Meade LX90 EMC 8" Tracking self-located objects with Autostar (no GPS)

[newbostonian]

Hello folks,

After almost 4 decades without a decent telescope, I've just been lucky enough to acquire a second hand Meade LX90 EMC 8" in fantastic condition. I've never used Autostar/GoTo before. I always loved using star charts and star hopping to find deep sky objects. The Autostar's GoTo function could be handy to confirm the positions of faint objects, but I will almost certainly locate the majority of objects manually. I do want to take advantage of sidereal tracking though to keep my located object in view. Can anyone tell me if it's possible to just set the handset to track whatever I'm viewing if I've found it myself without GoTo and whether that involves doing the alignment process at the start of every observing session?

There was no manual with the 'scope and the closest I could find online to download as a pdf was for the ACF version. I have read and followed it when setting up the 'scope for the first time today. There are minor differences, but going through the menus on the Autostar handset, the settings were pretty intuitive. I set the date and time. The options to set location were too vague for positioning to be accurate (the nearest local city offered is a long way away from here!) so I looked for the option to set latitude and longitude and did so. I ran through the drive trainer process on a centred daytime object. There's no GPS or compass with the 'scope. I have a compass and used magnetic North during the day today to run through the alignment process. Obviously I can't check the 2 star alignment method until nighttime! I'm hoping to be able to self-locate objects, but to use the handset to keep them centred. Do I have to point the 'scope to North and do the 2 star alignment at the start of each observing session before I can expect the 'scope to automatically track whatever I MANUALLY find throughout the night (if it can do that at all)? I've checked that the tracking is set to sidereal in the menu). If that isn't possible, can I use the arrow keys on the handset to nudge drifting items back to the centre of the field of view?  I briefly had a Celestron C8 in the 1980s and that had an electric drive which you could just adjust by + and - keys and that kept objects centred nicely, though I rarely used it.

 

Edited December 8, 2022 by newbostonian
Omitted text

[Shimrod]

3 hours ago, newbostonian said:

Hello folks,

After almost 4 decades without a decent telescope, I've just been lucky enough to acquire a second hand Meade LX90 EMC 8" in fantastic condition. I've never used Autostar/GoTo before. I always loved using star charts and star hopping to find deep sky objects. The Autostar's GoTo function could be handy to confirm the positions of faint objects, but I will almost certainly locate the majority of objects manually. I do want to take advantage of sidereal tracking though to keep my located object in view. Can anyone tell me if it's possible to just set the handset to track whatever I'm viewing if I've found it myself without GoTo and whether that involves doing the alignment process at the start of every observing session?

There was no manual with the 'scope and the closest I could find online to download as a pdf was for the ACF version. I have read and followed it when setting up the 'scope for the first time today. There are minor differences, but going through the menus on the Autostar handset, the settings were pretty intuitive. I set the date and time. The options to set location were too vague for positioning to be accurate (the nearest local city offered is a long way away from here!) so I looked for the option to set latitude and longitude and did so. I ran through the drive trainer process on a centred daytime object. There's no GPS or compass with the 'scope. I have a compass and used magnetic North during the day today to run through the alignment process. Obviously I can't check the 2 star alignment method until nighttime! I'm hoping to be able to self-locate objects, but to use the handset to keep them centred. Do I have to point the 'scope to North and do the 2 star alignment at the start of each observing session before I can expect the 'scope to automatically track whatever I MANUALLY find throughout the night (if it can do that at all)? I've checked that the tracking is set to sidereal in the menu). If that isn't possible, can I use the arrow keys on the handset to nudge drifting items back to the centre of the field of view?  I briefly had a Celestron C8 in the 1980s and that had an electric drive which you could just adjust by + and - keys and that kept objects centred nicely, though I rarely used it.

 

I have the older (circa 2003) LX90 that I use for occasional visual viewing as it's much quicker to set up than by AVX mount. You've more or less described the same process I follow when I don't particularly need to use go to. This is what I do:

1) Set telescope level and north

2) Set date and time

3) Perform alignment procedure - but I don't bother trying to get it accurate - I just press enter as soon as it has finished slewing

4) Move telescope with handset to target

The tracking isn't perfect at this point but it will keep the object in the eyepiece for quite some time

[newbostonian]

Thank you Shimrod,

That's really helpful. Hoping to give it a go tonight! I'm not sure which of the handset arrow keys will move the 'scope (I was thinking of manually locating but I'll try using the handset to slew as well).

Edited December 8, 2022 by newbostonian
Omitted text

[catburglar]

You’ll definitely need to move the scope using the handset…if you loosen the clutches and move it by hand the scope won’t know where it’s pointing and therefore tracking is likely to be poor (I guess depending on how far you’ve moved it from the position it thinks it’s in).

If you’re not going to bother to centre the alignment stars (and if all you want is the tracking feature there may not be much value in getting a precise alignment) you may as well do a one star align. If your initial home positioning is reasonably accurate that might be good enough- you can always nudge the scope with the handset controls whilst it’s tracking to re-centre if the target drifts…

[newbostonian]

Thank you catburglar. I've discovered which of the arrows on the handset will do that nudging (the upper set) and that's OK, but  I really just want to be able to turn sidereal tracking on for (largely manually) located objects once they're in the centre of the field of view and I haven't yet discovered how to do that. I've experienced the drive slewing during alignment and GoTo functions, but it hasn't yet tracked an object. 

I also discovered that when doing the 2 star alignment, you don't just assume the GoTo system has correctly located the stars in the centre of the field of view (which I was having to do as it was hazy and I only had Jupiter visible on my only trial so far), but that you have to correct each of the 2 star located positions  with the arrow keys and confirm when the image is actually found and centred (that bit isn't in the manual that I downloaded, but I watched a YouTube video that was very helpful!).

We're in a prolonged period of freezing fog at the moment, so I've yet to be able to try the telescope properly. 

[catburglar]

I don’t think it’s going to be possible to track without doing some sort of alignment if you’re using the scope in alt-az configuration because the motor speed will vary depending on which direction the scope is pointing. Once you’ve aligned it then it can calculate the speed at which to drive the motors. 

How do you know it’s not tracking? You might not be able to see or hear the scope moving whilst it’s tracking unless you’re actually looking through the eyepiece to see the star is movin (or not) in the FoV. On my LX200 (and on several Autostar equipped ETX’s that I’ve used) tracking begins automatically as soon as the alignment is completed. Check the tracking rate is set correctly on the handset- go to the Setup menu, scroll down to tracking and select sidereal.

[newbostonian]

An update after a first clear night experimenting with the Autostar handset.

Several drive training sessions have made the 2 star alignment process a bit more accurate. The stars that the 'scope finds are now just outside the field of view of the telescope at low power instead of several constellations away(!) but I wasn't able to correct the positions with the arrow keys and hit enter to confirm they were centrally in the field of view as the arrow keys aren't live during the process! Still a work in progress. I also still haven't managed to get the drive to track the object that I'm viewing, even if I've located it using the drive slewing/arrow keys. I've read a different pdf manual online that says to make the telescope start tracking an object, you have to do this: (1) find desired object (2) press "Object: Astronomical" on the handset menu, then (3) AFTER centering object in field of view press "Enter". So I will be trying that on the next clear night!

So far deep sky object views are good, stars OK, but the 'scope cannot focus a planetary disc to save its life even in the clearest good seeing conditions! I tried defocussing stars to get a collimation check pattern and the central dark area is slightly off-centre, so I will have a very careful go at adjusting with an allen key, but the oddest thing is that the bright concentric rings around the dark centre were crossed (at lower left in the field of view if I remember correctly) by a large dark triangular shape with a slim rod. If this was a Newtonian with a flat mounted on one side of the inside of the main tube, I would suspect that, but it's an SCT with a centrally-mounted secondary! I have no idea what this is and can't see any images online like this. Any ideas? Sorry I don't have the means to photograph it.

It was -7 degrees out there between midnight an 2am. I put the 'scope outside for a couple of hours before observing and it didn't fog up once. Neither did any of the eyepieces. My coffee froze(!). Just shows how cold my unheated Victorian house is. I'm not sure the 'scope needs any cool down time from house to outside here!    

[newbostonian]

On 13/12/2022 at 07:48, catburglar said:

I don’t think it’s going to be possible to track without doing some sort of alignment if you’re using the scope in alt-az configuration because the motor speed will vary depending on which direction the scope is pointing. Once you’ve aligned it then it can calculate the speed at which to drive the motors. 

How do you know it’s not tracking? You might not be able to see or hear the scope moving whilst it’s tracking unless you’re actually looking through the eyepiece to see the star is movin (or not) in the FoV. On my LX200 (and on several Autostar equipped ETX’s that I’ve used) tracking begins automatically as soon as the alignment is completed. Check the tracking rate is set correctly on the handset- go to the Setup menu, scroll down to tracking and select sidereal.

Thank you catburglar. Yes it was set to sidereal tracking and no the tracking wasn't going - objects drifted out of the field of view. I found out from a different old Meade LX90 catalogue that once you have an bject located you then have to set "Object:Astronomical", centre your chosen object and then press "Enter" for the tracking to start. I wouldn't have guessed you needed to call up that menu AFTER you already had an object in view, but I'm going to give that a try next time!