Friday, June 09, 2023

helped improve pointing

Yesterday, Alister L messaged me.

He asked me if I might help him out. He was trying to sort an older telescope owned by the Edmonton Centre.

It worked but he wondered if it could be made to perform better... He tried searching for some solutions on the interwebs but didn't find anything appropriate.

It is a 2003-era two-arm computerized C8 we hand out in our loaner program.  It works "fine," but the hand controller firmware is at 2.2 which only has 2-star align and objects are frequently at the edge of the field [after a] go-to action.  I've installed Cartes du Ciel and "synced" it, but it doesn't seem to affect precision for the next go-to, even when 6 degrees away.  It's in Alt-Az mode...  Am I limited by what the handset can deliver?  I haven't tried the NexRemote yet...

As I read his message, I flashed back to the Carr Astronomical Observatory and using Toronto Centre's N11, the NexStar 11 GPS with carbon-fibre tube, alt-az fork mount, optical finder, data cable, with SkyTools. Oh yes, and NexRemote! Time warp.

Enjoyed using that instrument. Viewed a lot of things... My preferred 'scope which saved me haulin' my gear to the CAO.

Immediately, my brain lit up, I had a lot of questions, and I had other thoughts and ideas, maybe they'd help? I replied to Alister and asked if a phone call might be good, to make sure I was on the same page, transfer data at high speed. He rang me up a short time later.

He recounted their issue and I asked a few questions. I waxed nostalgic on using the N11 rig. Told Alister that in fact I had completely rebuilt the 'scope and mount. And that the Toronto 'scope had 2 hand controllers. I surmised I had used a newer one...

I recalled the start-up process involved getting the OTA level. Yep. He did that. Did I go so far as to use a spirit bubble level? I couldn't remember.

I recalled letting the mount try to find magnetic north and that I was worried, at time, how well that might work given the metal roof of the observatory I used it in. But that it seemed to work for me. Alister said he did the north alignment.

Then I said I went through the star-alignment process and immediately after that added calibration stars, sometimes one, sometimes a couple. Nope! He didn't do that. Or couldn't do that. The hand controller he had, with the version 2.2 firmware, did not offer this ability. No calibration star option. Oh. I understand.

Asked about the eyepiece he was using during the go-to slewing actions. Gut feeling it was small. 25mm, he said. There was something else but I missed it? Orthoscopic? If so, that's a 40 degree AFOV. Like lookin' down a tube... I suggested a lower power, below the 25, at least for the finding process. Maybe a 40? Might show the shadow of the secondary but if it captured the target, that'd be good. 'Course, the targets, say a planetary nebula, would now be smaller... Pros and cons. 

We talked about "The Celestron Way," how it was good to move toward alignment stars the right way to pre-load the gears.

We discussed firmware upgrade cautions. I had done it many times successfully but certainly we'd need to tread carefully to not brick anything... I thought it low risk, however.

I asked if he was using a cross-hair eyepiece during the alignment process. Alister hadn't but he said he'd try.

I asked if the 'scope had a Global Position System sensor. It did but he wasn't sure it was working. Odds were it wasn't, I remarked, with a 20 year old battery (or old super-capacitor). I shared a link for replacing the battery. He thanked me for the web site link. 

A working onboard GPS would make startup convenient and quick. Curious how accurately the location was specified on setup... I encouraged him to use very high precision on the latitude, longitude, and elevation. Right?!

I asked if the tube was steel or carbon-fibre. CF.

Reiterated I was happy to help but I needed more data. Make, model, serial, any other details.

He sent over some photos (huge, gah!) which helped me determine what we were dealing with. Curiously, it seemed to be the smaller version of the N11! 

CF 8-inch Celestron NexStar GPS telescope with dual-arm fork mount. Model 11052, I believe.

Known territory.

Read the manual. I kid you not. Nothing about calibration stars. Huh.

firmware numbers from Alister

Verified the HC firmware: 2.2.

Included a minor upgrade to support the NexStar 5i/8i. Also provided slightly more accurate Wedge Align routine.

Determined the motors firmware: 40.40.

Interesting! A beta (test) version but was released to the public. Fixed autoguider problems including runaway slew when autoguiding. Also fixed the hop in Alt-Az mode. 

But then, on reading another article at the amazing NexStar site, I learned about the hand controllers and the firmware. Michael Swanson's web page made it very clear that there were three scenarios.

  1. old original hand controller, could not be updated beyond firmware version 2.2, this is what they had
  2. newer hand controller, could be upgraded to firmware 4.x
  3. latest HC, in fact, the NexStar+ hand controller

I presented my findings to Alister. And I asked if he had access to a NexStar+ HC. Could he test it, try it with the mount? I was pleasantly surprised to hear that he could try one. He was going to borrow a friend's unit. All right!

Then on 9 Jun '23, 5:45 PM, I received the good news!

So the Evo Nexstar hand controller works and lets me have Precision Go-To.  I've placed an order to get one. 

That made me very happy. So, while I didn't lay a hand on anything, I think I was able to get Alister to a good place. And this makes this 'scope a really good instrument for their loaner programme.


A NexStar+ hand controller costs about $200.

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