M27 Dumbbell Nebula - Sony A7S

[MarkS]

Messier 27, the Dumbbell Nebula taken last night. Passing cloud and gusts of wind meant I only managed to get 50 minutes of useable data in 30sec subs at ISO 10000. H-alpha modified Sony A7S on Celestron C11 with Starizona LF reducer/flattener.



Full size version (cropped) is here:  http://www.markshelley.co.uk/Astronomy/2018/M27_C11_20180611.jpg

Mark

[Carole]

Lovely image Mark, good colour.

Carole

[MarkS]

Lovely image Mark, good colour.

Thanks.  I was pleased that the central star appeared blue.  Not many images seem to achieve that.

Mark

[ApophisAstros]

Thats a great image , i especially like the pinks and blues.
Definitely gone on my list.
Should i try 30s or higher subs with a high ISO , can go upto 12800 on my 750d?
Roger

[Carole]

You need 300secs for this target Roger 800iso.  High ISO will create too much noise.

Carole

[MarkS]

Thats a great image , i especially like the pinks and blues.
Definitely gone on my list.
Should i try 30s or higher subs with a high ISO , can go upto 12800 on my 750d?
Roger

Is that the Canon 750D (not the Nikon D750?)  In any case, you're better off sticking to longer exposures.  The only reason I use such short exposures is to prevent the Sony star-eater issue.  The Sony A7S read noise and dark noise is extremely low so I can actually get away with this strategy.

M27 is a bright target and definitely well worth a try.  Well positioned in July/August/September.

Mark

[MarkS]

Here's a version annotated in PixInsight (AnnotateImage script) using data from the ESA Gaia mission - specifically red and blue magnitudes from the Gaia DR2 catalogue.

I've only annotated stars of magnitude 14.5 and brighter otherwise the image would be totally cluttered (Click on it to see it full size)



It's very noticeable that the bigger the difference between the 2 magnitudes, the redder the star colour.

A plot of the Gaia DR2 passbands can be found here:
https://www.cosmos.esa.int/web/gaia/iow_20180316

Mark

[JohnP]

Nice image scale Mark & good colours - Background looks a little brownish at least on my monitor but knowing you its correctly balanced - John

[NoelC]

Pretty fantastic Mark.
To actually see the central star is good.
Noel