Meridian Flip - Can it be fixed in PP?

[swag72]

I have seen about meridian flip and have looked on the net for explanations etc. I saw an example of an image taken prior to and after the meridian flip. To me it just looked orientated through 180 degrees. So, could you not just rotate the affected images by 180 degrees and stack them in DSS?

[SteveP]

Sara

That's all that it is and merely a consequence of the mount having gone past a particular point requiring it to do an almost 360degree move to get back onto the object.

Some imaging software (I don't know about DSS in particular) can make the necessary re-orientation automatically and stack the images accordingly. The major problem however is that most mounts are not aligned sufficiently well to get back onto the object in exactly the same position prior to the flip. The result being that the images on one side of the meridian may not match up with those on the other side.

I try to avoid flips if I possibly can.

Steve

[JCJC]

I'm pretty sure DSS does this automatically.

The good thing about DSS is, you basically just chuck everything in and it does the rest.

Jordan

[blinky]

Yep, DSS does it automatically - here is an image I took a couple of days ago with 5 subs taken after a meridian flip. Just chuck 'em all into DSS and let it do it's stuff!

http://blinkysastroblog.files.wordpress.com/2011/02/jellyfish-ic443.jpg

[martin_h]

Yes I agree with the above - chuck them all in and let DSS sort them out, when its all stacked look at the angle information next to the file names, some will be 0.00 deg, and after the flip will be 180.00 deg (or there abouts)

[martin_h]

Here you go - DSS showing 2 images - 1 after the flip and 1 before, both stacked automatically.

[swag72]

If it's not a hue big deal for DSS, why am I picking up that it is something to be avoided?

[martin_h]

I dont know? I always do a flip if it needs it. What with the cloud cover here I need all the imaging time I can get on a target. It can be a bit of a faff getting it lined up on the chip again sometimes.

[Whippy]

If it's not a hue big deal for DSS, why am I picking up that it is something to be avoided?

It's not as such, but I find that flipping the mount, re-framing (the mount won't always go back to exactly the same place), re-balancing, recalibrating the guiding and what else needs doing when at some early hour of the morning when I'm normally half asleep is something I try and avoid!

Tony..

[jgs001]

Dss will deal with it perfectly, but... I've never had the target drop back into frame particularly well and you have to stop the guiding an recalibrate as the camera motions are reversed (took me a while to work that one out.