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when to do a meridian flip?

Posted: Tue Apr 02, 2019 8:58 am
by Rrowe
I know that you do one when your camera is about to hit the mount. But I am wondering how you can tell what time that will be. The other night i was imaging the Pinwheel and it was around 2:30 by the time I was able to use stellarium to do a flip. I would have liked to know that so i could get some sleep then get up do the flip and keep imaging.

I use a Skywatcher EQ6-r, backyard EOS, EQMod, Stellarium.

Thanks

Re: when to do a meridian flip?

Posted: Tue Apr 02, 2019 9:13 am
by Doug
I don't have an automated flip in software. I think it takes a little practice and knowing what works for your setup. On my mount, I can use the width of my fist to "estimate" one hour. When I image during the night, I'm always up, checking it, but, I like sleep too. I'll estimate how many hours and then decide when to setup my alarm clock using my one fist = 1 hour.

Have I made errors in my calculations? You bet! Sometimes I get up too early and I end up watching the mount. But, I'm getting better at knowing how much time I need before I need to flip the mount.

I should probably get some software to do this for me, but, that's just me!

Doug

:shrug:

Re: when to do a meridian flip?

Posted: Tue Apr 02, 2019 5:09 pm
by MikeM
Well, since M101 transits about 2:20 a.m. it would be around that time. What you need to know is how far past the meridian your mount can track before colliding with your gear.
More than likely it’s measured in degrees. Our limits maybe something like more than 90 so maybe 110 or 120 before the alarm and hard stop. Some mounts have the ability to adjust the limits.

Re: when to do a meridian flip?

Posted: Tue Apr 02, 2019 5:45 pm
by Rrowe
MikeM wrote:
Tue Apr 02, 2019 5:09 pm
Well, since M101 transits about 2:20 a.m. it would be around that time. What you need to know is how far past the meridian your mount can track before colliding with your gear.
More than likely it’s measured in degrees. Our limits maybe something like more than 90 so maybe 110 or 120 before the alarm and hard stop. Some mounts have the ability to adjust the limits.
Thanks Mike. I guess thats what im asking is how do you tell that M101 transits at 2:20 AM I use stellarium and I have tried to use both the equatorial grid and the alt az grid to try and figure that out but I'm just not looking at the right thing. what should i be looking for on stellarium.

Thanks

Re: when to do a meridian flip?

Posted: Tue Apr 02, 2019 5:51 pm
by Rrowe
Ok I just played around with Stellarium. I noticed a number on there HA/DEC and it has a time on it it goes to 24hr right at 2:20. I also turned on the azimuth grid and it crosses the 180 deg line at that time too. So i think i have it between those 2 things i should be able to figure out the time to get up and check it.

Thanks

Re: when to do a meridian flip?

Posted: Wed Apr 03, 2019 10:16 am
by MikeM
I do t use Stellarium but I read that there is an Observability plug-in that needs to be checked to get transit times.

Re: when to do a meridian flip?

Posted: Wed Apr 03, 2019 10:33 am
by h2opolo
There is and I think it is on the Stellarium Scope site. Not positive.

In SgPro it tells you the meridian time which is a great help. Different targets are going to have different times as you know. If you are shooting the same target each night mark the time for tonight and then deduct about 5 to 10 minutes for each consecutive night. That is probably a lot of time but you will get the feel for it.

There are bunches of APP's out there that will probably give it to you. Check Sky Safari out it has it.

Here is a link to the program page for that app. Take a look. It says it shows the time targets hit the meridian

https://skysafariastronomy.com/support/ ... _info.html