NORSTAR (NORthern Solar Terrestrial ARray)


The NORthern Solar Terrestrial ARray (NORSTAR) operates single-beam single-frequency riometers at 13 sites in north-central Canada. This is the continuation of the CANOPUS MARIA riometer array. The instruments are described in detail on the NORSTAR web site.

The riometers collect one data point every five seconds. There are three levels of data products that are produced by the array. The raw data is in volts, which is in turn converted to dBs. As well, when baselining is possible, the data is further converted to dB absorption. The level of data required depends on the scientific or space weather application. For example, timing and location of dispersionless injections can, in principle, be done using the raw data. On the other hand, quantitative studies of high energy electron precipitation invariably requires baselined data.

The raw data and (where possible) the baselined dB absorption is currently available from the CSSDP and the NORSTAR web site. Future plans include the development of CDF data files. Plans are underway to include the riometer data in numerous virtual observatories, as well as CDAWeb and the CEDAR data base.

Principal Investigator(s)

  • Dr. Eric Donovan


Each riometer site is equipped with a 30 MHz zenith oriented, 4-element antenna and a single 150 kHz broadband receiver. These instuments were supplied by La Jolla Sciences of Solana Beach, California.

A riometer is a radio receiver. Tuned to frequencies of 20-60MHz a riometer monitors the flux of cosmic radio waves travelling through the ionosphere.

As radio waves traverse the ionosphere they induce oscillations in the free electron population. If the electrons then come in collisional contact with neutral atoms the waves begin to lose energy (they are attenuated). From the ground, this is a perceived reduction in signal strength.


The array comprises four meridian scanning photometers, arranged in a "sideways" T, a N - S line of three stations and one to the West of the central station (originally a complete line). The Eastern line meridian instruments provides complete overlapping coverage over the full range of latitudes from approximately 55 to 73° EDFL.

This includes the whole range of latitudes where particle precipitation normally occurs, from the southernmost edge of the proton oval to the dayside cleft region in the north. The western extension permits viewing the auroral oval at a location separated in local time by 1-2 hours.