APOD: IC 342: Hidden Galaxy in Camelopardalis (2023 Nov 22)

Comments and questions about the APOD on the main view screen.
User avatar
APOD Robot
Otto Posterman
Posts: 5314
Joined: Fri Dec 04, 2009 3:27 am

APOD: IC 342: Hidden Galaxy in Camelopardalis (2023 Nov 22)

Post by APOD Robot » Wed Nov 22, 2023 5:05 am

Image IC 342: Hidden Galaxy in Camelopardalis

Explanation: Similar in size to large, bright spiral galaxies in our neighborhood, IC 342 is a mere 10 million light-years distant in the long-necked, northern constellation Camelopardalis. A sprawling island universe, IC 342 would otherwise be a prominent galaxy in our night sky, but it is hidden from clear view and only glimpsed through the veil of stars, gas and dust clouds along the plane of our own Milky Way galaxy. Even though IC 342's light is dimmed and reddened by intervening cosmic clouds, this sharp telescopic image traces the galaxy's own obscuring dust, young star clusters, and glowing star forming regions along spiral arms that wind far from the galaxy's core. IC 342 has undergone a recent burst of star formation activity and is close enough to have gravitationally influenced the evolution of the local group of galaxies and the Milky Way.

<< Previous APOD This Day in APOD Next APOD >>

Lasse H
Ensign
Posts: 56
Joined: Mon Jul 30, 2007 4:11 pm
Location: Stockholm

Re: APOD: IC 342: Hidden Galaxy in Camelopardalis (2023 Nov 22)

Post by Lasse H » Wed Nov 22, 2023 11:48 am

Similar photos of this galaxy have been published eight times (see Archive!); always with the title "IC 342: Hidden Galaxy".

I have nothing against this galaxy, but I would like to see just how it is "hidden". Each time the caption claims it is only glimpsed through the veil of stars, gas and dust clouds in our galaxy. The photos do not really show this veil of gas and dust---to me it comes forth as quite visible and similar to other photos of galaxies.

sc02492
Ensign
Posts: 22
Joined: Tue Apr 20, 2010 9:41 pm
AKA: Steve Cannistra

Re: APOD: IC 342: Hidden Galaxy in Camelopardalis (2023 Nov 22)

Post by sc02492 » Wed Nov 22, 2023 12:09 pm

Lasse H wrote: Wed Nov 22, 2023 11:48 am
I have nothing against this galaxy, but I would like to see just how it is "hidden". Each time the caption claims it is only glimpsed through the veil of stars, gas and dust clouds in our galaxy. The photos do not really show this veil of gas and dust---to me it comes forth as quite visible and similar to other photos of galaxies.
Lasse, I tried to explain this in the description on my website. The "Hidden" aspect is a term that originated from the days of visual astronomy. When I myself first attempted a visual observation of this galaxy many years ago, at a reasonably dark site and a large aperture Dobsonian, I could hardly detect it (in comparison to M81 for instance). It is really very difficult to appreciate visually. With astrophotography techniques (including film in the old days), it is much easier to increase the signal above the noise to allow detection, although even so it is a relatively dim target. I even used more blue filter exposure on this image, and yet it is still reddish/brown in overall color, due to preferential extinction of blue light as it passes through Milky Way dust.

Steve

Steve Cannistra
www.starrywonders.com

Christian G.
Science Officer
Posts: 105
Joined: Sat Apr 08, 2023 10:37 pm

Re: APOD: IC 342: Hidden Galaxy in Camelopardalis (2023 Nov 22)

Post by Christian G. » Wed Nov 22, 2023 1:00 pm

To further bring this galaxy out of hiding, here's another very nice and recent image, finely detailed:
You do not have the required permissions to view the files attached to this post.

Lasse H
Ensign
Posts: 56
Joined: Mon Jul 30, 2007 4:11 pm
Location: Stockholm

Re: APOD: IC 342: Hidden Galaxy in Camelopardalis (2023 Nov 22)

Post by Lasse H » Wed Nov 22, 2023 1:32 pm

Thank you, Steve and Christian! I think I would appreciate this "hidden galaxy" a lot more, and also appreciate the efforts behind revealing its appearance, if I could also be shown what it looks like when it is hidden--that is what it looks like before filtering and manipulating noise and signal.
Someone must have seen first, and become surprised that it was there! How little do you see of it when it is hidden?

User avatar
Chris Peterson
Abominable Snowman
Posts: 18049
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: IC 342: Hidden Galaxy in Camelopardalis (2023 Nov 22)

Post by Chris Peterson » Wed Nov 22, 2023 2:24 pm

Lasse H wrote: Wed Nov 22, 2023 1:32 pm Thank you, Steve and Christian! I think I would appreciate this "hidden galaxy" a lot more, and also appreciate the efforts behind revealing its appearance, if I could also be shown what it looks like when it is hidden--that is what it looks like before filtering and manipulating noise and signal.
Someone must have seen first, and become surprised that it was there! How little do you see of it when it is hidden?
Both Steve's image and mine above are pretty accurate "true color" representations. This is what it looks like visually (if our eyes were simply more sensitive). Were it not behind dust, it would be much brighter, which is impossible to show in an image, but visually we'd see something in our northern skies not unlike the LMC in the south. And photographically, we'd lose the striking reddish coloring, which is a consequence of dust reddening. The dust blocks most short wavelength light. Look at all of the HII regions in the arms of IC 342. There is a lot of new star formation going on. Which means there are lots of hot, blue stars. But we don't see them. The dust almost completely hides them. The few blue stars we see in these images are foreground objects, in front of the dust. Without the dust, I think this galaxy would look a lot like M 101 (below), which also has lots of star formation going on in it.
_
M101.jpg
You do not have the required permissions to view the files attached to this post.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
https://www.cloudbait.com

User avatar
Ann
4725 Å
Posts: 13306
Joined: Sat May 29, 2010 5:33 am

Re: APOD: IC 342: Hidden Galaxy in Camelopardalis (2023 Nov 22)

Post by Ann » Wed Nov 22, 2023 2:51 pm

Christian G. wrote: Wed Nov 22, 2023 1:00 pm To further bring this galaxy out of hiding, here's another very nice and recent image, finely detailed:
Thanks for posting Chris Peterson's recent image, Christian. It's very fine image, and in my book, it is better than the APOD. Not the the APOD isn't fine, too.

IC 342 is a "perfect Sc galaxy", similar to M74. It has a small yellow core and long, elegantly curved arms, which are often full of blue stars and pink nebulas. IC 342 and M74 are both grand design galaxies too, with just two major arms. (Even though IC 342 isn't the best example of a grand design galaxy, since it does seem to have some extra arms and spurs, too.)

ic342asi294large_1024[1].jpg
IC 342: Hidden Galaxy in Camelopardalis.
Image Credit & Copyright: Steve Cannistra

Note how similar IC 342 is to M74:


Onde difference between IC 342 and M74 is that M74 is a *pure" unbarred Sc galaxy, whereas IC 342 does have a small bar. Note the dust lane that seems to cross the center of IC 342.

Ann
You do not have the required permissions to view the files attached to this post.
Color Commentator

User avatar
orin stepanek
Plutopian
Posts: 8200
Joined: Wed Jul 27, 2005 3:41 pm
Location: Nebraska

Re: APOD: IC 342: Hidden Galaxy in Camelopardalis (2023 Nov 22)

Post by orin stepanek » Wed Nov 22, 2023 8:59 pm

ic342asi294large_1024.jpg
If memory serves; we had one called hidden several years ago called
hidden! :mrgreen:
You do not have the required permissions to view the files attached to this post.
Orin

Smile today; tomorrow's another day!

sc02492
Ensign
Posts: 22
Joined: Tue Apr 20, 2010 9:41 pm
AKA: Steve Cannistra

Re: APOD: IC 342: Hidden Galaxy in Camelopardalis (2023 Nov 22)

Post by sc02492 » Thu Nov 23, 2023 10:03 am

Lasse H wrote: Wed Nov 22, 2023 1:32 pm I think I would appreciate this "hidden galaxy" a lot more, and also appreciate the efforts behind revealing its appearance, if I could also be shown what it looks like when it is hidden--that is what it looks like before filtering and manipulating noise and signal.
Lasse, sorry for the late reply. You are making a good point. One way to answer your question would be to compare the relative brightness of IC342 against a more familiar target like M81 (for instance) by using a single subexposure, taken at 60 seconds at the same camera settings (ASI294MM, gain, offset, and chip temperature), same telescope (FSQ106N), and same conditions (new moon, same altitude) and then the same pre-processing calibration and post-processing curves stretch. I would have to dig into my old data to see if I have something comparable for M81 or M101. When I have more time I will try to find this and let you know. The comparison could be done visually but also by measuring flux in software like MaximDL. I can do all of that, but it will take a little time.

For those few commenters who are critical of my image of IC342, please understand that this is a difficult target to capture with a 4 inch scope in a Bortle 4-5 zone, with straight LRGB filters (no Ha). That was part of the fun and challenge for me, and it provides inspiration for those who might want to try it themselves. Unless you have actually tried to capture this particular target, you won't necessarily appreciate what goes into the effort. Based on the numerous positive comments that I received yesterday, a lot of viewers enjoyed the result and learned something about how dust in the galactic plane can affect the appearance of extra-galactic targets like IC342.

All of the images that you see on APOD reflect a great amount of effort, both on the part of the astrophotographers and the APOD editors. It's easy to be arm-chair critics of this kind of work, but remember that it's a privilege to have this resource available to us.

Happy Thanksgiving to all.

Steve


Steve Cannistra
www.starrywonders.com
Last edited by sc02492 on Thu Nov 23, 2023 11:36 pm, edited 1 time in total.

User avatar
johnnydeep
Commodore
Posts: 2711
Joined: Sun Feb 20, 2011 8:57 pm

Re: APOD: IC 342: Hidden Galaxy in Camelopardalis (2023 Nov 22)

Post by johnnydeep » Thu Nov 23, 2023 1:34 pm

sc02492 wrote: Thu Nov 23, 2023 10:03 am
Lasse H wrote: Wed Nov 22, 2023 1:32 pm I think I would appreciate this "hidden galaxy" a lot more, and also appreciate the efforts behind revealing its appearance, if I could also be shown what it looks like when it is hidden--that is what it looks like before filtering and manipulating noise and signal.
Lasse, sorry for the late reply. You are making a good point. One way to answer your question would be to compare the relative brightness of IC342 against a more familiar target like M81 (for instance) by using a single subexposure, taken at 60 seconds at the same camera settings (ASI294MM, gain, offset, and chip temperature), same telescope (FSQ106N), and same conditions (new moon, same altitude) and then the same pre-processing calibration and post-processing curves stretch. I would have to dig into my old data to see if I have something comparable for M81 or M101. When I have more time I will try to find this and let you know. The comparison could be done visually but also by measuring flux in software like MaximDL. I can do all of that, but it will take a little time.

For those few commenters who are critical of my image of IC342, please understand that this is a difficult target to capture with a 4 inch scope in a Bortle 4-5 zone, with straight LRGB filters (no Ha). That was part of the fun and challenge for me, and it provides inspiration for those who might want to try it themselves. Unless you have actually tried to capture this particular target, you won't necessarily appreciate what goes into the effort. Based on the numerous positive comments that I received yesterday, a lot of viewers enjoyed the result and learned something about how dust in the galactic plane can affect the appearance of extra-galactic targets like IC342.

All of the images that you see on APOD reflect a great amount of effort, both on the part of the astrophotographers and the APOD editors. It's easy to be arm-chair critiques of this kind of work, but remember that it's a privilege for us to have this resource available to us.

Happy Thanksgiving to all.

Steve


Steve Cannistra
www.starrywonders.com
Amen!
--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}