Dinium Observatory on the Isle of Rennes, southwest Norway.

Dinium Observatory


Dinium Observatory is a private backyard observatory on Rennesøy (Isle of Rennes) in south-west Norway. It was built by R.W. Williams, an amateur astronomer and professional paleontologist.


The fiberglass dome is produced by ScopeDome in Poland. The observatory's floorspace is only 8 sqm, yet the dome houses a 62 cm (24 in) cassegrain telescope. The telescope and German equatorial Mount have a total mass of 700 kg.


The equatorial mount and truss tube is produced by Astrosysteme Austria (ASA) near Freistadt. The optics are ground and figured on a spindel machine. The truss tube allows the optics to be configured as an f/10.4, 6450 mm cassegrain or a f/3.4, 2108 mm prime focus astrograph. Both foci have large flat-field correctors that yield a 50 mm diameter photographic field.

Left: Although this is Norway's largest optical telescope, the observatory's footprint is small.


Right: Cross-section showing the pyramid-shaped, mechanically isolated concrete pad which is cast and rebar-anchored on granitic basement rock. The German-type equatorial mount (560 kg incl. counterweight) is fastened to the concrete pad with expansion bolts. The total mass of the telescope and mount is 700 kg.

IC 1805 The Heart Nebula


Narrow-band image of IC 1805. North is down. 

Interference from clouds reduced the number of sub-exposures for ionized sulphur (SII) and oxygen (OIII).



Date: 16 December 2017 

Loc: Isle of Rennes (Rennesøy), Rogaland, Norway

Telescope: Skywatcher Esprit ED 120 mm f/7 apochromat

Mount: ASA DDM160

Camera: Apogee U16M, CCD temp -30 C

Exposure: Ha, OIII, SII 50/40/20 min


Astrophotography and projects.


How does one grind, polish and figure telescope optics at home?


The observatory dome, telescope mount, optical tube assembly and instrumentation.

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Fine grinding with a fixed-post grinding machine


The fixed-post polishing tool quickly polished the surface to s sphere, reaching the target center of curvature. The polishing compound was cerium dioxide. 

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Portland cement polishing tool

The pitch lap is cast as individual squares on the cement tool. Although this method is very time consuming, it avoids the risk of thermal shock to the cellular mirror blank.

So many satellites

We humans have sent many tonnes of technology into orbit from 1957 to the present, - more than 5000 satellites. 


During a 4.4 hour exposure covering 6.25 square degrees of sky, many old and new satellites cross the field.


Photo: RW Williams, 8-9 April 2019

Time: 20.55 - 02.28 UT 

Equipment: Esprit 120 ED + Apogee U16M

This is  mosaic of seventeen lunar images, each of which consists of more than one hundred images stacked and processed in  AviStack2. Composited digital resolution is 5200 x 6500 pixels.