Sky-Watcher Heliostar 76Ha Solar Telescope

Sky-Watcher Heliostar 76mm Overview

The Sky-Watcher Heliostar 76mm H-Alpha Solar Telescope is a precision-engineered, dedicated solar telescope optimized for narrowband Hydrogen-alpha (Hα) observations at 656.28 nm. Designed to reveal detailed chromospheric activity—including prominences, filaments, plages, sunspots, and surface granulation—this instrument provides sub-0.5Å bandpass performance without the need for costly double-stacking configurations.

• Aperture: 76mm (3")
• Tuning Method: Mechanical pressure tuning via Trifid Tuner
• Filter System: Internally integrated Solis™ etalon with <0.5Å bandpass
• Blocking Filter: 11.5mm, integrated into proprietary diagonal (non-removable)
• Focuser: Dual-speed 2" Crayford-style for precise critical focus control
• Eyepiece Interface: 1.25” format, supplied with 20mm 70° wide-angle eyepiece

Trifid Tuner – Precision Etalon Control

At the core of the Heliostar 76mm’s performance lies the Trifid Tuner, Sky-Watcher’s proprietary mechanical tuning system for its internal Solis™ etalon. Unlike tilt-tuned systems that adjust the angle of incidence to shift the transmission bandpass—often introducing optical aberrations and image shift—the Trifid Tuner employs a non-tilting, axial compression method.

This design uses three evenly spaced support veins arranged in a trident-like configuration (hence "Trifid") to apply uniform mechanical pressure to the etalon plates. This pressure modifies the optical path length between the etalon’s parallel surfaces, finely tuning the transmitted wavelength of light without disturbing collimation or introducing off-axis distortions.

Advantages of the Trifid Tuner system

• Precise central wavelength tuning within the Hα emission line at 656.28 nm
• Maintains image centering and flat field - avoids shifting or vignetting caused by tilt-tuning
• Increased structural rigidity - mechanical stress is distributed symmetrically to avoid damage or drift
• Compensates for Doppler shifts and atmospheric pressure variations in real-time observing conditions

The Trifid system is optimized for both visual and imaging applications, providing solar observers with a stable and consistent tuning experience. The absence of tilting components also contributes to the long-term mechanical durability of the etalon assembly.

Certified Safety and Compliance

Each unit undergoes individual solar testing on the Sun and conforms to ISO 12312-2 safety standards for direct solar observation. The included blocking filter is integral to the system’s safety design and must not be substituted. Misuse of this instrument outside of intended solar observation can result in permanent eye damage.