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Trip to Brenig Reservoir

By Dave Owen
Published 2004-09-02 15:31:44

After conferring, by phone, with Dave Thomson on the morning of Mon 29 Dec we decided to take the TROK 30 inch Dobsonian to Brenig Reservoir, in North Wales, that evening. This would be our last chance to observe in relatively dark skies before the Moon began to set too late.

I arrived at Brenig, with Geoff Regan and Dave Robinson, at about 21:40 to find that Dave Thomson, assisted by his rocket making friend Sean, had almost assembled the TROK 30 scope. Phil Harman and Steve King turned up about 20 minutes later with their friend Ian. Ian brought his Meade 125 scope. Unfortunately, due to the lack of a dew cap, this quickly dewed up.

After a mostly sunny day we were disappointed to find that mist was starting to rise from the reservoir, especially later in the night. However, we still had a 30 inch telescope and the Orion nebula was very bright and billowy. Saturn was an exquisite collection of 3 rings and a multi banded globe. Steve even said that he could see the elusive Encke division in the outer A ring. For me, on my second look, Saturn seemed strangely blue? This was due to frost forming on the primary and secondary mirrors. After all, it was about -6 degrees centigrade! Desperate measures were called for. A 12 volt hair dryer, attached to a car battery, soon dried out the secondary mirror.

For the primary mirror, Dave Thomson decided to fire up a gas stove and put it in the rocker box, while keeping the tube covered with its cloth shroud! Eventually, this worked. We were able to get a good, but not great, view of the Crab Nebula before the mist eventually became so bad that we decided to dismantle the 30 inch and relocate a few hundred yards further up the hill.

By this time, about 01:30, we were down to me, Geoff, Dave and Dave. Soon we were busy again with the hair dryer and gas fire trying to remove the frost. If you put a hair dryer over a gas fire you can generate even more heat. Unfortunately, as we noticed some plastic melting on the hair dryer, it went pop and refused to give out any more heat. Good job we had a spare hair dryer eh?

It was now about 02:25, but what did we care? Our main concern was that some of the mist had followed us up the hill from the reservoir and was spoiling our attempts to hunt down faint galaxies. We took a look at Jupiter with a 35mm eyepiece, about 130x, and then switched to a 26mm. This gave about 175x and, as well as showing the Great Red Spot, also revealed a small, non circular, dark spot on the disk. Jupiter's moon Io also hung tantalisingly on the limb, having just emerged from behind Jupiter.

We took at quick look at a trio of galaxies in Leo, M65, M66 and NGC 3628. However, the best object of the night, for me, was the small, but very rich star cluster NGC 2158, on the edge of the much bigger and brighter M35 star cluster, in Gemini. This can be quite difficult to resolve into stars with smaller telescopes, but it was now a rich powdery glow of points of light against the blackness of the sky. Beautiful.

The Eskimo Nebula, also in Gemini, was next. This is a very bright planetary nebula and showed lots of detail, although not as much as it might have shown in a sky less plagued by mist. Our final object was M51, the face on spiral galaxy in Canes Venatici, just below the tail of the great bear. Dave Thomson and Geoff both said that they could see the spiral arms, but they were too ghostly for me to convince myself that I could see them. Unlike on a previous visit to this site with the same telescope in a much clearer sky.

Well, that was the end of our observing, but our real adventure was about to start. We had no major difficulty in going down the icy road to the reservoir. However, going up again caused us major problems. Both my car and Dave Thomson's got stuck just before we crested the steepest part of the hill. Dave unhitched the trailer, turned it around, it almost slipped away from us here, and then drove downhill, with the trailer attached, to try again. This time, both cars got up the hill and, at about 04:30, we were on our way home. Perhaps next time we should pack about 30 pounds of salt? And a few more hair dryers?