Tracking on a celestron 127 slt

[Lipsmack]

The manual isn’t helping me troubleshoot my 127 slt. I have reset to factory settings but not much help. It doesn’t seem to be tracking at the correct rate. I have made sure the time/date/location/standard time is correct and it’s level and aligned. I made sure the altaz mount is checked using sidereal. This is the mount that came with the scope. I can hear it ticking as it is tracking. But my objects seem to move out of fov.  Exposures of 20-30 seconds are showing trails. I  tried using the hand controller and tied a SkyPortal WiFi and my phone of iPad for alignment - all verifying current location, date time etc are correct each time. (Using the gps on phone/iPad.) Still same slow tracking. How do I figure out how to adjust the tracking rate if possible. 

[happy-kat]

Hi

If using an eyepiece does the object stay in the field of view for observing?

If you are trying imaging then balance is another key factor and the 127 slt will be very demanding with the long focal length on the mount. Facing east or west below 60° will also help.

[SaberJeff]

You should set the tracking speed to 5.

[Cosmic Geoff]

Could you confirm that you are performing a GoTo star alignment? (On a Nexstar+ there will be Skyalign (IIRC), 2-star, 2-star auto 1-star and solar system align available.) If you complete the alignment properly, completing all the coarse/fine/accept steps, there is no reason why it should not track. The tracking speed can be set to siderial, lunar and solar in the menus.

[Paul M]

I've found the SLT mount to be "wanting" at best. OK for visual but it's useless for any kind of long exposure.

I even tried mine with an EQDir cable and connecting it to my imaging PC. I did actually manage to GOTO and take an image but trailing was truly dreadful. There is so much play and backlash in the primitive drive that, the technicalities of imaging with an alt-az mount notwithstanding, it's going to be a very frustrating time trying to image with it.

 

[Lipsmack]

10 hours ago, Cosmic Geoff said:

Could you confirm that you are performing a GoTo star alignment? (On a Nexstar+ there will be Skyalign (IIRC), 2-star, 2-star auto 1-star and solar system align available.) If you complete the alignment properly, completing all the coarse/fine/accept steps, there is no reason why it should not track. The tracking speed can be set to siderial, lunar and solar in the menus.

I am using the nexstar version 4 hand controller. I’ve tried skyalign, auto two star, and single star alignment. When I use the iPad sky safari and/or SkyPortal apps only 3 star skyalign is available. Tracking is set to sidereal. No matter what alignment process or controller, same results. 

Edited March 10, 2021 by Lipsmack

[Lipsmack]

14 hours ago, SaberJeff said:

You should set the tracking speed to 5.

How to change the tracking speed on the 127 slt on the 127 slt using nexstar version 4 hand controller or SkySafari/SkyPortal apps. I see the anti backlash adjustment and tracking mode, but not tracking speed. Are you meaning the slew rate speed?

[Lipsmack]

On 08/03/2021 at 02:38, happy-kat said:

Hi

If using an eyepiece does the object stay in the field of view for observing?

If you are trying imaging then balance is another key factor and the 127 slt will be very demanding with the long focal length on the mount. Facing east or west below 60° will also help.

When using just an eyepiece it is moving out of fov eventually. Especially if viewing large objects like Orion Nebula. Using a 90° diagonal and 25mm eyepiece it will move out of fov to the left. I know the image is flipped horizontally so not sure if that means the tracking is slow or fast depending on rotation of earth. As you can tell I am an extreme novice. I’ve had the scope 10 years and just now really getting into it. I have probably used it more this year than any previous 8. I thought it tracked better than what I am noticing now. Or maybe I just know a littlE more than before. I am not sure how to more accurately balance the scope to helP tracking. Especially if attaching my iPhone and NexYZ adapter to compensate for added weight. 
 

thanks for any advice. 

[happy-kat]

I have a virtuoso mount and for example if I don't make the mount very slightly weight bias to the rear when observing in the East direction then the mount doesn't track as well. If you remove the phone adapter does the tracking improve?

The key things are, is the tripod level, is the telescope balanced, and when aligning fine tune the object to being centred. Slew rate is the speed the mount will move when moving it with the directional buttons.

[Mick H]

7 hours ago, Lipsmack said:

How to change the tracking speed on the 127 slt

Press number 9 key and then the 5 key.

[Mick H]

For got to say this is the way to change the hand control arrow keys, also the tracing speed.

Press number 9 key and then select which speed  you want.

[Cosmic Geoff]

I don't know what's wrong, but even though the SLT is a rubbish imaging mount it should track well. I purposely tested mine and found it would keep an object in the low-power eyepiece field for literally hours.  I can see two possibilities: a mechanical fault, or you have not carried out the aligning procedure to completion.

It seems from your description that it it not tracking in azimuth. If this is a mechanical fault, then restraining or encouraging it with your hand may disclose the problem. (Note: the mount cannot normally be moved in azimuth by hand, while there is a slip clutch in altitude).  It may be that the mount is not tracking at all, which will cause objects to move out of field rapidly in a minute or two.  It is essential to complete the alignment procedure - with the handset you do the coarse align, then the fine align, finishing IIRC by pressing the ALIGN button, which should result in a message something like "Alignment Complete, Starpointer Off."

The handset may offer eqatorial alignment options, which you should not try to use.

[Lipsmack]

11 hours ago, Mick H said:

Press number 9 key and then the 5 key.

I believe that only changes the slew rate, not adjust a tracking speed once aligned. The scope is tracking per se but not correctly.  Image is moving slowly out of fov. 

[Lipsmack]

10 hours ago, Cosmic Geoff said:

I don't know what's wrong, but even though the SLT is a rubbish imaging mount it should track well. I purposely tested mine and found it would keep an object in the low-power eyepiece field for literally hours.  I can see two possibilities: a mechanical fault, or you have not carried out the aligning procedure to completion.

It seems from your description that it it not tracking in azimuth. If this is a mechanical fault, then restraining or encouraging it with your hand may disclose the problem. (Note: the mount cannot normally be moved in azimuth by hand, while there is a slip clutch in altitude).  It may be that the mount is not tracking at all, which will cause objects to move out of field rapidly in a minute or two.  It is essential to complete the alignment procedure - with the handset you do the coarse align, then the fine align, finishing IIRC by pressing the ALIGN button, which should result in a message something like "Alignment Complete, Starpointer Off."

The handset may offer eqatorial alignment options, which you should not try to use.

Yes I always complete the alignment method and get this message.  I very carefully level the mount before I install the ota and double check afterward. The scope does not turn manually in azimuth, but seems easily moved  in altitude by hand. Almost too much. But I am not sure if there is any tightening adjustment for that? How do you determine if the ota is correctly balanced?  

[Lipsmack]

11 hours ago, Mick H said:

For got to say this is the way to change the hand control arrow keys, also the tracing speed.

Press number 9 key and then select which speed  you want.

I believe that is the slew rate, not the speed adjustment to keep an object centered in the eyepiece after alignment.  I use that to fine tune an object when it is moving out of fov. 

[Cosmic Geoff]

It looks like the tracking can be turned off. See MENU/TRACKING/MODE/Off, Alt-Az, EQ North, EQ South.

The instruction manual confirms this, and states that 'Off' is for terrestial viewing.

If you do not have the instruction manual, I recommend that you locate and download it.

[Lipsmack]

7 hours ago, Cosmic Geoff said:

It looks like the tracking can be turned off. See MENU/TRACKING/MODE/Off, Alt-Az, EQ North, EQ South.

The instruction manual confirms this, and states that 'Off' is for terrestial viewing.

If you do not have the instruction manual, I recommend that you locate and download it.

Thanks. The point is I WANT it to track and object. I do have the manual and have searched it many times. But nothing is helping me troubleshoot. That is why I thought I’d try advice from others. 

[Cosmic Geoff]

2 hours ago, Lipsmack said:

Thanks. The point is I WANT it to track and object. I do have the manual and have searched it many times. But nothing is helping me troubleshoot. That is why I thought I’d try advice from others. 

So have you checked that the tracking is turned ON (Alt-az)?

[Lipsmack]

2 hours ago, Cosmic Geoff said:

So have you checked that the tracking is turned ON (Alt-az)?

Yes.  It is on altaz. It was the first things I checked.  It is aligning and it is “ticking “ when it is tracking. It just seems to be not tracking correctly.  Sorry I misunderstood your first post.  I thought you were telling me that I can turn it off. (Use it with no tracking)

 

I reset to factory settings and went back thru settings and manual. My location was set to almost 100 miles away where I purchased the scope.  After resetting everything I set my location on the handset to longitude and latitude. And when using the app I have verified that the locations and time  is correct.  I thought originally the distance of accurate location could be causing it not to track accurately. But it didn’t change anything. 

Edited March 11, 2021 by Lipsmack

[Paul M]

Have you ascertained which axis is drifting? Are both axes drifting?

Except for objects passing through your local meridian, tracking will be required in both axes. The further from the meridian that on object is the greater it's vertical motion. So objects in the east and west have as much, if not more vertical motion as horizontal. Perhaps only one axis is tracking? That would be weird given that both axes work during alignment, but you never know. I prefer Synscan to Nexstar and always need the manual when I'm looking for a setting. I just wonder if tracking is stuck in or reverting to EQ mode? Therefore only running the azimuth (RA) motor. 

I'll look at my SLT mount tomorrow and see if I can replicate any of this.

 

[Lipsmack]

4 hours ago, Paul M said:

Have you ascertained which axis is drifting? Are both axes drifting?

Except for objects passing through your local meridian, tracking will be required in both axes. The further from the meridian that on object is the greater it's vertical motion. So objects in the east and west have as much, if not more vertical motion as horizontal. Perhaps only one axis is tracking? That would be weird given that both axes work during alignment, but you never know. I prefer Synscan to Nexstar and always need the manual when I'm looking for a setting. I just wonder if tracking is stuck in or reverting to EQ mode? Therefore only running the azimuth (RA) motor. 

I'll look at my SLT mount tomorrow and see if I can replicate any of this.

 

Thanks. We are enduring cloudy days and rain over the weekend. The next time I align I will make a definite note of any particular direction. I think it is drifting out of fov to the left (on a 90° diagonal.  All the advice I have gotten here means I need to make more notes on the drift. But until these clouds get out of here I have nothing to lock on. 🤨

[SaberJeff]

You should upgrade the firmware of the handset to the latest version.

[Mick H]

 

On 08/03/2021 at 06:07, Lipsmack said:

The manual isn’t helping me troubleshoot my 127 slt. 

Another thought, How are you powering the scope?

[Paul M]

I just had a gallop round my SLT handset.

It sounds like the OP has got everything covered that I can find. The main points being Tracking Rate = sidereal and Tracking Mode = Alt-Az.

I've found with my mount that rather than track incorrectly when the batteries get low, the handset reports motor faults and sulks.

Will be interesting to find out if only one or both axes are tracking when the sky clears up.

[Lipsmack]

15 hours ago, Mick H said:

 

Another thought, How are you powering the scope?

I have tried the 8aa battery pack. But I recently have used a 12 v power bank. I have never tried ac power. 

Edited March 13, 2021 by Lipsmack