How to leave my gear out overnight

[CraigD1986]

Here is my setup:

Star adventurer Pro, SkyWatcher 72ED, ASI533MC Pro, ASIAir Plus.

If I leave my gear out overnight, at some point, the RA axis rotates to the point that my scope/camera makes contact with the star adventurer and presumably this is bound to cause damage. I’m trying to find a way to figure out at what point I need to have my gear turn off before the scope hits the mount. My ASIAir Plus powers the Star adventurer so I can setup an autorun to take a certain number of subs and then turn off. I just need to figure out the time at which it needs to turn off. Would the following procedure work:

Setup the mount and scope, polar align, etc. Then locate the target and set the declination.

Then rotate the RA axis by hand to the point at which it nearly makes contact with the mount.

Plate solve and make a note of the RA.

Then is there an app or something I can use to see at what time the target will hit those co-ordinates?

Then make sure the autorun on the ASIAir Plus will finish before this time?

Or am I going about this the wrong way?

[barbulo]

Perhaps a meridian flip (rotate the mount when the target passes the meridian) would solve your problems. I can’t speak for star trackers such as the Star Adventurer, but in equatorial mounts you can fully automate the process by software: the mount follows the target until it’s time to do the meridian flip, then turns the mount, platesolves and resume imaging. 
I don’t know if the ASIAir is capable of doing so. I suppose 
If you need to do it manually, any planetarium software (Stellarium or CdC) will predict the exact time of the meridian pass of any object. 

[Clarkey]

I assume you cannot set mount limits on the Star Adventurer?

[CraigD1986]

I know the star adventurer isn’t capable of a meridian flip.

as far as I know, it’s not possible to set mount limits either. 

[Turix]

I use an almost identical setup (just using a Raspberry Pi instead of the ASIAir). The way I've considered doing this is to power the mount via the mini-USB port from the Pi (removing the batteries entirely) and configuring the Pi to shutdown after a set time / after the image sequence has finished.

This would still require you to manually work out how much "safe" imaging time you have though. And unfortunately I don't know if the above can even be configured on the ASIAir or not.

The general idea being to try and remove power to the mount after a certain amount of time.

Edited April 25, 2022 by Turix

[Wiu-Wiu]

Meridian flip is indeed not possible. Checking when the target will be at the set limit is a very good idea. 

I kinda use the same modus operandi with my setup when imaging. Due to several trees and houses I can only image targets between a certain window, I'm just not limited to one target, as you are. I use your trick to program the asiair during the day.

I use skysafari to simulate the sky at the start of an image run and select a target that is in range. Then fast forward until the target would run out of view, and program the amount of images (minus about 15 minutes to compensate for autofocus or meridian flips). That is the time when I can go look for a new target, and I do the same thing. I only park the scope before powering down the system. 

 

You could indeed start up the image capture at a certain time (but you would have to be there because I think the star adventurer starts tracking at power up); but once you are on target, your asiair would be programmed to take X pictures of X minutes, and will power down the entire system at the end of the session, including the star adventurer.

[CraigD1986]

Yep, this is what I’m trying to achieve. powering down the ASIAir and mount isn’t the problem. The issue is finding out at what time the mount will have rotated to the point at which I need to stop.

I’ve just had a thought… If i pointed my mount at my target right now and the RA was (for example) 05h 30m. Then I rotated the SA to the point I would need to stop it, plate solve and the RA of that point is 07h 30m, Does that mean I would have 2 hours to image?

[Wiu-Wiu]

One day is not a perfect 24 hour but I think you are on to something. 
Platesolving gives you celestial coordinates, and ra and dec “never” change for a (fixed!!) object.

what you could do instead is looking at where your tracker would be pointing when you will need to stop, see what star is near the center of that FOV, and using skysafari you could see when your object would pass there. That would be the end of your session, and you could plan the amount of exposures so the asiair is done taking subs by that time, depending on what time you wish to start (due to clouds, focus problems,…) 

 

for example: lets say, for ease, there is a tree right at the meridian from where you are looking. (The meridian is presented by a vertical line in the image)

you wish to image rho ophiuchi and are outside at midnight.

 

 You look at what object is there, and in this case, it is Kraz. 

now fast forward the time to the point where your object is at that limit:

 

That time is around 03:49 in this example.

 

so if you want to start to image at 01:00; you still have 2hours and 49 minutes of imaging time left and can plan , for example, 169 exposures of 1 minute.

 

 

 

 

 

 

Edited April 26, 2022 by Wiu-Wiu