Weird error in go-to for aligned LX-200

[AstroProfSmith]

Good afternoon,

I've had some Meade 8" LX-200 ACF scopes for a few years now, and I had never found their go-to feature particularly reliable, but I hadn't taken the time to systematically investigate the problem until last night. I'd been using them for public open houses at the observatory or for teaching beginner students, so the targets were usually ones you could see with naked eye and the go to feature wasn't critically necessary. But it was annoying, and I was always in the middle of something else and couldn't take the time to study it. Well, I finally did, and I'm baffled.

So, the telescope is on a vibration-isolated pier with an equatorial wedge. I took the time to carefully align the wedge to Polaris during the AutoStar set up, although I still need to do the drift checks. Then I did an "easy" one-star align, and it chose to go to Vega. I thought that was an odd choice, because it was *very* low in the East, but it was visible, so okay. This is about 9:30 pm EDT. It declared the alignment successful. Since it was over there already, I told it to go to M13. It put the cluster beautifully in the 26 mm eyepiece.

Next I thought, Mars is high in the West, let's go look at that. But the hand paddle tells me Mars won't rise until 9:30 am. So I try Procyon, high in the SW. The hand paddle says *that* won't be up until 12:30 am. How it gets Procyon rising nine hours before Mars, when it's to the East of Mars, I have no idea.

I don't see how it knows where Vega and M13 are, but thinks Procyon rises in three hours, and then Mars nine hours after that. I checked the time and the site location, and they were all correct (time to within a half-minute and location to within a few miles). I did not check whether it had the right RA/Dec for Mars at that time -- didn't think of that until just now.

I am at a bit of a loss. Has anyone run into this before, and were you able to solve it?

Thanks in advance for your help,

Don Smith
Guilford College Physics Department
http://www.facebook.com/guilfordobservatory

[sdbodin]

OK, baffled too. I am pier mounted and always do a one star align for the start of a night's work, but I usually pick a bright star from the 'Named Stars' list under objects, then slew out any pointing error, usually small, and press 'sync'. This assumes that the scope is placed in the 'Park' position at the end of the previous night. The scope puts every object in my field of view the rest of the night, except planets. The planets are generally in the finder fov, but not the scope. My thoughts are that the internal ephemeris does not carry enough decimal points to calculated the position properly from the initial installation a dozen years ago. So, that is all I know.

Welcome,
Steve

[Piet Le Roux]

Good day Don,
I have two Meade 8" LX90ACF scopes which I use in Az/Alt mode for visual observation and my goto's are very accurate, I believe that with a well set-up LX200 your goto's should be even better. The polar configuration with a wedge is, in my view, ideal for AP but not ideal for visual observation because it can produce uncomfortable viewing angles and less than optimal goto preformans. To get good goto performance you have to preform accurate drive training and in polar configuration this is not easy : You need a terrestrial target low on the east or west horizon to do this accurately but the torque on the drives does change a lot from one part of the sky to others where with a Az/Alt setup there is little change and it is easy to do drive training accurately because you can use any target in your 360 degree view. I think the Autostar II is much more complex than the Autostar but I have also experienced a bug where it tells me that somthing is not in view yet, I simply ignore and select goto. It could be that your minimum angels were set for a AZ/Alt setup and now it is being used in polar mode and is confused as to where the horizon is. Are you setting your coordinates, time and date manually or with the build in GPS? Are you using "real time" or DST?

[mikemarotta]

... Then I did an "easy" one-star align, and it chose to go to Vega. I thought that was an odd choice, because it was *very* low in the East, but it was visible, so okay. This is about 9:30 pm EDT. It declared the alignment successful. Since it was over there already, I told it to go to M13. It put the cluster beautifully in the 26 mm eyepiece.
Next I thought, Mars is high in the West, let's go look at that. But the hand paddle tells me Mars won't rise until 9:30 am. So I try Procyon, high in the SW. The hand paddle says *that* won't be up until 12:30 am. How it gets Procyon rising nine hours before Mars, when it's to the East of Mars, I have no idea.

I borrowed three different LX-200s from my local club, all classics, so a bit older. After a few days each time, I was only convinced that star-hopping was better than hassling with the interface.

That said, though,I did not have your problems, but I am confident that you do have them. All I can suggest is to run a better test. Do three stars for the alignment. Then test with a full range of points across the sky along both axes. Note any problems and see if a pattern is obvious.

Assign it to a student aide. They live for moments like that.

Best Regards,
Mike M.

[AstroProfSmith]

Good evening,

I didn't see a three-star alignment option. We had a clear night tonight, so I gave it another shot. Entered the date, time, location manually. Easy one star alignment claimed to work. It used Vega again and said align successful. But then when I tried to go to Spica, it said "Rises at 6:16 pm". (this was at 9:30 pm!). I tried the two-star alignment option, and it didn't list any stars to the west. Many of the stars listed weren't up yet. It was like it thought the horizon was rotated 100 degrees or so. I centered on Mizar and Arcturus, but it said "alignment failed, check stars". I'm pretty sure they were indeed Mizar and Arcturus. (sarcasm) So I am at a loss. I would have liked to have used two stars that were further apart, but none of the western stars were on the list.

Meade customer service wrote me back and said they think it's a GPS rollover problem that needs new firmware. I don't understand how that could be, since I'm not using the GPS, but I can give it a try.

Semester just ended yesterday, so I have (officially) no students for a few months. Unofficially, some about-to-graduate-this-week students might be interested in taking it on before they head out to their next phase of life. Very frustrating, though, when something that claims to be easy just simply doesn't work. I got these scopes so that beginning students could set them up and just *go*, but if *I* can't get them to work, I don't want to inflict them on the students. Unless they want to learn how to star-hop, of course.

Good night,

Don

[AstroProfSmith]

The Meade customer service person is insisting it's the GPS rollover problem. So I am guessing that means that manually setting the date, time, and location is insufficient -- it must still be drawing on the faulty GPS information somehow, unless I turn it off somewhere. They don't make "turn off GPS" a very easy menu item to find. Tomorrow I will try upgrading the firmware. They say you need their #507 serial cable, but I have run the telescope off a laptop before using one of our own serial cables, so I'm going to try that first before I spend $50 on what's essentially a phone cord. There are no clear nights forecast for the next couple weeks, so it's not urgent, but if I can't make our cable work for the firmware upgrade, at least that gives me time to order their cable.

Yours,

Don

[AstroProfSmith]

I got the official 507 cable, and the firmware update went smoothly. It's now 4.2L. I can run the GUI hand paddle on the laptop and successfully control the mount.

Tonight it's supposed to be clear, so I will come in and try putting it on the sky. If it works, I'll update the other telescopes the same way. Wish me luck!

Yours,

Don

[AstroProfSmith]

Seems to work just fine! I did an easy alignment and it worked first time. I had it go to some stars, and it put them in the FOV. I'm attaching some images I got. For M101 I jogged the pointing a bit, but for M13 and M57, that's where the pointing went. The M13 image is 30 s, and the others are stacked images, 10x30 s. For how frustrating those scopes have been until now, I am quite happy with the pointing and tracking on those. (No image reduction on these. Clearly need some flats.)

Yours,

Don

[Graeme1858]

Looks like the new cable and the firmware update did the trick.

Looking forward to seeing what you and your students can do with it now!

Regards

Graeme

[SkyHiker]

Congratulations on getting it working Don. I am curious what is so special about that expensive #508 cable that you can't crimp one yourself?

If you find yourself spending lots of time on the quirks of some closed source control system I recommend looking into OnStep. It is an open source project for control of EQ scopes with cheap components that works well. Combined with a Pi for the high level tasks running Ekos as part of Astroberry you have a completely open source solution that may be interesting for students in its own right. I built my own OnStep control system based on a Wemos/CNCv3 with a Pi4b and I'm glad I did.

[mikemarotta]

Seems to work just fine! I did an easy alignment and it worked first time. ...

Good news! We were all rooting for you. Congratulations.

Thanks for the images as proof of success.

Mike M.

[mikemarotta]

... I am curious what is so special about that expensive #508 cable that you can't crimp one yourself?

If you find yourself spending lots of time on the quirks of some closed source control system I recommend looking into OnStep. It is an open source project ...

I wouldn't know about that cable but I do know that DIY projects are easy for some folks and harder for others. I am not a builder or a constructor. I write. Right now I am reading this;

It is not that I am that smart, but that I would rather put my hard labor into this where my tools are a sheet of paper and a pencil. Even if I have to erase a page of equations and do the algebra over again to the get arithmetic right, that feels more satisfying than crimping a cable... and taking it apart... and doing it again... and throwing that one out because it is ruined now and starting over...

I do agree 100% about the open source. (Not that I am a coder, but software I do better than hardware: it is just writing in another language that is a lot like maths.) When Scott Roberts was our guest speaker at our local club (wonders of Zoom) he said that Explore Scientific only does Open Source because after working for Meade for many years he decided not to make his customers at Explore Scientific dependent on him for any future updates or support for old systems.

[mikemarotta]

Right now I am reading ...

I forgot the picture...

The astronomy is easy. Only the physics is hard. And the only hard part about the physics is the math. However, Dr. Weinberg integrates by parts for you and at the bottom of the page, you get algebra and arithmetic. Steven Weinberg is an engaging and cogent writer. The book is a good read. However, it is only lectures. If you want to get more from them, you have to follow the leads on your own.

[AstroProfSmith]

Congratulations on getting it working Don. I am curious what is so special about that expensive #508 cable that you can't crimp one yourself?

If you find yourself spending lots of time on the quirks of some closed source control system I recommend looking into OnStep. It is an open source project for control of EQ scopes with cheap components that works well. Combined with a Pi for the high level tasks running Ekos as part of Astroberry you have a completely open source solution that may be interesting for students in its own right. I built my own OnStep control system based on a Wemos/CNCv3 with a Pi4b and I'm glad I did.

That's very intriguing. My observatory budget keeps getting cut and cut, so a solution using Raspberry Pis would be very tempting. Would OnStep also have an opensource equivalent of MaximDL? I'll have to look into it...

To answer your question about crimping, I would imagine a crimping tool would cost more than the cable, no? I haven't crimped cables in a *really* long time, and I didn't buy the crimper back then, so I have no idea.

The story gets weirder, though, because I've spent some serious time over the last few days doing a loooong overdue cleaning, organizing, and inventory of the observatory. Sooo many ancient cables. What am I supposed to do with a pile of 25-pin printer cables??? Anyway, I found out that the cable I *was* using to try to upgrade the firmware the first time, the one that got stuck on 41%, when the customer service guy said I really needed to use a Meade cable... it *was* a Meade 507 cable. I found the bag it came in. Plus another one. So, well, now I have three. At least that's one for each LX-200, now. No idea why it failed at the upgrade, though. Maybe it wasn't seated properly and lost the connection or something.

Next step, get the Losmandy mount working with the 10" scope so I can get the spectrometer up and running, and get the focus motor on the 16" working again!

Yours,

Don

[SkyHiker]

Congratulations on getting it working Don. I am curious what is so special about that expensive #508 cable that you can't crimp one yourself?

If you find yourself spending lots of time on the quirks of some closed source control system I recommend looking into OnStep. It is an open source project for control of EQ scopes with cheap components that works well. Combined with a Pi for the high level tasks running Ekos as part of Astroberry you have a completely open source solution that may be interesting for students in its own right. I built my own OnStep control system based on a Wemos/CNCv3 with a Pi4b and I'm glad I did.

That's very intriguing. My observatory budget keeps getting cut and cut, so a solution using Raspberry Pis would be very tempting. Would OnStep also have an opensource equivalent of MaximDL? I'll have to look into it...

I use Ekos, it's open source and controls everything and the kitchen sink. Check indilib.org. It's a perfect combination with OnStep.

To answer your question about crimping, I would imagine a crimping tool would cost more than the cable, no? I haven't crimped cables in a *really* long time, and I didn't buy the crimper back then, so I have no idea.

Crimpers are cheap for sure or else I would remember it wasn't.

[AstroProfSmith]

Congratulations on getting it working Don. I am curious what is so special about that expensive #508 cable that you can't crimp one yourself?

If you find yourself spending lots of time on the quirks of some closed source control system I recommend looking into OnStep. It is an open source project for control of EQ scopes with cheap components that works well. Combined with a Pi for the high level tasks running Ekos as part of Astroberry you have a completely open source solution that may be interesting for students in its own right. I built my own OnStep control system based on a Wemos/CNCv3 with a Pi4b and I'm glad I did.

That's very intriguing. My observatory budget keeps getting cut and cut, so a solution using Raspberry Pis would be very tempting. Would OnStep also have an opensource equivalent of MaximDL? I'll have to look into it...

I use Ekos, it's open source and controls everything and the kitchen sink. Check indilib.org. It's a perfect combination with OnStep.

To answer your question about crimping, I would imagine a crimping tool would cost more than the cable, no? I haven't crimped cables in a *really* long time, and I didn't buy the crimper back then, so I have no idea.

Crimpers are cheap for sure or else I would remember it wasn't.

I got a Raspberry Pi, installed INDI, Kstars, and Ekos, and I was able to control both the LX-200 and the DSLR on the lab bench! Next clear night, I'll try putting it on the sky. Thanks for the tip -- this is very impressive!

Yours,

Don