Re: can someone give me some info about trackers?

Your are talking about autoguiding. I've never heard of any amateur
using autoguiding for guiding when taking amateur solar pictures. Maybe
it can be done. Anyone group member know?

As Mitch has noted in this thread, a telescope GOTO mount that tracks
at a solar rate provides more accuracy that than your tolerance of 0.1
degree.

Most GOTO mounts these days will do standard tracking at three rates of
speed:

1) the celestial sphere rate;
2) a lunar rate for photographing the Moon; and,
3) a solar rate.

Standard tracking simply involves the mount moving at a predetermined
known rate of motion counter to the direction of the celestial sphere.
There is no information "connection" between the celestial object and
the mount.

E.g. -

Orion Atlas EQ-6 Mount (holds 30lbs)
http://www.telescope.com/shopping/product/detailmain.jsp?itemID=71977&itemType=PRODUCT&iMainCat=6&iSubCat=24&iProductID=71977

Orion Sirius EQ-5 Mount (holds 40lbs)
http://www.telescope.com/shopping/product/detailmain.jsp?itemID=125881&itemType=PRODUCT&iMainCat=6&iSubCat=24&iProductID=125881

0.1 degree is 360 arcsecs. For stellar astrophotography, we usually
think in terms of tracking errors in the range of 2-3 arcsecs with
autoguiding, more with standard tracking.

Most GOTO mounts these days also have small computer ports in them that
allow a separate laptop computer to control and fine tune the mount's
movement.

Autoguiding is the next step up in tracking. Autoguiding works by
having a CCD or small webcam camera (modified for use in astronomy -
you can't use your off-the-shelf Logitech) that views a guide star
through a second "piggy-back" or "guiding" telescope on top of the main
telescope. A "tracking star" is centered in the webcam using the
piggyback scope. Software and the laptop view and analyze the image.
The laptop sends commands back to the mount that keeps the star's dot
centered in the screen.

The setup consists of the following main components - 1) Guiding piggy
scope. 2) A CCD or inexpensive astro web camera like a Tou Cam
(~$100). 3) Laptop software that drives the video camera, analyzes the
image, and sends adjusting commands to the telescope. (~$50) 4) A
small hardware adapter that takes the parallel port of a computer and
converts its into a signal into something the GOTO mount can
understand. (~$30) 5) Software drivers (called ASCOM drivers) that
allow the laptop to talk to the scope in a language it understands.
(Freeware) 6) A laptop. 7) a GOTO mount that can be computer controlled
(anywhere from $1000-$3000).

In your case, you would also need a solar filter to block out most of
the Suns rays ($80-$150 depending on scope aperature size).

This covers most mounts except Meade, which has its own proprietary,
but excellent, system.

Autoguiding software -

Barkes, S. 2005. GuideDog: Standalone Autoguiding for Webcams. (Web
site) http://barkosoftware.com/GuideDog/

Katreniak, P. 2005. K3CCDTools Home Page. (Website)
http://www.pk3.org/Astro/index.htm?k3ccdtools.htm

Laptop to scope drivers -

Ascom. 2005. Ascom: Standards for Astronomy. (Web
site) http://ascom-standards.org/

Parallel port adapter -
Shoestring Astronomy. 2005. GPINT-PT Autoguiding Adapter.
http://www.store.shoestringastronomy.com/products_gp.htm

One of many astronomy webcameras -
Meade LPI webcam
http://www.telescopes.com/products/Meade_Lunar_Planetary_Imager_LPI_wAutoStar_Suite_21600.html

In closing, this is a setup for autoguiding at night using a guide
star. I don't know if anyone has tried to use it or whether it can be
used to autoguide on the Sun.

As Mitch has noted, you may not need autoguiding at all depending on
the requirements of your application. A simple GOTO mount might be
sufficient.

- Peace - Canopus56

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