"Unguided" - definition

[Purplehayze104]

Hi All

hope your well,

bit of a newbie question really, i've read people talking about taking 2min etc, etc, unguided subs, just wondering if you could clear up what this means !! Ive assumed no autoguider is involved hence unguided, but does that mean they are using synscan or any other form to track the object involved ?

regards

john

[Cornelius Varley]

No, just allowing the mount to track at sidereal rate with no intervention.

[themos]

Synscan is not a method for tracking, it is a method of finding targets as the full name "SynScan GOTO" suggests. "Unguided" can mean different things but one thing is excluded: imaging a guide star every second or so and adjusting the tracking in a closed loop according to the movement of the guide star. Some unguided shots rely only on sidereal rate tracking, some may use sidereal rate plus Periodic Error Correction, some may use a full mount model that takes into account mechanical errors, polar alignment error, atmospheric refraction and the like. 

[Steve Ward]

They'll be using an Equatorial mount with RA tracking motor , the mount will have been accurately polar-aligned and left tracking the object being photographed.

The length of exposures used will be reliant on the accuracy of the polar-alignment / drift alignment.

Go-To has absolutely no bearing on the results .

Guiding involves using a separate scope/camera set-up attached to the imaging scope that "locks on" to a nearby star and adjusts the mount to keep the target in the centre of the imaging chip.

[Purplehayze104]

thanks you all for your reply's

that has cleared up my confusion with this subject, only referenced synscan, etc as it tracks the object once found, so assumed that would be sorta unguided but just wanted clarity

thanks again

john

clear skies

[LukeSkywatcher]

Ive always assumed that "unguided", just means you use a manual scope such as a refractor or whatever and move it under your own power to track objects while imaging.

[Cornelius Varley]

Ive always assumed that "unguided", just means you use a manual scope such as a refractor or whatever and move it under your own power to track objects while imaging.

 

That would still be guided. In the old (pre computer / digital)age astrophotographers would observe a guide star through a guidescope and make manual corrections to the mount's tracking.