Sky-Watcher HELIOSTAR 100 H-alpha Solar Telescope

Designed for serious solar observers and H-alpha imaging enthusiasts, the Sky-Watcher HELIOSTAR 100 H-alpha Solar Telescope combines a 100 mm aperture with a 760 mm focal length, providing an f/7.6 focal ratio.

Its bandwidth of less than 0.5 Å isolates the hydrogen H-alpha line at 656.28 nm, revealing the dynamic structures of the solar atmosphere in fine detail.

100 mm Aperture for Solar Observation

With its 100 mm aperture, the HELIOSTAR 100 H-alpha is designed for detailed solar observation and imaging.

In H-alpha light, it reveals prominences around the solar limb, active sunspot regions, bright plage areas, plasma filaments and other structures visible across the solar surface.

Bandwidth Below 0.5 Å

The H-alpha system selects light around the 656.28 nm hydrogen wavelength while blocking light at other wavelengths.

With a bandwidth below 0.5 Å, the HELIOSTAR 100 H-alpha provides highly selective spectral filtration designed to reveal characteristic H-alpha solar structures.

Solis Etalon Technology

Sky-Watcher uses its Solis etalon technology to achieve a bandwidth of 0.5 Å or better with a single etalon system.

According to Sky-Watcher, this design provides detailed solar-disk images directly out of the box without requiring a second etalon to achieve the same bandwidth performance.

Pressure Tuning

Etalon adjustment is performed through a pressure-tuning system.

This allows the H-alpha system to be finely adjusted to optimise the contrast of solar structures according to observing conditions.

Protection Against Unwanted Radiation

The HELIOSTAR 100 H-alpha uses several filtering technologies designed to protect the observer during solar viewing.

The system incorporates an infrared thermal reflection film, a dedicated heat-blocking filter and a filter designed to prevent ultraviolet and unwanted stray light from entering the optical system.

Front and rear filters work together to transmit only the selected H-alpha wavelength.

20 mm Blocking Filter

The removable solar diagonal incorporates a 20 mm blocking filter forming part of the HELIOSTAR 100 H-alpha safety system.

Sky-Watcher specifically states that the telescope must not be used with another type of diagonal because the integrated blocking filter is an essential part of the solar filtration system.

Solar Guider

The HELIOSTAR 100 H-alpha is supplied with a solar guider for safely aligning the telescope with the Sun without looking directly towards it.

This accessory makes initial pointing and centring of the solar disk easier.

7.6 mm Solar Image at the Focal Plane

With its 760 mm focal length, the HELIOSTAR 100 H-alpha produces a 7.6 mm solar image at the focal plane.

This value is specified directly by Sky-Watcher for this model.

22 mm Wide-Angle Eyepiece

A 22 mm 1.25-inch eyepiece with a 70° apparent field of view is supplied with the telescope.

It provides 34.5× magnification with the 760 mm focal length of the HELIOSTAR 100 H-alpha.

Construction and Installation

The optical tube weighs 6 kg and has a length of 760 mm.

The telescope is designed as a complete solar instrument for both visual observation and H-alpha imaging.

Technical Specifications

• Manufacturer : Sky-Watcher

• Model : HELIOSTAR-100Hα

• Type : H-alpha solar telescope

• Aperture : 100 mm

• Focal length : 760 mm

• Focal ratio : f/7.6

• Bandwidth : less than 0.5 Å

• H-alpha wavelength : 656.28 nm

• Etalon technology : Solis

• Tuning method : Pressure tuning

• Blocking filter : 20 mm

• Solar image size at focal plane : 7.6 mm

• Back focus specified by Sky-Watcher : 20 mm

• Supplied eyepiece : 22 mm

• Eyepiece apparent field : 70°

• Magnification with supplied eyepiece : 34.5×

• Eyepiece size : 1.25 inch

• OTA weight : 6 kg

• OTA length : 760 mm

• Infrared protection : Yes

• Thermal protection : Yes

• Ultraviolet protection : Yes

• Solar guider : Supplied

• Solar diagonal : Supplied

• Safety compliance : ISO 12312-2:2015

Package Contents

• Sky-Watcher HELIOSTAR 100 H-alpha solar telescope

• 22 mm 70° wide-angle eyepiece

• Solar diagonal with 20 mm blocking filter

• Solar guider