-115 is likely only an
illusion but there's no way to know for sure either way from what I
could find.

I tried something different with the color data, taking only 1 20 minute
image rather than 2 10 minute ones as I usually do. When putting the
color together it really popped nicely. Usually I have to enhance the
color some but this time I actually turned it down slightly! Never had
that happen before. A couple other images I've taken this way did show
better color but I still had to give it a bit of help. Why things were
different this time I don't know.

Also I tried 20 minute rather than 10 minute luminosity subs. This did
bring up my background level some so I was closer to being sky limited
as far as system noise was concerned though still quite far from it.
But many stars saturated. This left me with great color in the bright
stars in the RGB but all white in the saturated stars of the combined
LRGB. So I reprocessed the luminosity image keeping the max level down
to about 200 rather than the max of 255. Then when I added the color it
worked well. I then used mask to bring up the cores to 255 but keeping
most of the star below this level. Lots of work but it did the trick.
Doubt I'll use many more 20 minute subs for the L layer unless the star
field is rather dim. Think I have a couple more shot this way to
process however.

Some images of this object show a green nebula just to it's east and an
even brighter one well to the southwest. These images were made from
DSS plates using a pseudo green created from the IR image. It appears
that image picked up ghosts from Deneb that created nebula like ghosts
the pseudo green process turned into green nebula. That had me confused
for a bit until I figured out what was going on with those images.

14" LX200R @ f/10, L=2x20' RGB=1x20'x3, 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 April 10th 10, 11:12 PM posted to alt.binaries.pictures.astro
Stefan Lilge
external usenet poster
 
Posts: 2,269
Default ASTRO: Sh2-116

Rick,

beautiful image, although the left part of the image seems to be out of
focus.
Most of the picture looks great. I have imaged this nebula with a UHC
filter, which certainly helps.
Your image is deeper even without narrow band though.
I'd really like to know the nature of this nebula, while you are probably
right that it is no planetary nebula (too red for that) it looks unusual for
a HII region too.

Stefan


"Rick Johnson" schrieb im Newsbeitrag
. com...
Sh2-116 is also known as Abell 71. The latter is a mistake as it isn't
a planetary nebula but an HII region. It is "embedded" in the much
larger SH2-115 which is centered well southeast of my image. Sh2-115
really needs to be shot in H alpha with a wide angle telescope. So its
outskirts show up poorly in my image. I can't find much on this object,
not even a distance estimate. It is located in Cygnus not far from
Deneb which cast a nasty gradient across the image. Removing it without
removing nebula covering the entire image wasn't easy nor done all that
well. Another reason for H alpha data. Since the distance to Sh2-116
is unknown there's no way of knowing how it relates to Sh2-115 that is
also in my image. It may be in front, in it or beyond it. No way to
know. So the appearance of Sh2-116 being in Sh2-115 is likely only an
illusion but there's no way to know for sure either way from what I
could find.

I tried something different with the color data, taking only 1 20 minute
image rather than 2 10 minute ones as I usually do. When putting the
color together it really popped nicely. Usually I have to enhance the
color some but this time I actually turned it down slightly! Never had
that happen before. A couple other images I've taken this way did show
better color but I still had to give it a bit of help. Why things were
different this time I don't know.

Also I tried 20 minute rather than 10 minute luminosity subs. This did
bring up my background level some so I was closer to being sky limited
as far as system noise was concerned though still quite far from it.
But many stars saturated. This left me with great color in the bright
stars in the RGB but all white in the saturated stars of the combined
LRGB. So I reprocessed the luminosity image keeping the max level down
to about 200 rather than the max of 255. Then when I added the color it
worked well. I then used mask to bring up the cores to 255 but keeping
most of the star below this level. Lots of work but it did the trick.
Doubt I'll use many more 20 minute subs for the L layer unless the star
field is rather dim. Think I have a couple more shot this way to
process however.

Some images of this object show a green nebula just to it's east and an
even brighter one well to the southwest. These images were made from
DSS plates using a pseudo green created from the IR image. It appears
that image picked up ghosts from Deneb that created nebula like ghosts
the pseudo green process turned into green nebula. That had me confused
for a bit until I figured out what was going on with those images.

14" LX200R @ f/10, L=2x20' RGB=1x20'x3, 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 April 10th 10, 11:12 PM posted to alt.binaries.pictures.astro
Stefan Lilge
external usenet poster
 
Posts: 2,269
Default ASTRO: Sh2-116

Rick,

beautiful image, although the left part of the image seems to be out of
focus.
Most of the picture looks great. I have imaged this nebula with a UHC
filter, which certainly helps.
Your image is deeper even without narrow band though.
I'd really like to know the nature of this nebula, while you are probably
right that it is no planetary nebula (too red for that) it looks unusual for
a HII region too.

Stefan


"Rick Johnson" schrieb im Newsbeitrag
. com...
Sh2-116 is also known as Abell 71. The latter is a mistake as it isn't
a planetary nebula but an HII region. It is "embedded" in the much
larger SH2-115 which is centered well southeast of my image. Sh2-115
really needs to be shot in H alpha with a wide angle telescope. So its
outskirts show up poorly in my image. I can't find much on this object,
not even a distance estimate. It is located in Cygnus not far from
Deneb which cast a nasty gradient across the image. Removing it without
removing nebula covering the entire image wasn't easy nor done all that
well. Another reason for H alpha data. Since the distance to Sh2-116
is unknown there's no way of knowing how it relates to Sh2-115 that is
also in my image. It may be in front, in it or beyond it. No way to
know. So the appearance of Sh2-116 being in Sh2-115 is likely only an
illusion but there's no way to know for sure either way from what I
could find.

I tried something different with the color data, taking only 1 20 minute
image rather than 2 10 minute ones as I usually do. When putting the
color together it really popped nicely. Usually I have to enhance the
color some but this time I actually turned it down slightly! Never had
that happen before. A couple other images I've taken this way did show
better color but I still had to give it a bit of help. Why things were
different this time I don't know.

Also I tried 20 minute rather than 10 minute luminosity subs. This did
bring up my background level some so I was closer to being sky limited
as far as system noise was concerned though still quite far from it.
But many stars saturated. This left me with great color in the bright
stars in the RGB but all white in the saturated stars of the combined
LRGB. So I reprocessed the luminosity image keeping the max level down
to about 200 rather than the max of 255. Then when I added the color it
worked well. I then used mask to bring up the cores to 255 but keeping
most of the star below this level. Lots of work but it did the trick.
Doubt I'll use many more 20 minute subs for the L layer unless the star
field is rather dim. Think I have a couple more shot this way to
process however.

Some images of this object show a green nebula just to it's east and an
even brighter one well to the southwest. These images were made from
DSS plates using a pseudo green created from the IR image. It appears
that image picked up ghosts from Deneb that created nebula like ghosts
the pseudo green process turned into green nebula. That had me confused
for a bit until I figured out what was going on with those images.

14" LX200R @ f/10, L=2x20' RGB=1x20'x3, 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 April 11th 10, 02:03 AM posted to alt.binaries.pictures.astro
Rick Johnson[_2_]
external usenet poster
 
Posts: 3,085
Default ASTRO: Sh2-116

For reason's I still can't fathom, not tilt, the left side, especially
the upper left corner is always out of focus more than the rest as it is
more curved there. At least that's what CCDInspector says. At f/10 I
have a wide depth of field and if I remember to focus the center well in
near outside of that range then it isn't noticeable, sometimes I forget
and use the inside and this is the result. Didn't help that this time
there is a slight tilt issue as well as a set screw had come loose as
well but 905 of it is due to that curvature issue. Why it isn't
symmetrical I'm not sure but suspect its because the mirror is fixed as
to collimation and is slightly off so the secondary has to be tilted
slightly to compensate. If I decollimate the image then the field is
flat but the stars awful looking. Each time I relock the mirror this
all changes slightly. Not enough to fix it but it can make a
difference. Due to the way I have things put together to allow visual
use as well as imaging without removing the camera the CCD is a bit
further back than Meade recommends for best corrected field. When I had
the camera too close it was the opposite corner than had the problem so
if I could put it right I think it would pretty well vanish. Right now
I try and remember which side to focus on but sometimes forget as I did
here. It doesn't show until I stretch the image so miss it looking at
the frames as they come in.

Rick


On 4/10/2010 5:12 PM, Stefan Lilge wrote:
Rick,

beautiful image, although the left part of the image seems to be out of
focus.
Most of the picture looks great. I have imaged this nebula with a UHC
filter, which certainly helps.
Your image is deeper even without narrow band though.
I'd really like to know the nature of this nebula, while you are probably
right that it is no planetary nebula (too red for that) it looks unusual for
a HII region too.

Stefan


"Rick schrieb im Newsbeitrag
. com...
Sh2-116 is also known as Abell 71. The latter is a mistake as it isn't
a planetary nebula but an HII region. It is "embedded" in the much
larger SH2-115 which is centered well southeast of my image. Sh2-115
really needs to be shot in H alpha with a wide angle telescope. So its
outskirts show up poorly in my image. I can't find much on this object,
not even a distance estimate. It is located in Cygnus not far from
Deneb which cast a nasty gradient across the image. Removing it without
removing nebula covering the entire image wasn't easy nor done all that
well. Another reason for H alpha data. Since the distance to Sh2-116
is unknown there's no way of knowing how it relates to Sh2-115 that is
also in my image. It may be in front, in it or beyond it. No way to
know. So the appearance of Sh2-116 being in Sh2-115 is likely only an
illusion but there's no way to know for sure either way from what I
could find.

I tried something different with the color data, taking only 1 20 minute
image rather than 2 10 minute ones as I usually do. When putting the
color together it really popped nicely. Usually I have to enhance the
color some but this time I actually turned it down slightly! Never had
that happen before. A couple other images I've taken this way did show
better color but I still had to give it a bit of help. Why things were
different this time I don't know.

Also I tried 20 minute rather than 10 minute luminosity subs. This did
bring up my background level some so I was closer to being sky limited
as far as system noise was concerned though still quite far from it.
But many stars saturated. This left me with great color in the bright
stars in the RGB but all white in the saturated stars of the combined
LRGB. So I reprocessed the luminosity image keeping the max level down
to about 200 rather than the max of 255. Then when I added the color it
worked well. I then used mask to bring up the cores to 255 but keeping
most of the star below this level. Lots of work but it did the trick.
Doubt I'll use many more 20 minute subs for the L layer unless the star
field is rather dim. Think I have a couple more shot this way to
process however.

Some images of this object show a green nebula just to it's east and an
even brighter one well to the southwest. These images were made from
DSS plates using a pseudo green created from the IR image. It appears
that image picked up ghosts from Deneb that created nebula like ghosts
the pseudo green process turned into green nebula. That had me confused
for a bit until I figured out what was going on with those images.

14" LX200R @ f/10, L=2x20' RGB=1x20'x3, 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".





--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".
  #5  
Old April 11th 10, 02:03 AM posted to alt.binaries.pictures.astro
Rick Johnson[_2_]
external usenet poster
 
Posts: 3,085
Default ASTRO: Sh2-116

For reason's I still can't fathom, not tilt, the left side, especially
the upper left corner is always out of focus more than the rest as it is
more curved there. At least that's what CCDInspector says. At f/10 I
have a wide depth of field and if I remember to focus the center well in
near outside of that range then it isn't noticeable, sometimes I forget
and use the inside and this is the result. Didn't help that this time
there is a slight tilt issue as well as a set screw had come loose as
well but 905 of it is due to that curvature issue. Why it isn't
symmetrical I'm not sure but suspect its because the mirror is fixed as
to collimation and is slightly off so the secondary has to be tilted
slightly to compensate. If I decollimate the image then the field is
flat but the stars awful looking. Each time I relock the mirror this
all changes slightly. Not enough to fix it but it can make a
difference. Due to the way I have things put together to allow visual
use as well as imaging without removing the camera the CCD is a bit
further back than Meade recommends for best corrected field. When I had
the camera too close it was the opposite corner than had the problem so
if I could put it right I think it would pretty well vanish. Right now
I try and remember which side to focus on but sometimes forget as I did
here. It doesn't show until I stretch the image so miss it looking at
the frames as they come in.

Rick


On 4/10/2010 5:12 PM, Stefan Lilge wrote:
Rick,

beautiful image, although the left part of the image seems to be out of
focus.
Most of the picture looks great. I have imaged this nebula with a UHC
filter, which certainly helps.
Your image is deeper even without narrow band though.
I'd really like to know the nature of this nebula, while you are probably
right that it is no planetary nebula (too red for that) it looks unusual for
a HII region too.

Stefan


"Rick schrieb im Newsbeitrag
. com...
Sh2-116 is also known as Abell 71. The latter is a mistake as it isn't
a planetary nebula but an HII region. It is "embedded" in the much
larger SH2-115 which is centered well southeast of my image. Sh2-115
really needs to be shot in H alpha with a wide angle telescope. So its
outskirts show up poorly in my image. I can't find much on this object,
not even a distance estimate. It is located in Cygnus not far from
Deneb which cast a nasty gradient across the image. Removing it without
removing nebula covering the entire image wasn't easy nor done all that
well. Another reason for H alpha data. Since the distance to Sh2-116
is unknown there's no way of knowing how it relates to Sh2-115 that is
also in my image. It may be in front, in it or beyond it. No way to
know. So the appearance of Sh2-116 being in Sh2-115 is likely only an
illusion but there's no way to know for sure either way from what I
could find.

I tried something different with the color data, taking only 1 20 minute
image rather than 2 10 minute ones as I usually do. When putting the
color together it really popped nicely. Usually I have to enhance the
color some but this time I actually turned it down slightly! Never had
that happen before. A couple other images I've taken this way did show
better color but I still had to give it a bit of help. Why things were
different this time I don't know.

Also I tried 20 minute rather than 10 minute luminosity subs. This did
bring up my background level some so I was closer to being sky limited
as far as system noise was concerned though still quite far from it.
But many stars saturated. This left me with great color in the bright
stars in the RGB but all white in the saturated stars of the combined
LRGB. So I reprocessed the luminosity image keeping the max level down
to about 200 rather than the max of 255. Then when I added the color it
worked well. I then used mask to bring up the cores to 255 but keeping
most of the star below this level. Lots of work but it did the trick.
Doubt I'll use many more 20 minute subs for the L layer unless the star
field is rather dim. Think I have a couple more shot this way to
process however.

Some images of this object show a green nebula just to it's east and an
even brighter one well to the southwest. These images were made from
DSS plates using a pseudo green created from the IR image. It appears
that image picked up ghosts from Deneb that created nebula like ghosts
the pseudo green process turned into green nebula. That had me confused
for a bit until I figured out what was going on with those images.

14" LX200R @ f/10, L=2x20' RGB=1x20'x3, 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".





--
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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