by alter-ego » Sat Jun 01, 2019 7:53 pm
MarkBour wrote: ↑Wed May 29, 2019 11:10 pm
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I note that you gave me an assignment in your comment, perhaps a simple student's assignment. But I confess I'm a bit lost as to how to identify a star field in an image of the Milky way. I tend to just start from ignorance and take the APOD caption at its word ("okay, they said that one was Antares") and go from there. I'm not sure how to go from a very rich image with a million dots in it to pick out which is which. Perhaps this comes from a bit of study of the Milky Way, to get some landmarks? (Would "skymarks" be a better word for that?)
Hi Mark - Yeah, I just thought you might be interested to look deeper so I wanted to nudge you to do so. I knew I added detail that wouldn't be easy to jump into, but was by no means intended as a talking-down-to. I apologize if I came across that way. I just wanted to remove all speculation, "put the last nail in the coffin so to speak.
Regarding "skymarks", or signposts, in this image, finding familiar star asterisms is difficult because of the quantity of stars and how they appear. The apparent relative star brightnesses are compressed so much that it's hard to see familiar constellations and identify stars. However, I did immediately recognize some Milky Way dark nebula and dust lanes. With these structures identified, I could then look and smaller regions and identify stars (
Hint: In Stellarium, you can similarly compress relative star brightness to simulate quite well the star density and appearance in this image). The
Pipe Nebula is one familiar nebula. Interestingly, I've known it, but I just learned that the Pipe Nebula is the butt and hind leg(s) of the
Dark Horse Nebula. In the APOD, Jupiter is positioned very near the hoof of the bent front leg. From here, identifying surrounding stars is straight forward as you can focus on that region. That is how I located Jupiter, and the image exposure date. Oh, further refinement of the time is possible by accounting for photographer's location. I only cared about the day, not the exact time.
[quote=MarkBour post_id=292605 time=1559171459 user_id=141361]
...
I note that you gave me an assignment in your comment, perhaps a simple student's assignment. But I confess I'm a bit lost as to how to identify a star field in an image of the Milky way. I tend to just start from ignorance and take the APOD caption at its word ("okay, they said that one was Antares") and go from there. I'm not sure how to go from a very rich image with a million dots in it to pick out which is which. Perhaps this comes from a bit of study of the Milky Way, to get some landmarks? (Would "skymarks" be a better word for that?)
[/quote]
Hi Mark - Yeah, I just thought you might be interested to look deeper so I wanted to nudge you to do so. I knew I added detail that wouldn't be easy to jump into, but was by no means intended as a talking-down-to. I apologize if I came across that way. I just wanted to remove all speculation, "put the last nail in the coffin so to speak.
Regarding "skymarks", or signposts, in this image, finding familiar star asterisms is difficult because of the quantity of stars and how they appear. The apparent relative star brightnesses are compressed so much that it's hard to see familiar constellations and identify stars. However, I did immediately recognize some Milky Way dark nebula and dust lanes. With these structures identified, I could then look and smaller regions and identify stars ([b]Hint:[/b] In Stellarium, you can similarly compress relative star brightness to simulate quite well the star density and appearance in this image). The [url=http://www.astroeder.com/pipe_eder_en.html]Pipe Nebula[/url] is one familiar nebula. Interestingly, I've known it, but I just learned that the Pipe Nebula is the butt and hind leg(s) of the [url=http://www.astronomyufo.com/Astronomy/Prancinghorse.htm]Dark Horse Nebula[/url]. In the APOD, Jupiter is positioned very near the hoof of the bent front leg. From here, identifying surrounding stars is straight forward as you can focus on that region. That is how I located Jupiter, and the image exposure date. Oh, further refinement of the time is possible by accounting for photographer's location. I only cared about the day, not the exact time.