Re: Argonavis and servocat for astrophoto with NINA
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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Re: Argonavis and servocat for astrophoto with NINA
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 :-).
?
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.
?
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). 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. 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. 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? 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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Thank you for your support, and CS Fr¨¦d¨¦ric
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Re: UC22 and Argo Navis for imaging
Sevan,
Just a clarification of what is going on. The "beep" is actually issued by the ServoCAT to the AN. It is indeed issued when the slew is finished. There is no motion after that, other than tracking which happens immediately, with 2 exceptions.?
1) the backlash is unresolved and indeed it isn't motion but the lack of motion (at the actual point of rotation - the bearing for ALT or the ground board for the AZ. Note that backlash isn't only there in the ServoCAT gearboxes but its also in the mechanics of the scope - which the ServoCAT has no measurement of nor any control over. So there are two sources of lash that need to be resolved. Even if LMIS is in play there still can be backlash seen.?
2) If AutoLOCK is on AND there is backlash there will be drift --- AL will ultimately bring the center point (where it was last left - whether through the results of a GOTO or if moved after that - its center) back to the center. Note that "center" in one persons eyes - depending on the angle they're looking at through the eyepiece isn't?necessarily?center for someone else... so "center" just means where it was left and where the ServoCAT believes that point to be.?
Additionally the update rate from the ServoCAT to the DSC is about 3X a second... so there's no "timing issues".?
Gary Myers ?
------ Original Message ------
Date 5/18/2025 10:52:18 AM
Subject Re: [ServoCAT] UC22 and Argo Navis for imaging
On Fri, May 16, 2025 at 01:12 PM, Gabriel Wiklund wrote:
sometimes after a GoTo/Slew/Recenter the scope slews away as if the backlash has not been cleared
I get that too, from time to time, even with an ArgoNavis.? I have reason to believe it's just a timing issue with ServoCAT talking to the DSCs.? ArgoNavis gives beeps indicating when the slew is "done", after ServoCAT having done the talking to the DSCs thing and recentering.? ServoCAT still moves along with that beep from time to time, and less often, after the beep.? Highly intermittent, and I have found nothing making it more likely than not to happen.? On one night, and one night only, I had it happen a few times, so I unplugged and re-plugged the serial connections on the SC and the AN, and it went away.? That's not enough to say it's related, but maybe perhaps?
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That this doesn't happen with slews, but only with gotos, is what makes me believe it's a timing issues.? With a slew, there is no talking to the DSCs for refinement.? You could try just letting PHD2 take care of it, which only slews rather than sending gotos, but the issue is that with PHD2 and alt/az, you need to recalibrate every so often as the parallactic angles changes - the camera chips are rotating relative to the sky as the scope tracks.
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Re: UC22 and Argo Navis for imaging
In NINA there is something called "Slew to RA/DEC" or "Slew to ALT/AZ". Does this still mean the Meade Generic driver is causing Nexus to send GoTos since Nexus can't "slew" only?
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Re: UC22 and Argo Navis for imaging
On Fri, May 16, 2025 at 01:12 PM, Gabriel Wiklund wrote:
sometimes after a GoTo/Slew/Recenter the scope slews away as if the backlash has not been cleared
I get that too, from time to time, even with an ArgoNavis.? I have reason to believe it's just a timing issue with ServoCAT talking to the DSCs.? ArgoNavis gives beeps indicating when the slew is "done", after ServoCAT having done the talking to the DSCs thing and recentering.? ServoCAT still moves along with that beep from time to time, and less often, after the beep.? Highly intermittent, and I have found nothing making it more likely than not to happen.? On one night, and one night only, I had it happen a few times, so I unplugged and re-plugged the serial connections on the SC and the AN, and it went away.? That's not enough to say it's related, but maybe perhaps?
?
That this doesn't happen with slews, but only with gotos, is what makes me believe it's a timing issues.? With a slew, there is no talking to the DSCs for refinement.? You could try just letting PHD2 take care of it, which only slews rather than sending gotos, but the issue is that with PHD2 and alt/az, you need to recalibrate every so often as the parallactic angles changes - the camera chips are rotating relative to the sky as the scope tracks.
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Re: UC22 and Argo Navis for imaging
Thank you Sevan!
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I use the latest Meade Generic driver.
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Serge sent me a firmware version for Nexus DSC Pro that fixes the lat/long issue. After that it reported the correct lat/long every session. It was a bug causing the issue he said.
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Strange with the alignment... i have always done the 2-star remotley starting at 30 AZ and 65 Alt then 135 Az 70 Alt. Points and tracks well. (i live 63 degrees north). My alt ref is 0 Az 63 Alt, i platesolved the position one session and then i made markings on the scope so i just position the scope, start everything up and walk inside then everything can be done from the house.
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I have created a 2-star alignment sequence in NINA so it is fully automated provided the settle time is 60s, to speed things up i am hands on and check what the guidecamera is seeing so the scope has settled, then platesolve and sync. Since 60s is "just to be sure".
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The only thing standing in the way of full automated imaging all night long, is that sometimes after a GoTo/Slew/Recenter the scope slews away as if the backlash has not been cleared, if i quickly slew in the opposite direction with NINAS virtual handpad which offers slowmotion control then the scope stops and tracks as it should.
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I am not sure what is going on since after a GoTo ServoCATs last move is supposed to be sidereal, also this issue does not always occur.
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In the beginning of a session this is not a problem since i am hands on anyway, and i enjoy that. But if i need some sleep and the scope has drifted NINA has a function called "Center after drift" which works by detecting drift, so if i set 3 arc minutes it will automatically slew and center untill it's within 3 arc minutes again. The problem though, is that after slewing back within 3 arc minutes, even though the correction is so minor the scope starts moving away which causes center after drift to fail.
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I wrote about this in the Meade Generic driver discord and CJdawson (spelling?) was not aware of any slewing issue in the new drivers but suggested i used ascom tracelog to see what was going on, i can't do this now though since the season here has ended, would be nice to solve this problem for the coming season!
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/Gabriel
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Re: UC22 and Argo Navis for imaging
*** (section break, to help avoid confusion)
For the following, one is connected to the Nexus DSC through their computer, using the LX200 driver:
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The first two align points sent to Nexus DSC (Pro or not) are treated as the two alignment points.? It is advisable to have done the alt ref beforehand.? Treat these first two align points as you would when doing the alignment with the panel (the actual keypad of the Nexus DSC body) - far away enough, backlashes cleared, ... .
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Every align point sent after those first two is treated as a local sync in Nexus DSC.? If you so choose, you can use those additional syncs to develop an MPoint model.
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It does not matter you you obtain those syncs, i.e.: actually centering things yourself and pushing a sync button; or, through plate solving then syncing.
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You can run this programmatically, eventually.? There are two hiccups with the latest Nexus DSC Pro firmware I received, which is far ahead of the firmware available on the site.? For starters, the Nexus DSC Pro is sending out the wrong latitude and longitude, but it's a simple formatting error, so that should be fixed easily.? The lat/lon is rather necessary to do this programmatically, if you know where the trees are, for example.? You would go to where the trees aren't, then solve and sync there.? But the gotos are in RA/Dec, so you need the lat/lon/time to get the proper RA/Dec to send it to, from the alt/az where the trees aren't.? The second hiccup is that it doesn't align when the first alignment point is between zenith and the celestial pole (I'm in the Northern hemisphere).? This will be harder to deal with fixing, but the workaround is to slew to the South first, then start from there.? It just adds the time it takes to slew from my park position (toward North) to the South.
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Gotos are sent to Nexus DSC, which passes it along to ServoCAT through the USB cable.? ServoCAT then talks to the DSCs for the refinement, as usual.
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***
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For the following, one is connected to the ServoCAT through their computer, using Hilios' driver, for example:
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A sync is just a local sync sent to the ServoCAT itself.? Nexus DSC does not see the sync at all.? Gotos are sent directly to ServoCAT.? ServoCAT then talks to the DSCs for the refinement, as usual.
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***
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When connected to ArgoNavis from the computer, none of the above is possible.? One can't align from the computer with an ArgoNavis, and one can't send gotos from the computer with an ArgoNavis.? I never connect to the ArgoNavis through ascom or the like, for any sort of control (because there is none); simply to update elements for comets, asteroids, and satellites in ArgoNavis itself.? One MUST be on "From Planetarium" in ArgoNavis, even when connected to ServoCAT from a computer, otherwise the goto is to whatever is on ArgoNavis' screen.? The tracking rate is always sidereal when on "From Planetarium", as it's just coordinates, rather than an object.? If your computer tells ServoCAT to goto M51, but ArgoNavis' screen is on Moon, it will go to the Moon, and track at lunar.
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***
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In practice, I use Nexus DSC Pro, so I can do an alignment programmatically, without having to center stars myself.? Once I do an alignment programmatically, through platesolving (being mindful of the wrong lat/lon), I switch the connection to ServoCAT from the computer.? There is nothing left to do with NexusDSC from the computer really, so I may as well go straight to ServoCAT.? It doesn't really matter though, so dealer's choice there.? I only use an ArgoNavis when I specifically need some function that Nexus DSC and ServoCAT together can't provide.? At the moment, that's only satellite tracking, but then I am forced to center stars myself.
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Re: Argonavis and servocat for astrophoto with NINA
Nice! I am the author of this driver and a NINA contributor so I am thrilled to see the pairing. Let me know if you have any feedback.
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Re: Argonavis and servocat for astrophoto with NINA
Thank you Richard, your answer is pushing me forward :-). I can tell you that NiNa is a fantastic tool especially if you want to trigger a capture sequence and go to sleep ;-)
CS Fr¨¦d¨¦ric?
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Re: Argonavis and servocat for astrophoto with NINA
Hi ¹ó°ù¨¦»å¨¦°ù¾±³¦,
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Looks like you are on track for a great time remotely controlling your scope and capturing images.
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I use my camera and remotely connected laptop to image the stars in the 2-star alignment step.??
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I have yet to try NINA but do enjoy remotely controlling my UC18 from my recliner (via Remote Desktop) and projecting to the big screen TV.
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Here is M95 from my UC18 and DS287c camera taken a few years ago and just post processed today (took me 3 years to discover PixInsight and the RC Astro tools).
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Can't wait to hear about your success.
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Richard
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Re: Argonavis and servocat for astrophoto with NINA
Hi ¹ó°ù¨¦»å¨¦°ù¾±³¦,
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Happy to see you here. Regarding Pulse guiding i tried this with the Meade Generic driver and it did not work, the author of the Meade Generic driver showed me how to check the driver tracelog for if commands where sent/received and what the problem was, the problem was communication in RA/DEC. Can't remember exactly but something about Alt/Az and RA/DEC.
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Pherhaps that is not a problem with AN and the ServoCAT driver. Anyway i use a ST4 cable and that works very well!
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I only calibrate once in PHD2 and not even every session provided nothing has changed like the friction on the bearings or so.
I connect the Meade Generic driver to PHD2 only for providing pointing information so that dec compensation can be used.
If using ST4 only and dec compensation PHD2 will prompt before starting to guide so you enter which dec(alt) your scope is at.
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/Gabriel
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Argonavis and servocat for astrophoto with NINA
Hi all,
I discovered the work of on Astrobin and decided to try it with my Obsession UC22 Argonavis/ servocat 3 last firmware. (I am the guy he mentionned in a recent post ;-) on this group)
I would like to check with the "people who know" that what I plan to do is going the right direction. I am going to install a guide camera as well as a main imaging camera on my AN/SC alt/az dobson.
I plan to connect my PC (a mini one in fact sitting on the scope) to servocat as usually recommended for AN/SC configurations (cf chapter 8 of servocat manual). In this configuration I understand that servocat is passing to AN some of the request sent by the ascom driver after converting it to the AN/SC interface specific langage.
I already made a first test with this configuration and was able to establish the connection using the servocat ASCOM driver from .
Here is what I plan as my setup procedure.
1 turn everything on
2 do initial 2 stars alignement with Argonavis as I would do for visual use
3 clutch the servocat motors on both axis
4 turn AN catalog to "from planetarium"
4 choose a target with my planetarium (carte du ciel or directly NINA)
5 slew and center: I expect AN/SC to slew to the coordinates, Nina to launch a capture with the imaging camera, platesolve it and loop to center and synch the AN/SC to this location in the sky and track it
6 I have noticed that the servocat Ascom driver supports Pulse guiding so I expect that PHD2 will be able to guide assuming that I will have to calibrate PHD2 for each new target as the guide speed will translate to different "sky speed" depending on Altitude and lat/long position.?
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Am I on the good track?
by the way for those not aware of, I just discovered the application that let you command NINA remotely from a smartphone, cool app :-)
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CS Fr¨¦d¨¦ric
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UC22 and Argo Navis for imaging
Hi all,
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There is a guy on Astrobin who mentioned he will try deep sky imaging with his Obsession UC22 and AN using NINA. I mentioned this group in case he needs help.
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So I became curious how the DSC and ServoCAT actually works.
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In the case of AN i assume one has to do the 2-star alignment with the handpad/AN unit and not remote?
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Then connect to the Ascom ServoCAT driver.. does the Meade Generic driver work with AN?
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When sending a slew command this goes directly to ServoCAT without any "interference" from AN?
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When platesolving in a capture software and the scope needs to move a specific distance, the ServoCAT understands the distance without help from the DSC?
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In my case with Nexus DSC Pro if I understand things correctly it does not allow a command to just pass through to ServoCAT so instead it "pretends" to be (emulates) ServoCAT and translates the first slew and platesolve + sync as the first star in the 2-star alignment, and second star with the second platesolve + sync.
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So all commands are sent from Nexus to ServoCAT, in other words ServoCAT has no idea that the Meade Gneric driver is behind the wheel operating Nexus?
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Clear skies
Gabriel?
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Re: Optimising gear ratio : alt ratio correction calculation
GEMs are the worst choice for tracking satellites.? It's not the equatorial mounting, per se, but rather, the need for a meridian flip with GEMs.? A fork mounted EQ mount on a wedge, for example, has no need for a meridian flip.? When polar aligned, as most EQ mounts are, a meridian flip occurs ... near meridian.? Meridian has nothing to do with a general satellite track, particularly not those that show details in our scopes.? They culminate where they culminate, and that's rarely meridian.? It's not the better build either, but rather, the ability to get a good alignment because of that better build, much more easily.
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For OP, use the "Simple Track Improvements Test" that Gary recommended, and round down rather than rounding up.? That way, it will be slower and lagging, so all your corrections will be to "speed up", while maintaining the proper direction.? The alternative, rounding up, will have you sending command to "slow down".? Rarely, except around culmination, will simply "slowing down" switch directions (it's moving too fast for that, except in alt around culmination), but there are practical benefits of keeping the satellite slightly behind the center of the fov.? That benefit is reacquisition should it slip out of the fov.? When it's slightly behind center, there is typically more room in the eyepiece when it does drift out, so you are better able to know where it went.
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Back to the "better alignment" issue, AN + SC has some odd features that make that more cumbersome that it need to be.? Typically, satellites that show details are low, so they have passes shortly after sunset, or shortly before sunrise.? If the pass is before sunrise, there is plenty of time to gather a large run of data to run TPAS, resolve issues, get comfortable, ... .? When the pass is shortly after sunset, there is hardly any time at all to run a new TPAS model.? Unfortunately, ArgoNavis will JUNK your alignment any time you update a TLE, so you have to do another TPAS run to get those non-constant terms.? Because ArgoNavis JUNKS the alignment, it is best to avoid having to rely on TPAS at all.? That is unfortunate, and no fix to this bug is likely coming soon.? Because TLEs need to be updated often, it is even better to not rely on ArgoNavis at all.
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SkyTrack is seemingly an alternative, but ServoCAT is not ready for that yet.? SkyTrack loads TLEs into its own software, and has the ability to plate solve along the projected path to make its own model.? It works incredibly well with my other commercial mounts from Celestron and SkyWatcher.? Those are not incredibly well built mounts, but the alignment is what overcomes that.? One can build an excellent alignment using those mounts respective control software, through plate solving, without user intervention.? One can then further refine those models using SkyTrack itself, through plate solving, without user intervention.? SkyTrack then has the ability to fine tune the tracking rates with a gamepad or the like, adjusting the corrections based on the present tracking speeds.
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What keeps SkyTrack from working with ServoCAT at the moment ServoCAT's inability to accept custom rates through ServoCAT's USB port.? One is limited to the preprogrammed rates of the handcontroller.? Because the satellites' rates change along the pass, that is now a limitation of ServoCAT itself.? ArgoNavis need not be involved anywhere, and any other DSC (or none at all) would do otherwise fine, preferably one that does not junk your alignment when one you update a TLE.? As soon as ServoCAT's USB port is "up to snuff", SkyTrack will be my preferred solution for satellite tracking with my dob.
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For OP, for now, ArgoNavis is the only workable solution.? But again, it JUNKS your alignment whenever you update a TLE, which is all the time.? In practice, that means getting by with as few stars as your are able to do so, when the pass is shortly after sunset, to get the best alignment you can.? Adjust your mount itself to make those non-perpendicularity terms as close to zero you can get them, use classical bi-directional offset so that your mirror points where your mount points, and level your mount as best as you can.? Structural rigidity will keep flexure terms at bay, and they are the hardest to deal with.? Once you can get as best an alignment as you can, with as few stars as are available, then, and only then, will AutoLock work properly.? Getting the ratios adjusted in ServoCAT as best as you can at that point simply means that the tracking rate adjustments because of AutoLock are now minimal.
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Bear in mind that you will still need to make tracking corrections.? TLEs are never exact, and their utility decays as one gets farther from their epoch.? Your time and location need to be as precise and accurate as you can get them.? Your alignment needs to be as precise and accurate as you can get it.? Even then, you cannot account for variables such as refraction, without actually modelling them first.? All of your efforts will lead you to having to make smaller corrections to the tracking speed.
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Even with all of these challenges with the present ArgoNavis + ServoCAT, I can still keep ISS and CSS in the FOV of my 15" with a 6 Ethos, yielding about 300x in a 100 degree AFOV.? The TFOV is about twenty arcminutes from one side to other, so the "available room" for error is about half of that, at only about ten arcminutes.? That's rather good!? But, there is always room for improvement, and a better protocol of ServoCAT's USB port is the way forward, for things such as updating TLEs, doing alignments through plate solving (which can align closer to sunset than my eyeball), getting the most precise and accurate times and locations as one can, and having the ability to make better models on the fly.
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With respect to the zenith problem of an alt/az mount, I can simply tip my dob to change the mount's zenith with respect to the sky's zenith.? That avoids a pass straight through the pole of the mount.? With a computer, making the adjustments for having "changed" one's latitude and longitude because of that tipping is rather straightforward.? It's much harder with a fixed single purpose computer that expects you to enter those values yourself.? Clearly, with any sized telescope, there is a limit to how far your structure can handle such tipping (the az bearing is the weakest point), but that limit increases rather quickly with larger sized scopes.? The solution that specifically designed satellite trackers employ is going to alt-alt-az, rather than simply alt-az, or a full gimbal.? That's not an option for us, so tipping in the poor man's solution to getting alt-alt-az, then simply telling the alignment software our "new" latitude and longitude (preferably through plate solving at the mount's pole).
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programing for servocat for skyvision D500
Can any one tell me the settings for the servocat on a skyvision D500.
Thanks
Frank
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Re: Optimising gear ratio : alt ratio correction calculation
Hi Fernando
I believe your point is not inappropriate but I¡¯m not owner of group
In fact I was discussing about ISS but I m more into small galaxies : I look at ISS because the scope has just been put out, of observatory waiting for night?
But I like the challenge to be able to follow ISS and see some details in the big dob?
I say some detail but not that much as for the moment i ve only seen ISS at beginning of night so with mirrors not in thermal equilibriums?
I hope I could see in morning this Thursday morning and it may be wonderful?
I know also that fine tune ratio will be a good starting point if I decide to take pictures?
Anyway it seems so far it¡¯s ok with my setting as ISS is only seen by opportunity?
Anyway maybe one day I will buy one a the refractor or mount you indicate so thanks for giving advices?
Last thing : argonavis fully compute the trajectory of ISS but I believe you knew this
Thanks?
Raphael?
I hope this is not "inappropriate" for posting to the group, but here it goes:
Raphael, have you considered perhaps a different type of setup for tracking the ISS? For example, there are Astro-Physics mounts out there that when paired up with software like APCC [Astro-Physics Command Center] it helps a lot when tracking satellites,
ISS, Hubble Space Telescope "HST", etc. Not sure, but I think also the Software Bisque Paramounts can be programmed to do the same thing <The Sky X software, T-Point, etc>. I figure the extreme CNC precision machining that goes into these mounts would make
the task/goal easier (however, with a smaller aperture scope).
I mention this because many astronomers have multiple setups (mounts: alt-az & German Equatorials, push to or electronic drive systems, solar or nighttime telescopes, etc)
I know not everyone is into German Equatorial Mounts "GEM's". They are a different animal, or beast, versus a big dob light bucket. I mentioned it here as "just a thought" or "friendly suggestion".
Perfectly understandable if your preference is to stay committed to your project.?
I hope this doesn't get me banned/ kicked out of the group. I don't think it hurts or is harmful to look at alternative means of doing things.?
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Re: Optimising gear ratio : alt ratio correction calculation
Fernando,?
Good day sir - good to hear from you. I hope all is well.?
No worries on this post. Indeed I'd guess that some not insignificant percentage of dob owners are also owners of other "forms" of scopes. I myself have always been a "photon in the eye" guy... but since retiring I began looking around and realized that the equipment has come a long long way - most definitely the one piece of kit that has pushed it are indeed the CMOS cameras that are now available. They are extremely sensitive with extremely low read noise.?
So - I've 'gone to the dark side' myself getting an 8" f4 imaging newt, an APS-C camera and a harmonic EQ drive. Just testing it out now.?
That stated my guess is Raphael is just wanting to do all he can with that BIG scope of his... understandable and commendable.?
Gary Myers
ps: the local club that I belong to has a 25" Obsession w/ServoCAT/AN that was donated to the club... we had a club 'dark sky night' last night and had some decent views. I DO however miss the skies of SE AZ.?
------ Original Message ------
Date 4/28/2025 11:08:59 AM
Subject Re: [ServoCAT] Optimising gear ratio : alt ratio correction calculation
I hope this is not "inappropriate" for posting to the group, but here it goes:
Raphael, have you considered perhaps a different type of setup for tracking the ISS? For example, there are Astro-Physics mounts out there that when paired up with software like APCC [Astro-Physics Command Center] it helps a lot when tracking satellites, ISS, Hubble Space Telescope "HST", etc. Not sure, but I think also the Software Bisque Paramounts can be programmed to do the same thing <The Sky X software, T-Point, etc>. I figure the extreme CNC precision machining that goes into these mounts would make the task/goal easier (however, with a smaller aperture scope).
I mention this because many astronomers have multiple setups (mounts: alt-az & German Equatorials, push to or electronic drive systems, solar or nighttime telescopes, etc)
I know not everyone is into German Equatorial Mounts "GEM's". They are a different animal, or beast, versus a big dob light bucket. I mentioned it here as "just a thought" or "friendly suggestion".
Perfectly understandable if your preference is to stay committed to your project.?
I hope this doesn't get me banned/ kicked out of the group. I don't think it hurts or is harmful to look at alternative means of doing things.?
|
Re: Optimising gear ratio : alt ratio correction calculation
I hope this is not "inappropriate" for posting to the group, but here it goes:
Raphael, have you considered perhaps a different type of setup for tracking the ISS? For example, there are Astro-Physics mounts out there that when paired up with software like APCC [Astro-Physics Command Center] it helps a lot when tracking satellites, ISS, Hubble Space Telescope "HST", etc. Not sure, but I think also the Software Bisque Paramounts can be programmed to do the same thing <The Sky X software, T-Point, etc>. I figure the extreme CNC precision machining that goes into these mounts would make the task/goal easier (however, with a smaller aperture scope).
I mention this because many astronomers have multiple setups (mounts: alt-az & German Equatorials, push to or electronic drive systems, solar or nighttime telescopes, etc)
I know not everyone is into German Equatorial Mounts "GEM's". They are a different animal, or beast, versus a big dob light bucket. I mentioned it here as "just a thought" or "friendly suggestion".
Perfectly understandable if your preference is to stay committed to your project.?
I hope this doesn't get me banned/ kicked out of the group. I don't think it hurts or is harmful to look at alternative means of doing things.?
|
Re: Optimising gear ratio : alt ratio correction calculation
TPAS is not flaky! It was proven over years of development work by WCI including but not limited to using the publicly available Keck Telescope data where TPAS achieved the same results. It is, however, by its very nature complicated. The vast majority of issues are either user misunderstandings or user error.
?
Please reframe from derogatory comments.?
?
Gary Myers
StellarCAT
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Re: Optimising gear ratio : alt ratio correction calculation
TPAS won't help you much. It's flaky. Nexus uses an algorithm that works better in this regard. But again, it's not for the purpose you're trying to use.
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Fr¨¦d¨¦ric Ruciak
Gabriel Wiklund