Omega Centauri Deep Field (ONAG Test)

[Eden]

After a fairly long wait for the Melbourne weather to improve (albeit only somewhat), I finally had an opportunity to put the Innovations Foresight On-Axis guider to the test.

I selected a readily available target and came away with this image, being a composite of 6 x 15 minute exposures and 10 x 10 minute exposures. No darks, bias or flat frames.

Full resolution version available here:
http://www.astrobin.com/155390/

A full review of ONAG goodness is forthcoming.

Thanks for taking a look! :)

[Placidus]

Very fine. Your gear seems to be working well.

Omega Centauri is famous for having a mix of young and old stars, in many different colours. See http://apod.nasa.gov/apod/ap140529.html

You might be able to reprocess to see the warmer coloured stars better.

Best,
Mike

[alpal]

Nice result Eden,
do you have a link that shows a picture of your ONAG setup & also
a link for the actual ONAG?

cheers
Allan

[Eden]

Hi Mike and thanks, I agree, I rushed the processing on this one a bit and will take another look at it later to bring out the redder stars.

Al, thanks -- I have several images of the ONAG connected to my setup and will be posting them later today along with a review, so stay tuned for that.

Details on the ONAG can be found here:
http://www.innovationsforesight.com/

Cheers,
Brett

[RickS]

A very successful first light, Eden. Look forward to your review.

Cheers,
Rick.

[Amaranthus]

Nice work Eden.



Curious as to why??

[Eden]

Thanks for the feedback, gentlemen. Always very much appreciated.

Hi Barry, I would have liked to have applied calibration but in a nutshell, changes to the gain and offset settings in this session mean a whole new set of calibration frames need to be shot and owing to problems with the TEC cooling on the QHY12 and it not being able to reach the desired setpoint during the day, that will have to wait until it comes back from a service.

[strongmanmike]

That looks a lot like an eyepiece view really, nice job :thumbsup:

Mike

[alpal]

Thanks Brett,
I am always fascinated by any equipment that can have the potential to
reduce seeing effects - in this case by by guiding with near infrared.
( as per your link )
And
"...The guide stars available to the ONAG® are closer to the telescope's optical axis and are thus of much better quality for guiding."

Unfortunately the 68mm back focus would prevent it being applied in most Newt's.

It would be interesting to compare guiding with your ONAG to guiding with a normal OAG on the same night.

cheers
Allan

[Amaranthus]

I agree it's a fascinating concept! But is it worth thrice the price of OAG?

[gregbradley]

Nice tight stars. Do you need an ONAG if you have an AO unit though? I suppose you still need an OAG of some sort to get the guide star?

Greg.

[Rod771]

Yeah! That's what I thought.

Nice natural result Brett, well done! :thumbsup:

[Eden]

Hi Mike, I appreciate your comments. Owing to the weather here I don't get to post too often and it's always nice to get some positive feedback. By the way I really enjoyed your work on the extended Sculptor region, very impressive. :thumbsup: I noted hints of it in one of my own sessions and thought I had made a cock-up of the processing!



You're welcome, Allan. The claims regarding the ONAGs ability to reduce the effects of seeing are by no means exaggerated and this is clearly visible when looking at the images coming off the guide camera. I thought my guide camera had come unplugged or that PHD Guiding had crashed, that's how steady it is.

Some telescopes are not compatible due to backfocus requirements but most OTA can manage it.

I only have an ONAG vs ONAG+AO comparison to date, next time I go out I'll throw on the old Orion OAG and see how it fares. Compared to an ordinary 80mm guide scope in visible light I've been seeing an improvement of 20% -> 25%. The potential gains are higher still.

[Eden]

Thanks Rod, Greg.

Yes, you'd still need some sort of means through which to get a guide star. Unless you simply don't have the backfocus, there's no reason why you would choose the OAG over the ONAG for AO operation. Consumer AO (Active Optics, as opposed to Adaptive Optics) won't save you from poor seeing, if anything it will chase it. The ONAG delivers in that department and the two together are a great combination.

Barry -- I think it's it worth every cent. Imaging might be out of the question on nights of worst seeing, but the fact that the ONAG will always give you better guiding than what you would get in visible light with an OAG or a guide scope, makes it an improvement worth taking advantage of.

[alpal]

I look forward to the comparison results.

[alistairsam]

Nice results Eden, I've always wanted to use the ONAG mainly for the NIR guiding aspect but I have a newt with an AO,

I was thinking, is it possible to use a 1.25inch NIR filter in front of the guide camera atleast to reduce effects of seeing?
I use a Lodestar X2 so no issues with a guide star, being F4 I am way off the centre with my AO, so any addition to reducing seeing would be great.
I've been looking for an NIR filter, haven't found one yet.

Cheers
Alistair

Edit: I found this, not sure if it can be used

http://www.ebay.com.au/itm/400585985158?_trksid=p2060778.m1438 .l2649&ssPageName=STRK%3AMEBIDX%3AIT

sorry I know this isn't the right thread, will start a new one in another section.

[Eden]

Hi there Alistair,

No need to apologize mate, I don't care if you bring this up in here... no need to make a new thread since we're already discussing NIR guiding here and here:

http://www.iceinspace.com.au/forum/showthread.php?t=131801

I've tried a Near-IR pass filter and unfortunately there's no comparison, as the ONAG completely blocks anything below 750nm. By contrast, the Near-IR pass filter allows light < 400nm through and has some other small but significant leaks between 400nm and 742nm.

I don't know if you've seen a conventional Near-IR pass filter but when you hold them up they basically look like a mirror and this is the other problem. In an AO scenario where you have an OAG, if you tried introducing something like a Near-IR pass filter in front of the Lodestar, it would most likely reflect visible wavelengths back down into the system and you'd have a 1970's Disco on your hands. Anodized metal surfaces like this inside the AO body (and indeed in some parts of aftermarket focusers) will reflect stray light in ways that your images will hate you for. There's an insightful article over at SBIG that covers this subject in-depth:

http://www.sbig.com/about-us/blog/flat-fields-the-ugly-truth/

Cheers,
Brett

P.S. If you can find the necessary backfocus you're welcome to borrow my ONAG and try it out. I'm just down the road from where you are.

[alistairsam]

Thanks Eden

I just ordered a long pass filter to test . This one blocks everything below 750nm.
http://www.edmundoptics.com.au/optics/optical-filters/longpass-edge-filters/optical-cast-infrared-ir-longpass-filters/1918

I didnt think of the disco light paradox. Good point. The Prism in my AO can be tilted independently and im not sure if that'll help with reflections.

Thanks for the offer. I have an RCC1 so have 93mm to play with and I could fit the onag and an oag. So would love to test if my nir test fails.

Cheers
Alistair