Re: Argonavis and servocat for astrophoto with NINA
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Frederic,?
Good day sir.?
my comments are shown intermixed? with your note to George Hilios:?
------ Original Message ------
Date 5/19/2025 7:29:26 AM
Subject Re: [ServoCAT] Argonavis and servocat for astrophoto with NINA
[Edited Message Follows]
Hi, here is an update of my first experience.
Episode 1: for VISUAL Use first: remote wireless slew and center to a target with NINA connected to a UC22 Servocat Argonavis with the servocat ascom driver of George Hilios
IT WORKS but the sequence to let it happen has to be followed precisely.
00: I installed a very light guide/finder scope with a zwo camera on top of my UC22 side by side with the telrad finder on the same aluminium tube. The camera is declared as the imaging camera in NINA.
0: the on board PC is not yet connected to servocat. The PC is controled with RemoteDesktop from another one
1: I did a 2 stars alignement with AN as I would to for visual observation
2: when servocat acknowledge I immediately clutch the servocat drive in alt/az
3: connect NINA to the scope right after
4: switch Argonavis catalog to Planetarium (mandatory of course but I forgot several times)
5: and that's it, from now on you just choose a target in NINA or get it from carte du ciel (light on my mele quieter 2) and click on slew and center. When it is done the target is right at the center of the guide scope
6: spend some time to tune the alignment of the guide scope with the optical axis of the main scope as the targets were not visible at first of course. You center the targer in the eyepiece and you take a picture of the guide camera and solve (without centering) it to look at the error distance and you play with the alignement screws of the guide camera holder to center the target on the camera sensor. You need a lot of trials and errors because error in RA/DEC do not translate always in Alt/Az but it is feasible.
Once this is done, it is cool to just wait for the beast to center and discover the target dead center in the eyepiece without spiral search :-).
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In Episode 2 I will try to attach a main camera to the focuser (my 12v cable was not working yesterday night :-( ) and check if I can reach focus.
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For George Hilios: Regarding steps 3 and 4, I ended with this conclusion as I understood that the position reported by the servocat driver to NINA after connection is coming from the servocat and not from AN (appears to be different from the real position of the scope if I moved it after the 2 stars alignenment without clutching).?
The ServoCAT has no knowledge of anything related to the sky. ONLY the AN has this info - after all it is what has had a 2 star alignment. ALL positions are from the AN. Note you might want to ensure that the planetarium program is using the same format as the AN. I don't remember which it uses but I think it is Jnow. If CduC were using J2000 or vice versa there would be a discrepancy.?
Here, I have a question for you George: Once I have done 2 stars alignement, AN knows where it is, ALWAYS, even if I move the scope by hand. If I move the scope without clutching the SC motors, SC does not know where it is.?
Again: the ServoCAT never "knows where it is". It receives a relative move value for ALT/AZ from the DSC. It also receives tracking speeds for each axis.?
Later if I clutch the SC motors somewhere, far away from the last star used for 2 stars alignment and trigger a GOTO with AN (SC still not connected to the PC) AN will send to SC the commands with updated info to SC to make it work, and SC has to update its knowledge of where it "looks" to execute the right slew in ALT/AZ and tune the ALT/AZ drive speeds accordingly for tracking.?
Your understanding of the system is completely flipped. First the ServoCAT is always the "master" in comms to the DSC (AN in this case). It asks how far to go, from where the scope currently is to where the AN's current "new" object is ... and it asks what the tracking rate is. There is never a 'command' from the DSC to the ServoCAT. Also planetarium information passes through the ServoCAT because some of that info is for the ServoCAT and some of it is for the DSC. The ServoCAT parses this information taking what it needs and then sending the rest to the DSC. The position values are always sent in whole to the DSC. Also note if you are using a program that has the latest native driver - I believe Sky Safari is the only one - the resolution will be super high - I don't remember for sure but it is well under 1 arcsec. Likewise the original ASCOM driver, Pete Eschman's driver, has this 'high resolution' capability. I don't know if George's supports this or now - I suspect it does but I don't know for sure. The original resolution was more like an arcmin. This has almost no bearing overall in the positioning systems as the error in the scope almost always is greater than an arcmin .... but it will make the planetarium program appear much smoother without the slight 'jerks' of the scope position on the screen.? So if I connect the PC to SC once clutched and resynchronized with AN (with any command from AN to SC), it should work, do you agree? Subsequently, if I have to unclutch the SC motors and move the scope manually, and if I want to restore a proper synchronized status between the scope and the PC, I have to trigger something from AN ( a goto for example) to resynchronize AN and SC before using NINA to slew somewhere with a propre origin position. Am I right??
No.?
Or am complicating too much? Does the servocat ascom driver systematically ask to servocat "where alt/az are we in the sky?" before executing a goto from a software running on the connected PC?
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Last: I tried George's ASCOM driver on my system and had dropouts. So I went back to the original driver - Peter's. I believe I notified George of this and I think he is testing. Also he is working on a new system - not sure where he is on that. That work is currently private.?
Gary Myers
Thank you for your support, and CS Fr¨¦d¨¦ric
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