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ELBRUS - BD 2 :

THE MAGIC FINDERSCOPE
FOR EASY TELESCOPE POINTING

Elbrus - DB2: ayuda para llegar fácilmete al objeto
Elbrus - DB2: pour arriver facilement a l'objet

INTRODUCTION

Pointing a telescope to an object is not always an easy job. Specially for faint objects and not experimented observers.
This program is a helping tool to easely reach the objects. A webcam captures images, a program analyzes them and gives us advices about how to move the telescope toward the target.
This way you can convert the time wasted in searchig the object into useful time for observing it.

WHAT DO YOU NEED

The necessary equipment is a telescope, a camera, a computer and obviously the program Elbrus with the DB2 database.
A planetarium software like Cartes du Ciel may also be useful.

The assembly I used for testing. At right a spotting scope, at left the Toucam webcam with an objective lens of 58mm focal length at f2.



THE TELESCOPE

You can use any telescope. The camera must be well fixed to the scope. You must have some adjustment screws for collimation. That means for adjusting the position of the camera in order to have the optical axis of the camera parallel to the optical axis of the telescope.

THE MOUNT

The mount can be equatorial or altaz type. Motorized or not. If the mount is not motorized, the stars would be alongated for exposures of several seconds. But this has no effect, as you can see in the example bellow.

THE CAMERA

The camera must satisfy a very simple condition. It must give us sky images with several stars. About 10 or 20 stars. With a CCD webcam, this can be done with a few seconds exposition. Usually the webcams come with a very simple lens. You must change the objective lens and put a more powerful one. Nevertheless, a common lens for normal photography will do.

For the tests we are using a 58 mm focal lens, open at f2 from a Zenit camera.

THE COMPUTER

Any computer can do. It must be able to control the camera and run the programs.

THE CAPTURING PROGRAM

Any program than can control the camera. For example AstroSnap.

THE PLANETARIUM

It is not indispensable, but a software like Cartes du Ciel can help when shoosing the object by a simple click. Besides, the target coordinates should be transferred to Elbrus.

THE PROGRAM ELBRUS

This is the program that will guide us to the target. For images with several degrees field, only the DB2 database is needed (about 10 MegaBytes). For more details about how to use Elbrus see the Elbrus page.

AN EXAMPLE

Suppose you want to go to the NGC3521 galaxie. When everything is configured, we do as follows.
-- in Cartes du Ciel we put NGC3521 in the center of the window,
-- we launch the image capturing cycle,
-- at Elbrus configured in the 'Most recent image' mode, we click on 'Analyze',
-- Elbrus will tell us how many degrees (or minutes) and in which direction you have to move the tube,
-- we move the tube, and wait for a new image. This new image will give us a new correction and so on until we arrive to the target.

Now let us see that step by step:
- step 1- in Cartes du Ciel we put the targeted object in the center of the window.

- step 2- at AstroSnap or at the program that controls the camera, we launch a capture. As you can see the stars are slighly elongated. But this has no bad effect.

- step 3- Elbrus being in the 'Most recent image' mode, we click the 'Analyze' button.

- step 4- now Elbrus solves the image and gives us the angular distances to the target in degrees or in minutes.

- step 5- we move the mount as indicated, and go back to the new image (step 3) until we are at the object.


Just a little practice, and you will see it's realy easy.

A few words about this system:

During years astronomers used different methods for pointing their telescopes. From the simple sight to sophisticated softwares modeling the deformations of the mount. Through the scope finder, the red LED pointer, encoders, etc...

Today we have little cheap webcams, we have little inexpensive PCs ... It's time to know where is the telescope pointing to directly and absolutely. Without any intermediate stuff. With independence of the mount quality and robustness.

Just put a camera as a finder, and solve the image.

(Updated 10-JUNE-2009 Alfonso Pulido)

... this is ... http://www.astrosurf.com/pulgar ... enjoing astronomy ...

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