HowTo Improve Tracking.

[Tandum]

How do I improve tracking on my mount. I want longer subs on my images, I want smaller stars and better FWHM figures.

I know the answer is to buy a better mount but that's not going to happen any time soon so what else can I do.

Ive been told if I use a longer FL guide scope I'll just be chasing atmospheric ghosts. Then how does adaptive optics work? Doesn't it just update guide commands faster in order to chase the atmoshpere?

Should I pec train the mount? I was told you dont need to pec train if your are guiding?

Who has the answers, can you tell me please.

[AlexN]

adaptive optics doesnt chase atmospherics by sending guide commands quickly to the mount, rather the camera measures the atmospheric movement and tilts an optical window to match it, so that when the star appears to shift left due to the seeing, the optical window will tilt right in order to keep the star exactly in the same spot on the sensor... It will issue a guide command to the mount to compensate for drift after a while, but for the most part it will compensate for any movement, be it drift or atmospheric, by tiping or tilting the optical window... Its really designed for longer focal lengths, however I've seen it used well on as low as 1000mm... smaller stars and better FWHM is less to do with your tracking, more to do with your optics and seeing. If the seeing is poor then you cant expect to get 1.8FWHM star measurements.. I dare say your problem is seeing, as the Tak should be able to provide you very tight stars...

It can also be a matter of camera/scope resolution... What are the figures with your scope/camera combos?

Pec training is only really nessacary if your PE curve is really rough, if its nice and smooth guiding will take care of it... On the other hand, even if its rough as guts, adaptive optics will counteract it...

essentially - adaptive optics is awesome. but it is expensive...

with what the Starlight Xpress AO setup would cost you, you could sell your EQ6 and get a Losmandy G11... Although, as I mentioned above, that would probably not solve your problems...

[Gama]

Just increase your guide times to around 4 seconds, and you should remove most seeing issues.
Also reduce the aggressivness down a bit too.
But a longer fl will help the most.



Theo

[g__day]

I image at 2300mm focal length (and guide at the same). I find around 3 seconds is the most frequent I want to send guide adjustments and using PHD I set RA aggressiveness down to 30% Hystersis up to 40%, resist DEC switching and this gives me around +/- 2 arc seconds drift to manage (near sub pixel for my location).

Other than that - balance your gear really, really well, tune and remove backlash as well as possible and understand seeing and bin your shots appropriately for your focal length, pixel size and well depth and quality of night skies / seeing conditions.