Telescopes I've Used - European Southern Observatory

European Southern Observatory (ESO) Cerro La Silla, Chile

About 100 km north of Cerro Tololo (within sight when the lighting is just right), atop Cerro La Silla, are the facilities of ESO, which can nearly match telescope for telescope the facilities operated by both Kitt Peak and Cerro Tololo. First-time observers actually need a map to guide them to the right dome. Forming and maintaining ESO was a major factor in contributing to a specifically European astronomical community, which has made enormous advances culminating in ESO's construction of the 4x8m VLT well to the north at Cerro Paranal. My visits here came when I was on the staff at Leiden Observatory, while Harry van der Laan took every opportunity to try making me a good European. The overall view below shows the astrograph and Danish 1.5m domes in the right foreground, then moves past the 2.2m and 1-m Schmidt domes, sweeping up to the 3.6m (with the characteristic outrigger dome of the coude auxiliary telescope) at the summit itself. The dome just to the lower left of the 3.6m was for the Swiss 60-cm instrument, since replaced at that location by the 3.58-m New Technology Telescope (NTT). This view does not include a cluster of six 0.5-1.5m telescopes behind the viewpoint, nor the 15-meter Swedish/ESO Submillimeter Telescope (SEST) located around the mountaintop past the 3.6m.

General view of ESO, La Silla

3.6m telescope

ESO 3.6-meter dome ESO 3.6-meter telescope The ESO 3.6m telescope ("el tres-seis") was equipped in the mid-1980s with a powerful and flexible imager/spectrograph, EFOSC, which could be used to examine very faint targets. We turned it to the identification of faint, high-redshift IRAS galaxies whose IR positions were poorly determined, sometimes using slitless spectroscopy to identify our quarry before obtaining a more detailed slit spectrum. This showed clearly which object corresponds to IRAS 0622-645, and also showed that IRAS 1344-363 is a symbiotic star that managed to masquerade as a low-redshift Seyfert galaxy on a quick look at the raw data. One more reason to do the numbers!

To come: data on AO objects, including slitless spectra
ESO/Max-Planck-Institut 2.2m telescope
ESO/MPI 2.2m dome ESO/MPI 2.2m telescope The 2.2m often delivers very good seeing, despite its (traditionally poor) location in a saddle point on La Silla. Rumor has it that for a while, ESO would receive proposals asking for 2 nights in the 2.2m or four nights on the 3.6m. To judge from its control panel, this telescope speaks German, which made me wonder why the telescope operator made fun of me for not knowing French. I just asked him to sit in the corner reading his French novel and keep away from the controls, so we got along fine after that. I used this instrument (whose control room has the thoughtful addition of a hot-chocolate dispenser) in part of a search for optical jets in galaxies. This included an emission-line map of the whole optical jet of Centaurus A (NGC 5128), whose analysis was a real lesson in "do the numbers, don't just look at the pictures". At first it appeared that the inner knots were more sharp-edged than the outer ones, but it turns out that they all have almost exactly the same cross-sectional structure, only differing in size (so of course the smaller ones look sharper-edged). This changes how one interprets the pressure balance (or lack thereof) between the visible gas and surrounding hotter material. Here's a view of the telescope console when observing Centaurus A:

ESO/MPI 2.2m console

And here's a mosaicked image, rotated by 60°, of some of the Hα filaments along the radio jet of Centaurus A:

and an especially nice color-composite image of the IR-bright merger NGC 6240:

La Silla is also home to the Swedish-ESO Submiillimeter Telescope (SEST), a high-accuracy 15-meter dish which has proven especially valuable in mapping molecular gas in the Magellanic Clouds as well as the southern Galactic plane. It is shown here while still under construction (just after that embarrassing incident involving software limits, the Sun near zenith, and a melted secondary reflector), and against a fog bank after coming into operation a year later.

SEST radio telescope under construction SEST radio dish against coastal fog

Telescope Collection

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