Sun outage
Encyclopedia
A sun outage, sun transit or sun fade is an interruption in or distortion
of geostationary satellite
signals caused by interference from solar radiation. The effect is due to the sun's radiation overwhelming the satellite signal. Generally, sun outages occur in February, March, September and October, that is, around the time of the equinox
es. At these times, the apparent path of the sun across the sky takes it directly behind the line of sight between an earth station
and a satellite. As the sun radiates strongly at the microwave
frequencies used to communicate with satellites (C-band, Ka band
and Ku band
) the sun swamps the signal from the satellite. The effects of a sun outage can include partial degradation, that is, an increase in the error rate, or total destruction of the signal.
(Bombay Stock Exchange) and NSE
(National Stock Exchange) use VSAT
s (Very Small Aperture Terminal) for members to connect to their trading systems. VSATs depend upon satellites for connectivity between the terminals/systems. Hence these exchanges are affected due to the sun outage. These exchanges normally remain closed from 11:45 to 12:30 during 'sun outages', but times vary depending on the scientific factors. The interference in satellite signals disturbs smooth transmission of data of online transactions, hence these share markets remain closed for the duration of sun outages. Due to these outages, the trading sessions are normally extended in the same day to compensate for the lost time. In September 2006, however, only the NSE intended to shut down during the sun outage; the BSE did not. The reason for which is unknown.
suffers from island-wide loss of Internet and telecommunications connections during sun outages because all telecommunications traffic to and from the island is carried on a single satellite link. Sun outage times are published in local newspapershttp://www.saint.fm/independent/20111007.pdf.
Distortion
A distortion is the alteration of the original shape of an object, image, sound, waveform or other form of information or representation. Distortion is usually unwanted, and often many methods are employed to minimize it in practice...
of geostationary satellite
Geosynchronous satellite
A geosynchronous Satellite is a satellite whose orbit on the Earth repeats regularly over points on the Earth over time. If such a satellite's orbit lies over the equator, the orbit is circular and its angular velocity is the same as the earth's, then it is called a geostationary satellite...
signals caused by interference from solar radiation. The effect is due to the sun's radiation overwhelming the satellite signal. Generally, sun outages occur in February, March, September and October, that is, around the time of the equinox
Equinox
An equinox occurs twice a year, when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the center of the Sun being in the same plane as the Earth's equator...
es. At these times, the apparent path of the sun across the sky takes it directly behind the line of sight between an earth station
Earth station
A ground station, earth station, or earth terminal is a terrestrial terminal station designed for extraplanetary telecommunication with spacecraft, and/or reception of radio waves from an astronomical radio source. Ground stations are located either on the surface of the Earth, or within Earth's...
and a satellite. As the sun radiates strongly at the microwave
Microwave
Microwaves, a subset of radio waves, have wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz and 300 GHz. This broad definition includes both UHF and EHF , and various sources use different boundaries...
frequencies used to communicate with satellites (C-band, Ka band
Ka band
The Ka band covers the frequencies of 26.5–40 GHz. The Ka band is part of the K band of the microwave band of the electromagnetic spectrum. This symbol refers to "K-above" — in other words, the band directly above the K-band...
and Ku band
Ku band
The Kμ band is a portion of the electromagnetic spectrum in the microwave range of frequencies. This symbol refers to —in other words, the band directly below the K-band...
) the sun swamps the signal from the satellite. The effects of a sun outage can include partial degradation, that is, an increase in the error rate, or total destruction of the signal.
Effect on Indian stock exchanges
In India, the BSEBombay Stock Exchange
The Bombay Stock Exchange is a stock exchange located on Dalal Street, Mumbai and is the oldest stock exchange in Asia. The equity market capitalization of the companies listed on the BSE was 1.63 trillion as of December 2010, making it the 4th largest stock exchange in Asia and the 8th largest...
(Bombay Stock Exchange) and NSE
National Stock Exchange of India
The National Stock Exchange is a stock exchange located at Mumbai, Maharashtra, India. It is the 9th largest stock exchange in the world by market capitalization and largest in India by daily turnover and number of trades, for both equities and derivative trading. NSE has a market capitalization...
(National Stock Exchange) use VSAT
Very small aperture terminal
A very-small-aperture terminal , is a two-way satellite ground station or a stabilized maritime Vsat antenna with a dish antenna that is smaller than 3 meters. The majority of VSAT antennas range from 75 cm to 1.2 m. Data rates typically range from 56 kbps up to 4 Mbps...
s (Very Small Aperture Terminal) for members to connect to their trading systems. VSATs depend upon satellites for connectivity between the terminals/systems. Hence these exchanges are affected due to the sun outage. These exchanges normally remain closed from 11:45 to 12:30 during 'sun outages', but times vary depending on the scientific factors. The interference in satellite signals disturbs smooth transmission of data of online transactions, hence these share markets remain closed for the duration of sun outages. Due to these outages, the trading sessions are normally extended in the same day to compensate for the lost time. In September 2006, however, only the NSE intended to shut down during the sun outage; the BSE did not. The reason for which is unknown.
Other locations
Saint HelenaSaint Helena
Saint Helena , named after St Helena of Constantinople, is an island of volcanic origin in the South Atlantic Ocean. It is part of the British overseas territory of Saint Helena, Ascension and Tristan da Cunha which also includes Ascension Island and the islands of Tristan da Cunha...
suffers from island-wide loss of Internet and telecommunications connections during sun outages because all telecommunications traffic to and from the island is carried on a single satellite link. Sun outage times are published in local newspapershttp://www.saint.fm/independent/20111007.pdf.