nebula Tarantula Nebula ( NGC 2070 ) in the Large Magellanic Cloud ( LMC )

[MikeODay]

Tarantula Nebula ( NGC 2070 ) in  Large Magellanic Cloud ( LMC ) by Mike O'Day.

The Tarantula Nebula ( NGC 2070 ) is the largest and brightest emission nebula in the  nearby irregular galaxy, the Large Magellanic Cloud ( LMC ).  At a distance of 160,000 light years away from us, the Tarantula Nebula is so bright that it would cast shadows on the Earth if were as close to us as the Orion Nebula in our galaxy.

New version ( April 9 ):

( please click / tap on image to see larger and sharper image )

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

Older versions:

And here it is re-processed to try to reduce the red background ( due to light pollution I think ) without impacting the colour of the stars too much

 

( please click / tap on image to see larger and sharper )

Details:

Nebulae:

NGC 2070 Tarantula Nebula
NGC 2048
NGC 2060
NGC 2077

Open clusters:

NGC 2042
NGC 2044
NGC 2050
NGC 2055
NGC 2091
NGC 2093
NGC 2100 

Image centre  ... (nova.astrometry.net)
Field of view (arcmin): ...
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 AZ Eq6 GT.
Guiding:      TSOAG9 Off-Axis-Guider, Starlight Xpress Lodestar X2, PHD2  
Camera:     Nikon D5300 (unmodified) (sensor 23.5 x 15.6mm, 6016x4016 3.9um pixels).
Filter:          none.

Exposures:

100 sub exposures ranging from 1s 100ISO to 240Sec 400ISO HDR processing of 5 sets of images
Pixinsight & Photoshop
20 December 2016 / April 2017

[MikeODay]

And this is a slightly different version...

I think that the colours in the image above are more "correct"; or at least the colours of the stars are closer to their published vaues.  However, I think I might prefer the one below in which the background colours have been toned down ( albeit with some small impact on the star colours; they are a little bit too blue ).

[Knight of Clear Skies]

Nice shot and composition but the second image still has a very purple background, would be good to see a more neutral version.

[MikeODay]

25 minutes ago, Knight of Clear Skies said:

Nice shot and composition but the second image still has a very purple background, would be good to see a more neutral version.

Thanks for that.

I'm still not sure about the colour .,..  I am pretty sure that the background in this region of the LMC is strongly coloured - I'm just not sure that I have the right colour

[MikeODay]

This crop taken from an image by Robert Gendler and Josch Hambsch on  https://www.cfa.harvard.edu/news/2007-22

 

It shows that most of this region is covered in an extensive complex of Ha emitting clouds.

And this crop of  Debra and Peter Ceravolo's image perhaps shows it best  http://www.ceravoloimages.com/gallery1/deep_sky/nebulae/tarantula_nebula.html

Now my image is not as red as this of course because my DSLR is unmodified - this means that Ha can tend to look more magenta than red.

Both of these make me want to see what mine would like if I really push up the saturation / vibrancy

 

 

[Knight of Clear Skies]

Yes, there is certainly lots of extended Ha in the region but it's pretty faint and I'm not sure if your unmodified camera would pick it up. What's your total integration time please? If you're interested it might be worth overlaying your image onto the Ha map in World Wide Telescope to see how well things match up - but the only way I can find to do this is by uploading the image to Flickr and then submitting to the Astrometry group (which then plate-solves and leaves a comment with a link). I use this to sanity check my images and to check what I brightness level I can go down to, to help plan future images.

[MikeODay]

8 minutes ago, Knight of Clear Skies said:

Yes, there is certainly lots of extended Ha in the region but it's pretty faint and I'm not sure if your unmodified camera would pick it up. What's your total integration time please? If you're interested it might be worth overlaying your image onto the Ha map in World Wide Telescope to see how well things match up - but the only way I can find to do this is by uploading the image to Flickr and then submitting to the Astrometry group (which then plate-solves and leaves a comment with a link). I use this to sanity check my images and to check what I brightness level I can go down to, to help plan future images.

Thanks for the heads up about World Wide Telescope - I will have a look.

I already use Astrometry.net; although it seems to be struggling with this image.

Total exposure time for long subs was around 2hrs, with additional shorter subs for the stars.  I understand that aperture is relevant for diffuse subjects, so, with the coma corrector, the effective aperture for my 12" scope is f4.7.

If the red / magenta is not in the nebula then I guess it must be uncorrected light pollution.  What I find confusing though is that light pollution is additive and should be impacting all parts of the linear image to the same extent.  I did check, in order to remove the red I would have to subtract a very large amount from the linear image and this significantly messes up the star colour balance.  Or to put this another way, if the stars are approximately the correct colour then the light pollution should have already been mostly taken care of.  Either that or I am really confused ...

I'll have another go tomorrow and see if I can find a way to reduce the red / magenta without impacting the stars.  ?

 

[laudropb]

A very nice image. It's always nice to see objects from the Southern sky.

[MikeODay]

11 hours ago, laudropb said:

A very nice image. It's always nice to see objects from the Southern sky.

Thanks

[wxsatuser]

I took the liberty and reduced the red out of the background, balanced at 24/24/24.
I think you captured a reasonable amount of red.

Anyway, nice part of the sky and you got some good data with a dslr.

[MikeODay]

18 hours ago, wxsatuser said:

I took the liberty and reduced the red out of the background, balanced at 24/24/24.
I think you captured a reasonable amount of red.

Anyway, nice part of the sky and you got some good data with a dslr.

 

Thanks for that - a very different and quite attractive version that gives me something to think about.  Would you mind giving a brief description of the tool(s) and steps you used?

I have tried various ways to reduce the red and I have ended up with images that, whilst not the same as yours, do share the fact that the star colours have been significantly altered.  I have been trying to find a process that will give me good colour in all of the stars and also have a reasonably attractive and accurate nebula and background colour.  With this image it may not be possible.  I have had a look at the in-camera daylight balanced JPEGs ( that I keep for ease of reference ) and they are quite red and noisy.  The weather over the past months has been very wet and humid around Sydney and I suspect the image is suffering from increased light pollution due to low altitude humidity.  I guess I need a way to remove random red noise in post processing without impacting the rest of the image - mmm, perhaps Pixinsight needs to develop a magicWand tool

 

[wxsatuser]

Even without light pollution the sky background will most likely not be a neutral colour.
A dark site will still have airglow that could be a brownish red with may be green thrown in as well.
This is normal and most imagers will neutralize the background to neutral grey.

Basically all I did was neutralize the background in Photoshop so the three colours were equal at 24.
This makes the background a neutral grey, you can set this value to taste, most likely 23 to 30 is a good level.

What we do in Photoshop is place an eyedropper on what looks like pure background and adjust the blackpoint
to the right so all the three colours are equal.

Here Jerry Lodriguss explains basic Photoshop image correction.

[MikeODay]

On 13/03/2017 at 15:59, wxsatuser said:

Even without light pollution the sky background will most likely not be a neutral colour.
A dark site will still have airglow that could be a brownish red with may be green thrown in as well.
This is normal and most imagers will neutralize the background to neutral grey.

Basically all I did was neutralize the background in Photoshop so the three colours were equal at 24.
This makes the background a neutral grey, you can set this value to taste, most likely 23 to 30 is a good level.

What we do in Photoshop is place an eyedropper on what looks like pure background and adjust the blackpoint
to the right so all the three colours are equal.

Here Jerry Lodriguss explains basic Photoshop image correction.

Thank you for the detail of how you adjusted the colours.

I'm still thinking of a way to do so without impacting the stars... 

One thought is to try to reduce the visual impact of the high red levels by stretching to the left the red histogram peak.  That is, try to keep the right of the red histogram where it is ( to protect the colours of the bright stars ) and just stretch the left until the shadow tones are better balanced.  

[MikeODay]

On 15/03/2017 at 11:06, mike005 said:

...

I'm still thinking of a way to do so without impacting the stars... 

One thought is to try to reduce the visual impact of the high red levels by stretching to the left the red histogram peak.  That is, try to keep the right of the red histogram where it is ( to protect the colours of the bright stars ) and just stretch the left until the shadow tones are better balanced.  

It looks a bit soft but that is just from the compression applied by the site.  Please click/tap on the image to see larger and sharper.

[MikeODay]

Re-processed again ...

( Please click / tap on image to see larger and sharper )

[MikeODay]

100% crops from 6000x4000 image:

 

 

[MikeODay]

Tweaked again - this time saturation has been increased to bring out the colour of the stars ...

Please click / tap on image to see larger and sharper.

 

[MikeODay]

Tarantula Nebula ( NGC 2070 ) in the Large Magellanic Cloud ( LMC ) - annotated

( please click / tap on image to see larger )

objects include:
IC 2145
NGC 2091
NGC 2092
NGC 2102
NGC 2042
NGC 2044
NGC 2048
NGC 2050
NGC 2052
NGC 2055
NGC 2060
NGC 2069
NGC 2070 Tarantula Nebula
NGC 2077
NGC 2074
NGC 2078
NGC 2079
NGC 2080
NGC 2081
NGC 2083
NGC 2084
NGC 2085
NGC 2086
NGC 2091
NGC 2092
NGC 2093
NGC 2094
NGC 2100
NGC 2102