Quick Trifid - RC6 first light

[pluto (Hugh)]

Had a chance to get my new (2nd hand from an IIS member) RC6 set up and test it out. It was forecast to be cloudy here in Sydney tonight but I couldn't wait any longer!
Anyway I got 2x5min + 2x10min Ha before the clouds thickened up.

The focus was the best I could get but the stars are still a little soft, I think because of the high clouds I was imaging through.

Also I wanted to have a go guiding with my Orion mini guide scope and QHY5L-II to see how it would go at the longer FL of the RC and evaluate the need for an OAG. Seems to have worked pretty well though I'll wait until I try it all out under better conditions before I make a decision.

Can't wait to get this thing to dark skies!

[nebulosity. (Jo)]

That looks awesome

[RickS (Rick)]

Very good, Hugh! You can see the jets.

[pluto (Hugh)]

Originally Posted by nebulosity.

That looks awesome

Thanks Jo

Originally Posted by RickS

Very good, Hugh! You can see the jets.

Thanks RIck


I'm a little concerned at the pointy stars in the left side of frame.
I'm thinking that's due to the camera not being quite flat? I don't think it's focuser slop as it didn't change when imaging a target on the other side of the meridian?

Or is it a collimation issue?
I'm new to scopes with mirrors and the collimation I performed the other night was my first so any advice would be appreciated!

[alistairsam]

Hi,

Nice image.
which camera was it?
I'd suggest checking the collimation as I think it needs a minor tweak.
there is a method for collimating RC's using the secondary edge.
you can use a normal cheshire as well.
do work out the image scale of the guide combo vs the main scope and see if its not too far off.
phd uses sub pixel guiding, but seeing will be a major factor.

OAG would be the way to go but the guide cam will need to be very sensitive as the aperture of the main scope is not that large, so is the pixel on the qhy5l2.
with the rc8, an oag and lodestar is a proven solution as the lodestar has larger pixels than the L2.

Look forward to more results.

Cheers
Alistair

[alistairsam]

looks like you have caught a hint of the famous jet in the trifid.
well done.

[alistairsam]

Originally Posted by pluto

Or is it a collimation issue?

pretty sure it is. that comet shape is commonly attributed to collimation errors.

[pluto (Hugh)]

Originally Posted by alistairsam

Hi,

Nice image.
which camera was it?
I'd suggest checking the collimation as I think it needs a minor tweak.
there is a method for collimating RC's using the secondary edge.
you can use a normal cheshire as well.
do work out the image scale of the guide combo vs the main scope and see if its not too far off.
phd uses sub pixel guiding, but seeing will be a major factor.

OAG would be the way to go but the guide cam will need to be very sensitive as the aperture of the main scope is not that large, so is the pixel on the qhy5l2.
with the rc8, an oag and lodestar is a proven solution as the lodestar has larger pixels than the L2.

Look forward to more results.

Cheers
Alistair

It's using my Atik 314L+.

I was thinking I'd end up with an OAG but I thought I'd see how the mini guide scope and 5LII would go first. I think going OAG would mean getting a new guiding camera so I'm trying to hold off for a bit as I'm in the process of trying to sell a property I own and if that works out then I'll look at a major equipment upgrade.

The results from last night are promising with my existing setup especially if the comet-shaped stars are a fixable collimation issue. As I said that was my first go at collimating so I'm sure there's room for improvement!

I've attached a screengrab of a defocused star and it does look a little bit off centre?

Thanks for the advice

[alistairsam]

Hi Hugh,

yes, very slightly off centered. should be easily fixable.

I have successfully used the qhy5l2-mono with an OAG on my 10inch F4, and the GSO RC6, however far fewer stars on the RC6 as expected, but still there.

But you can easily add a 0.5x 1.25inch focal reducer to the 5L2 and get it guiding at 1/2 main scopes focal length if using on the RC6.
That should give you heaps more stars to guide on.

or add a barlow to the mini guidescope.

but looking at your guiding, it looks very good so may not even need it.
so I'd suggest testing for soft stars again under better seeing and then deciding.

Cheers
Alistair

[pluto (Hugh)]

Thanks Alistair.

I have the colour 5LII, bought so I could use it for quick planetary imaging too, so I guess it's not as sensitive as the mono for guiding.
I had thought of using a barlow with the guide scope, that'll probably be the quickest/easiest/cheapest thing to try if I'm not getting good results.
Good to know you can use a reducer with an OAG, I hadn't thought of that.

Thanks for your help Alistair.