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ASTRO: M51 with 2 hours clear and 3 hours Halpha
I added three hours of halpha to my previous 1h57m of clear data
it is definitely accentuates the HII knots ... http://www.narrowbandimaging.com/m51...camel_page.htm |
#2
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ASTRO: M51 with 2 hours clear and 3 hours Halpha
Richard Crisp wrote: I added three hours of halpha to my previous 1h57m of clear data it is definitely accentuates the HII knots ... http://www.narrowbandimaging.com/m51...camel_page.htm That's what I'd like to do with my color shot of it. But so far this season the skies haven't been up to it. I use 30 minute subs and am lucky to get 20 clear minutes any spot in the sky the last 8 months. I've fallen for too many sucker holes as it is. Then too I need seeing to match. That's rare too. I took the M51 shot on one of the best nights I've seen here. They don't happen often though just finished processing 5053 taken on the best night ever here. I'll be posting that next. 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
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ASTRO: M51 with 2 hours clear and 3 hours Halpha
"Rick Johnson" wrote in message ... Richard Crisp wrote: I added three hours of halpha to my previous 1h57m of clear data it is definitely accentuates the HII knots ... http://www.narrowbandimaging.com/m51...camel_page.htm That's what I'd like to do with my color shot of it. But so far this season the skies haven't been up to it. I use 30 minute subs and am lucky to get 20 clear minutes any spot in the sky the last 8 months. I've fallen for too many sucker holes as it is. Then too I need seeing to match. That's rare too. I took the M51 shot on one of the best nights I've seen here. They don't happen often though just finished processing 5053 taken on the best night ever here. I'll be posting that next. well you could back off on the exposure time and take more exposures if that gives you a window of opportunity 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
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ASTRO: M51 with 2 hours clear and 3 hours Halpha
Nice image Richard. Actually I prefer the version without Halpha, it looks
sharper. Of course the Halpha will come in handy once you get RGB images... Stefan "Richard Crisp" schrieb im Newsbeitrag .. . I added three hours of halpha to my previous 1h57m of clear data it is definitely accentuates the HII knots ... http://www.narrowbandimaging.com/m51...camel_page.htm |
#5
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ASTRO: M51 with 2 hours clear and 3 hours Halpha
Richard Crisp wrote: "Rick Johnson" wrote in message ... Richard Crisp wrote: I added three hours of halpha to my previous 1h57m of clear data it is definitely accentuates the HII knots ... http://www.narrowbandimaging.com/m51...camel_page.htm That's what I'd like to do with my color shot of it. But so far this season the skies haven't been up to it. I use 30 minute subs and am lucky to get 20 clear minutes any spot in the sky the last 8 months. I've fallen for too many sucker holes as it is. Then too I need seeing to match. That's rare too. I took the M51 shot on one of the best nights I've seen here. They don't happen often though just finished processing 5053 taken on the best night ever here. I'll be posting that next. well you could back off on the exposure time and take more exposures if that gives you a window of opportunity I don't like doing that as the noise goes up. 3 20 minute shots give more noise than 2 30 minute ones in H-alpha. 10 minutes gives the best result with Luminosity at 2x2 and color 3x3. This is when the sky is really dark. Add some extra background light and shorter exposures aren't any more noisy as it is lost in the background. On a good night I can get a background count of less than 350 in 10 minutes with the Lum filters, 500 on an average night. H-alpha takes 30 minutes for the same background even with some moon out. With such a low background count longer exposure times for the subs are better. At least that's my experience. 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". |
#6
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ASTRO: M51 with 2 hours clear and 3 hours Halpha
"Richard Crisp" wrote ... I added three hours of halpha to my previous 1h57m of clear data it is definitely accentuates the HII knots ... Richard, Interesting! I'm surprised that there are no 'knots' in NGC 5195, but then I guess this entire disturbed galaxy is a mass of star formation. BTW, for those not familiar with the look of M-51 in a larger scope from dark sky: The thin 'cloud' of displaced stars around NGC 5195 shows easily in my 20-inch Dob from a dark location, not to mention considerable detail in the spiral arms. However it takes mag 6.5 sky and good seeing, at least for my eyes to see this level of detail. George N |
#7
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ASTRO: M51 with 2 hours clear and 3 hours Halpha
"Rick Johnson" wrote I don't like doing that as the noise goes up. 3 20 minute shots give more noise than 2 30 minute ones in H-alpha. ...... If I took three 20 minute long exposures I'd have images of at least three airliners and/or satellites! George N |
#8
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ASTRO: M51 with 2 hours clear and 3 hours Halpha
George Normandin wrote: "Rick Johnson" wrote I don't like doing that as the noise goes up. 3 20 minute shots give more noise than 2 30 minute ones in H-alpha. ...... If I took three 20 minute long exposures I'd have images of at least three airliners and/or satellites! George N With H-alpha they aren't much of a problem. They are poor H-alpha emitters. Since I get less noise at 10 minutes with visible light I do catch a lot of satellites. I'm off the plane route so they aren't much of a problem. If the star field isn't dense I usually clone them out. A few stars have been erased in the process. Better not use such shots to look for changes in the star field! My normal 4 or so frames isn't enough to use a sigma clip type routine to eliminate them. Then too it eliminates asteroids. So far I've hit two that are unknown to the Minor Planet Center. Unfortunately, I found them long after the image was taken so they will remain unknown for a while longer. 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". |
#9
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ASTRO: M51 with 2 hours clear and 3 hours Halpha
"Rick Johnson" wrote ...... I'm off the plane route so they aren't much of a problem...... Rick, For some reason there is a lot of air traffic to the south of Kopernik (Scranton PA??), and I live only 2 miles from a regional airport. Last night while I was testing out my new Denk II binos on my Obsession 20 a C-130 was practicing touch and goes at the airport. It's a little exciting being up a ladder in the dark and having a C-130 with gear and flaps down charging by just overhead. George N |
#10
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ASTRO: M51 with 2 hours clear and 3 hours Halpha
George Normandin wrote: "Rick Johnson" wrote ...... I'm off the plane route so they aren't much of a problem...... Rick, For some reason there is a lot of air traffic to the south of Kopernik (Scranton PA??), and I live only 2 miles from a regional airport. Last night while I was testing out my new Denk II binos on my Obsession 20 a C-130 was practicing touch and goes at the airport. It's a little exciting being up a ladder in the dark and having a C-130 with gear and flaps down charging by just overhead. George N Twice last summer a C130 (two one time) flew by only a few feet above the lake. My living level is 55 feet above lake level and I saw the TOP of its wings both times. What the hell it was doing I've never figured out. There is an island right in front of them. The first time there were two. One was 200' high but the other was maybe 5 feet above the water headed right for the island. It was at full throttle and pulled up just in time to clear the trees but the other one above it had to veer left to avoid a collision. I'd have loved to hear the radio after that! Next time it was only one and it was in a sharp bank. There's a narrow channel between the island and shore. No way its wings fit through unless you put it in a very steep bank. That's what he did! Both were Air National Guard planes. There is a cabin right on that point but no one was there at the time so if he was showing off for them it was wasted effort. I'd swear that wing tip was less than 2' off the water. I expected it to be cartwheeling down the channel but it made it. The bank had to be held as that channel ends in yet another island he had to curve around. He was banked the right way to do so. There'd not be time to level the wings and climb. He had to pull a sharp, high G turn with at least a 70 degree bank to pull it off. Several of us filed some complaints but of course heard nothing but a form letter in reply. If a boat had turned into that channel it would have been very toasty around here. 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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