Tracking rates

[patricmooriamnot]

Hi Guys, In my synscan az control it has three tracking rates, Sidereal,Lunar and Solar. It used to have auto tracking before I upgraded the control. I assume it auto tracks an object if asked to find it. but what is the difference between the other rates? Again the manual does not say and I have to work this out for myself. I assume Luner rate is for tracking the moon, ok , Solar rate could mean tracking the sun or the planets. I also assume that side real rate compensates for the Earths rotation in tracking other distant objects. The thing is I`m not sure. Any advice would be helpful thanks.

Phil.

[ronin]

The reality is there is almost no difference.

I spent yesterday at an event solar observing with a small goto, the sun was more or less centered and the scope left to track, two hours latr the sun was still in the centre of the eyepiece.

The point is the scope does not have a solar tracking rate option, so it was just tracking at the normal sidereal and after 2 hours the sun, at a "different rate", hadn't moved in the view. So whatever the difference is it is not a lot.

Lunar may be a little difference but for visual observing for yourself sidereal will be more then adaquate, you will not be doing as yesterday and take is having a scope pointed at the object for two hours.

You right in that Lunar = Moon, Solar = Sun, Sidereal = The rest. :grin:

Easy answer = forget Solar, Lunar and use Sidereal on everything (makes life easy).especially if you are just observing, for some imaging changing rate may be advantaguous. However lunar and solar imaging is usually via a video and they are short time scales so again sidereal will I very much expect be fine - would be surprised if they were not.

The other thing is does the tracking rate actually change? Ever had the sneaky idea that Solar may just be Sidereal with a different name displayed? :eek:

[Stu]

Good info here.

https://en.m.wikipedia.org/wiki/Sidereal_time

As Ronin says, there is actually very little difference in the rates - about 4 minutes in 24hrs so for observing purposes Sidereal would be fine. When I'm solar observing I'm regularly move the scope around manually so precise tracking is not so important.

https://en.m.wikipedia.org/wiki/Sidereal_time

[Gazabone]

Yep, you've got it right, lunar = moon, solar = sun and sidereal = almost everything else. There are very small differences between them so, for example, that's why some people may perceive the moon to go from West to East during an eclipse (so a good illustration of different rates because both go East to West, the sun simply appears to traverse the sky more quickly).

Not worth worrying about unless you're very fussy about tracking an object, for example for photography.

[patricmooriamnot]

Thanks guys that puts my mind at rest. At least I know now that it is my alignment that might be off and not the tracking rate Im using. While I`m on, I would like to get a web cam for my SW 130 P goto. I made the mistake of buying a cheap one on ebay (useless) My thinking is I can align the scope by using my computer with a webcam and the synscan control. also would the webcam take good enough pics or would I need a different camera. What webcam do you guys suggest and what camera if any? My wife says I`m not allowed to spend a lot of money, never helps!

Phil. 

[ollypenrice]

Webcams have tiny chips so putting an alignment star on them might be a royal pain. I would just centre visually by using a high powered eyepiece. That is all you need.

Webcams, or webcam-like fast frame cameras of higher quality, take the best lunar and planetary images bar none. Take a quick look at the master's efforts; http://www.damianpeach.com/best.htm

You may conceivably find that your first results are not quite as good as these.     

Olly