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G1 Guider at Work
 No astronomical mount is precise enough to keep the star images perfectly round during long exposures without small corrections. Astronomical CCD cameras and digital SLR cameras allow perfectly sharp and high-resolution images, so only very small irregularity in mount tracking appears as star image deformations. G1 CCD cameras were designed especially with automatic mount guiding on mind, but they are also usable as simple imagers for taking pictures of Moon, planets and also deep space objects.

It is possible to guide the telescope mount manually, by keeping the selected star in the crosshair of the guiding eyepiece. But better results can be obtained by using of automatic guider. Autoguider does not get tired, detects also very faint stars and performs mount tracking corrections very exactly.

The G1 cameras were designed to operate without any mechanically moving parts (with the exception of magnetically levitating fan). Absence of mechanical shutter requires e.g. covering of the telescope when you take dark frame on the one side, on the other side electronic shutter allows extremely short exposures and also obtaining thousands of images in a short time, which is necessary for quality guiding. CCD chips used in G1 cameras are sensitive enough to capture even a faint stars within few seconds. The limiting magnitude of G1 cameras is much higher compared to sensitive TV or Web cameras.

G1 series cameras are very lighweight and compact

G1 cameras work in connection with a host computer (PC). Guiding corrections are not calculated in the G1 camera itself, it only sends acquired images to the PC. The software running on the PC calculates the difference from required state and sends the mount appropriate corrections. These corrections can be sent using PC-to-mount link, more accurate guiding can be achieved using so called “Autoguider” port. This port become de-facto standard and G1 cameras have connector conforming to this standard. It is enough to connect the G1 camera and the mount using 6-wire cable and guide the mount through the G1 camera.

Single 4 minutes long exposure of M31 by Nuccio D'Angelo, autoguided with G1-0300

Single 4 minutes long exposure of M31 by Nuccio D'Angelo, autoguided with G1-0300

Exposure taken by Nuccio D'Angelo. The image was not processed.

  • Exposure: 4 minutes (single frame).

  • Camera: Canon EOS 20Da.

  • mount: Orion Atlas EQ-GOTO, ST4 standard autoguider port.

  • Telescope: Astrophysics Starfire 4" APO refractor, f/6 reduced with William Optics 0.8x compressor.

  • Guider scope: 100 mm f/9 Orion ED refractor.

  • Guider: G1-0300, Single Star Match.

The G1 cameras can also work as simple imaging cameras. The following images show s few very well known deep-sky objects imaged by the G1-0300 camera and 20cm, f/4 Newtonian telescope. Images were created by stacking of 10 exposures, each only 10 s long. Total exposure time was only 100 s.

M13 Globular Cluster

M13 Globular Cluster

M57 Ring Nebula

M57 Ring Nebula

G1 cameras can work as entrance ticket to the world of astronomical photography. They can provide the first experience with digital imaging, later they can work as powerful and reliable guider camera for bigger cooled CCD camera or digital SLR camera.

 
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