LX-200 GMT OFFSET

Started by Mike Dolceamore, 10/19/2003 02:47PM
Posted 10/19/2003 02:47PM Opening Post
I have an 8 inch LX-200 scope and I am spending hours on my alignment process. Whenever I enter my local time and enter my GMT offset the Siderail time does not reflect the proper offset. I will go back an forth between Polaris and Altair and make wedge adjustments when aligning on polaris. I can get dead nuts on the two stars within the cross hairs of my 9mm reticle eyepiece after about six or sever iterations, however, as soon as I goto another star or planet, I am not centered within the eyepiece. I beleive my problem may be with the offset time in the keypad. I believe that when I goto a subject after aligning on Altair and Polaris, the scope is looking for the subject in its location several hours away from where it should be.
I even tried entering the local time as the actual GMT time with 0 GMT offset and it seems that the keypad changes back somewhere in the process.
Any help would be appreciated.
Thank you,
Mike
Posted 10/19/2003 03:38PM #1
Mike, a couple of questions. What do you mean by not centered? Is the target in the field of view with a 26mm eyepiece? Where are you located? EST is an offset of +5 and CST is +6, etc. You will find a description of these numbers on pages 10 and 11 of the LX200 manual.

I suspect that things are working fairly well if your target comes up in the field of view even though it is not dead center. I keep my 12" LX200 on a permenant pier and before I shut the telescope off, I align it to the LST with a DEC of 0. When I bring it up later, it is close enough in alignment that my first goto places the target within about 4 or 5 minutes of center in a 13.7 UWA eyepiece. I correct this error and resync, and than I expect to find every target within the FOV of that eyepiece--about 30 minutes --for the rest of the night. I ocasionally tweek the polar alignment a little which makes everything better. It takes some time to get everything aligned perfectly.
Ted
Posted 10/22/2003 01:04AM #2
Mike, I have a hunch that your are mixed up on your times. I would pay no attention to sidereal time when you are setting up. The sidereal time is not tightly related to the time-of-day in Pa or London for that matter. The sidereal time is the Right Assention of the zenith meridian at your location. Don't expect to find the ST to be related to your local time. The sidereal time changes about 4 minutes per day relative to the local clock. Set the time offset to 4 hours, the Longitude and Latitude to the correct values, and I am certain that everything will work out, especially if you are using GPS.

Ted
Posted 10/23/2003 11:12PM #3
Steve,
Yes, it is a classic. I think that I am OK. I guess I was a little confused because the example in the Meade manual shows an offset of 7 hours which was almost identical to the siderail time for that example. I will go back and enter the correct offset and take it from there.
Thank you,
Mike