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?
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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
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.?
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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.?
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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.
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Please reframe from derogatory comments.?
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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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Re: Optimising gear ratio : alt ratio correction calculation
Raphael,
I'm all for 'getting the best out of the system' .... kudos to you and the best in your work.?
g.
------ Original Message ------
Date 4/27/2025 4:17:38 PM
Subject Re: [ServoCAT] Optimising gear ratio : alt ratio correction calculation
Gary,
"My suspicion is you might be asking too much from such a large scope"
Yes, for sure !!
In fact trying to get the maximum from my scope is really a target in itself.
With my small field of view, it is necessary to have pointing and ratio as accurates as possible to follow as perfectly as possible ISS.
You know it's like Gabriel Wiklund that is optimising again and again the autoguiding with wonderfull results at the end. Great to obtain the very best from a scope !
I want to go as deep as possible for optimising the scope. Maybe I will be blocked by mechanical problem, but at least I want to go to this point.
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I will continue using drifting test, either by tweaking the ratio 5 by 5 as you suggest, either using the "track improvment" method but with the correction I was mentionning in my initial message for the alt correction. Even if I'm wrong with the correction I mentioned in my initial message, it will just take more iterations to achieve the best ratio I could achieve before mechanicalo limitation.
I will post the results after the iterations
Thanks for your help
Rapha?l
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Re: Optimising gear ratio : alt ratio correction calculation
Gary,
"My suspicion is you might be asking too much from such a large scope"
Yes, for sure !!
In fact trying to get the maximum from my scope is really a target in itself.
With my small field of view, it is necessary to have pointing and ratio as accurates as possible to follow as perfectly as possible ISS.
You know it's like Gabriel Wiklund that is optimising again and again the autoguiding with wonderfull results at the end. Great to obtain the very best from a scope !
I want to go as deep as possible for optimising the scope. Maybe I will be blocked by mechanical problem, but at least I want to go to this point.
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I will continue using drifting test, either by tweaking the ratio 5 by 5 as you suggest, either using the "track improvment" method but with the correction I was mentionning in my initial message for the alt correction. Even if I'm wrong with the correction I mentioned in my initial message, it will just take more iterations to achieve the best ratio I could achieve before mechanicalo limitation.
I will post the results after the iterations
Thanks for your help
Rapha?l
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Re: Optimising gear ratio : alt ratio correction calculation
Raphael,
The "stop" might be with only 0.1+ degrees left. It would then just go to the second move and you'd not notice the stop. That is extremely good for the purpose for which it was designed - visual astronomy. Keep in mind - on the vast majority of 'hand made' scopes, there's enough variability in the dimensions and mounting of the drive surfaces on either the ALT or the AZ (ground board or bearings) that it isn't going to be one value.?
If your alignment is accurate and especially if you are using TPAS to correct for mount errors then it should track extremely well since it is closed loop (based on the user centering the object at the start).
If you want to take the time since you are dialed in so well the only way to do so is indeed to do the drift test you did over a longer period of time. Alternatively you can do the drift method for shorter period but just tweak the ratio (on the axis you're testing for - do one at a time!) by a count of say 5. Then repeat the test and see what that gives you. You can then ratio the results on 2 tests to get it (better) corrected.?
The other thing is there could well be?issues like friction and slippage and other mechanical things that the system is not designed to account for. Even torque induced bending might well be enough to move the object.?
My suspicion is you might be asking too much from such a large scope.?
g.
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------ Original Message ------
Date 4/27/2025 11:33:22 AM
Subject Re: [ServoCAT] Optimising gear ratio : alt ratio correction calculation
Dear Gary,
I did it already one and corrected ratio. But there is still a remaining of correction of ratio needed.?
I mean yesterday night, the scope was pointing accurately because I had just calculated the IE of TPAS (with other persistant terms already computed from previous test)so I had a computed TPAS leading to RMS of 6'. OK
Then I centered a star and after 35 min it was 20' offcenter (0.33¡ã). Frankly this is OK for visual follow up but still not accurate enough to follow ISS that move 200 times quicker than sideral.
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But I?can't I achieve anymore the "Simple Track Improvements Test" because :
In the "Simple Track Improvements Test" it is said :? ?
"Push the GOTO ¨C it will start to move ¨C now watch carefully the GUIDE value for this axis (left for AZ, right for
ALT). The scope will move a distance and then come to a stop. It will will then quickly pick up and start moving
again. You need to get the GUIDE value when it first stops"
The problem is since I'm already close to perfect ratio I can't notice any stop even if I put 170¡ã instead of 100¡ã in the procedure.
Maybe this is because my scope is massive, so I need to put? a 5 seconds deceleration => could this make it more difficult to notice the "stop" if it occurs during the deceleration ? I don't know... but I can't notice any stop.
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So this is why I wanted then to use? the "track improvment" method described in the Sercocat quick V3 file since this one is unsensitive to deceleration.
But then I have the calculation issue I indicated in my first message
I hope this clarify my original question
Regards
Rapha?l
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Re: Optimising gear ratio : alt ratio correction calculation
Dear Gary,
I did it already one and corrected ratio. But there is still a remaining of correction of ratio needed.?
I mean yesterday night, the scope was pointing accurately because I had just calculated the IE of TPAS (with other persistant terms already computed from previous test)so I had a computed TPAS leading to RMS of 6'. OK
Then I centered a star and after 35 min it was 20' offcenter (0.33¡ã). Frankly this is OK for visual follow up but still not accurate enough to follow ISS that move 200 times quicker than sideral.
?
But I?can't I achieve anymore the "Simple Track Improvements Test" because :
In the "Simple Track Improvements Test" it is said :? ?
"Push the GOTO ¨C it will start to move ¨C now watch carefully the GUIDE value for this axis (left for AZ, right for
ALT). The scope will move a distance and then come to a stop. It will will then quickly pick up and start moving
again. You need to get the GUIDE value when it first stops"
The problem is since I'm already close to perfect ratio I can't notice any stop even if I put 170¡ã instead of 100¡ã in the procedure.
Maybe this is because my scope is massive, so I need to put? a 5 seconds deceleration => could this make it more difficult to notice the "stop" if it occurs during the deceleration ? I don't know... but I can't notice any stop.
?
So this is why I wanted then to use? the "track improvment" method described in the Sercocat quick V3 file since this one is unsensitive to deceleration.
But then I have the calculation issue I indicated in my first message
I hope this clarify my original question
Regards
Rapha?l
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Gabriel Wiklund
Fr¨¦d¨¦ric Ruciak