Observatory Cerro Murphy (OCM) is an international astrophysical project hosted by the ESO Paranal Observatory and operated by the Nicolaus Copernicus Astronomical Center of the Polish Academy of Sciences. The observatory is located on Cerro Murphy, which is a hill located 1 km to the southwest and 230 m below the summit of Cerro Armazones (where ESO’s Extremely Large Telescope is being built), and about 120 km south of Antofagasta city. OCM is located at 2,817 m (9,242 ft) altitude and currently houses 5 telescopes, whose diameters range between 0.3 and 1.5 m.
Due to its harsh atmospheric conditions, such as dry air and extremely low rainfall, the Atacama Desert is the best place for astronomical observations in the world, providing over 330 starry nights per year.
The observatory was established in 2005, owned and operated jointly by the Ruhr University Bochum (RUB) and the Catholic University of the North (UCN) until 2020, when it was transferred to the Nicolaus Copernicus Astronomical Center of the Polish Academy of Sciences (CAMK), and is now run by the Araucaria Project.
On 28 November 2023, the inauguration of the renovated observatory took place, which was the occasion to announce the renaming of the observatory from the Cerro Armazones Observatory (OCA) to the Rolf Chini Cerro Murphy Observatory, abbreviated as the Observatory Cerro Murphy (OCM). The name change highlights a new chapter in the observatory’s history featuring scientific projects related to the calibration of the cosmic distance scale (the main specialisation of the Araucaria Project), and emphasises the contribution of Prof. Rolf Chini, who supervised and participated in all construction work at the observatory. The name change also removes ambiguity regarding the location of the observatory; in Chile it is customary for observatories to bear the names of the hills on which they stand, and the ELT is being built on the top of Cerro Armazones.
The largest Polish telescope, with a mirror of diameter of 2.5 m, is currently being built by Astro Systeme Austria (ASA) and will start operations at OCM in 2026. This huge scientific and technical undertaking is made possible thanks to the financial support from the Polish Ministry of Education and Science, and the European ERC Synergy scientific grant.
- 1.5-m telescope Janusz Kałużny (jk15) is an Alt-Az telescope built by an Austrian company ASA, equipped with a professional 4k x 4k Andor iKon-XL 230 camera. It has an impressive number of filters (16): Strömgren (u b v y), Hα wide, Hα narrow, Hβ wide, Hβ narrow, Sloan (u g r i z), and Johnson-Cousins (B V Ic). It also supports a high-resolution spectrograph, BESO (which is a clone of the ESO high-resolution spectrograph FEROS, and has a wavelength range = 3700Å–8600Å, resolution λ/Δλ = 48000).
- 0.8-m telescope Zbigniew “Zibi” Kołaczkowski (zb08) is an Alt-Az telescope built by an Austrian company ASA. In one of its 4 foci a professional 2k x 2k Andor iKon-L 936 camera is mounted, guaranteeing a field of view of 17.2′ x 17.2′. One filter wheel accommodates Sloan filters (u g r i z) and Johnson-Cousins filters (B V Ic), while the other has a diffuser, that allows to observe bright stars without saturation.
- 0.6-m telescope Wojtek Krzemiński (wk06) is a telescope built by an Austrian company ASA on the equatorial mount, and equipped with a professional 2k x 2k Andor iKon-L 936 camera. The collection of filters – Strömgren (u b v y), Hβ wide, Hβ narrow, Johnson-Cousins (B V Ic) – is complemented by a diffuser, that allows to observe bright stars without saturation.
- 0.8-m IRIS (InfraRed Imaging System) telescope on an Alt-Az mount with two Nasmyth foci that can be reached via a computer-controlled movable third mirror. It was founded by RUB, made by Halfmann Teleskoptechnik, and installed in 2010. IRIS is equipped with a 1k x 1k infrared camera, donated by the Institute of Astronomy at the University of Hawaii; there are various broad and narrow band filters between 1.1 and 2.5 µm. The optical system provides a resolution of 0.74”/pixel and a field-of-view of 13′ x 13′; the limiting magnitude is K ≈16 mag. Thus IRIS exceeds the capabilities of 2MASS.
- 0.3-m Ballistische Messkammern (BMK), built by Carl Zeiss Jena, is a robotic refractor, equipped with wide-field 10k x 10k camera, providing a field of view of 13.6° x 13.6°. It was installed in 2017-2019 by the Leibniz Institute for Astrophysics in Potsdam with the purpose of observing the Southern Plato Field (SPF).
- 1.5-m Hexapod Telescope (HPT) was named for its unusual mount, consisting of six high-precision struts supporting a platform to which the telescope was attached. It was developed and tested by RUB in Germany, and moved to the observatory in 2006. Due to its peculiar design, the HPT was sheltered not inside a dome, but inside a pyramid, that would split into halves, exposing the telescope and enabling observations. The handling of the HPT proved to be extremely complex: six legs for pointing and tracking, six support legs for the control on the secondary mirror, and 36 piezo-actuators for the active primary mirror – all this kept two observers fully occupied during an observing night. The HPT was decommissioned in 2017, as it had accumulated several technical problems, and could not be repaired due to a lack of replacement parts.
- 0.25-m Berlin Exoplanet Search Telescope II (BESTII), made by Takahashi Seisakusho and owned by the DLR Institute for Planetary Research, was installed in November 2006. BEST II was dedicated to photometric measurements of stellar intensity variations, its prime use was robotic observational ground-based support of the COROT space mission to hunt for extra-solar transiting planets in the southern hemisphere. In the northern hemisphere, BEST I had already been working since 2001.
- The Bochum Monitoring Telescope (BMT) was a 41-cm (16 in) Newton reflector, known also as VYSOS 16, because it was used for the Variable Young Stellar Object Survey (VYSOS) in prominent Galactic star forming regions. It was equipped with a 3k x 2k CCD camera, with a field of view of 41′ x 27′. It was installed in 2006, and decommissioned in 2020.
- The Robotic Bochum Twin Telescope (RoBoTT), known also as VYSOS 6, was a twin refractor, consisting of two 15-cm (6 in) refractors made by Takahashi Seisakusho on a common German equatorial mount. The first of the twin telescopes was installed in May 2008 in the eastern telescope room of the main building, and operated as a single telescope until August 2010, when a second telescope was installed at the same mount, transforming VYSOS 6 into a double system that allowed simultaneous observations in two filters. Both telescopes were equipped with 4k x 4k CCD cameras giving a field of view of about 2.5°. This twin refractor was moved into a new building in the most western part of the observatory.
A new 2.5-m telescope is under construction at ASA, while its foundations and the telescope pillar have already been erected at OCM. Subsequent construction phases are expected in 2024-2026.
There are also plans to build the Thirty Millimetre Telescope (TMMT), which will be the smallest telescope in the world, equipped with a professional infrared camera. Its purpose will be to observe the brightest stars in the sky, which are saturated by larger telescopes.
Coordinates: 24° 35′ 55.21″ S, 70° 12′ 4.61″ W (-24.59867, -70.20128)
Elevation: 2817 m (9993 ft)