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TIL: The Galactic Hub, Simeis 147 and the Winter Hexagon

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#1 BQ Octantis

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Posted 28 July 2021 - 08:46 AM

G'day all,

 

I was collecting some fun facts for a southern sky tour tomorrow night, and I was pondering what was opposite the central hub of the Milky Way. In trying to convey one of the fun facts—that the farthest edge of the galaxy from Earth is 70,000 light years in the direction of the edge of the Great Sagittarius Star Cloud—I wanted to provide the contrast of the 30,000 light years to the edge opposite the core. I had no idea what was in that direction, so I fired up Stellarium and turned on the galactic coordinates grid. To my surprise, the point on the galactic plane opposite the core is almost at the center of the "Winter Hexagon" (winter in the Northern Hemisphere). But even more surprising was a ghostly nebula almost 4˚ across that looked a lot like a supernova remnant. A quick search of the Google found it: Simeis 147.

 

So to sum up the fun fact:

 

180˚ opposite the central hub of the Milky Way is the center of the Winter Hexagon asterism, the point where the constellations Auriga, Gemini, Taurus, and Orion meet. 8 arcminutes from the point lies the magnitude 8 star HIP 27088. The star also marks the edge of a Simeis 147, a supernova remant almost 4˚ wide from a star 3000 light years from earth that exploded 40,000 years ago.

 

Today I learned.

 

BQ


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#2 j.gardavsky

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Posted 28 July 2021 - 02:09 PM

Auriga, and around is the home of 3 nice SNRs:

 

Sh2-216 close to the Perseus-Auriga border

Sh2-224 in Auriga, and close to the very large Sh2-223 HII nebula

Sim 147 crossing the Auriga-Taurus border

 

All of them are within the reach of the 6" and larger apertures.

 

Narrow passband OIII filters are required for these SNRs, and an H-Beta for the Sh2-223.

 

Clear skies,

JG

 

PS:

On the other side of the Milky Way, and still well visible in this season,

is the extra large bow shock nebula Sh2-27, around Zeta Ophiuci.

It can be best seen through the low magnification binoculars, as it extends across 8 degrees.

Its bright condensations, visible through the 15x85 binoculars and small telescopes, have been catalogued by Beverly Lynds (LBN), and by Magnani, Blitz, and Mundi  (MBM, 1985).

The H-Beta, and the blue(RGB)CCD filters, help.



#3 BQ Octantis

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Posted 28 July 2021 - 04:15 PM

Thanks JG! Sh2-27 will be high in the sky, but it's a little advanced for this group (it's a bare-eye sky tour). But for the southern hemisphere, this region will be accessible well into October, and I've never shot it. If the clouds ever clear up, I might try shooting it.

 

BQ


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#4 j.gardavsky

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Posted 29 July 2021 - 04:51 AM

BQ,

 

here are some astropics,

https://forum.astron...ntraeger.42427/

http://www.astropix....images/page/25/

 

I have seen this nebula the first time in the Dolomiti Mountains (Italy), through the 10.5x70 binoculars.

From our backyard, this nebula requires the filters.

 

Best,

JG



#5 BQ Octantis

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Posted 29 July 2021 - 07:18 AM

Thanks JG. That might not be such a good target for my unmodded Canon 600D/T3i…


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#6 Keith Rivich

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Posted 29 July 2021 - 06:38 PM

Auriga, and around is the home of 3 nice SNRs:

 

Sh2-216 close to the Perseus-Auriga border

Sh2-224 in Auriga, and close to the very large Sh2-223 HII nebula

Sim 147 crossing the Auriga-Taurus border

 

All of them are within the reach of the 6" and larger apertures.

 

Narrow passband OIII filters are required for these SNRs, and an H-Beta for the Sh2-223.

 

Clear skies,

JG

 

PS:

On the other side of the Milky Way, and still well visible in this season,

is the extra large bow shock nebula Sh2-27, around Zeta Ophiuci.

It can be best seen through the low magnification binoculars, as it extends across 8 degrees.

Its bright condensations, visible through the 15x85 binoculars and small telescopes, have been catalogued by Beverly Lynds (LBN), and by Magnani, Blitz, and Mundi  (MBM, 1985).

The H-Beta, and the blue(RGB)CCD filters, help.

I have to challenge seeing Simeis 147 in a 6". I have tried this remnant many times over the years, from 6" to 25" scopes, along with every filter imaginable, and have only caught glimpses of the brighter parts in my 18 and 25" scopes under very dark west Texas skies. 

 

Have you bagged this one in a 6"? Kudos if you have!


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#7 j.gardavsky

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Posted 30 July 2021 - 07:35 AM

I have to challenge seeing Simeis 147 in a 6". I have tried this remnant many times over the years, from 6" to 25" scopes, along with every filter imaginable, and have only caught glimpses of the brighter parts in my 18 and 25" scopes under very dark west Texas skies. 

 

Have you bagged this one in a 6"? Kudos if you have!

Hello Keith,

 

I have 4 entries in my observing log book, all of them through my 15x85 binoculars:

 

April 20th, 2020: Northern segment through the blue(RGB)CCD filters

February 28th, 2021: Complete ring through the OIII filters

March 5th, 2021: N, E, S segments through the H-Beta filters

March 31st, 2021: Faint but complete ring through the OIII filters

 

The binoculars don't resolve the individual "spaghetties", the visually perceived ring is not structured, just showing different thickness when followed with the binoculars.

 

Filters used:

OIII 10nm Baader visual filter

H-Beta 12nm Astronomik (the old Profi Line)

blue(RGB)CCD 400nm - 510nm interference Baader filter

 

Observing conditions: Bortle 3-4 over the backyard

 

I have made these observings on a side line of my program of "recovering" the forgotten Gaze-Shajn (1955) nebulae in Auriga, during the seasons in 2020 and 2021.

 

Yes, this SNR is difficult to observe, but doable.

 

Happy hunting,

JG


Edited by j.gardavsky, 30 July 2021 - 07:35 AM.



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