Accessories
Star-test and collimate your telescope anytime, anywhere. Five precision pinholes (50/100/150/200/250 microns) let you instantly find the best star for your particular telescope at any distance and lighting environment.
$27-$32 USD
To accurately test and collimate reflectors, catadioptric telescopes, and refractors, you must perform a star test. Sadly, a real star is not always available due to poor weather conditions or location. Even when a star is available, you need a good tracking system because the star is always moving. Air turbulence may affect your test, and the real star may not reveal the true quality of your telescope or give you a perfect collimation. Traditional artificial stars require many different sizes for different telescopes of different apertures and focal ratios, different distances, and different lighting environments.
The innovative Hubble 5-Star Artificial Star has 5 bright white LEDs with 5 precision pinholes (50/100/150/200/250 microns), enabling accurate star testing across virtually all telescope types — from small refractors to fast, large-aperture Newtonians — when paired with the appropriate pinhole and setup distance. The multi-star design also lets you compare pinhole sizes side-by-side and adapt quickly when your available distance isn't ideal. Simply choose the smallest star that gives a clear defocused image, then mask out any 4 of the 5 stars with the provided magnetic mask. Works in any lighting condition, day or night.
The artificial star must be placed far enough away that the pinhole appears smaller than your telescope's Airy disk. Larger apertures need significantly more distance — a 4" refractor works at just a few meters indoors, while a 20" telescope typically needs tens of meters for basic collimation and 50 meters or more for a clean, high-quality star test (especially on fast f/3–f/4 systems). If in doubt, start far and move closer until the defocused image is clean but still bright.
For a valid star test, the pinhole must appear as an unresolved point — smaller than your telescope's Airy disk. If the pinhole is resolvable, you're imaging a disc instead of a point source, and the diffraction pattern will not be clean. This is exactly why fast, large-aperture systems (f/3 – f/4) need the tightest 50-micron pinhole: a single commercial 50-micron laser-drilled hole typically runs $40+ on its own.
Start with the smallest pinhole that gives a clear defocused image, then use the magnetic mask to isolate it by covering the other four. Fast or large apertures usually need 50 microns; slower or smaller scopes can use a brighter 150–250 micron star at shorter distances.
Powered by 3 AAA batteries (not included). Insert batteries and switch on. Keep the mask clean and use only when needed to prevent blockage of the pinholes. Store in a Ziploc bag when not in use, separated from the magnetic mask. There are no printed instructions in the package.
Star Testing Astronomical Telescopes, Second Edition
by Harold Richard Suiter — a must-have reference.
Build Your Own Telescope
by Richard Berry — includes an excellent chapter on the star test.
For the full set of setup physics, aperture-vs-distance calculations, and additional test notes:
Detailed Setup & Theory Guide (PDF)
"This little thing is fabulous value for the few dollars you are charging. I've been contemplating various other types of artificial star gadgets, but, they all seemed so expensive. This little guy is simplicity in itself, and does the job fabulously. Extremely good value at the price you are selling it for."
"My SCT was collimated better than it's ever been that night, and, I did the collimation in broad daylight."
"The best $20 astronomical investment I have ever made."
"I measured the holes using a scanning electron microscope at work... The microscope can reliably measure down to less than 10 nanometers (0.01 micrometers). Considering a single 50 micron laser drilled hole in stainless steel disc (unmounted and no LEDs) can run $40-50 from commercial suppliers here in the US, this is a fantastic bargain!"
"Your 5-Star Artificial Star is GREAT! I've never had an easier time collimating my SCT. Thanks for a great product."
"It's the best astro tool that I ever bought... In my opinion, it looked much better than a real star."
"Achieved the best collimation I have had in a long time..."
"Great product, good price! I wish I had bought this sooner!"
"Great little item! Collimation's a snap with this tool."
"Every telescope user should have one."