nebula NGC 2014, 2020, 2030, 2032 ( Dragon's Head nebula, N59 Complex ) in the Large Magellanic Cloud ( LMC )

[MikeODay]

Identification of the elements of the N59 Complex ( including the Dragon's Head Nebula ) ( ref: http://astronomyandobservation.blogspot.com.au/2015_06_01_archive.html, Leo Cavagnaro)

Note: I'm not too sure about the designation of the upper part of the Dragon's Head Nebula - different sources give this the designation 2029 or 2030; SkySafari and Pixinsight ( VizieR data ) both agree on 2030.

[MikeODay]

Re-processed with updated workflow:

 ( click on image to see without compression softness )

Dragon's Head Nebula ( NGC 2032 & 2035 ) in the N59 Complex in the centre bottom of the image and NGC 2014 and NGC 2020 in the centre.

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Scaling the 14bit files by 4.125 instead of 4 and Integrating with normalisation set to "none" forced the RGB individual clipping points to align at the far right edge of the histogram.  This means that one does not have to manually clip the right of the histogram in order force the stars to clip 'white'.  I thinks this will both save me time and result in more uniformity of star colour.

Anyway, the impact on the image above is subtle but the stars are somewhat smaller and the colour balance of each integration set was more uniform and hence the HDR combination was able to produce more uniform colour in each star.

[MikeODay]

In case anyone is interested, here is my updated workflow to try to maintain star colour throughout the process so I don't have the problems I have been having trying to correct the colour balance after stretching (when the image is no longer linear ).

..........

A. set up DSLR conversion ( in Format Explorer ) to:

 - RGB CFA ( not debayered )
- no black point correction
- no colour balance 
- all weights = 1

B. Calibrate 14 bit NEF format DSLR files with master bias ( not super bias ) using ImageCalibration tool

C. Use PixelMath to white balance and scale the 14 bit images to the full 16 bit range:

    R:  $T[0]*2.12*4.125

    G: $T[1]*4.125

    B: $T[2]*1.49*4.125

    ( this ensures that the un-clipped stars have close to the "right colour" and the brightest stars clip to white ) 

D. Calibrate with master flat

E. Batch Debayer

F. SubframeSelector script to identify 'best' subs for alignment and to be reference for Integration

G. Integrate set of longest exposure subs:

- Combination:  Average
- Normalisaiton: none.      (Note:  normalisation scales the subs resulting in the clipping point of each sub being shifted to a different value before integtration; this impacts star colour )
- Weights:  Average Signal Strength
- Winsorised Sigma Clipping ( if a large number of subs )
- Sigma low: 4
- Sigma high: 2  ( ie. low number to eliminate parts of stars that are out of round compared to those in the ref sub )

H. Integrate sets of short subs ( usually just a small number of each )

- as for long subs, except:
- Sigma clipping ( due to small number of subs )
- Sigma low : 2. ( to reduce noise in darker parts of image (?))

I. HDRComposition to  combine integrated images

J. Adjust left hand side of histogram curves using the Histogram Tool to align the left hand 'side' of the histogram curves.
( note: there is in fact no "left hand side" as these are continuous distribution curves.  However, by maximising the vertical scale of the histogram tool, the start of the histogram curve becomes near vertical in the display and it is possible align the three RGB curves at this point.  The result is a set of curves that start at the same point rather than peak at the same point. )

K. MaskedStretch

L. Deconvolution 

M. Load in Photoshop and make final minor tweaks to colour balance if necessary 

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Note:

I have only tested this with the image in this post.  This part of the LMC has an extensive Ha region and so one might expect the background to be red.  However, I still need to test step J above with an area of the sky with "neutral" background to make sure that I am not adding "red" to the image.

 

 

[MikeODay]

Large Magellanic Cloud ( Dragon's Head Nebula region) - annotated

- NGC 2004
- NGC 2011
- NGC 2014
- NGC 2020
- NGC 2021
- NGC 2030
- NGC 2032
- NGC 2035
- NGC 2040

Note:  I'm not too sure about the designation of the upper part of the Dragon's Head Nebula - different sources give this the designation 2029 or 2030; SkySafari and Pixinsight ( VizieR data ) both agree on 2030.

[MarsG76]

Excellent image... lots of interesting nebulosity visible in and around the LMC.

[MikeODay]

2 hours ago, MarsG76 said:

Excellent image... lots of interesting nebulosity visible in and around the LMC.

Thanks 

[MikeODay]

Updated version.  Re-processed from the original subs to try to improve the colour balance and reduce the red in the background.

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

[MikeODay]

Some crops of detail ...

 

 

[PatrickGilliland]

Nice work Mike - a glorious target as well.

[MikeODay]

14 hours ago, PatrickGilliland said:

Nice work Mike - a glorious target as well.

Thanks Paddy, much appreciated.

[MikeODay]

I spent some time searching and finally managed to identify the small yellow object not far from NGC 2004.

2MASX J05314916-6721339 "Galaxy in a group of galaxies"

( J2000:  5h 31m 49.16s   -67d 21' 33.92"  )

Ref: Simbad. ( http://simbad.u-strasbg.fr/simbad/sim-id?Ident=%403123415&Name=2MASX J05314916-6721339&submit=submit )

 

[MikeODay]

As published in July 2017 Australian Sky and Telescope magazine ...

 

[wimvb]

Congratulations on getting published.

[MikeODay]

20 hours ago, wimvb said:

Congratulations on getting published.

Thanks Wim.

[StargeezerTim]

Congrats Mike... Well deserved...

[MikeODay]

On 06/06/2017 at 05:14, StargeezerTim said:

Congrats Mike... Well deserved...

Thanks Tim, much appreciated.