The Coronado P.S.T. (Personal Solar Telescope) is a dedicated hydrogen-alpha solar telescope designed and tested by Meade Instruments to provide safe viewing of the Sun. It is specifically engineered for amateur astronomers interested in observing solar features in the H-alpha wavelength.
Function Description:
The Coronado P.S.T. is a specialized solar viewing instrument that allows users to observe the Sun's chromosphere, including features like prominences, active regions, filaments, sunspots, and granulation. It operates by filtering sunlight to a very narrow bandpass around the hydrogen-alpha line (6562.8 Angstroms), which is crucial for revealing these dynamic solar phenomena. The system consists of two critical parts: an etalon filter and a blocking filter. The etalon filter may be mounted at the front of the telescope or internally, while the blocking filter is mounted at the back, typically within a dedicated diagonal that also holds the eyepiece. Both components must be properly installed for safe solar viewing.
The telescope features an internal Sol Ranger™ Sun spotting device, which aids in aligning the telescope with the Sun. A small pinhole on the front face projects a harmless ball of light onto an opaque window on top, indicating proper alignment when the light ball is near the center.
The P.S.T. is equipped with a tuning mechanism, the RichView™ tuning ring, which allows for minute spectral adjustment of the etalon filter. This adjustment compensates for detuning caused by changes in operating conditions, such as barometric pressure, and helps optimize contrast for various solar features. Different features on the Sun are Doppler shifted, requiring slight tuning adjustments to achieve the best high-contrast views.
Important Technical Specifications:
- Aperture: 40mm
- Focal Length: 400mm
- Focal Ratio: f/10
- Bandwidth (Single Stacked): <1 Å
- Bandwidth (Double Stacked): <0.5 Å
- Thermal Stability: 0.005 Å/°C
- Blocking: Full blocking >10⁻⁵ EUV to far IR
- Etalon Clear-Aperture: 30mm
- H-alpha Wavelength: 656.3nm or 6562.8 Angstroms (1nm = 1 billionth of a meter)
- Angstrom (Å): Unit of measurement for the wavelength of light (1Å = 0.1nm)
- Bandpass: A filter's bandpass tells how wide a region of the light spectrum is transmitted around the primary wavelength.
- E.R.F. (Energy Rejection Filter): Prevents UV and IR light from entering the telescope.
- Etalon: The heart of a Coronado filter, composed of optics with tolerances 4 times tighter than those used in the Hubble telescope.
Usage Features:
- Safety First: The manual emphasizes that looking at the Sun can be very dangerous without proper precautions and specialized solar viewing equipment. Users are warned never to look directly at the Sun with their eyes or through unfiltered optical systems. All Coronado instruments are tested and sealed as complete, safe, and working units. Disassembly voids the warranty and can compromise safety.
- Mounting: The PST has ¼ -20 mounting threads on the bottom, compatible with most standard photographic mounts and mounting hardware, as well as piggyback mounting systems. A vixen-style dovetail rail (#07932) can also be attached for use with mounts featuring a vixen-style dovetail receiver.
- Alignment (Finding the Sun): The internal Sol Ranger™ allows for easy alignment. The telescope is properly aligned when the light projected from the pinhole onto the opaque glass window forms a small, harmless ball of light, ideally near the center.
- Tuning and Focusing: The focusing knob is used to achieve a sharp solar disk. The RichView™ tuning ring (knurled rubber ring) allows for minute spectral adjustment of the etalon filter to enhance contrast for specific solar features. The maximum rotation of the adjustable tuner is approximately 130°, and excessive force should not be applied.
- Double Stacking: The PST can be "double stacked" by adding an optional Coronado SME-40 double stacking filter to the front. This narrows the bandpass to <0.5Å, increasing contrast and providing a spectacular 3D effect with enhanced surface detail. When double stacking, the external RichView™ Tuner on the SME-40 is adjusted for best contrast, and then the internal RichView™ tuning ring is fine-tuned.
- Eyepieces: The PST uses a 1.25" eyepiece holder. Coronado offers CEMAX Eyepieces (25mm, 18mm, 12mm) and a 2x Barlow, specifically designed for H-alpha observing, with optimized coatings to enhance contrast and minimize glare.
- Dark Cloth: Using a dark cloth over the head and eyepiece can reduce incidental light, improving viewing contrast.
- GOTO and Tracking: Meade AutoStar or AudioStar equipped mounts can be "mock aligned" in the daytime to enable motorized tracking of the Sun. Selecting Mercury from the database after mock alignment can guide the scope to the Sun's vicinity.
- Perception of Detail: H-alpha light is in the red end of the spectrum, and eyes may not initially be very sensitive to it. Observers report that perception of detail improves with time and experience.
Maintenance Features:
- Cleaning: Loose dirt particles on the filter surface should be gently "swept" clean with a static-free lens brush. Fingerprints and other residue can be cleaned with a high-grade optical solution applied to an optical tissue, working from the outside edge towards the center with a circular motion. A static-free lens cloth should be used for finishing. Users are explicitly warned against using compressed air, acetone, acidic properties, non-optical cleaning fabrics, or household cleaners on any part of the filter.
- Care and Storage: The telescopes and filters are designed not to degrade with exposure to the Sun's rays and can be left set up and tracking all day. When not in use, the system should be stored in its foam-lined case in a cool, dry location with all protective caps securely in place. In humid environments, a silica packet in the box is advised. The system uses hard coatings for uniform performance over many years. It is safe to carry filters on airplanes and through X-ray machines.
- Warranty & Registration: Meade Instruments provides a limited warranty for Coronado products, with details available on their website. Product registration is encouraged to receive updates and important information.
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