Drift aligning again

[Marke]

Sorry to bring this topic up again :sadeyes: I know how it works and what
to do but when I get out side and look up I have know idea which stars
to use :mad2:
I have reasonable views SE - S - NW but low down obstructed
by trees bushes. If someone can suggest which stars to try
or which ones are you using atm would be a big help.

[kinetic]

look no further than in the Article section...
Geoff (ghsmith45) has written a great article step by step...and he describes
the best stars for each step of the refinement.

http://www.iceinspace.com.au/63-405-0-0-1-0.html

Another good one by Al Sheehan using K3's Drift Explorer capability
http://www.iceinspace.com.au/63-544-0-0-1-0.html
This is the method I use to refine bumps due to kids/dogs/soil movement
in my permanent setup :)

Further to this I long ago setup a laser on the GEM Pier which shines on
an X on the wall of my house. More about it in this post:
http://www.iceinspace.com.au/forum/showpost.php?p=416432 (http://www.iceinspace.com.au/forum/showpost.php?p=416432&postcount=2)

Steve

[peter_4059]

Mark,

I'm in a similar situation with the horizon at home. I don't know about suggesting named stars to answer this post as it will depend on what time and your location as to what is suitable. I tend to focus on the scope position and then find a bright enough star:

For AZ adjustment you are looking for a star near the intersection of the meridian and the celestial equator. I find the easiest way to do this is to set the scope up with the counterweight bar horizontal and with the OTA at right angles to the polar axis and the look through the finder scope for a bright enough star in this region. It doesn't have to be exactly on the intersection - just near it.

For ALT you want a star on the celestial equator near either horizon. To find this point leave the DEC axis as it was for the AZ step and rotate the RA axis (I tend to go for the Eastern horizon however the West will also work) so the scope is pointing somewhere closer toward the horizon - the best I can do is about 30-40 degrees in the East. Again look through the finder scope and find a bright enough star in this region and centre it.

Hope this is what you were looking for. If you have a licensed copy of Astroplanner it has a function that suggests suitable stars and will drive the scope to them for you.

Peter.

[taxman]

There is always this: http://www.minorplanetobserver.com/Misc/PolarAlignNoDrift.htm

I tried it once (#$@% cloudy weather!) and it worked a treat.:)

[Marke]

Guys thanks but I know how it all works and have read the articles
just want to know which specific stars you guys are choosing at the moment ? That will give me a better idea of when to start looking.

[Marke]

Thanks Peter thats what I was looking for :)
All the tutorials and such seem to assume you have a perfect
360 horizon and like you 30-40deg is about what I have too.
Its all simple in theory but not that practical .

[Octane]

Peter,

That is exactly the way I do it, too. :thumbsup:

H

[dannat]

i don't think you need to worry about getting specific stars.just find something bright near the meridian (overhead - sirius at the moment) & something bright on the east horizon (though there isn't a whole lot there at the moment after sunset..they are all fairly dim

[telecasterguru]

I'm the same. I have no East view and no south view so I have to concentrate on North West and grab whatever star I can find.

I don't have much problem being close to the SSP. Guiding does the rest for imaging.

Frank

[[1ponders]]

Threads merged to prevent confusion

[okiscopey]

If it's difficult to find a bright enough star from his Sydney suburb, perhaps Mark could use Saturn for ALT aligning. It's very near the celestial equator at the moment, and its own motion should be negligible for the purpose.

According to my SNPro, Saturn is 30 deg. above the eastern horizon tonight (Tuesday) at 23:30 (daylight saving time) and at 30 deg. in the west tomorrow morning at 05:30 am. It might even be visible through the trees!

Will this work?

[kinetic]

Not reeeally a good idea if you want to really get it spot on.
Saturn, even with an inclination of 2 or 3 degrees to the ecliptic
will still exhibit some drift in DEC over the course of a few hours.
I just did a check in CDC and it will drift at least 30 arc seconds in
Dec as well as drift in RA over a few hours tonight.
That might not seem much, and probably would be ok for rough
polar alignment....but I wouldn't do it.
This would be considerably less if we were'nt coming up to
opposition.
There should be plenty of stars available, and if you add a webcam
to the OTA or spotscope you should get heaps more with the brightness
and gain tweaked.

FWIW.

Steve

[Marke]

Thanks for advise gave it a try last night and think I am making a little progress hardest part is a star low in east or west.
I got Az pretty good but cant get Alt adjustment right.