Potentially daft platesolving question!

[edarter]

Hi,

This evening I've got EQMOD talking to my NEQ6 and have for the first time managed to control the mount through my laptop, using Stellarium (directly, not through Stellariumscope). To image I'm using APT.
My next goal is to get platesolving working, but I can't get my head round how it all hangs together. APT platesolves, but its Stellarium thats controlling the mount, so how does that all work together?!?!

Also - for platesolving (generally) is it a case that the rig takes an image, compares it to your reference image, works out the offset and automatically moves the mount the correct amount?

Thanks in advance!
Ed

[Shelster1973]

Ed

That is pretty much how platesolving works yes.  I do not use APT myslef, so cant say for sure how that functions, but for me using NINA, i just tell the mount where to go using Stellarium then platesolve in NINA.  It uses Astrometry for its solving solution.  Then when the result comes back, the software knows where it should bo pointing, compares this to where it actually pointing, resolves the differnec and moves the mount accordingly.  It then re-syncs the mount so that it knows where it is pointing, takes another image and goes through that cycle again, unitlk it within a set tolerance.  The you just carry on and image away.  No updates are sent to Stellarium just provides the co-ordaintes for the mount to slew too, the update as mentioned is in the mount.

I was a bit daunted when I first used it, but now would not go back at all.  Have given up doing 3 star aligns and using handset - everyting is done via direct PC connection and platesolving now.  Still have to do a Polar Align though.

Hope that helps

[edarter]

So are both Stellarium and NINA sending control commands to the mount? 

[almcl]

You select a target in Stellarium and ask it to 'goto' that target. 

Stellarium moves the scope to where it thinks the target is. 

You take an image and, If you are platesolving within APT, once it has solved, click the sync button. 

This repositions where Stellarium thinks it is pointing.  You can then either reselect the goto in Stellarium and it will move the scope to the (more accurate) target position or you can use the goto++ feature in APT.  This needs  a bit of setting up and, for me, usually takes a bit longer.

[RolandKol]

55 minutes ago, edarter said:

So are both Stellarium and NINA sending control commands to the mount? 

Hi Ed,

It's is a bit different...

Imaging software like APT or NINA do not control the mount directly.

The real control is done, in your case, by EQMOD, which is the main software which controls the mount, it is the main engine, the rest are the steering wheels, breaks and etc.....

EQMOD calculates how fast mount has to rotate and into which direction, current position and etc and etc.

Software like APT and NINA and even Stellarium, can send commands to EQMOD to change the position/target, - and EQMOD does the rest.

Platesolving software (any), usually interacts with imaging software, which almost immediately passes the command/coordinates to EQMOD and to Stellarium, but only EQMOD does the rest (adjusts the position and etc), Stelarium will show the result based on the data from EQMOD.

In other words, - if you managed to make EQMOD to control your mount, don't forget about it, read and learn more about it, as it is the backbone of the whole  system you building around.

P.S.

And yes, platesolving works as you described. It is a VERY handy tool in our hobby.

As I can see you even have DYI newtonian, so you probably know about the cone error and etc. 
Platesovling, removes all that headache... Once meridian flip is done, - if mount missed the target due to the cone error, - platesolving will adjust the targeting.

All up to date Imaging software has Automeridian flip option, but it will not work if that option is not enabled/ticked on the EQMOD.

Also, if you keep camera on the rig, you can do several sessions on the same target with almost ideal framing, APT and NINA both have options to record/save Framing coordinates, which you can re-use next session for re-targeting with the help of platesolving. 

However, there are different ways imaging software "speaks" to EQMOD, for example, in order for Platesolving to work on SGP imaging software, EQMOD has to be set to work in the "Dialog Based" mode.

For APT, if I recall it correctly as have not used it for a while, EQMOD has to be in the "Append on Sync" mode.

 

Edited March 27, 2020 by RolandKol

[edarter]

thanks for the replies everyone. I shall have a look at all of this tonight and try to get it working

[edarter]

All working now, thanks for the tips! Took a bit of getting my head round it but eventually got there using a frame from the previous nights imaging session to line up in the same spot last night. Very happy! 

[RolandKol]

On 28/03/2020 at 10:12, edarter said:

All working now, thanks for the tips! Took a bit of getting my head round it but eventually got there using a frame from the previous nights imaging session to line up in the same spot last night. Very happy! 

Nice

Just in case, - maybe you will find it handy, you can save your Frame/Target details in the Object list on APT, so next session simply select your object from the list and use Goto++.

 

[edarter]

Ah cool, thanks for the tip! 

[mark skelton]

On 27/03/2020 at 08:26, RolandKol said:

For APT, if I recall it correctly as have not used it for a while, EQMOD has to be in the "Append on Sync" mode.

Cheers for the info. Been having fun and games trying to get the platesolveing to work.