Talk:Coordinated Universal Time/GA1

GA Review

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Reviewer: Looie496 (talk) 17:01, 15 October 2011 (UTC)

I will review. Pyrotec (talk) 19:57, 9 August 2011 (UTC)

Sorry for the delay. I will review from today.

Initial comments

On the basis of a very quick read, perhaps the article will make GA-status time round. However the WP:Lead appears to be quite poor and the Uses section is somewhat under-referenced.

I'm now going to work my way through the article starting at the Uses section and considering the WP:Lead last. This is likely to take at least one day, possibly more. Pyrotec (talk) 20:05, 30 August 2011 (UTC)

• Uses -

• The first two paragraphs are unreferenced.
• The claim in the third paragraph, i.e. "International broadcasters such as the BBC World Service also use UTC ..." is unreferenced.
• The claim in the fourth paragraph about Zulu time is unreferenced.
• The claim in the final paragraph about the international space station is unreferenced.
• Most of these paragraphs are short, very short, sometimes a single sentence, so they should be merged.

• The first paragraph is probably OK as it stands. The second paragraph is a single sentence about about global commerce: I see no reason why it can be merged with the fifth paragraph which is about global transportation.

• Definition and relationship to other standards -

• This has much more in-line citations but also suffers from mostly single sentence paragraphs, one two-sentence paragraph and a three-sentence paragraph. The first three paragraphs could be merged into one.
• There is no need to wikilink both occurrences of Universal Time is a single section, this is WP:Overlinking.

Pyrotec (talk) 18:00, 4 September 2011 (UTC)

• Notation -

• Looks OK. I'll accept Notation as a section title, but is it really notation that is being discussed (its more like abbreviations)?

• Mechanism -

• Poor grammar: I'm not convinced that the second paragraph is a paragraph, i.e. "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." It seems to a single sentence that has escaped from the first paragraph.
• The second proper paragraph, i.e. the 86,400 second-day paragraph is unreferenced. I'm happy to accept that 24 hr x 60 min x 60 sec = 86,400 seconds, but all the claims and statements about 59 second and 61 second minutes need a citation, i.e. compliance with WP:Verifiability.

....Stopping for now. To be continued. Pyrotec (talk) 18:54, 4 September 2011 (UTC)

• • Time zones -

• Looking at my old school atlas, Reykjavik is listed as 21° 53' W so it is not obvious that "is always on UTC time and does not use daylight saving". There are two claims here that need a citation (possibly only one citation is needed).

• • Daylight saving -

• The given example about East Coast time needs a citation.

• History -

• The first, fourth, fifth and sixth paragraphs are unreferenced.

• Rationale -

• This is mostly unreferenced, but as it is mostly explanation, and the one statement is referenced, I'll accept this as it is.

• Future -

• There is a {{who}} flag that needs to be addressed.
• The penultimate paragraph states: "....An ITU study group was to have voted on this possibility during 2008, possibly leading to official approval by the World Radiocommunication Conference in 2012 and the subsequent cessation of leap seconds.", as we are now 75% of the way through 2011 I would have expected an update as to whether the 2008 vote took place, and whether approval next year (in 2012) is possible?

• WP:Lead -

• This part of the article has to functions: to introduce the topic cover by the article and summarise the main points. What we have is four paragraphs: one comprised of two sentences and three paragraphs of one sentence. Perhaps they are bullet points with out the points.
• For a short article such as this, I would have expected one or two (proper) paragraphs introducing the topic (yes it possibly does) and summarising the main points. Its not really my job to state what the main points are: perhaps they are all covered, in which case perhaps a more detail is needed e.g. Atomic time has a link, but no mention of a Caesium clock, GMT is mentioned by not Zulu time.

At this point, I would regard the article as non-compliant in respect of prose/grammar and WP:Verifiability. The article is well referenced in parts and some of the existing references might provide adequate verification for the statements discussed above that are not currently verifiable. I'm therefore going to put this review On Hold to allow corrective actions to take place. None have taken place in the last five days. I've been distracted elsewhere on wikipedia, so I know that distractions do occur. Pyrotec (talk) 19:23, 9 September 2011 (UTC)

I believe I have addressed this to some degree, although I'm sure some editors will feel the writing can be further improved. Jc3s5h (talk) 16:56, 21 September 2011 (UTC)

Status check

This review seems to be inactive at the moment, and it's been open for two months. Do we have a decision? Do you need some help? WhatamIdoing (talk) 15:17, 11 October 2011 (UTC)

I observe that Pyrotec has not made any Wikipedia contributions since 15 September. Jc3s5h (talk) 16:34, 11 October 2011 (UTC)

It appears that s/he announced a wikibreak on the user page. No e-mail, either. What would you like to do? WhatamIdoing (talk) 22:00, 13 October 2011 (UTC)

I think it would be best to have another editor do the review. Pyrotec has made a real contribution by finding a number of issues, and it couldn't hurt to have someone else look at it from a different point of view. Jc3s5h (talk) 22:32, 13 October 2011 (UTC)

Picking up review

I'm not quite sure what has been going on here, but I'll pick up this review. Contrary to the previous reviewer, the first thing I would like to address is the lead, which is seriously lacking. I would like to see the lead give brief answers to these questions:

• How is UTC information provided to clients?
• Where is the clock located?
• How are UTC times determined? The lead currently says that UTC is based on TAI, but the reader should not need to go to the TAI article for a basic answer.
• How precisely are UTC times specified?
• What is the rationale for deciding when to add a leap second? In other words, who makes this decision and what is the basis for the decision?
• In what way does UTC differ conceptually from TAI and UT1?
• Where did the acronym UTC come from?
• Who decided to make UTC a standard, and when did this happen?
• Will UTC be the standard forever?

Most or all of this information is in the article, of course, but it should all be addressed in the lead. Looie496 (talk) 17:01, 15 October 2011 (UTC)

That's too much for the lead, in my view. Some of these questions cannot possibly be answered (will UTC be the standard forever?). Others have multiple interpretations and answers (How is UTC information provided to clients?) Some can't really be answered in their present form (where is the clock located?) Let me give some off-the-cuff answers to show the complexity:

1. How is UTC information provided to clients? Pure UTC with no source designated is not provided in real time; instead, a list of how far off each of 68 laboratories were is issued retrospectively in Circular T.
2. Where is the clock located? There is no one clock that provides UTC. There are quite a few laboratories around the world that are included in the computation of UTC (listed in Circular T), and there are many more clocks that provide approximations of UTC.
3. How are UTC times determined? The lead currently says that UTC is based on TAI, but the reader should not need to go to the TAI article for a basic answer. The requirement is to provide leap seconds to keep |UT1 - UTC| < 0.9 s.
4. How precisely are UTC times specified? UTC is computed, not specified. The largest difference between the retrospectively computed UTC and a time laboratory in the latest Bulletin C that I can pick out by eye is for Budapest, -56436.6 ns.
5. What is the rationale for deciding when to add a leap second? In other :words, who makes this decision and what is the basis for the decision? The criterion is stated in the answer to question 3. The decision appears to be made by the International Earth Rotation AND Reference Systems Service and is contained in Bulletin C.
6. In what way does UTC differ conceptually from TAI and UT1? It is a compromise between them, having seconds of uniform length (as measured by atomic clocks) like TAI, but, because of leap seconds, staying close to mean solar time (as implemented by UT1).
7. Where did the acronym UTC come from? It was chosen by the CCIR (now named ITU-R) in 1967, according to McCarthy and Seidelmann. That organization also stated the names were Coordinated Universal Time in English and Temps Universel Coordonné in French. (2009, p. 227)
8. Who decided to make UTC a standard, and when did this happen? See previous answer. Also, various other organizations and governments have explicitly or implicitly endorsed UTC.
9. Will UTC be the standard forever? There is a big fight about this going on in the precision time community.

Do you think the following draft might serve as a starting point for creating a more informative lead?:

Coordinated Universal Time (abbreviated UTC) is the primary time standard by which the world regulates clocks and time. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose. If only limited precision is needed, clients can obtain the current UTC time from a number of official internet UTC servers . For nanosecond precision, clients can obtain the time from radio or satellite signals. Time zones around the world are expressed as positive or negative offsets from UTC, as in this list.

Coordinated Universal Time is closely related to International Atomic Time (TAI), a time standard calculated using a weighted average of signals from over 200 atomic clocks located in over 70 national laboratories around the world. The only difference between the two is that UTC is occasionally adjusted by adding a leap second in order to keep it within one second of Universal Time, which is defined by the Earth's rotation. In the 49 years up to 2010, a total of 24 leap seconds have been added.

The UTC standard was officially initiated in 1961 by the International Radio Consultative Committee, at the request of five national laboratories. The system was changed several times over the following years, until it reached its final form until 1972. A number of proposals have been made to replace it with a new system, but no consensus has yet been reached to do so.

Looie496 (talk) 22:21, 15 October 2011 (UTC)

That looks promising. I intend to break it down into a list of claims, and see what claims are presented as introductory information in the current article and one or two books I have. Then I'll suggest additions or deletions. Jc3s5h (talk) 22:28, 15 October 2011 (UTC)

That isn't quite the right way to think about it. In a Wikipedia article, lots of readers only look at the lead, so it should give them as comprehensive a picture as it can without going into too much detail. In books and printed articles the introduction serves a different purpose -- a Wikipedia lead is more like the abstract of a paper than the introduction of a paper. Looie496 (talk) 22:43, 15 October 2011 (UTC)

Can I suggest, 'Coordinated Universal Time is based on International Atomic Time' because that is the way things work. The actual clocks determine TIA and UTC is calculated from this. Martin Hogbin (talk) 11:59, 16 October 2011 (UTC)

I will put a draft lead section derived from Looie496's version below. Jc3s5h (talk) 15:21, 16 October 2011 (UTC)

Proposed lead section

Coordinated Universal Time (abbreviated UTC) is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose. If only limited precision is needed, clients can obtain the current UTC time from a number of official internet UTC servers . For sub-microsecond precision, clients can obtain the time from satellite signals. Time zones around the world are expressed as positive or negative offsets from UTC, as in this list.

Coordinated Universal Time is based on International Atomic Time (TAI), a time standard calculated using a weighted average of signals from atomic clocks located in nearly 70 national laboratories around the world.(International Bureau of Weights and Measures 2011) The only difference between the two is that UTC is occasionally adjusted by adding a leap second in order to keep it within one second of UT1, which is defined by the Earth's rotation. In the 50 years up to and including 2011, a total of 34 leap seconds have been added.

The UTC standard was officially standardized in 1961 by the International Radio Consultative Committee, after having been initiated by several national time laboratories. The system was changed several times over the following years, until leap seconds were adopted in 1972. A number of proposals have been made to replace it with a new system, which would eliminate leap seconds, but no consensus has yet been reached to do so.

• International Bureau of Weights and Measures (10 October 2011). "Circular T". {{cite web}}: Invalid |ref=harv (help)

Jc3s5h (talk) 15:21, 16 October 2011 (UTC)

As I see it, my role here is to make suggestions, and perhaps to copy-edit, but not to add substantive content to the article, because if I did I would not be a neutral reviewer. So you should edit the article in any way you think is appropriate, and if I think there is a problem with it I'll say so. In this particular case, the version above looks fine to me. Looie496 (talk) 15:31, 16 October 2011 (UTC)

I have made changes substantially as I described above; I hope the review process can continue. Jc3s5h (talk) 12:33, 22 October 2011 (UTC)

Picking up review again, sorry for delay

• Uses: Is the bit about amateur radio important enough for this article? If so, a ref should be added to support the statement.

I think the use by amateur radio operators is relevant because they illustrate that UTC is used by a widely-distributed group of people with a wide range of educational background; not just by physicists, astronomers, and telecommunications engineers. It will also raise in readers mind the possibility that any geographically dispersed group might use UTC for scheduling. I added a citation, and reworded the article to mention scheduling, rather than logging. A general readership would be rightly uninterested in amateur radio logs. Jc3s5h (talk) 17:03, 24 October 2011 (UTC)

• Mechanism: I think this section should probably mention that the schedule of addition of leap seconds can't be predicted because of tectonic events that cause small but significant changes in the earth's rate of rotation.
• "UTC is derived from International Atomic Time..." This paragraph is very hard to understand. Can I suggest that you leave out the material about what happened before 1972, and simply describe how it works now? I don't think that alone will solve the problem, but at least it should help.
• "As with TAI, UTC is only known with the highest precision in retrospect." I don't understand what this sentence means.
• "Because of time dilation,..." This paragraph doesn't seem to belong in this section, since it describes how UTC is conveyed, not how it is calculated.
• Daylight savings: This doesn't really justify a separate section -- I think it could just be a paragraph added to the previous section.
• History "The signal frequency was changed less often." I don't understand this sentence.
• "In 1958, data was published linking the frequency for the caesium transition, newly established, with the ephemeris second." You should either explain what this means and why it is relevant, or delete it.

• It will take a little time to look into all these points, but I can answer one right off. "As with TAI, UTC is only known with the highest precision in retrospect" means that there are many atomic clocks being compared; each is an approximation to TAI or UTC. These comparisons are carried out by the International Bureau of Weights and Measures and published in Circular T, which is issued at one month intervals. So if one wanted the most accurate value of UTC possible, one would obtain the best real-time transmission from a time laboratory as is availible in one's locality, and record events according to that time scale. Then one would wait about a month and adjust the value by the amount in Circular T to get the best possible estimate of the time of the event.

For example, if the best time source available to someone was UTC(MKEH) in Budapest, and on that time scale an event occurred at 00:00:00.000 000 000 0 on Sept 30, 2011, one would see that UTC was 56436.6 ns slower than UTC(MKEH), so a better estimate of the time of the event would be 00:00:00.000 056 436 6 Jc3s5h (talk) 20:10, 28 October 2011 (UTC)

• I think "Daylight saving" should remain as a separate section, because it is one of the key points a person learning to convert between zone time and UTC must keep in mind. Jc3s5h (talk) 15:30, 29 October 2011 (UTC)

• A colloquium on the future of UTC was held, and the presentations have just become available. I intend to consider these papers before making further edits. Jc3s5h (talk) 19:50, 3 November 2011 (UTC)

Closing review

Due to the lack of progress I am going to fail this GA review. I think the article still needs significant work -- feel free to renominate it when it is ready. Looie496 (talk) 18:33, 14 November 2011 (UTC)