- Steel Pier
- Telescope mount
- Optical tube
- Computer
- Camera and filters
The Cretney Observatory
Images
Drawings
Video
Wellington Astronomical Society
The Wellington Astronomical Society entrusted Testar Australia to design and supply a professional astronomical observatory including:
The setup is optimised for astrophotography thanks to the fast focal ratio of the telescope and the precision of the mount.
PIER:Testar Pier 3000
Designed by Testar following the strict specification of 10Micron, our piers provide a solid base for mounts. Made from structural steel, hot dip galvanized for a long lasting corrosion protection and painted, this pier is designed to last. The base and the top steel plate have a thickness of 25mm, the tube is 9.3mm thick while the vertical reinforcements increase the frequency of resonance. In telescopes, low frequencies of resonance due to wind or motor tracking must be avoided.
MOUNT: 10Micron GM3000 HPS
10 Micron is leader in manufacturing precise telescope mounts. The success of their products is due to their astonishing experience in precision mechanics since 1960 and the use of absolute encoders that deliver a superior tracking capability. In most cases, 10Micron mounts do not require to be guided making their mounts ideal for astrophotography. The GM3000 has a payload capacity of 100kg.
This optical tube combines fast optics and an excellent field correction for large format cameras. With a focal ratio of only f/3.8, the signal received by the sensor is more than 4 times higher than in a standard f/8 telescope, allowing to capture dim details of deep sky objects. The corrector on the back of the telescope provides a flat field for medium format sensors, a feature that is very difficult to achieve in fast telescopes with the camera on the back.
FILTERS: Chroma Technology LRGB and SHO 3nm
Telescope filters with a high quality are essential components of an optical train. Chroma is among the best producers of astronomical filters minimizing the halos around bright stars and delivering a narrow band transmission of only 3nm. Moreover, the technology used for the depositing of the coating on the substrate, deliver an high transmission even with telescope as fast as f/3, where the band shift can be significative.
CAMERA: QHY 600M PRO
It installs the Sony IMX455 back illuminated full frame sensor that currently is among the most advanced sensors for astronomical imaging. With a QE above 90% and true 16-bit A/D, translating to a dynamic range of 14 stops. The pixels have a size of 3.76 µm and a resolution of 61 Megapixels.
COMPUTER: Prima Luce Lab Eagle
Embodied in a solid aluminium case, the Eagle combines a powerful computer with a handy power distribution system. Being compact and sturdy, it can connect directly on a telescope, drastically reducing the amount of cables hanging from the telescope.
Our collaboration with the Wellington Astronomical Association involved:
PROCUREMENT: We supplied most of the components of the observatory which was sourced from Italy (10Micron, Prima Luce Lab, Officina Stellare), China (QHYCCD Camera), Australia (Testar Pier) and USA (Optec Focuser, Chroma Filters). Once we received all the components at our facility, we carefully inspected and double checked the quality of the parts.
MANUFACTURING: We design and 3D print the frames to hold the filters, which allow to hold the filters more firmly than simply use the shims provided with the filter wheel.
To reduce the backfocus and allow to use all parts needed in the optical train, we design and have manufactured a low profile adapter between the filter wheel and the camera.
DRAWING: to optimise the space inside the dome, we correctly provided the measure of the offset of the pier, allowing to have the tube positioned symmetrically when pointing toward the zenith.
The observatory is currently open for the members of the Wellington Astronomical Society, you can read more at this link.
A special thanks to Matt Balkham who supported this project and helped us with all the stages. He is the author of the images below taken with this instrument. You can visit his astrophotography page here .
