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Crossing meridian during a imaging run

kirkster501

By kirkster501
in Imaging - Discussion

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kirkster501

kirkster501

Posted
Posted

Hi, does it matter if I so cross the meridian mid-way between a set of exposures.  I was looking at CdC at realised that such a flip would have occurred during my run the other night.  However, stacking the subs revealed no issues as such that Ic an see - everything stacked up ok.

I don't think I fully understand meridian flip and its consequences if I am honest.....

Thanks, Steve

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Gina

Gina

Posted
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The only problem AFAIK is the possibility of a collision between the imaging rig and the mount or something else.  If you're going to leave your equipment to run on its own unattended you'll want to check that there will be nothing in the way of the moving parts.  Also, that you scope won't end up below the sides of the obsy (if you have one) though the only trouble with this will be duff subs.

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Freddie

Freddie

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Not an issue as long as your stacking prog can cope, which obviously it did. It is important to try and get the same image alignment after the flip though to avoid poor edges on the stacked image if the two sets don't over lay very well.

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kirkster501

kirkster501

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Thank you guys.  I understand now!  Unfortunately no permanent set up for me so the rig is never left unattended for long periods and has to be taken down at 01:00.  So the issues you kindly highlight won't really apply to me.

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Russe

Russe

Posted
Posted

In EQMOD you can redefine your limits. Very easy to do and there's a tutorial on YouTube.

What I do nowadays is, I slew to my target, frame it with short exposures, then click the west button in EQMOD and slew the mount so far until my scope almost touches the mount. Now I set my limit, slew back to my target and calibrate PHD.

This way you know how long you can image for and how many exposures you can plan.

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swag72

swag72

Posted
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I have done a little testing and know that I can run for at least one and half hours past the meridian without any issues. If I do need to flip, I have found the process these days to be utterly painless. If I have a set of images prior and post flip I just chuck them all into PI together and it sorts them all out into one aligned image.

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Gina

Gina

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I don't rotate the camera after meridian flip and DSS is quite happy the take the 180 degree image rotation part way through the data set.  I use AT to get back precisely on target, after the flip.  The flip only takes a minute or so and I'm back capturing subs.

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Zakalwe

Zakalwe

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As long as you get the framing, post-flip, similar to pre-flip, then you'll be OK.  I normally just do it by eye (must sort out Astro-Tortilla someday!). I use Registar to align and register my subs and it has no problem coping with the flipped images.

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RikM

RikM

Posted
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Yes, that's what I do; I don't physically turn the camera. In most image capture programs you can either set 'rotate 180°' or 'flip horizontal & flip vertical'. I use either Maxim DL or APT depending on what I'm doing and it is possible with both of those.

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glappkaeft

glappkaeft

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If you search for "camera (de)rotator" you'll find lots of different products. I can't see why you would want one though unless you are using a Alt-Az mount, they are an unnecessary complication and the decent ones costs a lot of money.

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