KAIRA

Kilpisjärvi Atmospheric Imaging Receiver Array
Organization Sodankylä Geophysical Observatory
Location Kilpisjärvi, Enontekiö, Finland
Coordinates 69°4′15″N 20°45′43″E / 69.07083°N 20.76194°E / 69.07083; 20.76194Coordinates: 69°4′15″N 20°45′43″E / 69.07083°N 20.76194°E / 69.07083; 20.76194
Altitude 495 metres
Established 2011 (2011)
Website http://www.sgo.fi/KAIRA/
Telescopes
KAIRA HBA 50 x 30 metre radio telescope
KAIRA LBA 34 metre radio telescope

The Kilpisjärvi Atmospheric Imaging Receiver Array (KAIRA) is an astronomical observatory operated by the Sodankylä Geophysical Observatory on behalf of Oulu University.[1][2] It is located at Kilpisjärvi, Enontekiö near the border with Norway. It comprises two LOFAR-derived radio telescope systems and is capable of observing at HF and VHF radio frequencies. It is used for atmospheric, near-Earth space and astronomical research. KAIRA uses LOFAR phased-array antennas and digital signal-processing hardware. The phased array configuration has no moving parts and with digital control, allows KAIRA to quickly scan the sky, giving KAIRA a large field of view. KAIRA can produce a continuous all-sky image of the radio transparency of ionosphere, using cosmic radio noise for "illumination" (riometry). KAIRA can also obtain electron density profiles in the atmosphere. In addition to near-space imaging, the use of KAIRA has been demonstrated for long-baseline interferometry observations of pulsars.[3]

It operates as either a stand-alone passive receiver, as a receiver for the EISCAT VHF incoherent scatter radar located at Ramfjordmoen, near Tromsø, Norway, or for use in conjunction with other regional VHF experiments.[2] The site is also a pathfinder for the EISCAT_3D system.[4]

The system consists of a phased array receivers grouped in two separate arrays – one composed of 48 LOFAR Low-Band Antennas (LBA) covering the 10–90 MHz band and another composed of 48 LOFAR High-Band Antenna (HBA) covering the 110–270 MHz range. The HBA array is oriented in the direction of the EISCAT Tromsø radar, which transmits at approximately 224 MHz.[5] Together with the EISCAT transmitter, KAIRA forms a bistatic radar system, capable on performing observation with at least 20 simultaneously beams pointing at different altitudes along the EISCAT transmitter beams.[6]

The LBA array has been configured approximately the same as the inner configuration of a LOFAR remote station (RS-INNER). The circular, quasi-random antenna distribution has been chosen to optimise the beam pattern of the array. The LBA array is used for solar astronomy, general radio astronomy, ionospheric scintillation, multi-frequency riometry[7] and other passive receiver experiments.

See also

References

  1. ↑ Vierinen; et al. (July 2012). "KAIRA". 39th COSPAR Scientific Assembly, Mysore, India. Abstracts (PSD 1-29-12): 2089.
  2. 1 2 McKay-Bukowski; et al. (2015). "KAIRA: the Kilpisjärvi Atmospheric Imaging Receiver Array -- system overview and first results". IEEE Transactions on Geosciences and Remote Sensing. 53 (3): 1440–1451. Bibcode:2015ITGRS..53.1440M. doi:10.1109/TGRS.2014.2342252. Retrieved 1 January 2015.
  3. ↑ http://kaira.sgo.fi/p/achievements.html
  4. ↑ "SGO: KAIRA". SGO. Retrieved 2015-05-24.
  5. ↑ "SGO: KAIRA Data Sheet". SGO. Retrieved 2015-05-24.
  6. ↑ "Lag-profile inversion". SGO. Retrieved 2015-05-24.
  7. ↑ Kero; et al. (2014). "Ionospheric electron density profiles inverted from a spectral riometer measurement". Geophys. Res. Lett. 41: 5370–5375. doi:10.1002/2014GL060986. Retrieved 20 May 2016.


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