by andyc » Sat Nov 04, 2023 12:55 am
Chris Peterson wrote: βSat Nov 04, 2023 12:37 am
andyc wrote: βSat Nov 04, 2023 12:31 am
Chris Peterson wrote: βFri Nov 03, 2023 4:07 pm
My assumption is that the image was made near Cortina, Italy (consistent with "northern Italy" and the imager's bio). In which case, the eclipse maximum was at 22:14 on 28 October (local time). At that time, the Moon and Jupiter were 6.19 degrees apart. In the image (taking the angular diameter of the Moon at the time to be 32.3 arcmin), Jupiter is 5.17 degrees from the Moon. That actual separation did not occur until later, at 00:53 on 29 October. After the eclipse. The separation, angle of the Moon, and moons of Jupiter are all consistent with an image made well after the eclipse was over, when no shadow would have been visible.
Hi Chris and Johnny, I think the explanation is a lot more innocent in this case. I think the images were taken at the correct date and time (eclipse phase and Galilean Moons position are both close enough to be correct IMHO. First exposure was a wider one with Moon and Jupiter, and the Moon is overexposed so that the Galilean Moons show up. The overexposure blooms the Moon image to about 10% larger. The photographer takes a second image well exposed for the eclipse shadow very shortly afterwards, possibly at a different focal length. When she went to scale & overlay the correctly-exposed Moon image on the overexposed Moon, she slightly misjudged the scaling of the Moon due to the bloomed and whited-out Moon in her first image. So Moon and Jupiter are in the right position for the event, but the Moon is just a bit too big, which throws off the separation calculation. For some reason she slightly mis-corrected the Moon's rotation, partly as there wouldn't have been a reference in the first image for the lunar features.
The resulting image is a fair representation of the scene, just with some oddities in there. It's why I called it "true to the source material" - she really did take the shots at the time and all elements are there, and I don't think in this case there's any intent at all to deceive the viewer. It must have been a lovely sight from northern Italy that night!
An overexposed image of the Moon should still have the right angular distance between the center of that Moon and Jupiter.
For an approximate image time of 22:07 local time (a few minutes here and there won't matter), and measured off an enlarged version of the image:
The image scale of the frame as calculated from the Galilean Moons (Io to Ganymede is ~22.3 pixels, ~7.92arcmin) is 2.816pixels/arcmin
The image scale as calculated from the centre of the Moon to the centre of Jupiter (~1049pixels, ~372arcmin) is 2.819pixels/arcmin
Even allowing for measurement and time error, these are far within uncertainty bounds for this sort of measurement! I'm completely satisfied that the Moon, Jupiter and the Galilean Moons are all in the right place, just the Moon is a little too large (and while that is a pity it's not quite spot on, I really doubt there was any intent to deceive).
[quote="Chris Peterson" post_id=334840 time=1699058226 user_id=117706]
[quote=andyc post_id=334839 time=1699057916 user_id=142431]
[quote="Chris Peterson" post_id=334828 time=1699027656 user_id=117706]
My assumption is that the image was made near Cortina, Italy (consistent with "northern Italy" and the imager's bio). In which case, the eclipse maximum was at 22:14 on 28 October (local time). At that time, the Moon and Jupiter were 6.19 degrees apart. In the image (taking the angular diameter of the Moon at the time to be 32.3 arcmin), Jupiter is 5.17 degrees from the Moon. That actual separation did not occur until later, at 00:53 on 29 October. After the eclipse. The separation, angle of the Moon, and moons of Jupiter are all consistent with an image made well after the eclipse was over, when no shadow would have been visible.
[/quote]
Hi Chris and Johnny, I think the explanation is a lot more innocent in this case. I think the images were taken at the correct date and time (eclipse phase and Galilean Moons position are both close enough to be correct IMHO. First exposure was a wider one with Moon and Jupiter, and the Moon is overexposed so that the Galilean Moons show up. The overexposure blooms the Moon image to about 10% larger. The photographer takes a second image well exposed for the eclipse shadow very shortly afterwards, possibly at a different focal length. When she went to scale & overlay the correctly-exposed Moon image on the overexposed Moon, she slightly misjudged the scaling of the Moon due to the bloomed and whited-out Moon in her first image. So Moon and Jupiter are in the right position for the event, but the Moon is just a bit too big, which throws off the separation calculation. For some reason she slightly mis-corrected the Moon's rotation, partly as there wouldn't have been a reference in the first image for the lunar features.
The resulting image is a fair representation of the scene, just with some oddities in there. It's why I called it "true to the source material" - she really did take the shots at the time and all elements are there, and I don't think in this case there's any intent at all to deceive the viewer. It must have been a lovely sight from northern Italy that night!
[/quote]
An overexposed image of the Moon should still have the right angular distance between the center of that Moon and Jupiter.
[/quote]
For an approximate image time of 22:07 local time (a few minutes here and there won't matter), and measured off an enlarged version of the image:
The image scale of the frame as calculated from the Galilean Moons (Io to Ganymede is ~22.3 pixels, ~7.92arcmin) is 2.816pixels/arcmin
The image scale as calculated from the centre of the Moon to the centre of Jupiter (~1049pixels, ~372arcmin) is 2.819pixels/arcmin
Even allowing for measurement and time error, these are far within uncertainty bounds for this sort of measurement! I'm completely satisfied that the Moon, Jupiter and the Galilean Moons are all in the right place, just the Moon is a little too large (and while that is a pity it's not quite spot on, I really doubt there was any intent to deceive).