Even cheaper than the solarquest (and in my opinion far more reliable) would be a simple clock-drive eq mount.
With such kind of device you have basically to worry only about the drift due to azimuthal error of your PA because if level the tripod and align the mount by night through its polarscope once do not have to worry anymore about altitude error unless mess with the polar wedge (which is not something you should do anyway).
Then aim the Sun and will know that only have to nudge the azimuth knobs if notice it drifts (which is something you can do without prejudice even while observing once the Sun reaches the S quadrant).
It has been several years since the last partial eclipse here in Italy but remember I used a TAL 100/1000 refractor with my clock-driven mount and it kept the Sun in the fov of the eyepiece (I used a 12mm/60°) for the whole event.
Anyway, to your question, which I assume is limited to alt/az gotos (for eq gotos applies the same above), I believe that a big role is played by the model employed by the mount.
6-7 years ago the Synscan was very coarse (almost a beta!) if compared to Celestron's Nexstar (which is not the state of the art either, but probably good enough for the majority of us, especially with smallish telescopes): being not a software engineer I can not tell why, but since one of the most striking issue was how quickly the goto accuracy deteriorated I believe it was most likely a consequence of a very basic model.
I do not know if or how much it has been improved, nor if using a gps unit would do any good (if the model uses very rough approximations I assume there is little need for great accuracy when entering time and place), but in any case I do not think the starsense would help (again, as far as I remember this thing needed a pretty dark sky to work as advertised).
Personally have a roughly ten years old SLT, and in the past have used it for low level solar system imaging (3.5" mct and 4" refractor, with focals around 2200mm) but do not remember much, except that I was amused to see how rough and uneven looked its tracking if observed on the laptop screen; If temperature get a bit cooler (now we have 38-40° C, and neither I nor the SLT are willing to test our mettle) I will gladly take it out for a run
I have noticed some deterioration in GOTO accuracy with extended use. I assumed that this was due to the mechanical limitations of the entry-level GOTO mount, and not due to any software problems. Even with StarSense though, it is recommended to periodically realign the mount to maintain accuracy but you probably do not want to do this in the middle of an eclipse.
I don't like SynScan, but the Celestron StarSense for Sky-Watcher is sold out until at least October 2022. Adding StarSense should improve the alignment accuracy for both daytime and nighttime use.
Regarding SynScan Daytime Alignment, I think this was a new feature that was added in the excitement leading up to the 2017 Solar eclipse in the USA so that SynScan mounts could be aligned in the daytime for Solar eclipses. However as far as I know, SynScan Daytime Alignment is still exclusively available only on SynScan altazimuth mounts, and not available at all on SynScan equatorial mounts. The fact that Sky-Watcher hasn't been able to figure out how to align a SynScan equatorial mount on the Sun is troubling since NexStar equatorial mounts have been able to do this for a while, and both NexStar and SynScan are built by the same company (Synta). The only way to align a SynScan equatorial mount in the daytime is using the Celestron StarSense Solar System Alignment for Sky-Watcher, but a SynScan altazimuth mount can use either the SynScan or NexStar alignment routines in the daytime.
Since the StarSense is currently unavailable, I have to fully test out the StarSeeker within the 30-day return period without using StarSense. I thought about trying to hold the order for the StarSeeker until the StarSense was also available, so that I could order them together, but I decided that it might be better to make sure that I have a fully functional mount without needing any additional add-ons such as StarSense. As far as I can tell, the mount is working correctly. I can find and track Venus in the daytime, and I can track the Sun for at least a few minutes at a time. That might be good enough, especially since my calculations indicate the Solar tracking error is small enough to not affect long exposures of the Solar corona during totality. So the mount seems to be functional with just the SynScan Daytime Alignment, but the accuracy should be improved by adding StarSense at a later date.
The point of this thread was to try to figure out if there were any mounts that I could exchange the StarSeeker for to get better tracking of the Sun without needing a Solar autoguider, setting up the mount at night, or using StarSense. Unless there are software differences in the daytime alignment between SynScan and NexStar like you suggest, without any data on the Solar tracking from any other mounts, my gut says that all GOTO mounts will likely have about the same amount of daytime tracking error since all of the mounts will be aligned on the same object (the Sun) with about the same amount of initial alignment error, regardless of the cost or superior mechanical design of the mount.
The only big difference is that NexStar mounts can be realigned without needing to return to a home position first. This allows for example to align on the Sun, then GOTO Venus, and then realign on Venus for better accuracy. I can't do this with SynScan unless I add the StarSense to use the NexStar alignment instead. SynScan can only align on the Sun.
A GPS may help slightly. I am not sure what portion of the 0.6 arcseconds per second tracking error is due to the manual time entry (which should be accurate to within a second or two).
Celestron StarSense consists of the StarSense camera and the StarSense handcontroller. You do not use the StarSense camera in the daytime. You use only the StarSense handcontroller without the camera attached. The StarSense Solar System Alignment allows you to align on multiple objects in the daytime. For example, you can have a three-object alignment using Sol, Luna, and Venus for much better accuracy than you can get with an alignment on just one single daytime object. You align on the Sun, then GOTO Venus. On NexStar, you would have to replace the initial alignment with a new alignment on Venus. On StarSense, you can instead add Venus as a second alignment point within the current alignment. I think you can add up to 10 different alignment points (objects) in the daytime, which is probably more than you can see. I was able to find Vega in the daytime last year but I don't think you can add stars (other than Sol) to a Solar System Alignment.
Sky-Watcher tests all of their mounts to make sure that they work from 0 degrees Fahrenheit (-17 degrees Celsius) to 120 degrees Fahrenheit (48 degrees Celsius). Sky-Watcher and Celestron are the same company (Synta) so Celestron mounts should be able to tolerate a similar temperature range. I was operating the StarSeeker at 100 degrees Fahrenheit (38 degrees Celsius) without any problems but did not test it in any temperatures below freezing (32 deg F or 0 deg C) last year. On a hot day, you should set up the mount on grass and not on pavement though.
I am using a 1000/90 MCT so have a wider field of view than you might have with a 1250/90 MCT. I had thought about upgrading to a 1300/102 MCT for the upcoming annular Solar eclipse, but this seems like a bad idea unless I have a Solar autoguider to keep the Sun centered in the field of view. I added the 2X Barlow and was able to track Venus at 2000/90. The drift is primarily an inconvenience but it means that frames will have to be aligned before they can stacked or time-lapsed. The other problem is that if you walk away from the mount for too long, you lose the alignment, which is also an annoyance.
NexStar would be easier to use out of the box, but I can still use NexStar alignments on the StarSeeker if I add the StarSense adapter, so that might not be a good reason to exchange a SynScan mount for a NexStar mount if the SynScan mount is mechanically superior. The biggest problem with Celestron is that none of the NexStar altazimuth mounts can go to zenith with a DSLR camera (not even the 90SLT). So switching from SynScan to NexStar might mean getting an AVX instead, but that would be a lot heavier and less portable than a StarSeeker.
I bought the Celestron NexStar 90SLT last year but didn't measure the Solar tracking error before I returned it due to the clearance issue (unable to go to zenith). Let me know if you get anything similar to the Orion StarSeeker (Sky-Watcher Star Discovery).
Edited by Nicole Sharp, 08 August 2022 - 07:03 PM.