I photographed Cat's Eye Nebula and noticed a ring at the top of the picture. Does anyone know what that might be? Exposure time: 900s, Ha. Other images don't have this.
My first post. Sorry if it's not suitable to post here.
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Looks like a reflection of one of the glass surfaces (filter or similar) in your optical train. You can actually see 2 more, weaker reflections adjacent to it. The cats eye nebula has an extremely bright outer ring, which you seem to see here.
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I agree, it is clear you have some issue with your image train. Your image suffers from bad tracking based on what I see, it is also out of focus, and that could be a poorly focused star. The other stars in the background also seem fainter than they should be for that DSO. Even if it is caused by reflection, the other points are contributing to this.
What would be useful to know is what equipment was this taken with.
The more I look at it, the more it looks like an out of focus image.
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Robert Winslow:
I agree, it is clear you have some issue with your image train. Your image suffers from bad tracking based on what I see, it is also out of focus, and that could be a poorly focused star. The other stars in the background also seem fainter than they should be for that DSO. Even if it is caused by reflection, the other points are contributing to this.
What would be useful to know is what equipment was this taken with.
The more I look at it, the more it looks like an out of focus image.
I very much doubt it. The faint reflections aren't from NGC6543 but of the "object" whatever that is. Also note the smearing indicating some motion during the exposure. It might an off-axis reflection of something bright within the FOV of the scope. It could be well out-of focus on its own if it is much closer to the observer than infinity. While the stars aren't that well focused this got nothing to do with the appearance of the "blob", for lack of better words.
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Robert Winslow:
I agree, it is clear you have some issue with your image train. Your image suffers from bad tracking based on what I see, it is also out of focus, and that could be a poorly focused star. The other stars in the background also seem fainter than they should be for that DSO. Even if it is caused by reflection, the other points are contributing to this.
What would be useful to know is what equipment was this taken with.
The more I look at it, the more it looks like an out of focus image.
Hi, Robert
I used an iTelescope T24 to shoot and last night it was 92.91% moon illumination.
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andrea tasselli:
Robert Winslow:
I agree, it is clear you have some issue with your image train. Your image suffers from bad tracking based on what I see, it is also out of focus, and that could be a poorly focused star. The other stars in the background also seem fainter than they should be for that DSO. Even if it is caused by reflection, the other points are contributing to this.
What would be useful to know is what equipment was this taken with.
The more I look at it, the more it looks like an out of focus image.
I very much doubt it. The faint reflections aren't from NGC6543 but of the "object" whatever that is. Also note the smearing indicating some motion during the exposure. It might an off-axis reflection of something bright within the FOV of the scope. It could be well out-of focus on its own if it is much closer to the observer than infinity. While the stars aren't that well focused this got nothing to do with the appearance of the "blob", for lack of better words.
Totally agree, Andrea.
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My final Cat's Eye Nebula image:
Ha 900s x 2
Sii 900s x 1
Oiii 900s x 1
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Besides the "blob", one can see two additional faint blobs (one at 2 to 3 o'clock and another at around 7 o'clock). They're making up a nice triangle: my guess is that you've captured the anti-collision strobe lights of an aircraft at rather low altitude. As @andrea tasselli has mentioned, the object seems to be close and hence defocused.
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Besides the "blob", one can see two additional faint blobs (one at 2 to 3 o'clock and another at around 7 o'clock). They're making up a nice triangle: my guess is that you've captured the anti-collision strobe lights of an aircraft at rather low altitude. As @andrea tasselli has mentioned, the object seems to be close and hence defocused.
This is a good explanation, Björn.
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andrea tasselli:
Robert Winslow:
I agree, it is clear you have some issue with your image train. Your image suffers from bad tracking based on what I see, it is also out of focus, and that could be a poorly focused star. The other stars in the background also seem fainter than they should be for that DSO. Even if it is caused by reflection, the other points are contributing to this.
What would be useful to know is what equipment was this taken with.
The more I look at it, the more it looks like an out of focus image.
I very much doubt it. The faint reflections aren't from NGC6543 but of the "object" whatever that is. Also note the smearing indicating some motion during the exposure. It might an off-axis reflection of something bright within the FOV of the scope. It could be well out-of focus on its own if it is much closer to the observer than infinity. While the stars aren't that well focused this got nothing to do with the appearance of the "blob", for lack of better words.
Yes, it is clear that tracking is not doing well for that length of exposure time. As I had said, even if it is reflection, the fact remains that the image is out of focus, even the nebula looks like a blob. It very much looks like what I see when I am way out of focus, a while circle with a black middle. Seeing that this was 900's I would have expected more movement and more streaking as it flew into and out of frame. 900 Sec is a very long time, and would have left much worse trail IMHO. The movement of the blob is very consistent with how the trails on his stars look.
Regardless, you need to examine your image train and fix the guiding a bit better, or reduce exposure time, and check your focus. Do not know what software you use, but many imaging software has features to help you improve focus.
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Robert Winslow:
andrea tasselli:
Robert Winslow:
I agree, it is clear you have some issue with your image train. Your image suffers from bad tracking based on what I see, it is also out of focus, and that could be a poorly focused star. The other stars in the background also seem fainter than they should be for that DSO. Even if it is caused by reflection, the other points are contributing to this.
What would be useful to know is what equipment was this taken with.
The more I look at it, the more it looks like an out of focus image.
I very much doubt it. The faint reflections aren't from NGC6543 but of the "object" whatever that is. Also note the smearing indicating some motion during the exposure. It might an off-axis reflection of something bright within the FOV of the scope. It could be well out-of focus on its own if it is much closer to the observer than infinity. While the stars aren't that well focused this got nothing to do with the appearance of the "blob", for lack of better words.
Yes, it is clear that tracking is not doing well for that length of exposure time. As I had said, even if it is reflection, the fact remains that the image is out of focus, even the nebula looks like a blob. It very much looks like what I see when I am way out of focus, a while circle with a black middle. Seeing that this was 900's I would have expected more movement and more streaking as it flew into and out of frame. 900 Sec is a very long time, and would have left much worse trail IMHO. The movement of the blob is very consistent with how the trails on his stars look.
Regardless, you need to examine your image train and fix the guiding a bit better, or reduce exposure time, and check your focus. Do not know what software you use, but many imaging software has features to help you improve focus.
Thanks for your suggestion, Robert. I use a remote telescope, I will report this problem to iTelescope.
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My final Cat's Eye Nebula image:
Ha 900s x 2
Sii 900s x 1
Oiii 900s x 1
900 seconds are not that much of integration time. Also with using nearly single shots only has a high probability of any distraction in the single images are also showing up in the final image.
How did you processed the image? The colors seem a little bit off.
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