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

The Celestron Telescope Astrograph S 203/400 RASA 800 CGEM II GoTo is an advanced astrograph for high-level deep-sky photography. The Rowe-Ackermann Schmidt Astrograph (RASA). Combines a 203 mm aperture with an extremely short focal length of 400 mm (f/2), giving you sharp, in-depth shots of nebulae, star fields and galaxies in minutes. Combined with the CGEM II mount this system constitutes a powerful and fully automated setup for serious astrophotographers.

The RASA optics is specifically designed for modern CMOS, CCD and DSLR cameras. Thanks to the f/2 system, the luminosity is 25 times greater than in a classic f/10 Schmidt-Cassegrain. This means: shorter exposure times, less noise and more detail. The optical correction ensures razor-sharp, round stars right to the edges of large sensors - without the need for a separate field flare or corrector.

The front-focused design places the camera at the front of the telescope, keeping the optical path short and distributing the balance perfectly across the mount. The optics feature StarBright XLT coating for maximum transmission and contrast. The internal fan reduces cooling time, which is important during nighttime temperature changes.

The CGEM II mount is the robust heart of this setup. With a carrying capacity of 18 kg it provides ample stability for the RASA 8 and heavy cameras. The mount features Permanent Periodic Error Correction (PPEC). for accurate tracking, and thanks to All-Star Polar Alignment you can quickly and precisely align without a polar finder. The wide mounting base and steel legs (51 mm) ensure absolute stability even in long exposures or wind.

The NexStar+ hand controller with 40,000 objects makes manual control and tracking easy. For maximum control, you can pair the telescope with Celestron CPWI-software or through the SkyPortal WiFi module control with tablet or laptop. The CGEM II can also track objects smoothly beyond the meridian without re-alignment - ideal for nights when you are collecting data nonstop.

The Celestron RASA 800 CGEM II is made for those who don't want to wait for results: pure speed, precision and simplicity for professional astrophotography.

What you can photograph with it:

• The Orion Nebula (M42) with full detail in just a few minutes of exposure
• Large star fields such as Cygnus or Scorpius
• The Andromeda Nebula (M31) with subtle structures
• Emission nebulae and dark dust trails with extremely low exposure time
• Comet shots with pin-sharp stars, thanks to short focal length

Application
The RASA 800 is intended exclusively for astrophotography. Visual observation is not possible, as the camera occupies the eyepiece position. The telescope is aimed at photographers who want to get the most out of their sessions: fast imaging, large field and minimal post-processing. In combination with a camera such as the ZWO ASI2600MC Pro or ASI533MC Pro achieve professional results without an observatory.

Specifications
Type: Rowe-Ackermann Schmidt Astrograph (RASA)
Aperture: 203 mm
Focal length: 400 mm
Aperture ratio: f/2
Resolution: 0.57″
Boundary magnitude: 13.8
Coating: StarBright XLT
Focuser: Ultra Stable focusing unit with 25 mm range
Ventilation: Active cooling with fan
Camera interface: M42, M48, Canon, Nikon, Sony adapters included
Backfocus: 29 mm
Tube length: 670 mm
Tube diameter: 232 mm
Tube weight: 7.7 kg

Mounting: CGEM II GoTo
Carrying capacity: 18 kg
Motors: Servo with PPEC
Alignment: 1-/2-Star, Quick Align, Solar System Align, All-Star Polar Alignment
Tracking: sidereal, sun, moon
GoTo database: 40,000 objects
Power supply: 12 V / 3.5 A
Hand controller: NexStar+
Compatibility: CPWI, SkyPortal (WiFi optional)
Tripod: Steel, 112-163 cm, 51 mm legs
Counterweights: 2 × 7.7 kg
Total weight of set: ±40 kg

Suitable for
Moon & planets: ✗ (only photography with short focal length camera)
Nebulae & galaxies: ✔
Astrophotography: ✔ (deep-sky, wide-field)
Nature observation: ✗
Beginners: ✗
Advanced / semi-pro: ✔
Sun: Only with suitable sunscreen