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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". |
#2
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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
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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
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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
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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
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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
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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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