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73-551: On 2 February 2014, NBN Co of Australia chose Optus for a five-year contract to operate two purpose-built satellites (the Sky Muster satellites) to deliver high speed broadband across rural and remote Australia. The Aussat A-Class satellites were funded by the Government for Aussat Pty Ltd. When Optus was granted a telecommunications carrier licence in 1991, it was bundled with the purchase of Aussat Pty Limited as part of

146-405: A 'price war' between RSPs. NBN Co contracts mainly with RSPs to provide wholesale broadband access, with limited supply of backhaul to other organisations (for example providing backhaul services to Vodafone ). UTC This is an accepted version of this page Coordinated Universal Time ( UTC ) is the primary time standard globally used to regulate clocks and time. It establishes

219-553: A close approximation to UT1 , UTC occasionally has discontinuities where it changes from one linear function of TAI to another. These discontinuities take the form of leap seconds implemented by a UTC day of irregular length. Discontinuities in UTC occurred only at the end of June or December. However, there is provision for them to happen at the end of March and September as well as a second preference. The International Earth Rotation and Reference Systems Service (IERS) tracks and publishes

292-545: A leap second are announced at least six months in advance in "Bulletin C" produced by the International Earth Rotation and Reference Systems Service . The leap seconds cannot be predicted far in advance due to the unpredictable rate of the rotation of Earth. Nearly all UTC days contain exactly 86,400 SI seconds with exactly 60 seconds in each minute. UTC is within about one second of mean solar time (such as UT1 ) at 0° longitude , (at

365-453: A mean solar day in the mid‑19th century. In earlier centuries, the mean solar day was shorter than 86,400 SI seconds, and in more recent centuries it is longer than 86,400 seconds. Near the end of the 20th century, the length of the mean solar day (also known simply as "length of day" or "LOD") was approximately 86,400.0013 s. For this reason, UT is now "slower" than TAI by the difference (or "excess" LOD) of 1.3 ms/day. The excess of

438-418: A mean solar day to lengthen by one second (at a rate of 2 ms per century). This rate fluctuates within the range of 1.7–2.3 ms/cy. While the rate due to tidal friction alone is about 2.3 ms/cy, the uplift of Canada and Scandinavia by several metres since the last ice age has temporarily reduced this to 1.7 ms/cy over the last 2,700 years. The correct reason for leap seconds, then,

511-478: A meridian drifting eastward faster and faster. Thus, the time system will lose its fixed connection to the geographic coordinates based on the IERS meridian . The difference between UTC and UT would reach 0.5 hours after the year 2600 and 6.5 hours around 4600. ITU-R Study Group 7 and Working Party 7A were unable to reach consensus on whether to advance the proposal to the 2012 Radiocommunications Assembly;

584-516: A particular time zone can be determined by adding or subtracting the number of hours and minutes specified by the UTC offset , which ranges from UTC−12:00 in the west to UTC+14:00 in the east (see List of UTC offsets ). The time zone using UTC is sometimes denoted UTC+00:00 or by the letter Z —a reference to the equivalent nautical time zone (GMT), which has been denoted by a Z since about 1950. Time zones were identified by successive letters of

657-667: A plan over the nbn access network – compared with 4.9 million in February 2019. NBN Co developed a satellite internet program named Sky Muster aimed at rural areas. As of July 2023, over $ 620 million had been invested. However, the program experienced fierce competition from Starlink satellites. Sky Muster consists of two geosynchronous satellites orbiting over 35,000 km above Earth's surface, resulting in latency times around 600 milliseconds (at 25 Mbps), compared to Starlink's latency of below 40 milliseconds (for 100-200 Mbps). In February 2017, CEO Bill Morrow stated that there

730-517: A reference for the current time, forming the basis for civil time and time zones . UTC facilitates international communication, navigation, scientific research, and commerce. UTC has been widely embraced by most countries and is the effective successor to Greenwich Mean Time (GMT) in everyday usage and common applications. In specialized domains such as scientific research, navigation, and timekeeping, other standards such as UT1 and International Atomic Time (TAI) are also used alongside UTC. UTC

803-593: A resolution to alter UTC with a new system that would eliminate leap seconds by 2035. The official abbreviation for Coordinated Universal Time is UTC . This abbreviation comes as a result of the International Telecommunication Union and the International Astronomical Union wanting to use the same abbreviation in all languages. The compromise that emerged was UTC , which conforms to the pattern for

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876-547: A shift of the sun's movements relative to civil time, with the difference increasing quadratically with time (i.e., proportional to elapsed centuries squared). This is analogous to the shift of seasons relative to the yearly calendar that results from the calendar year not precisely matching the tropical year length. This would be a change in civil timekeeping, and would have a slow effect at first, but becoming drastic over several centuries. UTC (and TAI) would be more and more ahead of UT; it would coincide with local mean time along

949-476: A source of error). UTC does not change with a change of seasons, but local time or civil time may change if a time zone jurisdiction observes daylight saving time (summer time). For example, local time on the east coast of the United States is five hours behind UTC during winter, but four hours behind while daylight saving is observed there. In 1928, the term Universal Time ( UT ) was introduced by

1022-442: A standard clock not on the geoid, or in rapid motion, will not maintain synchronicity with UTC. Therefore, telemetry from clocks with a known relation to the geoid is used to provide UTC when required, on locations such as those of spacecraft. It is impossible to compute the exact time interval elapsed between two UTC timestamps without consulting a table showing how many leap seconds occurred during that interval. By extension, it

1095-420: A value to be chosen for the length of the atomic second that would accord with the celestial laws of motion. The coordination of time and frequency transmissions around the world began on 1 January 1960. UTC was first officially adopted in 1963 as CCIR Recommendation 374, Standard-Frequency and Time-Signal Emissions , and "UTC" became the official abbreviation of Coordinated Universal Time in 1967. In 1961,

1168-451: Is affected by the leap seconds introduced in UTC). Time zones are usually defined as differing from UTC by an integer number of hours, although the laws of each jurisdiction would have to be consulted if sub-second accuracy was required. Several jurisdictions have established time zones that differ by an odd integer number of half-hours or quarter-hours from UT1 or UTC. Current civil time in

1241-541: Is an abbreviation for the time laboratory. The time of events may be provisionally recorded against one of these approximations; later corrections may be applied using the International Bureau of Weights and Measures (BIPM) monthly publication of tables of differences between canonical TAI/UTC and TAI( k )/UTC( k ) as estimated in real-time by participating laboratories. (See the article on International Atomic Time for details.) Because of time dilation ,

1314-481: Is approximately +1.7 ms per century. At the end of the 21st century, LOD will be roughly 86,400.004 s, requiring leap seconds every 250 days. Over several centuries, the frequency of leap seconds will become problematic. A change in the trend of the UT1 – UTC values was seen beginning around June 2019 in which instead of slowing down (with leap seconds to keep the difference between UT1 and UTC less than 0.9 seconds)

1387-410: Is based on TAI, which is a weighted average of hundreds of atomic clocks worldwide. UTC is within about one second of mean solar time at 0° longitude, the currently used prime meridian , and is not adjusted for daylight saving time . The coordination of time and frequency transmissions around the world began on 1 January 1960. UTC was first officially adopted as a standard in 1963 and "UTC" became

1460-679: Is expected to be launched in Q4 2025 by an Ariane 6 rocket. The Ariane 64 configuration for this mission will provide enhanced launch energy performance to directly insert the Optus-11 satellite into a high-energy geostationary transfer orbit, enabling it to be commissioned more quickly. NBN Co NBN Co Limited , known as simply nbn , is a state-owned corporation of the Australian Government , tasked to design, build and operate Australia's National Broadband Network (NBN) as

1533-487: Is no significant demand for wired connections above 25 Mbit/s and consideration of upgrading the network will not be undertaken until demand for high-bandwidth services is proven. In August 2019, CEO Stephen Rue, announced the completion of the $ 51 billion National Broadband Network by June 2020. However, some service areas were still being rolled out in 2020 and 2021 with FTTP to properties with FTTN or FTTC. On 6th May 2024, CEO Stephen Rue announced his departure from

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1606-485: Is not possible to compute the precise duration of a time interval that ends in the future and may encompass an unknown number of leap seconds (for example, the number of TAI seconds between "now" and 2099-12-31 23:59:59). Therefore, many scientific applications that require precise measurement of long (multi-year) intervals use TAI instead. TAI is also commonly used by systems that cannot handle leap seconds. GPS time always remains exactly 19 seconds behind TAI (neither system

1679-407: Is not the current difference between actual and nominal LOD, but rather the accumulation of this difference over a period of time: Near the end of the 20th century, this difference was about ⁠ 1 / 800 ⁠ of a second per day; therefore, after about 800 days, it accumulated to 1 second (and a leap second was then added). In the graph of DUT1 above, the excess of LOD above

1752-468: Is very slowly decreasing because of tidal deceleration ; this increases the length of the mean solar day . The length of the SI ;second was calibrated on the basis of the second of ephemeris time and can now be seen to have a relationship with the mean solar day observed between 1750 and 1892, analysed by Simon Newcomb . As a result, the SI second is close to ⁠ 1 / 86400 ⁠ of

1825-592: The Bureau International de l'Heure began coordinating the UTC process internationally (but the name Coordinated Universal Time was not formally adopted by the International Astronomical Union until 1967). From then on, there were time steps every few months, and frequency changes at the end of each year. The jumps increased in size to 0.1 seconds. This UTC was intended to permit a very close approximation to UT2. In 1967,

1898-659: The Commonwealth Bank of Australia and leased back to Singtel Optus. It was replaced by Optus D2. Partially funded by the Australian Government (Defence Department) - Optus C1's use is shared between Defence and Telecommunications, in particular the supply of Television services to Australia. Mitsubishi Electric was the prime contractor responsible for manufacturing all the Optus C1 communications systems. The D1 and D2 satellites replace and expand

1971-547: The Gregorian calendar , but Julian day numbers can also be used. Each day contains 24 hours and each hour contains 60 minutes. The number of seconds in a minute is usually 60, but with an occasional leap second , it may be 61 or 59 instead. Thus, in the UTC time scale, the second and all smaller time units (millisecond, microsecond, etc.) are of constant duration, but the minute and all larger time units (hour, day, week, etc.) are of variable duration. Decisions to introduce

2044-515: The IERS Reference Meridian ). The mean solar day is slightly longer than 86,400 SI seconds so occasionally the last minute of a UTC day is adjusted to have 61 seconds. The extra second is called a leap second. It accounts for the grand total of the extra length (about 2 milliseconds each) of all the mean solar days since the previous leap second. The last minute of a UTC day is permitted to contain 59 seconds to cover

2117-598: The Line Islands from UTC−10 to UTC+14 so that Kiribati would all be on the same day. UTC is used in many Internet and World Wide Web standards. The Network Time Protocol (NTP), designed to synchronise the clocks of computers over the Internet, transmits time information from the UTC system. If only milliseconds precision is needed, clients can obtain the current UTC from a number of official internet UTC servers. For sub-microsecond precision, clients can obtain

2190-546: The SI second was redefined in terms of the frequency supplied by a caesium atomic clock. The length of second so defined was practically equal to the second of ephemeris time. This was the frequency that had been provisionally used in TAI since 1958. It was soon decided that having two types of second with different lengths, namely the UTC second and the SI second used in TAI, was a bad idea. It

2263-591: The Seven Network , the Nine Network , Sky Television New Zealand and New Zealand's Kordia (formerly known as BCL). D1 also supports VSAT users. Kordia is leasing a full transponder for sublease to TVNZ (TVNZ 1 & TVNZ 2) and Discovery New Zealand (Three & Bravo) for the Freeview service. The Kordia transponder will be on 12.4697 GHz. During in-orbit testing of the satellite, it

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2336-936: The UT1 variant of universal time . See the " Current number of leap seconds " section for the number of leap seconds inserted to date. The first leap second occurred on 30 June 1972. Since then, leap seconds have occurred on average about once every 19 months, always on 30 June or 31 December. As of July 2022 , there have been 27 leap seconds in total, all positive, putting UTC 37 seconds behind TAI. A study published in March 2024 in Nature concluded that accelerated melting of ice in Greenland and Antarctica due to climate change has decreased Earth's rotational velocity, affecting UTC adjustments and causing problems for computer networks that rely on UTC. Earth's rotational speed

2409-631: The WWV time signals, named for the shortwave radio station that broadcasts them. In 1960, the U.S. Naval Observatory, the Royal Greenwich Observatory, and the UK National Physical Laboratory coordinated their radio broadcasts so that time steps and frequency changes were coordinated, and the resulting time scale was informally referred to as "Coordinated Universal Time". In a controversial decision,

2482-438: The de facto company name. It was officially named "NBN Co Limited" on 6 October 2009 . It traded as "NBN Co" until 26 April 2015 when it began trading simply as "nbn". In 2019, NBN Co announced that by May 2020 retail service providers will be able to pool all their connectivity virtual circuit (CVC) bandwidth nationally. In February 2020, the company announced that 6.7 million homes and businesses were connected to

2555-419: The 13th General Assembly in 1967 (Trans. IAU, 1968). Time zones around the world are expressed using positive, zero, or negative offsets from UTC , as in the list of time zones by UTC offset . The westernmost time zone uses UTC−12 , being twelve hours behind UTC; the easternmost time zone uses UTC+14 , being fourteen hours ahead of UTC. In 1995, the island nation of Kiribati moved those of its atolls in

2628-598: The 25th century, four leap seconds are projected to be required every year, so the current quarterly options would be insufficient. In April 2001, Rob Seaman of the National Optical Astronomy Observatory proposed that leap seconds be allowed to be added monthly rather than twice yearly. In 2022 a resolution was adopted by the General Conference on Weights and Measures to redefine UTC and abolish leap seconds, but keep

2701-572: The D series of Optus satellites was successfully launched into a geostationary transfer orbit on 21 August 2009 at 22:09 UTC by Arianespace using an Ariane 5 ECA launch vehicle from Europe's Spaceport in Kourou , French Guiana . The satellite will be co-located with Optus C1 at 156° east . Optus sold 25% of the transponder capacity (6 out of 24) to Foxtel to provide High Definition programming as well as "new channels, expanded digital services and enhanced picture and sound quality". "Optus 10",

2774-603: The DUT1 correction (UT1 − UTC) for applications requiring a closer approximation of UT1 than UTC now provided. The current version of UTC is defined by International Telecommunication Union Recommendation (ITU-R TF.460-6), Standard-frequency and time-signal emissions , and is based on International Atomic Time (TAI) with leap seconds added at irregular intervals to compensate for the accumulated difference between TAI and time measured by Earth's rotation . Leap seconds are inserted as necessary to keep UTC within 0.9 seconds of

2847-603: The Earth's rotation has sped up, causing this difference to increase. If the trend continues, a negative leap second may be required, which has not been used before. This may not be needed until 2025. Some time in the 22nd century, two leap seconds will be required every year. The current practice of only allowing leap seconds in June and December will be insufficient to maintain a difference of less than 1 second, and it might be decided to introduce leap seconds in March and September. In

2920-540: The International Astronomical Union to refer to GMT, with the day starting at midnight. Until the 1950s, broadcast time signals were based on UT, and hence on the rotation of the Earth. In 1955, the caesium atomic clock was invented. This provided a form of timekeeping that was both more stable and more convenient than astronomical observations. In 1956, the U.S.  National Bureau of Standards and U.S. Naval Observatory started to develop atomic frequency time scales; by 1959, these time scales were used in generating

2993-506: The LOD over the nominal 86,400 s accumulates over time, causing the UTC day, initially synchronised with the mean sun, to become desynchronised and run ahead of it. Near the end of the 20th century, with the LOD at 1.3 ms above the nominal value, UTC ran faster than UT by 1.3 ms per day, getting a second ahead roughly every 800 days. Thus, leap seconds were inserted at approximately this interval, retarding UTC to keep it synchronised in

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3066-486: The NBN. There has been a significant failure of the nbn to deliver nominal performance to end users. There has been contention between RSPs and NBN on the reasons for this. Bill Morrow , then CEO of NBN Co, admitted in 2017 that 15% of end users received a poor service through the NBN and were 'seriously dissatisfied'. In addition, Morrow indicated that, at July 2017, prices and performance for end users were suppressed through

3139-455: The UTC second equal to the TAI second. This CCIR Recommendation 460 "stated that (a) carrier frequencies and time intervals should be maintained constant and should correspond to the definition of the SI second ; (b) step adjustments, when necessary, should be exactly 1 s to maintain approximate agreement with Universal Time (UT); and (c) standard signals should contain information on the difference between UTC and UT." As an intermediate step at

3212-523: The abbreviations of the variants of Universal Time (UT0, UT1, UT2, UT1R, etc.). McCarthy described the origin of the abbreviation: In 1967 the CCIR adopted the names Coordinated Universal Time and Temps Universel Coordonné for the English and French names with the acronym UTC to be used in both languages. The name "Coordinated Universal Time (UTC)" was approved by a resolution of IAU Commissions 4 and 31 at

3285-560: The alphabet and the Greenwich time zone was marked by a Z as it was the point of origin. The letter also refers to the "zone description" of zero hours, which has been used since 1920 (see time zone history ). Since the NATO phonetic alphabet word for Z is "Zulu", UTC is sometimes known as "Zulu time". This is especially true in aviation, where "Zulu" is the universal standard. This ensures that all pilots, regardless of location, are using

3358-654: The carrier licence deal. Aussat 1 was deployed by Space Shuttle Discovery during the first day of the STS-51-I mission. Aussat 2 was deployed by Space Shuttle Atlantis during the STS-61-B mission. Aussat 3 was launched from Guiana Space Centre by an Ariane 3 . The B-Class satellites were manufactured by Hughes and launched from the Xichang Satellite Launch Center by Long March rockets . The two satellites were

3431-557: The chairman of Study Group 7 elected to advance the question to the 2012 Radiocommunications Assembly (20 January 2012), but consideration of the proposal was postponed by the ITU until the World Radio Conference in 2015. This conference, in turn, considered the question, but no permanent decision was reached; it only chose to engage in further study with the goal of reconsideration in 2023. A proposed alternative to

3504-441: The civil second constant and equal to the SI second, so that sundials would slowly get further and further out of sync with civil time. The leap seconds will be eliminated by 2035. The resolution does not break the connection between UTC and UT1, but increases the maximum allowable difference. The details of what the maximum difference will be and how corrections will be implemented is left for future discussions. This will result in

3577-664: The company to take the CEO position at Optus . The NBN network, at 2022, draws together wired communication (copper, optical and hybrid fibre-coaxial ) and radio communication (satellite and fixed wireless networks) at 121 points of interconnect typically located in Telstra owned telephone exchanges throughout Australia. NBN Co also sells access for mobile telecommunication backhaul to mobile telecommunications providers. At 30 June 2016, Telstra had 45.5%, TPG group had 24.8% and Optus had 12.4% of all end users connecting to

3650-473: The difference between UTC and Universal Time, DUT1 = UT1 − UTC, and introduces discontinuities into UTC to keep DUT1 in the interval (−0.9 s, +0.9 s). As with TAI, UTC is only known with the highest precision in retrospect. Users who require an approximation in real time must obtain it from a time laboratory, which disseminates an approximation using techniques such as GPS or radio time signals . Such approximations are designated UTC( k ), where k

3723-483: The end of 1971, there was a final irregular jump of exactly 0.107758 TAI seconds, making the total of all the small time steps and frequency shifts in UTC or TAI during 1958–1971 exactly ten seconds, so that 1 January 1972 00:00:00 UTC was 1 January 1972 00:00:10 TAI exactly, and a whole number of seconds thereafter. At the same time, the tick rate of UTC was changed to exactly match TAI. UTC also started to track UT1 rather than UT2. Some time signals started to broadcast

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3796-533: The failure could not be determined at the time. However, the Long March 2E experienced the same payload fairing collapse when launching Apstar 2 in 1995. Based on instrumentation added to the satellite, Hughes determined that the failure was caused by aerodynamic forces and wind shear. The information provided by Hughes caused great political controversy in the United States, which subsequently banned U.S. satellites from being launched on Chinese rockets. Optus B3

3869-689: The first U.S.-built satellites to be approved by the Reagan administration for launch on Chinese rockets. To break into the commercial launch market, the Chinese offered to launch for less than half of what a U.S. launch company would charge. Optus B1 was moved to Junk orbit in May 2008. Satellite Control Processor On 21 May 2005 services were temporarily lost when the Primary Satellite Control Processor failed. The satellite

3942-509: The frequency for the caesium transition , newly established, with the ephemeris second . The ephemeris second is a unit in the system of time that, when used as the independent variable in the laws of motion that govern the movement of the planets and moons in the solar system, enables the laws of motion to accurately predict the observed positions of solar system bodies. Within the limits of observable accuracy, ephemeris seconds are of constant length, as are atomic seconds. This publication allowed

4015-399: The frequency of the signals was initially set to match the rate of UT, but then kept at the same frequency by the use of atomic clocks and deliberately allowed to drift away from UT. When the divergence grew significantly, the signal was phase shifted (stepped) by 20 ms to bring it back into agreement with UT. Twenty-nine such steps were used before 1960. In 1958, data was published linking

4088-602: The horizontally-aligned signals from the New Zealand spot beam. Accordingly, Sky was able to return to their original capacity allocation. D2 was successfully launched from the Guiana Space Centre by an Ariane 5 GS on 5 October 2007 at 22:02 UTC . Optus D2 replaced Optus B3, which had been in operation for 13 years at the time of D2's launch. D2 also carries a large number of Free To Air channels, many in languages other than English The third in

4161-435: The long term. The actual rotational period varies on unpredictable factors such as tectonic motion and has to be observed, rather than computed. Just as adding a leap day every four years does not mean the year is getting longer by one day every four years, the insertion of a leap second every 800 days does not indicate that the mean solar day is getting longer by a second every 800 days. It will take about 50,000 years for

4234-435: The more general Australia/NZ beam. Due to restrictions on broadcast rights (in terms of both broadcast licensing and copyright ), the unencrypted Freeview service could not make a similar allocation switch and was set up as a horizontally-aligned service on the New Zealand spot beam. On 31 July 2007, Sky successfully performed an over the air software upgrade to all of its customer set-top boxes , enabling them to receive

4307-468: The nation's wholesale broadband provider. The corporation reports to two shareholder ministers: the Minister for Finance and the Minister for Communications . NBN Co was established on 9 April 2009 under the name of its company number , "ACN 136 533 741 Limited". After the establishment, the Australian Government started referring to the company as "National Broadband Network Company", which became

4380-494: The nominal 86,400 s corresponds to the downward slope of the graph between vertical segments. (The slope became shallower in the 1980s, 2000s and late 2010s to 2020s because of slight accelerations of Earth's rotation temporarily shortening the day.) Vertical position on the graph corresponds to the accumulation of this difference over time, and the vertical segments correspond to leap seconds introduced to match this accumulated difference. Leap seconds are timed to keep DUT1 within

4453-529: The official abbreviation of Coordinated Universal Time in 1967. The current version of UTC is defined by the International Telecommunication Union . Since adoption, UTC has been adjusted several times, notably adding leap seconds in 1972. Recent years have seen significant developments in the realm of UTC, particularly in discussions about eliminating leap seconds from the timekeeping system because leap seconds occasionally disrupt timekeeping systems worldwide. The General Conference on Weights and Measures adopted

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4526-487: The remote possibility of the Earth rotating faster, but that has not yet been necessary. The irregular day lengths mean fractional Julian days do not work properly with UTC. Since 1972, UTC may be calculated by subtracting the accumulated leap seconds from International Atomic Time (TAI), which is a coordinate time scale tracking notional proper time on the rotating surface of the Earth (the geoid ). In order to maintain

4599-638: The same 24-hour clock , thus avoiding confusion when flying between time zones. See the list of military time zones for letters used in addition to Z in qualifying time zones other than Greenwich. On electronic devices which only allow the time zone to be configured using maps or city names, UTC can be selected indirectly by selecting cities such as Accra in Ghana or Reykjavík in Iceland as they are always on UTC and do not currently use daylight saving time (which Greenwich and London do, and so could be

4672-619: The services provided by the B1 and B3 satellites respectively, which had both been operating beyond their design lifetimes. The D3 satellite is co-located with C1 to expand capacity. D1 was successfully launched by an Ariane 5 ECA on 13 October 2006 at 20:56 UTC . It was the first satellite to sign contract for Launch Services Alliance mission assurance. Customers on D1 include the Australian Broadcasting Corporation (ABC), Special Broadcasting Service (SBS),

4745-640: The time from satellite signals. UTC is also the time standard used in aviation , e.g. for flight plans and air traffic control . In this context it is frequently referred to as Zulu time, as described below. Weather forecasts and maps all use UTC to avoid confusion about time zones and daylight saving time. The International Space Station also uses UTC as a time standard. Amateur radio operators often schedule their radio contacts in UTC, because transmissions on some frequencies can be picked up in many time zones. UTC divides time into days, hours, minutes, and seconds . Days are conventionally identified using

4818-444: The time of the start of the outage ranged from 14:52 AWST to 18:52 NZST , a peak time for listeners and viewers of the radio and television broadcast and subscription services provided directly or indirectly by the satellite. The Long March 2E rocket carrying Optus B2 experienced a collapse of the payload fairing, destroying the satellite. The rocket continued functioning and delivered the debris into low Earth orbit . The cause of

4891-489: The vertical range depicted by the adjacent graph. The frequency of leap seconds therefore corresponds to the slope of the diagonal graph segments, and thus to the excess LOD. Time periods when the slope reverses direction (slopes upwards, not the vertical segments) are times when the excess LOD is negative, that is, when the LOD is below 86,400 s. As the Earth's rotation continues to slow, positive leap seconds will be required more frequently. The long-term rate of change of LOD

4964-408: Was also dissatisfaction with the frequent jumps in UTC (and SAT). In 1968, Louis Essen , the inventor of the caesium atomic clock, and G. M. R. Winkler both independently proposed that steps should be of 1 second only. to simplify future adjustments. This system was eventually approved as leap seconds in a new UTC in 1970 and implemented in 1972, along with the idea of maintaining

5037-516: Was awarded to Space Systems/Loral, and announced on 21 March 2011 in a press release by Optus CEO Paul O'Sullivan. The satellite will provide "high quality broadcast services to households, and two way voice and data communication services to areas in and around Australia and NZ", and "satellite services to Australia and NZ Government departments, premium companies and broadcasters including FOXTEL, ABC, SBS, Seven Network, Nine Network, Network Ten, Globecast Australia and Sky TV New Zealand.". Optus 11

5110-412: Was discovered that the New Zealand spot beam had been configured with horizontal polarisation instead of the expected vertical polarisation - as had been used on its predecessor Optus B1 . As many existing receivers did not have the ability to receive horizontally aligned signals, Sky Television was unable to transfer services from Optus B1 to this beam as expected. Sky was instead assigned capacity on

5183-462: Was launched as a replacement for Optus B2. After the fairing failure that destroyed Optus B2, Hughes recommended reinforcement of the fairing. The Chinese chose not to follow the recommendations and instead added more rivets. The launch of Optus B3 was successful, but the next launch of the Long March 2E experienced another fairing failure and destroyed the Apstar 2 satellite. This satellite is owned by

5256-592: Was switched to use the Backup SCP in order to restore services. Thereafter the satellite continued to operate from the Backup SCP. March 2006 Positioning Failure At 06:52 UTC on 30 March 2006, a routine repositioning manoeuvre failed, resulting in loss of pointing control of the satellite. Although communication with the satellite was not lost, transmission services provided by the satellite failed due to its incorrect positioning. Services were progressively restored between 18:00 and 20:00 UTC . Local time at

5329-408: Was thought better for time signals to maintain a consistent frequency, and that this frequency should match the SI second. Thus it would be necessary to rely on time steps alone to maintain the approximation of UT. This was tried experimentally in a service known as "Stepped Atomic Time" (SAT), which ticked at the same rate as TAI and used jumps of 0.2 seconds to stay synchronised with UT2. There

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