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More on IC342, the hiddeen galaxy.

ollypenrice

By ollypenrice
in Imaging - Deep Sky

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ollypenrice

ollypenrice

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After fighting with an electric filterwheel and so getting nothing done two nights ago I bunged in a manual one for last night and got on with imaging. 7 hours of Ha (21x20 mins) to add to the IC342 LRGB image captured here by Tom before Christmas. So 23 hours all in. TEC140 Apo, Atik 460 mono, Mesu 200. As expected the Ha was liberally distributed throughout the spiral arms (we had this impression from the LRGB version) but everything about this galaxy is faint so I had to torture the Ha to get it into play. It also found some nice little Ha ring structures similar to those in M33. I've forgtten what they are called. Anybody?

Just before dawn I shot a single sub of M101 in the same rig so I could use Registar to resize Yves' and my M101 to the same scale for comparison. IC 342 is quite a size on the sky!

1C342%20SCALED%20TO%20M101%20WEB-X3.jpg

Cheers,

Olly

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ollypenrice

ollypenrice

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2 minutes ago, wimvb said:

Those two galaxies look amazingly similar. Maybe they'd have the same colour, if there was less dust between ic342 and us.

I was asking myself the same question.

3 minutes ago, Tom OD said:

very nice. It has a real 3D effect to it with the Ha areas now.

I was just about to email you to say I'd posted this! Did you get the Dropbox data?

Olly

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Tom OD

Tom OD

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11 minutes ago, ollypenrice said:

I was asking myself the same question.

I was just about to email you to say I'd posted this! Did you get the Dropbox data?

Olly

No the folder is empty when I login. You need to share the file with me.

T

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ollypenrice

ollypenrice

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10 hours ago, tomato said:

Great result, I wonder are there any other sizeable galaxies lurking out there behind the Milky Way?

Let us know if you find any! I've tried in vain to find a listing of galaxies by apparent size on the net. I'm sure such a thing must exist somewhere.

Olly

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Davey-T

Davey-T

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2 hours ago, ollypenrice said:

Let us know if you find any! I've tried in vain to find a listing of galaxies by apparent size on the net. I'm sure such a thing must exist somewhere.

Olly

Not exactly a list but Stellarium quotes sizes for galaxies, it puts IC342 as 21'24 x 20'54 and M101 as 28'48 x 26'54

Dave

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ollypenrice

ollypenrice

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2 hours ago, Davey-T said:

Not exactly a list but Stellarium quotes sizes for galaxies, it puts IC342 as 21'24 x 20'54 and M101 as 28'48 x 26'54

Dave

I'd obviously mis-read the dimensions quoted in SkyMap Pro because I thought they made IC342 larger than M101 but, on checking, I find they agree with Stellarium. However, there's evidence in our luminance data of an extended arm reaching beyond the limit of our framing of IC342. There's a hint of it in the final image above, to the right of the top part of the galaxy. It looks like a separate patch of luminosity in this image but if stretched to screaming point it looks more like an extended arm. Something to go after, perhaps...

Olly

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wimvb

wimvb

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32 minutes ago, ollypenrice said:

There's a hint of it in the final image above, to the right of the top part of the galaxy. It looks like a separate patch of luminosity in this image but if stretched to screaming point it looks more like an extended arm. Something to go after, perhaps...

https://apod.nasa.gov/apod/ap160129.html

The orientation is different (abt 90 degrees), but this image seems to show the arm you're referring to.

I think that if you image this galaxy in a wider setting, you'll have a hard time figuring out where it ends and the Milky Way begins.

But it sure is a fascinating patch of sky.

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ollypenrice

ollypenrice

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43 minutes ago, wimvb said:

https://apod.nasa.gov/apod/ap160129.html

The orientation is different (abt 90 degrees), but this image seems to show the arm you're referring to.

I think that if you image this galaxy in a wider setting, you'll have a hard time figuring out where it ends and the Milky Way begins.

But it sure is a fascinating patch of sky.

Yes, Senore Castelluzzo's image is deeper and does show that arm better. He has more frame available, too, but sadly the arm doesn't seem to go further in his image so maybe that's it. As you say, separating galaxy from Milky Way is never going to be easy.

When I set out to process our data I followed the conventional (for me) galaxy route of minimizing field stars as ruthlessly as possible to let the galaxy take the stage. However, most IC342 imagers seem to have accepted that the MW foreground does form part of the image and they've allowed stars to grow and background values to rise. I think I should try an alternative processing job along these lines. I think both approaches are valid. No new data will be coming in this week according to Meteo France so I might as well!

Olly

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