Re: [MaxImDL] Problems with ST-237 guider


Nov 16, 2004

 


----------------------------

#14867 Nov 16, 2004

Hi,



I have been getting some weird problem when I'm guiding with my ST-237.

My setup is : Temma Em-200, Vixen 700mm guide scope with side by side

Tak TAO-130 and MaxIm 4.06. The guiding camera it is bolted to the

Losmandy plate, so it won't move. When I calibrate It should move side

ways and up and down in a 90 deg angle and if the camera is align it

should also move more or less parallel to sides of the frame. however,

sometimes it makes different angles:

sideways (W-E) parallel to the side and up and down (N-S) not

perpendicular to the other axis (sometimes more that 90, sometimes less).

Other times times the axis are perpendicular but are not parallel to

the side of the frame, sort os if the camera where rotated.

and most of the times it does it perfect, axis perpendicular and

parallel to the the sides of the frame.

When this happens I have to calibrate a few times until it does it

right, sometimes what I do is choose a diffrent star in the same frame.

Another thing that I noticed is when I'm finally guiding, and the

scope is in the east side (looking west), the RA correction is just

perfect +- 0.2 however in DEC starts to drift to the + side slowly,

maybe in a 15 min. it moves about 1.5 pixels and it does not make any

correction just drift along and I check that the Y axis is anable both

ways. I stop the guiding choose a star again and it starts OK and

after a few minutes, starts to drift in DEC.

Also, sometimes I get a sudden jump (about 3-4 pixels) in RA and it

usually between 750- 800 sec. in the exposure ( I make 900 sec. exp.)

and afterward goes back to center but I lost the image. It does it 2

or 3 times in a row and afterwards works perfectly. This always

happens when I have the slow drift in DEC that I described before.

One thing I noticed last night ( I was having the problems described

above), and I do not know wheter this have to do with my problems: I

noticed that I disconected The Sky and I had a diferent declination in

the dec box of the guiding. I connected TheSky and checked the dec box

to have the right value, calibrated OK and guided OK.

I do not know if this is a camera, guide cable,,mount or software

problems.

It has been happening for three nights.





Pls Help !!!!



Antonio Borgonovo



----------------------------

#14896 Nov 17, 2004

Antonio,



First of all, you might want to increase the Cal. Time settings so that

the star moves a larger distance.



Make sure you're running the latest version (Help menu Check for Updates

command) because we've made some improvements to the calibration

functions recently.



Despite the Losmandy plate it is still possible that you have some

physical movement. It takes just arc-seconds of slippage to cause a

shift such as you are seeing. That's not something you would be able to

see with your eye. It might be as simple as the main scope shifting

slightly in its rings (I've had that very problem with a Ceravolo HD216

telescope; it would slip relative to the guide scope).



Try guiding with the main telescope instead of imaging, and see if you

still get the sudden jumps. That might help you figure out whether you

have a mechanical problem or not.



If you suspect other software may be interfering (I think it is

unlikely) then shut down the other software and see if you still get the

problem.



Doug



---------------



Doug George

dgeorge@...



Diffraction Limited

Makers of Cyanogen Imaging Products

www.cyanogen.com



25 Conover Street

Ottawa, Ontario,

Canada, K2G 4C3



Phone: (613) 225-2732

Fax: (613) 225-9688



---------------





antonioborgonovo wrote:

> I have been getting some weird problem when I'm guiding with my ST-237.

> My setup is : Temma Em-200, Vixen 700mm guide scope with side by side

> Tak TAO-130 and MaxIm 4.06. The guiding camera it is bolted to the

> Losmandy plate, so it won't move. When I calibrate It should move side

> ways and up and down in a 90 deg angle and if the camera is align it

> should also move more or less parallel to sides of the frame. however,

> sometimes it makes different angles:

> sideways (W-E) parallel to the side and up and down (N-S) not

> perpendicular to the other axis (sometimes more that 90, sometimes less).

> Other times times the axis are perpendicular but are not parallel to

> the side of the frame, sort os if the camera where rotated.

> and most of the times it does it perfect, axis perpendicular and

> parallel to the the sides of the frame.

> When this happens I have to calibrate a few times until it does it

> right, sometimes what I do is choose a diffrent star in the same frame.

> Another thing that I noticed is when I'm finally guiding, and the

> scope is in the east side (looking west), the RA correction is just

> perfect +- 0.2 however in DEC starts to drift to the + side slowly,

> maybe in a 15 min. it moves about 1.5 pixels and it does not make any

> correction just drift along and I check that the Y axis is anable both

> ways. I stop the guiding choose a star again and it starts OK and

> after a few minutes, starts to drift in DEC.

> Also, sometimes I get a sudden jump (about 3-4 pixels) in RA and it

> usually between 750- 800 sec. in the exposure ( I make 900 sec. exp.)

> and afterward goes back to center but I lost the image. It does it 2

> or 3 times in a row and afterwards works perfectly. This always

> happens when I have the slow drift in DEC that I described before.

> One thing I noticed last night ( I was having the problems described

> above), and I do not know wheter this have to do with my problems: I

> noticed that I disconected The Sky and I had a diferent declination in

> the dec box of the guiding. I connected TheSky and checked the dec box

> to have the right value, calibrated OK and guided OK.

> I do not know if this is a camera, guide cable,,mount or software

> problems.

> It has been happening for three nights.

>

>

> Pls Help !!!!

>

> Antonio Borgonovo







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