NGC6902 / NGC6902B / IC4946 - Galaxy Group in Sagittarius

SkyViking (Rolf) · #1 02-09-2013, 09:25 PM

Hi All,

I felt it was time to again pick some galaxies after my recent dabbling in bright nebulae - and even in Sagittarius one doesn't have to wander far off to find some obscure targets, so here are 17 hours on a beautiful but almost unknown galaxy group:

Link to large image (3MB)

About the image:
In the far south-eastern corner of Sagittarius, a constellation otherwise known for its spectacular highlights near the crowded Milky Way centre, lies the very rarely imaged galaxy NGC 6902 and a couple of its neighbours. Despite its beautiful and elegant appearance there is very little information about this galaxy to be found anywhere.
It contains a bright central ring and possibly also an elusive inner bar. The spiral arms are quite faint despite almost 17 hours of exposure, which is indicative of a rather weak population of O type stars. The arms also have a knotted appearance, perhaps due to the presence of brighter HII regions located within them.
The galaxy lies approximately 33 million light years away and was discovered by John Herschel.
A number of other galaxies can be seen scattered across the field of view, including the smaller face-on spiral NGC 6902B to the upper left. At the top of the frame lies edge-on galaxy IC 4649 with some traces of obscuring dust and a hint of a bar structure surrounding its core.
And far in the background countless distant galaxy groupings can be seen as small fuzzy yellowish dots throughout the image.

Image details:
Date: 29th July, 5th, 6th, 7th, 8th and 9th August 2013
Exposure: LRGB: 645:152:122:93 mins, total 16 hours 52 mins @ -30C
Telescope: 10" Serrurier Truss Newtonian f/5
Camera: QSI 683wsg with Lodestar guider
Filters: Astrodon LRGB E-Series Gen 2
Taken from my observatory in Auckland, New Zealand

I hope you enjoy the view of this rather obscure piece of sky

Regards,
Rolf

John Hothersall · #2 02-09-2013, 09:50 PM

This is very off the track image and an eyeopener. The tail of Sag also contains M55 giant glob, 2 terzans and ARPGC2 cluster and the curious 6845 galaxy quartet in Telescopium, but is relatively unimaged. Sag tail is packed with galaxies.

Great detail in the small spiral and other galaxies as well as star colour as usual.

John.

RobF (Rob) · #3 02-09-2013, 09:56 PM

The only thing you could do to surprise me Rolf is post a boring image

Beautiful field, and not one I'm familiar with. Beautifully rendered too BTW. Thanks for sharing.

pmrid (Peter) · #4 02-09-2013, 10:01 PM

Stunning stuff Rolf. Beautifully presented. Thank you.
Peter

RickS (Rick) · #5 02-09-2013, 10:12 PM

Very cool field, Rolf. Well done!

strongmanmike (Michael) · #6 02-09-2013, 10:13 PM

That's great Rolf and looks lovely on my new spiffy monitor too

I love the fine outer arms of the spiral NGC 6902. Actually, it's a reasonably small galaxy according to the LEDA data base at 5.6' X 4' but I recon you may have revealed a bit more than that in your image!?

Great stuff...galaxies in Sagittarius huh? Niiice

Mike

gregbradley · #7 02-09-2013, 10:25 PM

A beautiful image Rolf. That's quite stunning.

Greg.

Larryp (Laurie) · #8 02-09-2013, 10:49 PM

Great image, Rolf!

Lee · #9 03-09-2013, 09:59 AM

That's great work.... I never really thought of galaxy clusters in an area like Sagittarius.... I'm surprised the image isn't drowned out with Milky Way!

SkyViking (Rolf) · #10 03-09-2013, 10:39 AM

Quote:

Originally Posted by John Hothersall

This is very off the track image and an eyeopener. The tail of Sag also contains M55 giant glob, 2 terzans and ARPGC2 cluster and the curious 6845 galaxy quartet in Telescopium, but is relatively unimaged. Sag tail is packed with galaxies.
Great detail in the small spiral and other galaxies as well as star colour as usual.
John.

Thank you John, I was just cruising around looking for something different and stumbled upon this one. You've listed some other interesting targets thanks, maybe it's time to go hunting

Quote:

Originally Posted by RobF

The only thing you could do to surprise me Rolf is post a boring image
Beautiful field, and not one I'm familiar with. Beautifully rendered too BTW. Thanks for sharing.

Thanks very much Rob for your kind words!

Quote:

Originally Posted by pmrid

Stunning stuff Rolf. Beautifully presented. Thank you.
Peter

Thank you Peter, it's a nice galaxy indeed.

Quote:

Originally Posted by RickS

Very cool field, Rolf. Well done!

Thanks Rick, I felt the need for a galaxy field after the nebula season

Well at least that season is mostly over for me anyway since the Milky Way is now coming close to the trees in the west when viewed from my location.

Quote:

Originally Posted by strongmanmike

That's great Rolf and looks lovely on my new spiffy monitor too I love the fine outer arms of the spiral NGC 6902. Actually, it's a reasonably small galaxy according to the LEDA data base at 5.6' X 4' but I recon you may have revealed a bit more than that in your image!?
Great stuff...galaxies in Sagittarius huh? Niiice
Mike

Thank you Mike, I thought you'd be happy with this field

I was surprised with how faint those outer arms were, but yes there are some obvious extensions and one in particular reaching almost up to the orange star. That structure looks a bit distorted too, which is interesting.

Quote:

Originally Posted by gregbradley

A beautiful image Rolf. That's quite stunning.
Greg.

Thanks a lot Greg, I'm glad you liked it

Quote:

Originally Posted by Larryp

Great image, Rolf!

Thank you Larry

Quote:

Originally Posted by Lee

That's great work.... I never really thought of galaxy clusters in an area like Sagittarius.... I'm surprised the image isn't drowned out with Milky Way!

Thanks Lee, I didn't really consider Sagittarius to be a hunting ground for galaxies, but this particular corner seems to be. It wasn't until I looked for info about the galaxy that I found out how little is written about it.

Paul Haese · #11 03-09-2013, 05:51 PM

Love that spiral. Very nice and the star colour is lovely Rolf. A bigger image would be nice to surf through.

Octane (Humayun) · #12 03-09-2013, 06:15 PM

Oh, my. Rolf, that image just took my breath away.

Spectacular.

H

allan gould · #13 03-09-2013, 06:16 PM

Rolf, what a beautilful image. Fantastic result but I expect that from you.
Allan

David Fitz-Henr · #14 03-09-2013, 09:28 PM

Yeah, beautiful field chock full of galaxies! Nice colour processing on the stars and galaxies as well. One small point - the stars look slightly elongated left / right, is this a guiding issue?