APOD: Unexpected Clouds Toward the Galaxy... (2023 Jan 17)

Comments and questions about the APOD on the main view screen.
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johnnydeep
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Re: APOD: Unexpected Clouds Toward the Galaxy... (2023 Jan 17)

Post by johnnydeep » Thu Jan 19, 2023 8:44 pm

JKLassitterJr wrote: Thu Jan 19, 2023 8:37 pm The APOD for 1-17-23 is absolutely spectacular and looks almost like a painting. I've made it my desktop image.

Question: Why aren't there any light spikes -- that one usually sees in these kinds of photos -- around any of the local stars that are located within our Milky Way galaxy? Surprisingly, the stars in this view are perfect spheres of different sizes, and it is a pleasure to view them this way.

Was an app used to filter out the light spikes around the local stars?

JKLJ
The reason there are no spikes is because this image was taken using a refractor, which has no secondary mirror support struts that would have produced the spikes as in a reflector like Hubble or a large Dobsonian! The particular scope used in this case can be seen here: https://takahashiamerica.com/products/t ... -telescope (see this and other details of the hardware and software at the "shown in blue" link from the text).
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NGC3314
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Re: APOD: Unexpected Clouds Toward the Galaxy... (2023 Jan 17)

Post by NGC3314 » Thu Jan 19, 2023 10:19 pm

JKLassitterJr wrote: Thu Jan 19, 2023 8:37 pm Question: Why aren't there any light spikes -- that one usually sees in these kinds of photos -- around any of the local stars that are located within our Milky Way galaxy? Surprisingly, the stars in this view are perfect spheres of different sizes, and it is a pleasure to view them this way.
All the telescopes described in the research note for this discovery were (small) refractors, which do not have the central obstructions or supporting struts needed by (most) reflectors for secondary mirrors, so they do not produce the familiar diffraction spikes (caused by an illuminated aperture which is not a uniform circle) ) that reflecting systems do.

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Re: APOD: Unexpected Clouds Toward the Galaxy... (2023 Jan 17)

Post by OgetayK » Fri Jan 20, 2023 5:36 pm

AVAO wrote: Tue Jan 17, 2023 8:16 pm
Ann wrote: Tue Jan 17, 2023 6:50 pm
AVAO wrote: Tue Jan 17, 2023 4:56 pm
I see more similarities with NGC 4651 than with IC 2497.

Image

"...The jet-like feature is strikingly coherent and narrow. This feature was previously reported by Vorontsov-Velyaminov (1959) but never interpreted as a stellar tidal stream. Moreover, our deep image shows an additional spectacular crescent shaped shell surrounding the east side of the galaxy that corresponds to the apocenter of the dwarf galaxy. Interestingly, a possible second arc on the western side of the galaxy can also be seen in this image. This structure is less obvious because it is partially hidden by the galaxy's disk. This suggests we are observing a moderately inclined structure projected into the halo of NGC 4651..." https://www.cosmotography.com/images/st ... ights.html
Very good comparison, AVAO!

I found a link to that picture of NGC 4651, and I'm wondering about the insert and the small blue star in brackets. Could that possibly be the core of the small galaxy that was broken up to create that umbrella-like structure of NGC 4651? Although I really wouldn't expect a galactic core to be blue.

And if we are seeing anything even remotely similar in Andromeda, what could the intruding galaxy be? Not, say, M32?

Ann
If I compare the red Hα structures of today's APOD with those of https://apod.nasa.gov/apod/ap221024.html, the red hallo around M31 is completely missing on today's APOD. the red Hα structure of today's APOD therefore seems to be rather detached from M31 in our galaxy. the OIII shell structure, in turn, does not show any interaction with the red Hα structure. For me, M31, the OIII shell structure and the Hα structure are rather far apart. the fine stripe structure of the OIII shell structure indicates that it could also be very close to us. Research will show in the future.
I'm curious about this red Hα halo around Andromeda. Not to mention previous works, the following comparison has a significant part missing. Maybe the photographers can explain if this is caused by postprocessing (maybe DBE?).

Image 1: https://ibb.co/cX6Lqnz
Image 2: https://ibb.co/6N1c1Ny

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VictorBorun
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Re: APOD: Unexpected Clouds Toward the Galaxy... (2023 Jan 17)

Post by VictorBorun » Sat Jan 21, 2023 3:21 am

OgetayK wrote: Fri Jan 20, 2023 5:36 pm I'm curious about this red Hα halo around Andromeda. Not to mention previous works, the following comparison has a significant part missing. Maybe the photographers can explain if this is caused by postprocessing (maybe DBE?).
Image 1: https://ibb.co/cX6Lqnz
Image 2: https://ibb.co/6N1c1Ny
Sorry, what is DBE?
Does it imitate changing clouds in 2022 to 2023 APOD like this?
Click to view full size image 1 or image 2
Unexpected Clouds 2023.png
Unexpected Clouds 2022.png
...
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