Astro-5 equatorial mount & Gotostar™ GoTo upgrade
Astronomica — +44 (0)1132 037240 — Gotostar was £349
Written: ~5 years ago

gotostar_eq5_m
The Astro-5 German equatorial mount is one of the better Chinese-made EQ5s out there, if this sample is indicative of the batch. Both the declination and right ascension worm drives were nicely adjusted out of the box (something I would otherwise tinker with first), indicating good quality control and an above average engineering standard for a product of this genre. The built-in illuminated polar alignment 'scope is a nice touch. This mount is quite capable of supporting a normal focal ratio Newtonian up to around 8-inches, or a conventional achromatic refractor to about 5-inches (though the extendible two-piece aluminium tripod will be a bit low for the latter).

Gotostar — fully-featured GoTo control for the masses
Given there are so many EQ5s out there like the Celestron CG5, the Meade LXD and the Orion SkyView Pro to name but three, it was only a matter of time before a versatile GoTo upgrade kit would come to fit them all (well, just about all — including the Vixen SP and GP, it would seem). The Chinese-made Gotostar is made by Nanjing IDEA S&T Co. Ltd. and distributed in the U.K. by Leeds-based Astronomica.

The rather funky-looking but certainly ergonomic Gotostar hand controller, 12V servo motors (with built-in encoders) for the declination and polar axes, power supply, mounting hardware, cables (including RS232 serial lead) and motor covers all come in one rather packed styrofoam box. All parts of the upgrade appear to be very well made. Sadly, no detailed printed assembly or user's manual accompanies the kit, but Astronomica assures me that comprehensive documentation is being produced at the present time. That said, if you have ever installed dual-axis motors on an EQ3-2 or EQ5 then installing the Gotostar will not pose a problem.

The Gotostar is fortunately intuitive to use even without documentation, so you can get to grips with the menu structure and navigate your way around the system quite easily. While the screen font is not the clearest, having an 8-line LCD display (128 x 64 pixel) is a distinct advantage over most contemporary GoTo hand controllers. The manufacturers extol the virtues of its 32-bit CPU, which does seem to give quick screen refreshes and menu updates. As for the built-in database, it claims in excess of 120,000 celestial objects. I loved the built-in clock that retains the date, time and geographical coordinates after power off — why can't all GoTo hand controls have an internal backup battery like this one?!

Here's another great feature: when you power up you don't have to align if you just wish to use the motors under manual control. You just hit a single key to toggle sidereal tracking on or off. The maximum quoted slewing speed is 4°/sec., which seemed about right from my tests. Are the motors noisy? If you're used to an HEQ5 or EQ6 Pro then the answer's yes. The supplied Gotostar motors also emit a curious buzz when tracking. I also found it was marginally noisier than a SynScan-driven EQ5 (yes, that review's also coming, folks) when slewing. However, judicious adjustment of the declination and right ascension motor gear meshing will alleviate some of the noise.

When it comes to alignment, you have three choices: one, two or three star (see update below). The first assumes that you have a good polar alignment, so some form of well-adjusted polar alignment 'scope or a drift method-calibrated mount is essential if you wish to use this option. The two-star alignment doesn't need an accurately polar aligned mount and will display the polar axis alignment error after you've performed it.

I found that if you have to traverse the meridian (in which case the OTA will perform an east-west swap to avoid cable wraps) then the alignment will suffer if your mount possesses cone error — an inherent divergence of the 'scopes optical axis from being orthogonal with the declination axis. You may have to make mechanical adjustments to the dovetail/tube rings to correct for this. However, the new three-star alignment option provides a software compensation for cone error.

All told, the pointing accuracy of the Gotostar / Astro-5 combination for stellar and deep-sky objects was pretty good (<0.5° error for targets less than 60° from an alignment object). The pointing accuracy can be significantly improved by 'syncing' to a nearby star, then performing a short GoTo hop from there.

Update(s)
It is possible to download firmware updates from Nanjing IDEA S&T Co. Ltd., but since I only have access to an Apple Mac computer I can't evaluate PC-based software at the present time. However, I'm indebted to fellow U.K. Gotostar user Chris Blaylock for using his PC to update this hand controller to the latest firmware. Lo and behold, three-star alignment is now possible!

Three PDF manuals from Astronomica are now available: Astro-5 setup, Gotostar installation and Gotostar quickstart user's guide.