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MikeODay

A Cluster of Pearls in the Southern Skies ( NGC 3766 "The Pearl Cluster" in Centaurus ) - updated

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21st April: Re-processed to better show the colour of the fainter stars ...

 

06F21557-674D-4C93-9E6E-1B4AD5B798B4.thumb.jpeg.eb9ac214eb2a7413330b5faecca507f5.jpeg

 

.......

Shimmering like a pearl to the naked eye, this open cluster of mostly young blue stars ( known as the "Pearl Cluster" ) is approximately 5500  light years from Earth and was discovered by Abbe Lacaille in 1752 from South Africa.  

This HDR image is constructed from 11 sets of exposures ranging from 1/4 sec ( to capture the centre of the brighter stars ) through to 240 seconds ( for the fainter stars of the Milky Way ).  Total exposure time was around 5 hours.

5ad19037af8ea_aclusterofpearlsinthesouthernsky(ngc3766-thepearlcluster)-bymikeoday-2732pxwide-compressed.thumb.jpg.0b1d9ce88043aa06c8ed72a28c9b1385.jpg

A Cluster of Pearls in the Southern Skies ( NGC 3766 " The Pearl Cluster" ) 
( please click / tap on image to see larger and sharper - a full size image can be found here )

12 April 2018

.....

Image details:

Field of view ..... 58' 49.8" x 39' 36.4"
Image center ...... RA: 11 36 03.890  Dec: -61 35 30.17
Resolution ........ 0.586 arcsec/px  ( full size image )
Orientation: North is up

Telescope: Orion Optics CT12 Newtonian ( mirror 300mm, fl 1200mm, f4 ).
Corrector: ASA 2" Coma Corrector Quattro 1.175x.
Effective Focal Length / Aperture : 1470mm 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 3.91um pixels)

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

Capture ( 12 April 2018 ):
11 sets of sub-images with exposure duration for each set doubling ( 1/4s to 240s ) all at ISO250.
( 70 x 240sec + 10 each forthe other durations )

Processing:
Calibration: master bias, master flat and master dark
Integration in 11 sets
HDR combination 

Pixinsight April 2018

Edited by MikeODay
  • Like 9

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17 hours ago, pi_co100 said:

Beautiful! Thanks for sharing.

Cheers, thanks for that.

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4 minutes ago, Allinthehead said:

Wonderful work Mike. Your hdr method works very well with star clusters.

Thanks Richard.  It certainly helps to bring out the subtle colours :)

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A subtle tweak to lift the background a little ...

01738B2F-CEDA-417C-B598-94C70E1DDF6A.thumb.jpeg.f185444b536f193ee9769a17edd439b9.jpeg

What do you think, better or not ?

Edited by MikeODay

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And some crops from the full size image ( the top two can be enlarged further by clicking on them, the bottom three are already at 100% ).

 

2829489E-A40B-4C30-82DD-D318F72C761C.thumb.jpeg.7e15c13f1afe65de923b35451dbb4473.jpeg 

 

01661968-CB18-450C-B13B-CB9114BA1C10.thumb.jpeg.614a427f2b9e04e671c1772a732ff183.jpeg 

 

6245C1E1-A934-4DAE-8B78-B332A8B6323B.jpeg.adba62c005a50caa02dffe2dee129f8f.jpeg 

 

81F1BC84-E05C-4A09-9E06-D82DC941BD72.jpeg.429f10f0b88d4fda5731d31e8a307169.jpeg

 

81A55E51-3762-4A9F-A123-DB15461FFD88.jpeg.bf1ea3d243f63d830a107467125c6919.jpeg

 

I fascinated by the twirls, swirls and straight lines formed by the apparent positions of the stars.

Edited by MikeODay

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8 hours ago, MikeODay said:

What do you think, better or not ?

Yes the second is better, slightly brighter without making the stars bigger.

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Thanks Richard.  After working on and looking at an image for a long time I sometimes find it hard to judge the impact of small changes so another pair of eyes are much appreciated :)

 

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Re-processed to bring out the colour in the fainter stars ...

 

DFF64934-7909-41E6-88A6-A075C2F899A5.thumb.jpeg.9d87dedc80fa6a62f2e3f281ebda3a62.jpeg

 

F5C43D78-5AB9-4B3C-A039-8D210FB2D47F.thumb.jpeg.517c6903e5800a9f489e16cf2178fc2d.jpeg

 

24248D47-091E-409F-8CF6-E6C66277D786.thumb.jpeg.597f8541822fbbd7a88ef0c7ebc80863.jpeg

 

30E954B7-18E1-4032-AC86-E1FE89A238F0.jpeg.43a11f9d9d326173525c845fa2f0ec9d.jpeg

 

Edited by MikeODay

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Some more 100% crops showing patterns and the colours ranging from bright blue to deep orange

 

83F359E0-B704-4819-A58B-7C65B85323CF.thumb.jpeg.d47ec3df365f94f5671acdce906997e2.jpeg

 

AFB409F1-F6ED-4A63-B1A2-1F904C3EF2CF.thumb.jpeg.97c53f1fe9112bf393b80fcb921ad36e.jpeg

 

C725CDF7-0CA8-4EB1-A6B3-ADD5F2C8B709.jpeg.db310b07a0a9642488dc2b592221c2ee.jpeg

 

0D396888-B049-4519-ABBD-60F3290EE986.jpeg.fe0cc00a8562ac9b5de9a3f620842097.jpeg

 

0D97390A-21B0-4D3C-8A93-9174C9044824.jpeg.f94da243c9aebc7247b9b830a664fcd3.jpeg

Edited by MikeODay

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