another beginners M83 part 3

[muletopia (Chris)]

Very trite but:
After my last efforts I tried a different approach.
This image is as stack of 31 sixteen minute exposures at ISO 800 fro my Canon 60Da at prime focus of my Mewlon 210. An Orion thin off axis guider and PHD2 were used for guiding,
The data was collected over three nights, two with good seeing,PHD2 screen dump attached, and one with poor seeing PHD rms error .5 - .7 seconds. The difference in star sharpness is very obvious in the individual frames. However the picture generated from the two good nights (20 frames) is not as smooth as the 31 frame image attached.


Criticism would be appreciated.


Chris

[Sunfish (Ray)]

Great image. I wondered about stacking very long exposures.
I suppose that is a dark moonless sky.
What focal ratio is that. Native or with the reducer?

[sil (Steve)]

beautiful galaxy, lots of detail and colour. I think perhaps you should reduce exposure times to avoid blowing out the core and the stars (which all look to be core clipped to full white). I think reducing exposure will also help with overall detail and sharpness just by not bloating strong signal as much. its certainly a result to be happy with though.

[Startrek (Martin)]

Great image with plenty of detail in the Spiral arms
Stars in off axis area look to be affected by coma or tracking ?
Maybe exposures were to long ? Although your guiding numbers were superb !

[gb44 (Glenn)]

Chris,
Whats the yellow tracing along the top of the phd graph? I havent seen it on my system?

GlennB

[muletopia (Chris)]

Ray--What focal ratio is that. Native or with the reducer?


Native focal length no reducer or flattener 2514 mm F11.5


As the 'scope is an uncorrected Dall Kirkham cassergrain one expects coma off axis, just need to accumulate enough pennies to talk to Claude.


I have tried various exposure times and camera gain settings but this combination gives the best star colours. The core is not blown in the unprocessed stack but stretching to reveal other detail does saturate the core. For capture control and processing Nebulosity 3 was used. Seems like I have some way to go with processing.



I missed taking a screen dump of the best guiding rms .24 arc seconds; nice when it is dark, clear and the atmosphere co-operates.


Chris

[muletopia (Chris)]

Whats the yellow tracing along the top of the phd graph? I havent seen it on my system?


Glen,

AT the left of the picture there is a tab for settings


In settings you can select star mass and signal to noise ratio
if selected the two traces are scaled portrayals of these values


I find these lines helpful if they separate you probably have to adjust your camera exposure time or camera gain.


If they both descend you are probably about to loose guiding due to clouds.


Chris

[LostInSp_ce]

You got some nice details coming through the outer regions but like others have said the core and stars just got blown out. Keep this data and maybe next time take some shorter exposures to capture more detail in the core. Then reprocess your two sessions and combine them for a more balanced image. It's still a good image and nice scope you have there too.