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ASTRO: NGC 4051 colour



 
 
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  #1  
Old May 10th 08, 11:45 PM posted to alt.binaries.pictures.astro
Stefan Lilge
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Posts: 2,269
Default ASTRO: NGC 4051 colour

This is the colour version of my NGC 4051 shot.
Colour was 2x5 minutes each for RGB plus 5 minutes Halpha.

http://ccd-astronomy.de/temp/4051colourgut.jpg

Stefan


__________________________________________________ _______________
NGC 4051 under good skies

Last week I made two trips to dark(er) places, one of them was OK, the other
one was marred by seeing that can only be called abysmal.
This picture of NGC 4051 was from the first night (May 7th). I was an hour's
drive (20 kilometers in Berlin and 60 outside) to the northwest of Berlin
(near a small city called Fehrbellin), so the southeastern sky was quite
bright from the lights of Berlin, which didn't bother me as I was imaging to
the south and southwest. Limiting mag near the zenith was 5.7.
I have seen much better skies, but I would be very happy if I had something
like mag 5.5 skies every night.

One thing that struck me while processing the data was that some things like
deconvolution in CCDSharp and DDP in AstroArt do actually work if you have
good data. With the images I get from the city the above mentioned routines
only produce rubbish, while they did a good job on the data I acquired near
Fehrbellin. Also I would not have needed a flatfield, while having a good
flat is the most important thing of all when imaging from Berlin.

Colour will follow, my first try at processing turned out a bit odd though,
as if I have messed up the order of the colour filters.

I did two iterations of deconvolution in CCDSharp.


Taken with a 10" Meade ACF at f/5.7 on a G11 mount, SXV-H9 camera, 17x5
minutes.

The picture can also be found at
http://ccd-astronomy.de/temp/4051-17x5gut.jpg




Attached Images
File Type: jpg 4051colourgut.jpg (164.6 KB, 96 views)
  #2  
Old May 11th 08, 07:01 PM posted to alt.binaries.pictures.astro
DvandenH
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Posts: 143
Default ASTRO: NGC 4051 colour

Both excellent pictures Stefan!
reg
Dirk


"Stefan Lilge" wrote in message
...
This is the colour version of my NGC 4051 shot.
Colour was 2x5 minutes each for RGB plus 5 minutes Halpha.

http://ccd-astronomy.de/temp/4051colourgut.jpg

Stefan


__________________________________________________ _______________
NGC 4051 under good skies

Last week I made two trips to dark(er) places, one of them was OK, the
other one was marred by seeing that can only be called abysmal.
This picture of NGC 4051 was from the first night (May 7th). I was an
hour's drive (20 kilometers in Berlin and 60 outside) to the northwest of
Berlin (near a small city called Fehrbellin), so the southeastern sky was
quite bright from the lights of Berlin, which didn't bother me as I was
imaging to the south and southwest. Limiting mag near the zenith was 5.7.
I have seen much better skies, but I would be very happy if I had
something like mag 5.5 skies every night.

One thing that struck me while processing the data was that some things
like deconvolution in CCDSharp and DDP in AstroArt do actually work if you
have good data. With the images I get from the city the above mentioned
routines only produce rubbish, while they did a good job on the data I
acquired near Fehrbellin. Also I would not have needed a flatfield, while
having a good flat is the most important thing of all when imaging from
Berlin.

Colour will follow, my first try at processing turned out a bit odd
though, as if I have messed up the order of the colour filters.

I did two iterations of deconvolution in CCDSharp.


Taken with a 10" Meade ACF at f/5.7 on a G11 mount, SXV-H9 camera, 17x5
minutes.

The picture can also be found at
http://ccd-astronomy.de/temp/4051-17x5gut.jpg



  #3  
Old May 12th 08, 05:09 PM posted to alt.binaries.pictures.astro
Rick Johnson[_3_]
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Posts: 262
Default ASTRO: NGC 4051 colour

That's one from my to-do list. I didn't get to it last spring and
weather has me so backlogged for this year it won't get done this year
either.

The dark site picture looks good. How's it compare to what you get from
your in town location?

Only 10 minutes of color data and you still got some good color. Site
must have been a lot darker. Maybe Berlin doesn't have the light
pollution of our large towns. I went to an observing site for the
Chicago club in 1964 which was even farther outside of Chicago. They
thought the skies great. I thought them worse than my back yard in
Lincoln which was way too bright for me (a town of 150,000 at the time).
But compared to downtown Chicago they were good I suppose.

My version of CCDSoft has a problem with color filters in color mode.
It defaults to Lum, Red, Green, Blue. You can change that which I do
when imaging west of the meridian as I want to get blue when high in the
sky. But when I do it still labels the images in default order. So
while I took them Lum, Blue, Green, Red. The blue frames are named with
Red in the file name and Blue in file name of the Red images. If you
look at the header it is correctly labeled. When I process something
weeks later I've forgotten which side of the meridian I was on so often
end up with red armed, blue core galaxies. Very weird looking and quite
a shock to the system!

Rick

Stefan Lilge wrote:

This is the colour version of my NGC 4051 shot.
Colour was 2x5 minutes each for RGB plus 5 minutes Halpha.

http://ccd-astronomy.de/temp/4051colourgut.jpg

Stefan


__________________________________________________ _______________
NGC 4051 under good skies

Last week I made two trips to dark(er) places, one of them was OK, the other
one was marred by seeing that can only be called abysmal.
This picture of NGC 4051 was from the first night (May 7th). I was an hour's
drive (20 kilometers in Berlin and 60 outside) to the northwest of Berlin
(near a small city called Fehrbellin), so the southeastern sky was quite
bright from the lights of Berlin, which didn't bother me as I was imaging to
the south and southwest. Limiting mag near the zenith was 5.7.
I have seen much better skies, but I would be very happy if I had something
like mag 5.5 skies every night.

One thing that struck me while processing the data was that some things like
deconvolution in CCDSharp and DDP in AstroArt do actually work if you have
good data. With the images I get from the city the above mentioned routines
only produce rubbish, while they did a good job on the data I acquired near
Fehrbellin. Also I would not have needed a flatfield, while having a good
flat is the most important thing of all when imaging from Berlin.

Colour will follow, my first try at processing turned out a bit odd though,
as if I have messed up the order of the colour filters.

I did two iterations of deconvolution in CCDSharp.


Taken with a 10" Meade ACF at f/5.7 on a G11 mount, SXV-H9 camera, 17x5
minutes.

The picture can also be found at
http://ccd-astronomy.de/temp/4051-17x5gut.jpg


  #4  
Old May 13th 08, 08:13 PM posted to alt.binaries.pictures.astro
Stefan Lilge
external usenet poster
 
Posts: 2,269
Default ASTRO: NGC 4051 colour

Rick,

The dark site picture looks good. How's it compare to what you get from
your in town location?


I don't have any pictures of NGC 4051 under Berlin skies, the only time I
have imaged it before was also under good skies (but at a much smaller
scale).
The comparison I can give are the background values, the frames of NGC 4051
had a background of around 1050 counts, while the night before in Berlin
(same setup, similar weather conditions and the moon being one day
"younger") had a background of around 15200 counts. So the Berlin skies were
around 15 times brighter. Just by watching the sky with the naked eye the
difference was dramatic. I had difficulties indentifying some constellations
because there were so many stars...

Only 10 minutes of color data and you still got some good color. Site
must have been a lot darker. Maybe Berlin doesn't have the light
pollution of our large towns. I went to an observing site for the


I don't know about cities in the USA, but I read somewhere that Paris skies
are twice as bright as in Berlin because they have more lights pointing to
the sky instead of shining down. So from the standpoint of imaging from a
city with several million inhabitants Berlin might be the top site in Europe
;-)

Stefan






Stefan Lilge wrote:

This is the colour version of my NGC 4051 shot.
Colour was 2x5 minutes each for RGB plus 5 minutes Halpha.

http://ccd-astronomy.de/temp/4051colourgut.jpg

Stefan


__________________________________________________ _______________
NGC 4051 under good skies

Last week I made two trips to dark(er) places, one of them was OK, the
other one was marred by seeing that can only be called abysmal.
This picture of NGC 4051 was from the first night (May 7th). I was an
hour's drive (20 kilometers in Berlin and 60 outside) to the northwest of
Berlin (near a small city called Fehrbellin), so the southeastern sky was
quite bright from the lights of Berlin, which didn't bother me as I was
imaging to the south and southwest. Limiting mag near the zenith was 5.7.
I have seen much better skies, but I would be very happy if I had
something like mag 5.5 skies every night.

One thing that struck me while processing the data was that some things
like deconvolution in CCDSharp and DDP in AstroArt do actually work if
you have good data. With the images I get from the city the above
mentioned routines only produce rubbish, while they did a good job on the
data I acquired near Fehrbellin. Also I would not have needed a
flatfield, while having a good flat is the most important thing of all
when imaging from Berlin.

Colour will follow, my first try at processing turned out a bit odd
though, as if I have messed up the order of the colour filters.

I did two iterations of deconvolution in CCDSharp.


Taken with a 10" Meade ACF at f/5.7 on a G11 mount, SXV-H9 camera, 17x5
minutes.

The picture can also be found at
http://ccd-astronomy.de/temp/4051-17x5gut.jpg




 




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