Since the subtitle of my photoblog is "Photos of a traveling astronomer", I better post some travel related astronomy image. The one above shows some of the telescopes at the Las Campanas Observatory. Las Campanas is a large observatory near La Serena, Chile. The facility is managed by the Carnegie Observatories, and hosts a number of telescopes, including the du Pont telescope (large dome on the right), the Swope Telescope (isolated dome on the left) and the Warsaw telescope used for the OGLE survey (elevated dome in the center-right). The Warsaw telescope is one of those cases showing how you can do great science even with small telescopes (the primary mirror of the telescope, 51 inches diameter, is not completely out of reach for a very dedicated amateur). The OGLE survey it performs looks at two nearby satellite galaxies (the Magellanic Clouds) and towards the center of our own Galaxy for the flickering of stars caused by other objects passing in front of them. As Einstein showed with his theory of general relativity, massive objects (e.g. a star of a planet) deflect light similarly to an optical lens. This phenomenon (called gravitational lensing or, in this case, microlensing due to the relative small mass of the lensing object) causes the brightness of the lensed object to briefly increase as its light is "beamed" by a lensing object passing in front of it.
Magellan Telescopes, Chile (Jan 8, 2006)
By looking for microlensing signature caused by the chance alignment of a "lens" with a distance star in the Magellanic Clouds or the Galactic Center, it is possible to perform a census of very small mass and dim "lenses" that may lurk closer to home, and that would not be possible to detect otherwise. In this way several very low mass stars, and even extrasolar planets, have been detected. As a bonus, the OGLE surveys monitors the variability of million of stars, and has amassed one of the most complete catalog of light-curve of variable stars in the Magellanic Clouds, which I regularly use for my science. Another example is the HAT (Hungarian Automated Telescope) network, a collection of very small robotic telescopes dedicated to the search of exoplanets transiting in front of their parent star. The HAT telescopes were still not installed at the time I took the photo above. Missing from my picture are also the Magellan Telescopes, which are the twin large aperture telescopes (6.5 meters primary mirror diameter) in the small photo on the left. I was using one of them during the trip in January 2006 when I took the photos shown here.