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Sirius is a binary star consisting of a main-sequence star of spectral type A0 or A1, termed Sirius A, and a faint white dwarf companion of spectral type DA2, termed Sirius B. The distance between the two varies between 8.2 and 31.5 astronomical units as they orbit every 50 years.
Sirius 3 was stationed at 51.2° East at the end if its lifetime in an inclined orbit Sirius 3 was leased to SES immediately after its launch on 5 October 1998 for a period of 12 months (after which it was moved to its original destination of 5.0° East) to provide capacity at 28.2° East and to back up Astra 2A , pending the launch of Astra 2B ...
Sirius Satellite Radio Inc. was a satellite radio and online radio service operating in North America, owned by Sirius XM Holdings. Headquartered in New York City, with smaller studios in Los Angeles and Memphis, Sirius was officially launched on July 1, 2002.
The well-known binary star Sirius, seen here in a Hubble photograph from 2005, with Sirius A in the center, and white dwarf, Sirius B, to the left bottom from it. A binary star or binary star system is a system of two stars that are gravitationally bound to and in orbit around each other.
If a star is in a binary system, as is the case for Sirius B or 40 Eridani B, it is possible to estimate its mass from observations of the binary orbit. This was done for Sirius B by 1910, [31] yielding a mass estimate of 0.94 M ☉, which compares well with a more modern estimate of 1.00 M ☉. [32]
SES-5 (also known as Astra 4B and Sirius 5) is a commercial geostationary communication satellite operated by SES It was launched on 9 July 2012. The launch was arranged by International Launch Services (ILS).
Sirius FM-3, also known as Radiosat 3, was an American communications satellite which was operated by Sirius XM Radio, previously Sirius Satellite Radio. It was constructed by Space Systems Loral and was based on the LS-1300 satellite bus. Launch occurred on 30 November 2000, at 19:59 GMT.
The two orbit each other every 50 years. Their closest approach last occurred in 1993 and they will be at their greatest separation between 2020 and 2025. Sirius was the basis for the ancient Egyptian calendar. [6] The star marked the Great Dog's mouth on Bayer's star atlas. [33] Flanking Sirius are Beta and Gamma Canis Majoris.