Clayhole Observatory

Clayhole Observatory is a small astronomical observatory situated in the middle of Jokela, a small town about 40 km north of Helsinki, Finland, at 60,5° North, 25° East. The observatory is the culmination and manifestation of my interest in astronomy and space that has lasted over four decades and counting.

All observing projects are part of a master program named Clayhole Observatory Survey of Stars and the Universe - COSSU in short.

Ongoing projects mainly involves photometry of variable stars, occasional astrometry of asteroids and comets, and imaging of curious or interesting objects just for fun.

Clayhole Observatory is MPC station C03.
My AAVSO id is SJAR.

Messier 1 and Pulsar

February 22, 2017


KIC 9832227

February 10, 2017

This star is a contact binary variable which is projected to collapse into one and brighten to 2nd magnitude in a few years.

Asteroid flyby

September 14, 2016

Apollo type asteroid 2016 LX48 making a close approach to the Earth.

New observing season opens

August 11, 2016

After the mount stripdown some nights were by necessity spent on aligning and collimation.

Summer recess

July 2016

During the too light nights little observing can be done. So then it's an excellent time to take care of the equipment. During my summer vacation I stripped, cleaned and regreased my mount. I also fixed the design flaw in the altitude setting mechanism.


Clayhole Observatory started as a very humble enterprise with Starlight-Xpress MX516 and Celestron Ultima SCT on a tripod.


The founding of the observatory began with the modest initial step of building a permanent pier in summer 2003.

Control room

Also in 2003 the construction of the warm room was commenced. At this stage the observatory's equipment consisted of an 8-inch Meade LX-200 GPS and a second-hand Starlight Xpress MX916 CCD camera.

Observatory building

In summer 2005 a proper building was constructed to house the telescope.

Building ready

Initially the building housed a 8-inch SCT bought in 2002. In 2007 the mount was replaces by EQ6 Pro.

Sky Watcher EQ6 Pro

Bought in 2007

Serviced in summer 2016

Moravian Instruments G2-1600FW

Bought in 2013

Meade 8" SCT with UHCT

Bought in 2004

Sky Watcher Equinox 80

Bought in 2008


Bought in 2016 it replaced an earlier version QHY5 camera.

Dielectric Astrodon Photometrics filters

Bought in 2011

Johnson B, Johnson V, Cousins R, and Cousins I filters populate the filter wheel. To keep focussing a minimal hussle, a Clear filter is also used.