M17 finished.... sort of

[RyanJones]

Hi all,

It’s taken me over a month to collect all the data for this one. With the moon and the weather, finding enough time has been a challenge. I liken this one to Orion in its bright core with feint outer nebulosity although it’s not nearly as pretty. So here it is. I may still return for a bit more of a processing play next cloudy day....

198 x 180sec Subs
Canon 350d @ ISO 400
STC Duo Filter
Celestron C9.25 SCT w/ 0.63 reducer
HEQ5 pro guided by Nexguide SAG

Thanks for looking

[Startrek]

Ryan
Nice image plenty of detail , sounds like a lot of time put into this target
M17 is one of my favourite nebulas
Only one observation , stars look a little bit elongated
What was your guiding error ?

[RyanJones]

Thank you Martin,

I couldn’t tell you what my guiding numbers are. I use a stand alone guider which doesn’t show/record error data. It’s accuracy is not fantastic. Also the guider is peering down a 400mm guide scope to guide a 1500mm focal length SCT so I’m kinda pushing the proverbial up a hill to start with. It’s what I’ve got for now though.

In addition, I have made a few changes during this capture including the positioning of my counterweights and tuning of the worm drive. Overall it improved the elongation of the stars but I wasn’t about to throw out the previous 7hrs I already had so future images started fresh May show more improvement in that area.

Thank you for the feedback Martin

Ryan

[ChrisV]

Very nice Ryan. That's a loooong focal length you are working at. You are braver than me.

[RyanJones]

Thanks Chris.... I’m not sure brave is quite the word for it. I know I’m not really set up for it but hey, I’ve got it there, might as well give it a crack and if nothing else, the lessons I learn and the struggles I have to address will surely help me refine sorter my shorter focal length OTAs.

[LostInSp_ce]

It's always tough at long focal lengths to keep stars round but I think you've done a pretty good job here on getting the nebula's core up close and personal. I'm curious to know if you dithered with this one?

[RyanJones]

Thank you LostInSp_ce,

Despite the challenges, I’ve been enjoying trying to get up close with some targets this season. Re: Dithering. I don’t have the option with my guider to setup dithering..... however, the guiders inaccuracies over time does give me an uneven distribution of around 10-15 pixels in each direction over 4-5 hours effectively dithering for me.

[muletopia]

Hello Ryan,


As many many people have said, long focal length, moving primary mirror and flexure are only addressed with an off axis guider.


For me with a Mewlon 210 (2145mm focal length) on a HEQ5 PRO the only way I could get guiding was to use an off axis guider. Guiding with PHD2 produced round stars. I use an Orion thin off axis guider.


But the scope was too heavy for the mount (in my opinion) so I upgraded my mount but I use the same guiding setup.

Startrek as recently achieved arc second guiding on a Synta mount by careful attention to PEC correction (I seem to recall that he used the PEC function in PHD2).


Just thoughts


Chris

[RyanJones]

Thank you Chris for your input. I realize that why current setup is far from ideal and OAG is the way to go. This particular setup I’m using because it’s what I have and is transferable from my main imaging rig which is an 8” F/4 Newt. Down the track I’d like to be able to use the C9.25 properly for imaging but it’s going to require some dedicated gear which I just am not ready to fund just yet so I’m doing the best with what I have available.

Cheers