This is a transfered topic from the ASA Yahoo Group.
Posted By: philipp_keller Fri Oct 21, 2011 9:05 am
maybe somebody wants to be first to try this method I thought about ?
SuperfastPA.pdf 55.5KB 51 downloads
Super fast Polar Alignment with DDM mounts
This manual describes how to use the homefind and 1 star to quickly polar align
the DDM mount which will be very interesting for mobile observatories.
How it is done now
1. Use the Laser to roughly setup the mount
2. Make a 4 star pointing file on one pier side, let Autoslew move the star
according to the calculated error and re-center it with Azimuth and Altitude
3. Make one more pointing file containing both sides and use that for the
New Super Fast PA
1. Setup the mount roughly north aligned (+-4 degree)
2. If you are at another location compared to your last setup then set the right
mount location in Autoslew (Mount/Location).
3. Make a home find
4. Slew to a star in the south between 20 and 50 degree above horizon
5. Center the star not with the gamepad or motors but only with the Azimuth and
Altitude screws or of this is not enough by moving the tripod/pier.
6. Use the old pointing file from last time, it will do for most purposes. It
will definitely be good enough to work with the new MLPT method.
Requirements and understanding the new method
Homefind gives a very good repeatability usually better than 0.5 arc minutes.
When the only thing that changed is the position and angle of the mount (if you
have a mobile setup) then you should of course be able to get into the same
status as last time by simply making this homefind (Ra and Dec is OK now) and
then pointing the mount to the selected star by using Azimuth and Altitude
alignment. Its sounds incredibly easy.
Of course to successfully apply this method you must have set your homeposition
during your last session and you need a decent MASTER pointingfile. So here is
how to end the last session if you want to start your next sessions with the
Super Fast PA:
1. Be polar aligned as good as you can because you will COPY this polar
alignment error from now on to the next sessions. So try to be below 5 arc mins.
2. Make a homefind (if not done anyway on start)
3. Make a nice pointing file, calculate Configuration and select Use and Save
for next start.
4. Point to a star near south (roughly the same place AND PIER SIDE you will
take next day for your Super Fast PA), center it and synch
5. Set new home position (Mount / Set new Homepositon). The steps 4 and 5 ensure
that your offset (error) is minimized at the place where you will select a star
for PA the next day
Of course the accuracy of this method depends on how the repeatability of fixing
the telescope on the mount is. So try to keep this the same every time.