APOD: Galaxy by the Lake (2022 Sep 10)

Comments and questions about the APOD on the main view screen.
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APOD: Galaxy by the Lake (2022 Sep 10)

Post by APOD Robot » Sat Sep 10, 2022 4:05 am

Image Galaxy by the Lake

Explanation: This 180 degree panoramic night skyscape captures our Milky Way Galaxy as it arcs above the horizon on a winter's night in August. Near midnight, the galactic center is close to the zenith with the clear waters of Lake Traful, Neuquen, Argentina, South America, planet Earth below. Zodiacal light, dust reflected sunlight along the Solar System's ecliptic plane, is also visible in the region's very dark night sky. The faint band of light reaches up from the distant snowy peaks toward the galaxy's center. Follow the arc of the Milky Way to the left to find the southern hemisphere stellar beacons Alpha and Beta Centauri. Close to the horizon bright star Vega is reflected in the calm mountain lake.

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Re: APOD: Galaxy by the Lake (2022 Sep 10)

Post by Ann » Sat Sep 10, 2022 4:49 am

Traful-Lake-label1024[1].jpg

So Vega may look white in the APOD, but look at its reflection in the lake. Is it blue ███ or is it blue ███ ? Just saying!

The brightest star almost straight up from Vega, a little to the right and on the other side of the Milky Way, is Altair of the Summer Triangle. (Vega is also a part of the Summer Triangle, of course. So is Deneb, which can't be seen in this APOD.) And that indistinct grouping of stars some distance to the right of Altair must be Delphinus. 🐬


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Re: APOD: Galaxy by the Lake (2022 Sep 10)

Post by VictorBorun » Sat Sep 10, 2022 6:26 am

Ann wrote: Sat Sep 10, 2022 4:49 am Traful-Lake-label1024[1].jpg


So Vega may look white in the APOD, but look at its reflection in the lake. Is it blue ███ or is it blue ███ ? Just saying!

The brightest star almost straight up from Vega, a little to the right and on the other side of the Milky Way, is Altair of the Summer Triangle. (Vega is also a part of the Summer Triangle, of course. So is Deneb, which can't be seen in this APOD.) And that indistinct grouping of stars some distance to the right of Altair must be Delphinus. 🐬


Ann
I suspect Deneb is here
Galaxy by the Lake (2022 Sep 10)..jpg
And after I found this, I am pretty sure
Galaxy by the Lake (2022 Sep 10) -1.jpg
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Re: APOD: Galaxy by the Lake (2022 Sep 10)

Post by VictorBorun » Sat Sep 10, 2022 8:41 am

it's a pretty site to see the constellations of Milky Way, Ecliptic and Equator all at once:
Galaxy by the Lake (2022 Sep 10) -2.jpg
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Re: APOD: Galaxy by the Lake (2022 Sep 10)

Post by Ann » Sat Sep 10, 2022 9:58 am

VictorBorun wrote: Sat Sep 10, 2022 6:26 am
Ann wrote: Sat Sep 10, 2022 4:49 am Traful-Lake-label1024[1].jpg


So Vega may look white in the APOD, but look at its reflection in the lake. Is it blue ███ or is it blue ███ ? Just saying!

The brightest star almost straight up from Vega, a little to the right and on the other side of the Milky Way, is Altair of the Summer Triangle. (Vega is also a part of the Summer Triangle, of course. So is Deneb, which can't be seen in this APOD.) And that indistinct grouping of stars some distance to the right of Altair must be Delphinus. 🐬


Ann
I suspect Deneb is here And after I found this, I am pretty sure:
You're right, Victor. Deneb is in the picture.

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Re: APOD: Galaxy by the Lake (2022 Sep 10)

Post by canopia » Sat Sep 10, 2022 1:50 pm

Nice view. Annotated version has better, richer colours. :wink:

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Re: APOD: Galaxy by the Lake (2022 Sep 10)

Post by orin stepanek » Sat Sep 10, 2022 2:20 pm

Traful-Lake-label1024.jpg
Very nice for a 180 degree panorama! No war-page at all!
SouthIsland_Horalek_960_annotated.jpg
Good locator map, I think 8-) !
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Re: APOD: Galaxy by the Lake (2022 Sep 10)

Post by Chris Peterson » Sat Sep 10, 2022 2:36 pm

Ann wrote: Sat Sep 10, 2022 4:49 am So Vega may look white in the APOD, but look at its reflection in the lake. Is it blue ███ or is it blue ███ ? Just saying!
Bright stars saturate camera sensors. That is, they fill the red, green, and blue pixels to their maximum value. And what color do you get when red, green, and blue all have the same high value? White. So bright stars usually look white in images. How do we see them in something approximating their true colors? We can defocus the lens a bit (or our eyes, through a telescope). We can let them trail, so the exposure on any one pixel is shorter. We can image at a high enough magnification that stars show obvious halos, which don't saturate. Or we can see them reflected, especially in moving water, which spreads their light out over a lot more pixels. And indeed, we've seen all of these techniques (deliberate or accidental) used in APODs over the years.
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Re: APOD: Galaxy by the Lake (2022 Sep 10)

Post by VictorBorun » Sat Sep 10, 2022 3:19 pm

Chris Peterson wrote: Sat Sep 10, 2022 2:36 pm
Ann wrote: Sat Sep 10, 2022 4:49 am So Vega may look white in the APOD, but look at its reflection in the lake. Is it blue ███ or is it blue ███ ? Just saying!
Bright stars saturate camera sensors. That is, they fill the red, green, and blue pixels to their maximum value. And what color do you get when red, green, and blue all have the same high value? White. So bright stars usually look white in images. How do we see them in something approximating their true colors? We can defocus the lens a bit (or our eyes, through a telescope). We can let them trail, so the exposure on any one pixel is shorter. We can image at a high enough magnification that stars show obvious halos, which don't saturate. Or we can see them reflected, especially in moving water, which spreads their light out over a lot more pixels. And indeed, we've seen all of these techniques (deliberate or accidental) used in APODs over the years.
too bad Antares the Red is not reflected in the water or anything.
Deneb shows in the water as bright, yellowish and skewed
Galaxy by the Lake (2022 Sep 10).2.jpg
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Re: APOD: Galaxy by the Lake (2022 Sep 10)

Post by johnnydeep » Sat Sep 10, 2022 8:32 pm

Chris Peterson wrote: Sat Sep 10, 2022 2:36 pm
Ann wrote: Sat Sep 10, 2022 4:49 am So Vega may look white in the APOD, but look at its reflection in the lake. Is it blue ███ or is it blue ███ ? Just saying!
Bright stars saturate camera sensors. That is, they fill the red, green, and blue pixels to their maximum value. And what color do you get when red, green, and blue all have the same high value? White. So bright stars usually look white in images. How do we see them in something approximating their true colors? We can defocus the lens a bit (or our eyes, through a telescope). We can let them trail, so the exposure on any one pixel is shorter. We can image at a high enough magnification that stars show obvious halos, which don't saturate. Or we can see them reflected, especially in moving water, which spreads their light out over a lot more pixels. And indeed, we've seen all of these techniques (deliberate or accidental) used in APODs over the years.
How about using a shorter exposure time?
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Re: APOD: Galaxy by the Lake (2022 Sep 10)

Post by Chris Peterson » Sat Sep 10, 2022 9:00 pm

johnnydeep wrote: Sat Sep 10, 2022 8:32 pm
Chris Peterson wrote: Sat Sep 10, 2022 2:36 pm
Ann wrote: Sat Sep 10, 2022 4:49 am So Vega may look white in the APOD, but look at its reflection in the lake. Is it blue ███ or is it blue ███ ? Just saying!
Bright stars saturate camera sensors. That is, they fill the red, green, and blue pixels to their maximum value. And what color do you get when red, green, and blue all have the same high value? White. So bright stars usually look white in images. How do we see them in something approximating their true colors? We can defocus the lens a bit (or our eyes, through a telescope). We can let them trail, so the exposure on any one pixel is shorter. We can image at a high enough magnification that stars show obvious halos, which don't saturate. Or we can see them reflected, especially in moving water, which spreads their light out over a lot more pixels. And indeed, we've seen all of these techniques (deliberate or accidental) used in APODs over the years.
How about using a shorter exposure time?
Well, sure, if you don't mind losing all the dimmer stuff!
Chris

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Re: APOD: Galaxy by the Lake (2022 Sep 10)

Post by johnnydeep » Sat Sep 10, 2022 9:28 pm

Chris Peterson wrote: Sat Sep 10, 2022 9:00 pm
johnnydeep wrote: Sat Sep 10, 2022 8:32 pm
Chris Peterson wrote: Sat Sep 10, 2022 2:36 pm
Bright stars saturate camera sensors. That is, they fill the red, green, and blue pixels to their maximum value. And what color do you get when red, green, and blue all have the same high value? White. So bright stars usually look white in images. How do we see them in something approximating their true colors? We can defocus the lens a bit (or our eyes, through a telescope). We can let them trail, so the exposure on any one pixel is shorter. We can image at a high enough magnification that stars show obvious halos, which don't saturate. Or we can see them reflected, especially in moving water, which spreads their light out over a lot more pixels. And indeed, we've seen all of these techniques (deliberate or accidental) used in APODs over the years.
How about using a shorter exposure time?
Well, sure, if you don't mind losing all the dimmer stuff!
Is "trailing" any better? I guess that'd get you dim trails as opposed to dim points. Is that preferable?
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Re: APOD: Galaxy by the Lake (2022 Sep 10)

Post by bystander » Sat Sep 10, 2022 9:46 pm

johnnydeep wrote: Sat Sep 10, 2022 9:28 pm Is "trailing" any better? I guess that'd get you dim trails as opposed to dim points. Is that preferable?
Star trail images are among my least favorite, not quite in the realm of Matt Harding, but getting close.
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Re: APOD: Galaxy by the Lake (2022 Sep 10)

Post by Chris Peterson » Sun Sep 11, 2022 2:54 am

johnnydeep wrote: Sat Sep 10, 2022 9:28 pm
Chris Peterson wrote: Sat Sep 10, 2022 9:00 pm
johnnydeep wrote: Sat Sep 10, 2022 8:32 pm

How about using a shorter exposure time?
Well, sure, if you don't mind losing all the dimmer stuff!
Is "trailing" any better? I guess that'd get you dim trails as opposed to dim points. Is that preferable?
Dim trails are MUCH easier for our eyes to see than dim points. We can detect lines that are thinner than our resolution limit... but not points. And lines that are very near our contrast limit... but not points.
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Re: APOD: Galaxy by the Lake (2022 Sep 10)

Post by johnnydeep » Sun Sep 11, 2022 1:25 pm

Chris Peterson wrote: Sun Sep 11, 2022 2:54 am
johnnydeep wrote: Sat Sep 10, 2022 9:28 pm
Chris Peterson wrote: Sat Sep 10, 2022 9:00 pm
Well, sure, if you don't mind losing all the dimmer stuff!
Is "trailing" any better? I guess that'd get you dim trails as opposed to dim points. Is that preferable?
Dim trails are MUCH easier for our eyes to see than dim points. We can detect lines that are thinner than our resolution limit... but not points. And lines that are very near our contrast limit... but not points.
Thanks. Makes sense since there would be far more dim pixels in a dim line than in a single dim point.
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