APOD: Saturn at Equinox (2014 Sep 21)

Comments and questions about the APOD on the main view screen.
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alter-ego
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Re: APOD: Saturn at Equinox (2014 Sep 21)

Post by alter-ego » Wed Sep 24, 2014 5:12 am

Nitpicker wrote:But your comment made me go and download the 83 MB tif ... and I can still only see a single clump of dim pixels in the planet's shadow, and nothing else in the image apart from the obvious bright moons (and Saturn!). I didn't bother to dim the office lights or clean my monitor, but you must have some pretty keen eyesight there, alter!
Well I certainly have my lights off, and a pretty nice monitor, and I can see to the pixel level. The default jpg is really poor and the tif dots turn into fuzzier pixel cluster. Definitely not as sharp. The dots I see are much sharper. My count still stands. Maybe there is a hot pixel or two, but the brightness and size difference between them really make them appear as stars. Yeah, the tif is the best hands down compared to the full-res jpg. Dare r alot a dots dat r dare.
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Re: APOD: Saturn at Equinox (2014 Sep 21)

Post by Nitpicker » Wed Sep 24, 2014 5:20 am

alter-ego wrote:
Nitpicker wrote:But your comment made me go and download the 83 MB tif ... and I can still only see a single clump of dim pixels in the planet's shadow, and nothing else in the image apart from the obvious bright moons (and Saturn!). I didn't bother to dim the office lights or clean my monitor, but you must have some pretty keen eyesight there, alter!
Well I certainly have my lights off, and a pretty nice monitor, and I can see to the pixel level. The default jpg is really poor and the tif dots turn into fuzzier pixel cluster. Definitely not as sharp. The dots I see are much sharper. My count still stands. Maybe there is a hot pixel or two, but the brightness and size difference between them really make them appear as stars. Yeah, the tif is the best hands down compared to the full-res jpg. Dare r alot a dots dat r dare.
Oh, I believe you. Tis more a comment on my eyes and my (bog standard) monitor, which I ramped up to max brightness and contrast for the occasion of viewing the tif, and still couldn't see anything new. I'd probably have to edit the image file and bump up the brightness to spot da lot a dots dat r dare.

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Re: APOD: Saturn at Equinox (2014 Sep 21)

Post by geckzilla » Wed Sep 24, 2014 6:19 am

Moons can appear in the general vicinity of the shadow. I'm not saying one within the umbra would be visible but it is easy for one to be in on that side of the planet and not be in the umbra. Anyway, Saturn has a LOT of little moons encircling it. I wouldn't be surprised if the dots were a mixture of both moons and artifacts...but I would be surprised if a lot of them were stars.
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alter-ego
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Re: APOD: Saturn at Equinox (2014 Sep 21)

Post by alter-ego » Thu Sep 25, 2014 4:40 am

geckzilla wrote:Moons can appear in the general vicinity of the shadow. I'm not saying one within the umbra would be visible but it is easy for one to be in on that side of the planet and not be in the umbra. Anyway, Saturn has a LOT of little moons encircling it. I wouldn't be surprised if the dots were a mixture of both moons and artifacts...but I would be surprised if a lot of them were stars.
I agree there is likely a mix. Based on the allowable moon positions and conservatively assuming any dots visible within the lit rings (right side only) are artifacts, My educated guess for the 14 dots I can see are: Moons - 2, artifacts - 3 to 6, stars - 6 to 9. Since the dark side of the image is brightened by ~4.4 magnitudes, and there are a several stars passing behind the same region brighter than 5.8 mag (to 3.9 mag), I'm sure many are stars, which the journal stated were "other bright specks", and within the umbra is where the obvious bright specs are (except for the 2 moon candidates which I'm not including). One thing I am impressed with is how artifact-free this 75-image composite is.
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