thor’s helmet Thor’s Helmet ( NGC 2359 ) - Wolf-Rayet 7 ( HD 56925 ) - updated ( “Blue Bunny Nebula” )

[MikeODay]

“The Blue Bunny Nebula” 

..........

Edit: 27 Jan 2018 - updated again to try to draw more faint nebulosity out of the background;

( NGC 2359 - Thor’s Helmet )  ( please click / tap on image to see larger and without compression artefacts ( and double click on that image if you what to see it as I posted it ! ) )

.........

Edit: 24 Jan 2018 - stars a little brighter and tighter with no change to the rest of the image

    

( NGC 2359 - Thor’s Helmet )  ( please click / tap on image to see larger and without compression artefacts ( and double click on that image if you what to see it as I posted it ! ) )

 

.................

original:

Thor's Helmet ( NGC 2359 ) in the constellation Canis Major 

Thor’s Helmet ( Duck Nebula, NGC 2359 ) ( please click / tap on image to see larger )

This HDR image shows the bright nebula Thor’s Helmet in a sea of colourful stars against a background of red from dust and HA emissions.   The stars in this image range from the brightest ( bottom right, HD 56501 ) at magnitude +7.7 to around +20 or more.  HDR capture and processing allows all of the stars to be portrayed in colour without any burnt-out highlights.  The colours of the stars and nebula are as close as I can get them to their "true colours" by using a "daylight colour balance" and allowing for the extinction of blue-green due to atmospheric absorption/scattering ( mean altitude during capture ~ 60deg ).

The blue star in the centre of the bubble of expanding stellar material is HD 56925 ( WR7 ) - a massive, unstable and short-lived Wolf-Rayet star that one day will detonate in a supernova.

Image details:

NGC 2359  Thor’s Helmet / Duck Nebula: Magnitude +11.5, RA (2000.0) 7h 15m 37s, Dec -13deg 12' 8", approx. 1800 light years away
HD 56925 / Wolf-Rayet 7 ( WR7 ) ( blue 11.5 mag star at centre of “bubble” )
Haffner 6 ( open ster cluster centre left of image )

Plate Solution:
Resolution ........ 1.318 arcsec/px
Rotation .......... 0.00 deg ( North is up )
Focal ............. 1398.41 mm
Field of view ..... 57' 40.8" x 38' 29.0"
Image center ...... RA: 07 18 36.509  Dec: -13 11 53.38

Telescope: Orion Optics CT12 Newtonian ( mirror 300mm, fl 1200mm, f4 ).
Corrector: ASA 2" Coma Corrector Quattro 1.175x.
Effective Focal Length / Aperture : 1410mm f4.7

Mount: Skywatcher EQ8
Guiding: TSOAG9 Off-Axis-Guider, Starlight Xpress Lodestar X2, PHD2 

Camera:
Nikon D5300 (unmodified) (sensor 23.5 x 15.6mm, 6016x4016 3.9um pixels)

Location:
Blue Mountains, Australia 
Moderate light pollution ( pale green zone on darksitefinder.com map )

Capture ( 18 & 19 Jan 2018 )
9 sets of sub-images with exposure duration for each set doubling ( 1s to 240s ) all at ISO 250.
116 x 240s + 5 each @ 1s to 120s

Processing ( Pixinsight - 20 Jan 18  )
Calibration: master bias, master dark and master flat 
Integration in 9 sets
HDR combination 
arcSinH stretch

[NigeB]

That's a lovely image Mike - and really great detailed information provided as well. Thanks for posting.

[MikeODay]

8 minutes ago, NigeB said:

That's a lovely image Mike - and really great detailed information provided as well. Thanks for posting.

Cheers, thanks for that.

[Adreneline]

Very nice Mike - I am amazed at what can be achieved with an unmodified dslr. I keep wondering whether to get my Canon 70D modified. Thank you for sharing.

[MikeODay]

24 minutes ago, Adreneline said:

Very nice Mike - I am amazed at what can be achieved with an unmodified dslr. I keep wondering whether to get my Canon 70D modified. Thank you for sharing.

Thanks.  I have been quite pleased so far with what I have been able to produce but like you I sometimes think that I am missing out by not having a camera more sensitive to near IR.  I am giving a little bit of thought to perhaps changing to a cooled one shot colour astro camera with a low noise CMOS sensor - I will have to save up though; even the newer Chinese brands are still quite expensive...

Cheers

Mike

 

[StargeezerTim]

Lovely capture... great write up as well! 

[MikeODay]

46 minutes ago, StargeezerTim said:

Lovely capture... great write up as well! 

Thanks Tim.

[swag72]

Looking good Mike

[MikeODay]

Just now, swag72 said:

Looking good Mike

Thanks Sara.

[laudropb]

Very nice image and write up.

[MikeODay]

12 minutes ago, laudropb said:

Very nice image and write up.

Thanks, much appreciated.

[MikeODay]

Wolf-Rayet star WR7 ( NGC 2359 )

A partially annotated image of NGC 2359 ( Thor’s Helmet ) showing the location of the Wolf-Rayet star WR7 ( HD 56925 ).

A crop centred on HD 56925 at the heart of Thors’s Helmet:

HD 56925 ( WR7 ) has a distictly blue colour

 Simbad lists its type as WN4B and these stars are typically blue. 

The colour square below is for a WN4Ib type star

 

{ ref: http://www.vendian.org/mncharity/dir3/starcolor/   and  http://www.isthe.com/chongo/tech/astro/HR-temp-mass-table-byhrclass.html }

 

 

[lux eterna]

Wow, my favorite object ! Also, very nicely captured and processed. In the composition above, I think it looks like a rabbit :-)

The HDR processing is very rewarding for star colors and no bloating but I still miss some, just a little, of the dynamics that comes with different star light intensities.

Ragnar

 

[Mick J]

Really nice Mike, a blue nebula taken from the blue mountains, good work 

[Petergoodhew]

Great image Mike.  Both the wider-field framing and the HDR make it quite exceptional. It's rare to see a wide-field framing of this gorgeous target. I adore these oddly-shaped Wolf-Rayet and planetary nebulae. I never cease to be amazed at what you can achieve with a DSLR.

Peter

[MikeODay]

1 hour ago, lux eterna said:

Wow, my favorite object ! Also, very nicely captured and processed. In the composition above, I think it looks like a rabbit :-)

The HDR processing is very rewarding for star colors and no bloating but I still miss some, just a little, of the dynamics that comes with different star light intensities.

Ragnar

 

Thanks Ragnar, much appreciated.  And yes, I can see a rabbit’s head as well, it even has two ears and maybe some front feet sticking out ( not sure what the top right bit of blue is though ) 

I agree with you about the star intensities.  I am finding it difficult to have colour at the same time as tight bright stars.  Having said that, I think I can push the brightness a bit more; I did a little of that in the annotated image above working with the 8bit jpegs on my IPAD .  I will have a go with the proper files later in the week when I have some time off work.  

Cheers

Mike

[MikeODay]

1 hour ago, Mick J said:

Really nice Mike, a blue nebula taken from the blue mountains, good work 

Cheers Mick - made me smile

 

[MikeODay]

1 hour ago, Petergoodhew said:

Great image Mike.  Both the wider-field framing and the HDR make it quite exceptional. It's rare to see a wide-field framing of this gorgeous target. I adore these oddly-shaped Wolf-Rayet and planetary nebulae. I never cease to be amazed at what you can achieve with a DSLR.

Peter

Thanks Peter.  

I was not sure how it was going to turn out - the jpegs displayed by my capture program did not show the nebula at all, just the stars!  

Normally an 11.5 mag object would be so far down in the sky glow that I would just end up with a noisy mess, but not this time.  The skies were extraordinary over the weekend in Sydney; strong high pressure system hovering, very still air ( at all altitudes ) and very dry air for a change, contributed to the steadiest skies and lowest sky glow I have had so far in the nearly three years I have been at this hobby!

Cheers

Mike

 

[MikeODay]

2 hours ago, lux eterna said:

... In the composition above, I think it looks like a rabbit :-)

...

Ragnar

 

Perhaps we should start a petition to have it renamed “The Blue Bunny Nebula”

 

[MikeODay]

On 22/01/2018 at 20:24, lux eterna said:

Wow, my favorite object ! Also, very nicely captured and processed. In the composition above, I think it looks like a rabbit :-)

The HDR processing is very rewarding for star colors and no bloating but I still miss some, just a little, of the dynamics that comes with different star light intensities.

Ragnar

 

Updated:  Stars a little brighter and tighter with no change to the rest of the image ...

Version 2:

“The Blue Bunny Nebula”  ( NGC 2359 - Thor’s Helmet )   

( please click / tap on image to see larger and without compression artefacts ( and double click on that image if you what to see it as I posted it ! ) )

 

What do you think, better ?

Here is the original:

 

 

 

[lux eterna]

That´s the way (aha, aha) - I like it !

Ragnar

 

[MikeODay]

13 hours ago, lux eterna said:

That´s the way (aha, aha) - I like it !

Ragnar

 

Thanks Ragnar

[RobertI]

Beautiful image and informative write up! I was looking to see if it was a an RGB, narrowband, etc, but an unmodified DSLR?! Amazing results.

I think you have also picked up the open cluster Haffner 6 to the left if the frame?

[MikeODay]

4 hours ago, RobertI said:

Beautiful image and informative write up! I was looking to see if it was a an RGB, narrowband, etc, but an unmodified DSLR?! Amazing results.

I think you have also picked up the open cluster Haffner 6 to the left if the frame?

Thanks Rob that is very kind of you.  And thanks for mentioning the cluster; I have not heard of it before; I’ll have to look it up!

Cheers

Mike

[MikeODay]

5 hours ago, RobertI said:

...

I think you have also picked up the open cluster Haffner 6 to the left if the frame?

Is this it?