FAQs
Answers to a range of frequently-asked questions about clocks and timekeeping can be found here.
General Time FAQs
- The time at which summer time begins and ends is given in the relevant EU Directive and UK Statutory Instrument as 1 a.m. Greenwich Mean Time (GMT).
- The short answer is 'both', because the use of the word midnight is heavily dependent on its context.
- This is the responsibility of the European Parliament and the Council of the European Union.
- There are no standards established for the meaning of 12 a.m. and 12 p.m. and often a 24 hour time is less confusing.
- The standard notation for the date is the sequence YYYY-MM-DD or YY-MM-DD.
- A millennium is any period of a thousand years. So you could say that the next millennium begins now. The third millennium of the Christian Era began at the start of the year 2001 A.D.
- There are no 'official' definitions of the duration of spring, summer, autumn and winter for civil purposes. Many bodies, for example meteorologists, adopt a convention for the purpose of presenting statistics by grouping the twelve months of the year into four three-month seasons.
- Different religions and cultures have their own conventions about the significance of the days of the week, and where in the week the cycle is said to begin. Even in modern times there are variations to accommodate specific needs.
Clock FAQs
- There should be no interference as the Wi-Fi transmit frequencies are so different from the MSF frequency.
- If you look at several atomic clocks all set to the same time you'll find that they still agree within ten millionths of a second after a week.
- Your radio-controlled watch might be designed to work from the American station WWVB.
- Even allowing for the delay in the telephone network, you can probably expect the starts of the seconds pips to be accurate seconds markers within about one-tenth of a second.
- Battery powered radio-controlled clocks typically check the time only every hour or two, or even less, This is to conserve the battery.
- Users of the MSF service receive predominantly a ‘ground wave’ signal. However, there is also a residual ‘sky wave’ which is reflected off the ionosphere and is much stronger at night, this can result in a total received signal that is either stronger or weaker.
- There are a few possible answers...
Leap Second & Leap Year FAQs
- Yes, 2000 was a leap year. Since 1752, in this country, years exactly divisible by 100 are only leap years when they are also exactly divisible by 400.
- The International Earth Rotation and Reference Systems Service (IERS), based at the Paris Observatory, announces twice yearly whether or not there will be a leap second at the end of the following June or December.
- As UTC is running about one second per year faster than time based on the Earth's rotation (Greenwich Mean Time, or Universal Time), an extra second is occasionally inserted in the UTC time scale to let it fall behind and start catching up again.
MSF FAQs
- The Rugby radio station, with call-sign GBR, was brought into service in 1926 by the Post Office as a telegraphy station with world-wide coverage and a frequency of 16 kHz.
- Since 1995 October 22 there has been a permanent one-hour difference between British time (as broadcast by MSF) and Central European Time, as broadcast by DCF-77 in Germany.
- MSF is the three-letter call sign used to designate the UK’s 60 kHz standard-frequency and time signal.
- The MSF radio signal has a very long wavelength (5 km) which is comparible or larger than dimensions of the metalwork of buildings and pylons which act as a screening mesh and greatly reduce the signal strength.
- When they started in 1950 the MSF signals carried only seconds and minute markers, without any labels. In September 1974 a short burst of data at 100 bit/s was added during the first second of the minute to signal the hour and minute - the 'fast code'.
- The solid-state 60 kHz transmitter at Anthorn typically operates at around 27 kW of radio-frequency signal which gives an equivalent monopole radiated power of approximately 17 kW.
- The MSF time signal provides a good service throughout the British Isles, with signal strengths greater than 100 µV/m at 1000 km from Anthorn (in Cumbria) in all directions.
- The MSF h.f. services on 2.5, 5 and 10 MHz ceased at the end of February 1988 as they were of little use nationally, and more accurate methods were available for long-range comparisons.
Miscellaneous FAQs
- The time displayed on a well designed sundial will vary from the mean time during the year, up to 16 minutes ahead (November 3), and up to 14 minutes behind (February 11), only agreeing around April 15, June 13, September 1 and December 25th. Subject to these corrections a good sundial can be read to within a few minutes accuracy.
- To find the time in Hong Kong relative to the UK you need to know the time zone of Hong Kong and whether either country is on summer time (also known as daylight-saving time).
- GPS has its own date and time scale for expressing satellite positions, based on counting weeks, and seconds within a week. To limit the size of the numbers used in the data and calculations the GPS Week Number is a ten-bit count in the range 0-1023, repeating every 1024 weeks.
- The gigasecond is the only scientifically-preferred time interval that is passed in adult life.