|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
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 |
#2
|
|||
|
|||
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
|
|||
|
|||
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
|
|||
|
|||
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 |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
ASTRO: NGC 4051 under good skies | Stefan Lilge | Astro Pictures | 1 | May 10th 08 11:36 PM |
ASTRO: M65-M66 colour | Stefan Lilge | Astro Pictures | 2 | February 20th 08 04:59 AM |
ASTRO: NGC 7635 in colour | Stefan Lilge | Astro Pictures | 5 | November 6th 07 01:57 AM |
ASTRO: M74 colour | Stefan Lilge | Astro Pictures | 4 | October 21st 07 06:24 PM |
ASTRO: M51 colour | Stefan Lilge | Astro Pictures | 7 | June 6th 07 02:46 AM |