Observing at the Nordic Optical Telescope
After two and a half years out of astronomy, I returned to the field in September 2006. Shortly after that, I got an opportunity to go observing again, and my third trip to La Palma was fantastic. When I left astronomy, I didn't know whether I would ever try to get back into it, and I thought that in all likelihood my two trips to La Palma would be my lot.
On both of those two trips, the taxi to the mountain top had been a nightmare. This time, I was observing at a telescope which didn't have cars on the mountain top for the observer's use, so I needed to drive myself up. This was massively more fun than getting the taxi, and I was laughing like a fool as I swept around the hairpins. If I'd had a passenger, they would have been chundering within seconds.
At the top, conditions were perfect. The humidity was so low that I got violent electric shocks off everything I touched, the skies were deep blue, and the stars shone brightly. Unfortunately I was not observing until the next night. I watched the sun set over a sea of clouds, then stayed up until the small hours preparing my observations and getting into the night routine.
The next day when I rolled up the shutters in my room, I was a bit shocked to see that the perfect conditions had gone, and rain was whipping past my window. Conditions stayed appalling throughout the day. At 4pm I was supposed to meet my support astronomer at the Nordic Optical Telescope, so I could learn how to use it. I set off, but the rain was utterly torrential, and after a few minutes of driving at walking pace and not being able to see beyond the end of the bonnet, I turned back.
The first night looked like being completely lost, but I decided to stay up until dawn anyway. A few people on other telescopes also optimistically stayed up; most went to bed. I kept an eye on the weather station data from within the comfort of the Residencia.
At 5am there was drama. Conditions were suddenly dramatically improving, and observers were hurrying to their cars to get to the telescope. I stayed where I was: the NOT is the highest telescope on the island, and its weather sensors were still telling me it was too humid and too windy to open the dome. About twenty minutes later everyone who had rushed out was forlornly heading back anyway. It had just been a very temporary reprieve, and the monsoon was back.
The next night was also lost. I spent a miserable twelve hours in the telescope control room, thinking how ridiculous it was that I'd travelled two thousand miles just to sit in a small room on top of a mountain in thick cloud and do nothing. But on the third night, as I drove up to the telescope, the cloud level was dropping and there was an incredible sunset. As I got to the lip of the caldera, I could see towns lighting up far below. It was wildly windy and the car was rocking but before long it was calm enough to open the dome, and I started actually observing.
During the fourth night, all was going smoothly. The air was dry, the skies were clear, and I was running as quickly through my observing programme as I could. Suddenly, after a couple of hours, the telescope control system started beeping - the humidity was higher than the telescope could take and I had to close everything down quickly. A few minutes later it had dropped right back down. I opened up again and carried on.
It did this a couple more times during the night. At 5.45am I closed up and I couldn't open again. By dawn, the mountain was in thick cloud. The visibility was about ten metres, and the NOT quickly disappeared from sight as I drove back to the Residencia.
Driving down the mountain was much less fun than driving up it had been. There was thick cloud most of the way down, and when I got to Santa Cruz it was raining. It kept on raining for the whole of the evening, and I decided that La Palma in October was not as nice as La Palma in August had been.
I had a weekend to spare after my observing run, and I had thought I might drive around the island. But I hadn't got to Santa Cruz until late on the Saturday afternoon, so that just left Sunday. I set off south and thought I would see how far I got.
It was sunny when I left Santa Cruz, and for the first twenty minutes the drive was great. But then suddenly I was in thick cloud and more or less zero visibility. I had to drive at about 15 miles an hour for a lot of the way to Fuencaliente at the south end of the island.
I parked up near Volcán San Antonio, one of the two recently active volcanoes at this end of the island. For half an hour I could do nothing but sit in the car as the rain lashed down. It stopped, eventually, and I rushed out to do a quick walk around the crater. Then I drove on to the other volcano, Teneguía, and climbed over scenery that emerged from the ground in 1971. Through brief breaks in the cloud, I looked up the west coast of La Palma.