End of an observing run

Tonight is my sixth and final night using UKIRT.

During the night, I have been looking through the list of the various surveys we are working on, and each survey has its own priority (some require completion more urgently than others). The time-lapse movie below shows how the telescope has responded throughout the night to my and the telescope operators' instructions.

Not all the areas of sky we want to survey are visible above Hawaii at any one time, and so we are limited by what we can see that night. The Moon can also get in the way (it illuminates the entire sky, so the more sensitive surveys cannot be carried out when the Moon is up), as can high altitude clouds (star surveys can be done through thin cloud, but sensitive galaxy surveys cannot). And finally, it is always better to observe directly upwards, rather than at, say, half way up in the sky. Look up, and you are looking through about 30km of air and moisture; look towards the horizon, and you are looking through nearer 300km. The more air you look through, the more an image twinkles, resulting in blurred images - so to avoid this, we try to always look as directly upwards as possible.

As we go through the night, I am constantly considering all the limitations and all the possibilities of what we want to observe (which can change dramatically during the night, especially where the weather is concerned). As I do that, a telescope operator (Thor and Tim this week) controls the telescope, making sure it is guiding properly, fault fixing if needs be, and repeatedly making focus and other calibration observations throughout the night.

But after six long nights working at 4,200m, and getting at most just seven uncomfortable hours sleep during the day (due to the dryness of living on this volcano), I am more than ready to return home.