Astrophotography has a way of producing cables. The first camera needs one, then comes the guide camera, the focuser, the filter wheel, power, and finally a computer sitting on a folding table beside the tripod. Before long, half the night's wiring is hanging between something that moves and something that doesn't.
The C402AN3 CEM40-NUC takes a much cleaner approach. Put the computer on the mount.
A mounting plate at the front of the 6" dual saddle accepts a slim Intel NUC or similar compact computer up to 38mm thick. Power for the computer, Ethernet, and USB can be routed through the mount, so the machine controlling the cameras moves with the telescope instead of sitting on the ground beneath it.
Underneath all of that is the standard CEM40: a 40-pound-capacity center-balanced equatorial mount with internal iPolar, Permanent Periodic Error Correction, GPS, and the same belt-driven worm system used throughout the CEM40 family. This package adds the 1.75" LiteRoc tripod, a 5 kg counterweight, and a fitted hard case.
If you already know a mini computer is going to run your imaging system, the attraction is fairly simple. The C402AN3 gives it a proper place to live.
Put the Computer Where the Telescope Is
There are plenty of perfectly good ways to control an imaging rig. A laptop can sit beside the tripod. A mini PC can be strapped to the optical tube. A small control box can ride on an accessory plate.
The NUC version simply builds that arrangement into the mount from the beginning.
The computer sits at the front of the saddle, close to the cameras and accessories it controls. USB can be routed through the mount, and Ethernet passes through the mount as well. That means far fewer long cables have to cross the RA and DEC axes on their way to equipment sitting on the ground.
The difference becomes particularly noticeable as the mount slews across the sky or approaches the meridian. A cable that looked perfectly harmless while the telescope was pointing east can suddenly become very interesting when everything swings west. Keeping the computer and much of the wiring on the moving side of the system removes a lot of that opportunity for trouble.
It also makes a system easier to leave assembled. Camera cables can stay with the telescope rather than being rebuilt from scratch every clear night.
A Word About the NUC Power Connection
The NUC power connection deserves a little explanation because it is easy to misunderstand.
The mount does not take its normal 12V supply and convert it into 19V for the computer. The NUC connection is a pass-through. You connect the proper power supply for your computer at the mount, and that voltage is carried through the mount to the connection at the saddle.
iOptron originally designed the system around slim Intel NUCs that commonly use 19V, although some later computers use different voltages. Always use the supply specified for the computer you install.
There is also a separate 12V input for three auxiliary power outlets at the saddle, with a total capacity of 5A, along with another 12V output from the mount's main supply rated up to 3A. That gives you useful options for cameras and accessories without pretending the mount is an unlimited power-distribution box.
The basic idea is not that the cables disappear. They simply have a much better route.
The CEM40 Underneath It
The NUC hardware adds a little weight, bringing the mount head to about 18 pounds (8.2 kg), but the CEM40's published payload remains 40 pounds (18 kg), excluding the counterweight. The computer and its mounting hardware are part of that payload, along with the telescope, cameras, focuser, guider, filter wheel, and everything else riding on the saddle.
Both axes use 110mm, 216-tooth worm wheels driven by 17mm brass worms through synchronous belts. iOptron specifies the standard CEM40's periodic error at less than ±7.5 arcseconds over its 400-second worm cycle, and Permanent Periodic Error Correction lets the mount store a trained correction for the repeating part of that error.
This is the standard CEM40 rather than the encoder-equipped CEM40EC, so for demanding long-exposure imaging I would plan to autoguide it. That is not unusual. A good guide camera and PHD2 have been part of successful astrophotography systems for a long time.
If you specifically want the high-resolution RA encoder and Real-Time Periodic Error Correction, the C404AN3 CEM40EC-NUC is the version to look at. If you are already going to guide and would rather spend the difference elsewhere in the imaging system, this version gives you the same NUC-ready layout on the standard CEM40.
Everything Has Somewhere to Go
The C402AN3 includes iOptron's 1.75" stainless-steel LiteRoc tripod, which weighs about 15.4 pounds (7 kg). Compared with the lighter 1.5" tripod offered in some CEM40 packages, the LiteRoc puts a little more support underneath a system that is likely to carry a computer, cameras, and a fairly complete imaging train.
One 5 kg (11 lb) counterweight is included on the 28mm stainless-steel shaft. Depending on the telescope and where its center of gravity falls, additional counterweight may be needed as the system grows.
The 6" saddle accepts both Losmandy D and Vixen-style dovetails, so you are not tied to one rail system.
Internal iPolar handles polar alignment. Its camera photographs and plate-solves the sky around the celestial pole and shows you how to adjust the mount. Polaris itself does not have to be visible, although enough surrounding polar sky must remain unobstructed for the camera to solve successfully.
GPS supplies time and location information, automatic zero-position search gives the mount a known mechanical reference, and power-down memory helps preserve where the system was between normal shutdowns.
Features
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NUC-ready saddle. Mounts a slim Intel NUC or similar computer up to 38mm thick at the front of the 6" saddle.
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NUC power pass-through. Routes the computer's proper external power supply through the mount to the saddle.
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Ethernet pass-through. Carries a wired network connection through the mount.
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USB 2.0 hub and cable management. Keeps computer and accessory connections close to the telescope.
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40 lb (18 kg) payload capacity. Payload excludes the counterweight but includes the computer and all other equipment riding on the mount.
- 18 lb (8.2 kg) mount head.
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Permanent Periodic Error Correction. Stores a trained correction for the repeating component of the RA worm error.
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Periodic error below ±7.5 arcseconds. iOptron's published specification over the 400-second worm period.
- Internal iPolar electronic polar scope.
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1.75" stainless-steel LiteRoc tripod. Approximately 15.4 lb (7 kg).
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5 kg (11 lb) counterweight and 28mm stainless-steel shaft included.
- 6" Losmandy D / Vixen dual saddle.
- 32-channel GPS, automatic zero-position search, and power-down memory.
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Go2Nova hand controller with built-in heater and 212,000+ object database.
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Fitted hard case for the mount head included.
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Optional Wi-Fi. iOptron's external iStarFi adapter can add direct wireless mount control.
- Two-year limited warranty.
What Owners Say on Cloudy Nights
The CEM40-NUC never became the most common version of the CEM40, so there is less owner discussion than there is for the standard mount. The people who did choose it, however, tend to come back to the same feature that makes the design interesting in the first place.
"I found the cable management to be very useful."
That particular owner had first used the CEM40EC-NUC and later moved to the non-encoder CEM40-NUC. He even modified the NUC plate to carry an ASIAIR Pro instead of an Intel computer.
That is a useful real-world example because it shows what the NUC version really gives you. The value is not limited to one particular Intel computer. It is the location of the mounting plate and the power, network, and USB connections beside the saddle. Different computers may require their own mounting solution, so dimensions and hole patterns should be checked before assuming something other than a recommended NUC will bolt directly on.
Under the Night Sky
A computer-controlled CEM40 becomes especially pleasant on the nights when astrophotography stops being about a single exposure and starts becoming about collecting hours.
Put a small refractor on it and the winter sky offers the Jellyfish, the Rosette, the Seagull, and the faint outer structure around familiar Orion targets. Summer brings the North America and Pelican, the Cocoon at the end of its long dark lane, and the enormous emission fields around Sadr.
The computer does not make any of those objects brighter. What it does is let the system repeat the boring parts for you: slew, plate-solve, guide, refocus, change filters, and collect one exposure after another while you are somewhere warmer.
That is where a clean on-mount computer arrangement stops being cosmetic and starts being useful.
What's Included
- 1x iOptron CEM40-NUC Center-Balanced Equatorial mount head
- 1x Internal iPolar electronic polar scope
- 1x 6" Losmandy D / Vixen dual saddle with NUC mounting adapter
- 1x Go2Nova hand controller with built-in heater
- 1x iOptron 1.75" stainless-steel LiteRoc tripod, approximately 7 kg (15.4 lb)
- 1x 5 kg (11 lb) counterweight
- 1x 28mm × 280mm stainless-steel counterweight shaft
- 1x Fitted hard carrying case for the mount head
- 1x 100–240V AC adapter for the mount, for indoor use
- Mount connection accessories
Intel NUC or other control computer and its power supply are not included.
FAQ
- What is different about the C402AN3?
- It is the standard CEM40 packaged with iOptron's NUC-ready saddle and enhanced cable-management system. A compatible mini computer can ride at the saddle with power, Ethernet, and USB routed through the mount.
- Is an Intel NUC included?
- No. The mounting plate and through-mount connections are included, but the computer and its power supply are purchased separately.
- What size NUC fits?
- iOptron designed the mounting plate for slim Intel NUCs up to 38mm thick. Other mini computers may fit physically, but mounting-hole patterns can differ, so check dimensions and mounting requirements before ordering.
- Does the mount generate 19V for the NUC?
- No. The NUC power connection is a pass-through. Connect the proper power supply for your computer to the NUC power input on the mount, and that voltage is routed to the saddle.
- CEM40-NUC or CEM40EC-NUC?
- Both use the same basic NUC-ready idea. The CEM40EC-NUC adds a high-resolution RA encoder with Real-Time Periodic Error Correction. This CEM40-NUC uses conventional PPEC and costs less. If you plan to guide anyway and do not need the encoder, this is the simpler choice.
- Do I need to autoguide?
- For demanding long-exposure astrophotography, yes. The standard CEM40 provides Permanent Periodic Error Correction but does not have the high-resolution RA encoder found in the CEM40EC.
- How much can it carry?
- iOptron rates the mount for up to 40 lb (18 kg), excluding counterweights. The NUC, mounting hardware, telescope, cameras, focuser, guider, filter wheel, and other equipment riding on the saddle all count toward that payload.
- How do I connect to the computer?
- That depends on the computer and your network. The mount provides Ethernet pass-through, while many mini computers also have their own Wi-Fi. Remote-desktop software can then be used to control the imaging computer from another device.
- Does the mount itself have Wi-Fi?
- Not built in. The mount communicates over USB, and iOptron's optional iStarFi adapter can add direct wireless mount control.
Accessories
A compatible slim Intel NUC or mini computer (sold separately): provides the computer that rides on the saddle and runs the imaging software.
Guide camera and guide scope or off-axis guider (sold separately): provides conventional autoguiding for long-exposure imaging.
Electronic focuser (sold separately): allows the control computer to refocus automatically as temperature and conditions change.
iOptron 2.5 kg #8027-05 Counterweight (sold separately): useful when the complete imaging system requires more balancing weight than the included 5 kg counterweight provides.
iOptron iStarFi Wi-Fi Adapter (sold separately): adds direct wireless mount communication.
Final Thoughts
The C402AN3 is for the imager who knows the telescope is eventually going to have its own computer.
Instead of putting that computer on a table under the tripod and running another collection of cables up to the telescope, iOptron gave it a place at the saddle and routed power, Ethernet, and USB through the mount.
Underneath that cable management is still the standard CEM40: 40 pounds of payload capacity, internal iPolar, PPEC, GPS, a 1.75" LiteRoc tripod, 5 kg counterweight, and hard case.
If you're happy to autoguide and don't need the encoder in the CEM40EC-NUC, this version gives you the part of the NUC design that may matter most every night: a cleaner imaging system with the computer riding where the work is happening.
