Meridian flip?

[Daz Type-R]

Hi.

I have heard it mentioned a few times on here over the last few months and at a few meets and while it does not affect me (dob owner - keep it simple) I was wondering exactly what it is, why it affects EQ mounts and why can the software in the handsets not cater for it?

Cheers all, always lerarning!

[Guest Kheldar]

I don't know what the handsets do, but I can explain the rest to you.

When you use an EQ mount, to look at something in the West, the OTA needs to go on the East side of the mount and vice versa.

As things progress across the sky during the night you can see that obviously at one point the must cross the Meridian, and switch from the East side to the West side.

At this point software likes to flip the OTA to the other side of the mount, though this can be disabled in most software. However if you don't flip, you run the risk of the OTA/camera gear crashing into the mount which would not be good!

Once the flip has occured, it's not always certain that your GOTO setup will still be accurate, and imagers doing long exposures may lose a sub during the flipping process (I'm sure some real grown up software can be told to wait till a sub has finished, but most can't) and finally your subs after the flip will all be rotated by 180 degrees.

These concepts might be easier to explain/demonstrate in person, can run through it at Belper next time you're up there if it helps

Edited November 4, 2012 by Kheldar

[Sheila]

helped me there, i had heard all that before and sort of followed it, but this is much clearer

Thanks

Sheila

[philjay]

Yup Steves got it in a nutshell.

Some mounts are physically able to slew across the meridian but the manufacturers put a flip into the software as a safety device to stop long tubed OTAs hitting the mount/tripod.

Some mounts like my old CGE can slew across the meridian cos of a bledy great big motor box in the way but thankfully the mount is normally so accurate that when it does the flip the object is recentered nicely.

[Daz Type-R]

Thank you all, understood.

Will take you up on that demo Stephen.