HELP with drift alignment

swannies1983 (Dan) · #1 13-02-2007, 04:19 PM

I know there is quite a lot of tutorials on drift alignment but i want to just clarrify something as I can't quite get it to work.

Ok, so i pointed my scope to a star close to the intersection of the celestial equator and the meridian. I turned off the tracking to see the natural westwards movement of the stars. The stars moved visually quite quickly at 160x magnification to the right or east through the scope but west in real due to nature of the telescope. I then orientated one set of crosshairs in the east-west direction (parrallel with a star's movement). I turned on the motors and watched for north-south drift in declination (while the stars moved right in the reticle). I changed the azimuth until there was no dec drift and the stars moved align the reticle lines.

I then swung over the scope to a star about 20 degrees above the eastern horizon. Turned the tracking off and watched the star movement. Once again, the stars moved quite fast to the right in the eyepiece, which continued once I switched the mount's tracking back on. Now, the question is, if i got the RA alignment spot on, should I only see north-south drift at this point and not the rapid east-west drift?

When I got this mount, I was able to roughly set this scope up and keep objects in the FOV for quite a while at medium powers (in the order of 5 mins). I'm lucky to get anything to stay in the FOV for 5 mins even at low powers.

My RA is in sidereal mode and my emiglobe is set to south (austral hemisphere). I do also have an option to set RA and Dec rotation (clockwise or anti-clockwise). I haven't changed this at this stage but may have accidently done this when scrolling through the menu but what should this setting be?

sheeny (Al) · #2 13-02-2007, 05:01 PM

G'Day Swannies,

with the RA on you should only see N/S drift due to your misalignment. With the RA off, the drift will be rapid (as you describe) and in the RA direction.

You should not see much if any drift in RA while your drives are on, unless your rate is wrong (solar or lunar rate perhaps?)

Al.

swannies1983 (Dan) · #3 13-02-2007, 05:17 PM

Ok, i THINK i fixed it. I checked the RA and DEC rotation settings. Both were set to anti-clockise which meant the telescope was tracking to the EAST and not the WEST. Changed the rotation settings to clockwise and now the RA tracks to the west

[1ponders] (Paul) · #4 13-02-2007, 05:18 PM

Swannie, you don't turn your RA motor off. It must stay on for you to be able to drift align.

swannies1983 (Dan) · #5 13-02-2007, 05:25 PM

I just turned the motors off to see which way the stars drifted...right or left in the eyepiece (just so I know which way is west). Once done, I turn the motors on to start drift alignment

RB (Andrew) · #6 13-02-2007, 05:27 PM

Quote:

Originally Posted by swannies1983

I just turned the motors off to see which way the stars drifted...right or left in the eyepiece (just so I know which way is west). Once done, I turn the motors on to start drift alignment

Yes I do the same thing, I use this to line up my illuminated reticle with E-W.

xelasnave · #7 13-02-2007, 07:09 PM

I get into a mess with it sometimes I am probably tired but try this.
Point the scope at the ruff poss pointing at the pole (in home position) take a time exposure. Look at the image and you will see the strars starting to make circles adjust the mount and try to centre them and repaet the process until they are centred in the image, add a barlow and do it again. I have had good results and not so good but mostly good.
alex

sheeny (Al) · #8 13-02-2007, 08:05 PM

Quote:

Originally Posted by swannies1983

I just turned the motors off to see which way the stars drifted...right or left in the eyepiece (just so I know which way is west). Once done, I turn the motors on to start drift alignment

Yeah, that's OK. Just FYI I don't do that...

I centre the star in the reticle, drive the scope in RA till the star is near the edge of the field of view, rotate the reticle till it's on the star...

Technically I'm aligning the reticle with the RA axis of my scope and not with the axis of the earth... little difference... I just find it easier than messing about in the menus of my hand controller to start and stop the RA drive.

Same result in the end!

Al.