Kilodegree Extremely Little Telescope
Two robotic telescopes surveying bright stars for transiting exoplanets.
The Kilodegree Extremely Little Telescope, or KELT, is a pair of robotic telescopes used to find exoplanets that cross in front of bright stars. The project is run jointly by astronomers from Ohio State University, Vanderbilt University, Lehigh University, and the South African Astronomical Observatory (SAAO).
Each KELT telescope uses a wide-field telephoto lens with a 4.2 cm aperture and a 26-degree-by-26-degree view, paired with a 4k × 4k Apogee CCD. A narrower lens, with a 7.1 cm aperture and a 10.8-degree-by-10.8-degree field, can be swapped in for a narrow-angle campaign mode. KELT-North’s camera is an Apogee AP16E; KELT-South’s is an Apogee U16M. Both optical assemblies and cameras sit on Paramount ME mounts from Software Bisque. Because the telescopes were built from off-the-shelf parts, they cost far less than most observatories.
KELT-North was installed at Winer Observatory in southeastern Arizona, about an hour’s drive from Tucson, in 2005. It ran continuously until 2022, with breaks for equipment problems and bad weather, and was then decommissioned. KELT-South was deployed in 2009 at the SAAO observing station near Sutherland, South Africa, roughly 370 kilometers north of Cape Town.
The survey targets stars with apparent magnitudes between 8 and 10 in the V band. This range is just fainter than stars already thoroughly checked by radial-velocity planet searches, but brighter than those typically studied by most transit surveys.
Both telescopes observe a set of predefined sky fields every clear night, taking 150-second exposures optimized for stars in that magnitude range.
KELT has discovered several exoplanets and at least one brown dwarf (which might instead be an extremely massive super-Jupiter). In the table of discoveries, yellow rows mark planets that belong to binary star systems. Among the brown dwarfs found is KELT-1b.
- Number of telescopes
- 2
- Locations
- KELT-North at Winer Observatory in southeastern Arizona, United States; KELT-South at SAAO observing station near Sutherland, South Africa
- Aperture (wide field)
- 4.2 cm
- Field of view (wide field)
- 26 degrees × 26 degrees
- Aperture (narrow field)
- 7.1 cm
- Field of view (narrow field)
- 10.8 degrees × 10.8 degrees
- Exposure time
- 150 seconds
Lore & Background
KELT consists of two telescopes: KELT-North in Arizona and KELT-South in South Africa. KELT-North was installed at Winer Observatory in 2005 and operated continuously until 2022, with occasional interruptions for equipment failures and poor weather; it was decommissioned in 2022. KELT-South was deployed at Sutherland in 2009. Each telescope uses a wide-field medium format telephoto lens with a 4.2 cm aperture mounted in front of a 4k × 4k Apogee CCD, and can be equipped with an alternative narrower field lens with a 7.1 cm aperture for a narrow angle campaign mode. KELT-North uses an Apogee AP16E camera, while KELT-South uses an Apogee U16M. The optical assemblies and cameras are mounted on Paramount ME mounts manufactured by Software Bisque. The telescopes were made with off-the-shelf components and were thus much cheaper than many observatories.
Reader's Guide
KELT is dedicated to discovering transiting exoplanets orbiting stars in the apparent magnitude range of 8 < V < 10, a region just fainter than stars comprehensively surveyed for planets by radial-velocity surveys but brighter than those typically observed by most transit surveys. Both telescopes operate by sequentially observing a series of predefined fields around the sky all night, every night when the weather is good, using 150-second exposures optimized for the target magnitude range. KELT has made several exoplanet discoveries and at least one brown dwarf (which may be an extremely massive Super-Jupiter instead) to date. The survey has also discovered brown dwarfs like KELT-1b. Yellow rows in the discovery table indicate the planet is contained in a binary system. The project's low cost and use of off-the-shelf components demonstrate an alternative approach to exoplanet survey design, focusing on bright stars that are accessible for follow-up studies.
Did You Know?
- KELT-North was decommissioned in 2022 after operating since 2005.
- Each KELT telescope can use either a 4.2 cm aperture wide-field lens or a 7.1 cm aperture narrow-field lens.
- KELT-South is located at the SAAO observing station near Sutherland, South Africa, about 370 km north of Cape Town.
- The telescopes were made with off-the-shelf components, making them much cheaper than many observatories.
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