Gambled on the weather last night in Sydney and thanks to the new ACCESS data that was made available recently it seems to have paid off nicely. The night was relatively dry, with a little wind after sunset but it calmed down straight after and the seeing wasn't bad at all. Guiding at 2.8m FL is always interesting but I'm fairly happy with the data collected so far. Still a little on the furry side but personal best to date at that FOV size anyway. Alnitak didn't bother me at all. I was surprised because the same FOV with the Mewlon proved very problematic. I've attached the MEWLON 210 shot for comparison.
So this is 135min in 5min subs on a G11, C11 at prime and QHY9 mono, Baader Ha 7nm and OAG/lodestar. Not much light getting in at that FL especially Ha. Flats took 15s with the EL panel to full to register 10000ADU. Probably would need twice or three times that amount of data but the details and contrast are starting to come through.
Looking really nice Marc! The newer one is a LOT better without the reflections.
From experience I would say that you'd probably need at least half hour subs with the QHY9 Having never tried guiding at anything longer than 742.6mm or with an OAG, good stuff
Very Fine result Marc, grouse going on picking the right night aswell, reckon that is half the challenge of astroimaging !
You are guiding with an Off-Axis if memory serves, if so, hows finding stars with a little pick-off and F10'ish ? ?
Thanks H. Yes was very surprised. I might try a long dewshield see if it makes any difference.
Quote:
Originally Posted by billdan
Quote - Pity about the reflections in the Mewlon image.
Blo--y Alnitak, ruined plenty of my images.
Great shot with the C11 Marc, lots of detail.
Thanks Bill. Tell me about it. I can't wait this one goes supernova (if it does). Is it due yet?
Quote:
Originally Posted by RickS
The new version without the death ray looks great, Marc
Thanks Rick. I call it the "Luftwaffe Bombing Run" as Peter Ward named it in one of my early carina widefields. But that was the moon.
Quote:
Originally Posted by DJT
Wohoo! Spikes! Nicely done, Marc, loads of detail.
Thanks David. Spikes rule.
Quote:
Originally Posted by troypiggo
Nice! Don't even wanna think about guiding at that sort of FL - I have trouble at 506mm!
Thanks Troy. Mate, I'm having troubles guiding at any FL. At least here I have an excuse.
Quote:
Originally Posted by Placidus
Excellent clarity and sharpness Marc, and great depth for the time available.
Should there ever be another clear night ...
Thanks a lot Mike. Setting up tonight again and hopefully tomorrow and guess what I'll be imaging again If I can increase the SNR dramatically then I can sharpen the hell out of it and then it's going to look a lot more interesting.
Quote:
Originally Posted by Atmos
Looking really nice Marc! The newer one is a LOT better without the reflections.
From experience I would say that you'd probably need at least half hour subs with the QHY9 Having never tried guiding at anything longer than 742.6mm or with an OAG, good stuff
Thanks Colin. I might try 10min tonight. I kind of wussed out. If there's no wind and the guide graph is ok I'll give it a go. But a lot of things can go wrong in 10min.
Quote:
Originally Posted by Camelopardalis
Nice one Marc lovely depth to it, you can almost reach out and touch the clouds behind it!
Thanks Dunk. Yes those clouds are starting to look interesting but still a little bland. I'm hoping more subs will define the curtain at the back as well.
Very Fine result Marc, grouse going on picking the right night aswell, reckon that is half the challenge of astroimaging !
You are guiding with an Off-Axis if memory serves, if so, hows finding stars with a little pick-off and F10'ish ? ?
I'm going down this road soon
Looks like you have it rather sorted
Rgrds
Hi Bob, thanks for the feedback.
I've attached some pics of the backend so you can see how everything is bolted on and the approximate distance from the camera from the back of the primary cell. On the front you can just make up the pickup prism at the bottom of the field in focus, right in front of the Ha filter.
I also use a Sharskypro kit for focusing so I move the primary up and down. The focuser is not the original. I've replaced it with a 10:1 micro focuser from Starizona. A must for any SCT IMHO.
To successfully guide at that FL you'll need to collimate your scope pretty well if you want to get a guide star with a decent shape unless your SCT is ACF.
I guide with PHD, the old version. I don't use PHD2. Don't fret if you see your graph going up and down, given the image scale you're still guiding well within ball park. I think my calibration steps are 200ms so I get 10 steps for each. W E N and S. Other than that settings are default.
Your guiding will be determined by seeing conditions. Pick your night. Unless your seeing is good to exceptional don't even bother. Also no wind is a requirement. Obviously Lastly refrain from walking around your scope or even touching it while it's guiding. It will show in your guide graph and photo.
To find a guide star bright enough can be challenging but if your guider is focussed accurately, not impossible. The guider chip being so small on the lodestar I first do a couple of test unguided exposures on the main camera to see if my DSO is inside the fov. 1min or 2min. My FOV is pretty tight and my goto is not that accurate so I do a bit of fishing to find my targets unless it's very bright like M8 (go M8!). My fov is about 24'x18' at an image scale of 0.4 asp. So that's probably even tighter than my polar alignment accuracy.
So once you've got your framing ok you move your scope W,E,S and N slightly and look for anything zooming by the small FOV of your guider. That's how you fish. It's likely your framing won't be changing much by offsetting the fov of your guider.
Unless you're one of the superdoopa skyX users with plate solving, robotic mounts, remote operated rigs on top of distant mountains and you do everything by the numbers and land on it day after day, that's how I'd do it.
Quite a straight forward & compact Focal train you have there Marc, which looks Ideal (Appreciate the pics there aswell )
I have some parts & kit around, a meade OAG & an Orion thin OAG which I'd prefer but may not suit/adapt to the meade threads, may be some adapters, tho Id like to avoid them as 'simple is key ? Either way with most likely qhy5, its nice and tiny to sneak in cramped places & quite sensitive for a guide star - so they call it 'Fishing' I can understand this as have used the Orion OAG on the 10" Newt F4.7 tho ? Think my targets with the 12" will be determined by How many stars are in the small field Quite a few good galaxies out there in the middle of nowhere
My scope is a Meade 12" ACF which Id like to use with the Qhy10 C and Im hoping to fit the Moonlight motor focuser in there somewhere - then I can Lock the mirror down - It'll all be Trial & Error for a while, I'm sure of that And no doubt all easier said than done
Im currently in the process of sorting out some ventilation fan/s for the scope cover 'Cosmo Caboose', pretty hot in there otherwise, then Ill start rigging up and piecing things together...
Cheers for all your time, feedback, answers , pics and advice Marc
Quite a straight forward & compact Focal train you have there Marc, which looks Ideal (Appreciate the pics there aswell )
Yeah everything is bolted. Makes it rigid and square. Focus is via the primary, which is the best way to do it.
Quote:
Originally Posted by astronobob
I have some parts & kit around, a meade OAG & an Orion thin OAG which I'd prefer but may not suit/adapt to the meade threads, may be some adapters, tho Id like to avoid them as 'simple is key ?
Either OAG will be alright. Adapters are ok too as long as they don't narrow the light path. Try to keep the inner diameter of your rig as close as the inner diameter of your exiting baffle tube, right up to the camera sensor. An added benefit is that you can have more light getting in the pick up prism from your OAG. Most adapters to the back cell restrict the diameter to 1"1/4 already. If it's the case bin it and make your own.
Quote:
Originally Posted by astronobob
Either way with most likely qhy5, its nice and tiny to sneak in cramped places & quite sensitive for a guide star
The QHY5 will be nice for guiding with a pick up prism. Not sensitive enough for an AO but sufficient for standard guiding. Also it is quite big in diameter so sometime you won't be able to get it down close enough to the main light path and you might need spacers, then the same spacers before your imaging camera to match focus.
Quote:
Originally Posted by astronobob
- so they call it 'Fishing' I can understand this as have used the Orion OAG on the 10" Newt F4.7 tho ? Think my targets with the 12" will be determined by How many stars are in the small field Quite a few good galaxies out there in the middle of nowhere
My scope is a Meade 12" ACF which Id like to use with the Qhy10 C and Im hoping to fit the Moonlight motor focuser in there somewhere - then I can Lock the mirror down - It'll all be Trial & Error for a while, I'm sure of that And no doubt all easier said than done
Try not to do that. The 12" is a large heavy chunk of glass and will move regardless. Stick with the original design. Bolt everything at the back and focus with the primary. Keep it simple. Save a couple of bobs. No pun intended. Adding a focuser at the back will introduce an extra point of flexure and weight to the rig. Image close to the zenith. Your primary will always move whether you like it or not. Locking it won't work and will introduce aberrations with temperature gradients. It needs room to breathe.
Quote:
Originally Posted by astronobob
Im currently in the process of sorting out some ventilation fan/s for the scope cover 'Cosmo Caboose', pretty hot in there otherwise, then Ill start rigging up and piecing things together...
Cheers for all your time, feedback, answers , pics and advice Marc
I did add some fans at the back of my C11 primary cell. I use them only when the air is dry and when it's very hot. Other than that it's best to keep the air inside the scope as "clean" as possible. Don't push in moist air or you'll dew the inside of the corrector and possibly the primary. In QLD I assume you have high humidity. If the inside of your scope is hot and dry then it's better than cooler and moist. It will equalise eventually. May be a very tiny PC fan inside the scope tube aimed at the baffle tube to disrupt the boundary layer on your primary would work better.
great close up marc, especially considering f10ish and 5 min subs!!!!
Thanks Russel. It was a good night. I'm impatiently waiting to add some more data but the weather has changed and is not playing ball in Sydney. High altitude haze. The scope is just waiting on the kitchen bench still assembled ready to go outside. If this weather doesn't clear this week-end I'm going to be in the doghouse.
Having never tried guiding at anything longer than 742.6mm or with an OAG, good stuff 
It's likely your framing won't be changing much by offsetting the fov of your guider.
And no doubt all easier said than done 
The scope is just waiting on the kitchen bench still assembled ready to go outside. If this weather doesn't clear this week-end I'm going to be in the doghouse.
