Celestron Telescope Astrograph S 203/400 RASA 800 CGEM II GoTo (62859)

The RASA 800 Astrograph is designed to simplify astrophotography while delivering stunning results with modern DSLR, mirrorless, or astronomical CCD cameras. Its advanced optical design features a four-lens corrector made from rare earth glass, minimizing chromatic aberrations, coma, and field curvature. This ensures exceptional optical quality and minimal spot size across the entire image field. The RASA also offers reduced vignetting, making it ideal for wide-field astrophotography.

Key Features of the RASA 800 Astrograph:

• Super-Fast Optics: The 11" f/2.2 optics provide sharp imaging for APS formats and are optimized for sensor sizes up to a 70mm field diagonal.

• Extremely Short Exposure Times: Captures images twenty times faster than at f/10. A 30-second exposure at f/2.2 is equivalent to a 10-minute exposure at f/10, eliminating the need for precise tracking control.

• Wide Field of View: With a focal length of 620mm, the RASA is perfect for wide-angle shots while maintaining excellent detail.

• Precision Focusing Mechanism: Equipped with bronze bearings to reduce image shift and a 10:1 FeatherTouch micro-focuser for highly accurate focusing.

• Innovative Cooling Features: A quieter 12V MagLev fan reduces cooling time, prevents dust ingress, and optimizes air circulation within the OTA.

• Camera Compatibility: Includes adapters for popular camera brands. Back focus for supplied camera adapters is 55mm, while back focus for the front lens group is 69.26mm.

The RASA (Rowe-Ackermann-Schmidt Astrograph) was developed by renowned optical designers Dave Rowe and Mark Ackermann, ensuring top-tier performance and reliability.

Important Note: The RASA 800 is not compatible with regular DSLR cameras due to its short back focus. It is recommended to use mirrorless cameras or small dedicated CCD or CMOS astronomical cameras.

CGEM II Mount

The CGEM II mount is an upgraded version of Celestron’s popular CGEM mount, offering improved ergonomics, firmware updates, dual dovetail compatibility (Losmandy and Vixen standards), a USB port, and a sturdier tripod. It is designed to support OTAs up to 11 inches (279mm) in aperture and can also accommodate refractors and medium-sized Newtonian telescopes.

The dual saddle clamp securely holds telescopes without damaging the dovetail rail. The mount features All-Star Polar Alignment, allowing alignment using any star without requiring a polar finder or direct visibility of Polaris. With its advanced tracking capabilities and large celestial database, the CGEM II is ideal for astrophotography enthusiasts.

Additional Advantages of the CGEM II:

• Marked tripod legs for consistent height adjustment

• All-Star Polar Alignment for easy setup without Polaris visibility

• Large celestial database including deep-sky objects, double stars, and solar system objects

• Permanently Programmable Periodic Error Correction (PPEC)

• Backlit hand controller with USB port for firmware updates and PC connectivity

• Meridian tracking up to 30° for uninterrupted long-exposure astrophotography

The CGEM II sits between Celestron’s AVX and CGX mounts in terms of capacity and performance. It provides an excellent balance of carrying capacity, advanced features, and affordability, making it suitable for advanced astrophotographers.

Specifications:

Optics:

• Type: Reflector

• Type of Build: Astrograph

• Aperture: 203 mm

• Focal Length: 400 mm

• Aperture Ratio (f/): 2

• Resolving Capacity: 0.68 arcseconds

• Limiting Magnitude: 13.3 mag

• Light-Gathering Capacity: 843x compared to the naked eye

Tube:

• Material: Aluminum

• Diameter: 235 mm

• Length: 628 mm

• Weight: 7.9 kg

Reflector:

• Secondary Mirror Obstruction (%): 46%

Focuser:

• Gear Reduction: No

• Type of Build: Linear Crayford focuser

Mount:

• Type of Build: Equatorial (CGEM II)

• GoTo Control: Yes

• Polar Elevation Setting Range: 15°–70°

Tripod:

• Material: Steel tripod with 51mm diameter legs

• Weight: 9 kg

GoTo System:

• Software Included: NexStar+ Hand Controller with USB connectivity

• Alignment Methods: 2-Star Align, Quick Align, Solar System Align, Last Alignment, etc.

• Database: Over 40,000 celestial objects

Included Accessories:

• Counterweight: 1 × 7.7 kg

• Camera Adapters: M42 & C-Mount

• Deviating Optics: Filter holder included

• Cigarette Lighter Adapter: Yes

General Information:

• Series: CGEM II

• Total Weight (Mount + Tripod): 18 kg

• Load Capacity: Up to 18 kg

Applications:

• Astrophotography: Excellent performance

• Moon & Planets: Yes

• Nebulae & Galaxies: Yes

• Nature Observation: Not recommended

• Sun Observation: Not recommended (requires appropriate solar filter)

Recommended Use: This telescope is ideal for advanced users seeking high-quality optics and robust astrophotography capabilities but is not recommended for beginners or observatory-level applications.

Manufacturer Details:
The RASA Astrograph paired with the CGEM II mount offers exceptional performance for astrophotographers looking for reliable equipment with advanced features at an affordable price point.