Re: Inquiry to NICT about Japanese Summer time in 1948-1952.
Dear Nick, Thank you for your interest. We will respond to your inquiry. It is said that corresponding summer time was performed by instruction of the GHQ: General Headquarters (office of the Supreme Commander of the Allied Powers). We do not have detailed data about summer time then. According to the law of those days, the last day of summer time was made into 25 hours. What came after 12:59 p.m. of the last day was 00:00 a.m. of the next day. If you have any further questions, please let us know. Sincerely, Japan Standard Time Group Space-Time standards Laboratory Applied Electromagnetic Research Institute National Institute of Information and Communications Technology From: Phake Nick <c933103@gmail.com> Sent: Sunday, September 09, 2018 12:53 AM To: horonet@ml.nict.go.jp Cc: tz@iana.org Subject: [horonet 13333] Inquiry to NICT about Japanese Summer time in 1948-1952. To receivers of this email: Recently, I have read an article, which mentioned the history of Japanese Summer Time Implementation in the past at www.bengo4.com/internet/n_8461/ <http://www.bengo4.com/internet/n_8461/> . In the article, it was mentioned that the summer time (DST) end at 25 hours at the last day of the implementation period. Does that mean the clock would go up to the 25th hours back then and reach 24:59 before it continues toward 00:00 on the next day in standard time? If not then how did the clock switched from Summer Time back to Standard Time back then? Please use the "reply to all" function when replying to the message so that other receivers of the message can also hear answer on the matter. Sincerely, P.N.
On 9/11/18 12:28 AM, aya sekido wrote:
According to the law of those days, the last day of summer time was made into 25 hours.
What came after 12:59 p.m. of the last day was 00:00 a.m. of the next day.
Thank you for looking into it. The Japanese law that we found <http://www.shugiin.go.jp/internet/itdb_housei.nsf/html/houritsu/00219480428029.htm> says "第二条 四月の第一土曜日の翌日(日曜日)は二十三時間をもつて一日とし、九月の第二土曜日は二十五時間をもつて一日とする。" Google translates this as "Article 2. The day following the first Saturday of April (Sunday) shall be one day with twenty-three hours and the second Saturday of September shall be twenty-five hours a day." I see two ways to interpret how this law affected timekeeping during the September transition: 1. At 24:00 Saturday, people moved their 12-hour clocks back from 12 o'clock midnight to 11 o'clock P.M. Saturday, thus repeating the 23:00 Saturday hour, so that Saturday had 25 hours. 2. At 24:00 Saturday people left their clocks alone, and let them continue forward from 12 o'clock to 1 o'clock. The day was still Saturday, but the time was in the range 24:00 to 25:00. At 25:00 Saturday, people moved their 12-hour clocks back from 1 o'clock A.M. to 12 o'clock midnight and Sunday began at 00:00. This method also gives 25 hours to Saturday, and it is what you are suggesting. Method (1) would be likely used in the West; however, as I understand it method (2) is plausible in Japan (nowadays a Japanese bar might give a closing time of "26:00", for example). It is a tricky situation, since the law in question was done at the instruction of the Supreme Commander of the Allied Powers which may well have ordered method (1). Although method (1) is what we currently have in the Internet Time Zone Database (tzdb), if the Japanese people generally used method (2) we should try to fix tzdb as best we can; unfortunately we cannot do so perfectly, since the database format does not let us represent times like "24:59". Is there a good way to resolve the question? For example, are there archived versions of Japanese newspapers from the early 1950s?
2018-9-12 01:00, Paul Eggert <eggert@cs.ucla.edu> wrote:
Are there archived versions of Japanese newspapers from the early 1950s?
After some searches, there is a collection of Japanese newspaper of magazine known as "Gordon W. Prange Collection" which included thousands of newspaper and magazines from 1945-1949 in Japan. The collection is now stored as part of an archive in University of Maryland in the United States and can be accessed by physically visiting the reading room known as the Maryland Room in the University.
One other thing. The Japanese government is considering adopting daylight saving time for the 2020 Tokyo Olympics. Will this issue about 25-hour (or 26-hour) days come up in 2020? For example, could there be a 26-hour day in September 2020 with times ranging from 00:00 to 26:00? If so, a *lot* of computers will have to be reprogrammed, as no software I'm aware of supports timestamps like that now.
Dear Sirs, Thank you for your email dated September 12, 2018. We really appreciate your interest and comment. Unfortunately, we have no information on the official name of additional hours past the 12th o'clock midnight on the last DST day of Japan. If you ask NAOJ, you may be able to get more information. NAOJ and NAOJ Ephemeris Computation Office's Websites: https://www.nao.ac.jp/en/ https://eco.mtk.nao.ac.jp/koyomi/index.html.en Thank you for another question about DST in 2020. The government is considering future DST in Japan, but nothing has been decided yet. Thank you for your understanding. We wish good luck to you. Sincerely, Japan Standard Time Group Space-Time standards Laboratory Applied Electromagnetic Research Institute National Institute of Information and Communications Technology http://www.nict.go.jp/ On 2018/09/12 2:00, Paul Eggert wrote:
One other thing. The Japanese government is considering adopting daylight saving time for the 2020 Tokyo Olympics. Will this issue about 25-hour (or 26-hour) days come up in 2020? For example, could there be a 26-hour day in September 2020 with times ranging from 00:00 to 26:00? If so, a *lot* of computers will have to be reprogrammed, as no software I'm aware of supports timestamps like that now.
To clarify, I think the official name of the hours is less important than *when* the transition occurred. The law says that the last day of DST had 25 hours instead of 24. The question is whether in practice what happened was that starting 0:00 on Saturday, did people wait 25 hours (until 01:00 on Sunday) and THEN set their clocks back 1 hour, or did they wait 24 hours (until 00:00 on Sunday), and then set the clock back to 23:00? Best, Paul On 9/18/18 2:00 AM, horonet@ml.nict.go.jp wrote:
Dear Sirs,
Thank you for your email dated September 12, 2018. We really appreciate your interest and comment. Unfortunately, we have no information on the official name of additional hours past the 12th o'clock midnight on the last DST day of Japan. If you ask NAOJ, you may be able to get more information.
NAOJ and NAOJ Ephemeris Computation Office's Websites: https://www.nao.ac.jp/en/ https://eco.mtk.nao.ac.jp/koyomi/index.html.en
Thank you for another question about DST in 2020. The government is considering future DST in Japan, but nothing has been decided yet.
Thank you for your understanding. We wish good luck to you.
Sincerely,
Japan Standard Time Group Space-Time standards Laboratory Applied Electromagnetic Research Institute National Institute of Information and Communications Technology http://www.nict.go.jp/
On 2018/09/12 2:00, Paul Eggert wrote:
One other thing. The Japanese government is considering adopting daylight saving time for the 2020 Tokyo Olympics. Will this issue about 25-hour (or 26-hour) days come up in 2020? For example, could there be a 26-hour day in September 2020 with times ranging from 00:00 to 26:00? If so, a *lot* of computers will have to be reprogrammed, as no software I'm aware of supports timestamps like that now.
On 9/18/18 1:43 PM, Paul Ganssle wrote:
The law says that the last day of DST had 25 hours instead of 24. The question is whether in practice what happened was that starting 0:00 on Saturday, did people wait 25 hours (until 01:00 on Sunday) and THEN set their clocks back 1 hour, or did they wait 24 hours (until 00:00 on Sunday), and then set the clock back to 23:00?
Yes, that's the nub of the question. If people in Japan generally did the former, we should change tzdb to model the transition as one from 01:00 to 00:00 Sunday; this is not exact but is the best we can do. If people generally did the latter we're OK as-is. Possibly some people did one thing while others did the other, as the American occupiers did not always see eye-to-eye with the Japanese populace and I doubt whether it's entirely a coincidence that Japan stopped observing DST three days after US occupation ended. As we've already mentioned, old Japanese-language newspapers could help resolve this issue.
I have found a bit more information on the topic. In the webpage authored by National Astronomical Observatory of Japan https://eco.mtk.nao.ac.jp/koyomi/wiki/BBFEB9EF2FB2C6BBFEB9EF.html , it mentioned that using Showa 23 (year 1948) as example, 13pm of September 11 in summer time will equal to 0am of September 12 in standard time. It cited a document issued by the Liaison Office which briefly existed during the postwar period of Japan, where the detail on implementation of the summer time is described in the document. https://eco.mtk.nao.ac.jp/koyomi/wiki/BBFEB9EF2FB2C6BBFEB9EFB2C6BBFEB9EFA4CE... The text in the document do instruct a fall back to occur at September 11, 13pm in summer time, while ordinary citizens can change the clock before they sleep. * Note: despite the webpage being named as wiki, it is actually a collection of information maintained by the Ephemeris Computation Office, NAOJ, not something that can be edited by others. 2018-9-19 Wed 04:59, Paul Eggert <eggert@cs.ucla.edu> wrote:
On 9/18/18 1:43 PM, Paul Ganssle wrote:
The law says that the last day of DST had 25 hours instead of 24. The question is whether in practice what happened was that starting 0:00 on Saturday, did people wait 25 hours (until 01:00 on Sunday) and THEN set their clocks back 1 hour, or did they wait 24 hours (until 00:00 on Sunday), and then set the clock back to 23:00?
Yes, that's the nub of the question. If people in Japan generally did the former, we should change tzdb to model the transition as one from 01:00 to 00:00 Sunday; this is not exact but is the best we can do. If people generally did the latter we're OK as-is. Possibly some people did one thing while others did the other, as the American occupiers did not always see eye-to-eye with the Japanese populace and I doubt whether it's entirely a coincidence that Japan stopped observing DST three days after US occupation ended.
As we've already mentioned, old Japanese-language newspapers could help resolve this issue.
Thanks, this is just the sort of evidence I was looking for. Proposed patch attached. Note that this uses "25:00" in the zic input file, something that zic has supported since 2007 and so I hope is safe. Maintainers of other zic-format readers please take note.
On 2018-09-18 20:59, Paul Eggert wrote about the question whether Tokyo's switch to winter time in 1951 happened at 1951-09-08T14:00Z or at 1951-09-08T15:00Z::
Possibly some people did one thing while others did the other, as the American occupiers did not always see eye-to-eye with the Japanese populace and I doubt whether it's entirely a coincidence that Japan stopped observing DST three days after US occupation ended.
Just a minor correction: I think you mean the signing of the peace treaty with Japan, online at [assets.documentcloud.org/documents/1338718/san-francisco-peace-treaty-1951.pdf]. This happened on 1951-09-08 (a Saturday) in San Francisco, as stated in the text. It is quite likely that it was done after 08:00 PPT, so that local time in Tokyo was after 1951-09-09T00:00 in either interpretation, and not three days before the switch to winter time. US occupation of Japan ended only in 1952. Michael Deckers.
On 9/27/18 8:24 AM, Michael H Deckers via tz wrote:
I think you mean the signing of the peace treaty with Japan, online at [assets.documentcloud.org/documents/1338718/san-francisco-peace-treaty-1951.pdf].
This happened on 1951-09-08 (a Saturday)
I was referring to when that treaty was implemented, which was on April 28, 1952. See <http://www.columbia.edu/~hds2/BIB95/02occupation_augustine.htm>.
It now appears that Japan won’t mess with the clocks for the 2020 Olympic Games after all. After Japan’s ruling party held the first meeting of a study group on the topic, a party bigwig Toshiaki Endo told reporters that although he personally favored DST on an ongoing basis as “a step toward creating a low-carbon society”, that it likely would not happen in 2020, saying “It is physically difficult because of technical hurdles and public reluctance.” Endo’s stated motivation of energy saving is not well-supported by the science. In a recent meta-analysis I mentioned earlier that has now been published in a refereed journal, the bottom line was, “based on the available previous research, the best guess concerning the effect of DST on electricity consumption is close to zero.” This conclusion was for a world-wide analysis; the preprint’s entry for Japan gives a 95% confidence interval of (-0.666%, 0.933%) with a mean of 0.112%, meaning that the energy consumption change due to DST would be so close to zero as to be statistically insignificant and if we have to guess, we should guess that DST should slightly increase electricity usage in Japan. Okubo T. ‘Difficult’ daylight saving a no-go for 2020 Tokyo Games. Asahi Shimbun. 2018-09-28 13:55 +09. http://www.asahi.com/ajw/articles/AJ201809280033.html Havranek T, Herman D, Irsova Z. Does Daylight Saving Save Electricity? A Meta-Analysis. Energy J. 2018;39(2). https://doi.org/10.5547/01956574.39.2.thav with preprint at https://meta-analysis.cz/dst/dst.pdf
In fact there's a report from Japanese government back in year 1999 that said the total reduction of energy consumption due to summer time would be about 5 million liter petroleum, which is roughly 0.1% of the total annual energy consumption of Japan, however the report still say it's equivalent to the total energy need of 250 thousands families, and that 0.1% energy consumption would roughly equal to 1% of all energy consumption reduction policy or 10% of all policies that are within the aspect if "fundamentally changing lifestyle of citizens", therefore 0.1% isn't too little. The report also said that Global Warming cannot be solved by large policies that are unrelated to individuals but instead it would need to be solved by accumulation of small policies to attain a large effect and such every small bits count, and also it hypothesised that if summer time is implemented then the life style of citizens might shift accordingly which could reduce more energy demand than estimated. Also, while the report do agree that household energy consumption on air conditioning would increase after the implementation of summer time, the report think it's only going to increase 28 million liter petroleum consumption and is compensated by reduction in energy consumption in other sectors like industrial air conditioning http://web.archive.org/web/20021023004853/http://www.kokuminkaigi.gr.jp:80/g... 2018-9-29 17:13, Paul Eggert <eggert@cs.ucla.edu> wrote:
It now appears that Japan won’t mess with the clocks for the 2020 Olympic Games after all. After Japan’s ruling party held the first meeting of a study group on the topic, a party bigwig Toshiaki Endo told reporters that although he personally favored DST on an ongoing basis as “a step toward creating a low-carbon society”, that it likely would not happen in 2020, saying “It is physically difficult because of technical hurdles and public reluctance.”
Endo’s stated motivation of energy saving is not well-supported by the science. In a recent meta-analysis I mentioned earlier that has now been published in a refereed journal, the bottom line was, “based on the available previous research, the best guess concerning the effect of DST on electricity consumption is close to zero.” This conclusion was for a world-wide analysis; the preprint’s entry for Japan gives a 95% confidence interval of (-0.666%, 0.933%) with a mean of 0.112%, meaning that the energy consumption change due to DST would be so close to zero as to be statistically insignificant and if we have to guess, we should guess that DST should slightly increase electricity usage in Japan.
Okubo T. ‘Difficult’ daylight saving a no-go for 2020 Tokyo Games. Asahi Shimbun. 2018-09-28 13:55 +09. http://www.asahi.com/ajw/articles/AJ201809280033.html
Havranek T, Herman D, Irsova Z. Does Daylight Saving Save Electricity? A Meta-Analysis. Energy J. 2018;39(2). https://doi.org/10.5547/01956574.39.2.thav with preprint at https://meta-analysis.cz/dst/dst.pdfyo
Phake Nick wrote:
there's a report from Japanese government back in year 1999 that said the total reduction of energy consumption due to summer time would be about 5 million liter petroleum
Unfortunately I have no easy access to that 1999 report by the Japanese National Council to Think About Global Environment and Daylight-Saving Time, which is archived in the US Library of Congress <https://memory.loc.gov/cgi-bin/query/r?frd/jdc:@field(DOCID+@lit(LRSJ1999-30355))>. However, independent scientific research tends to be more reliable than government-sponsored reports for this sort of thing. And as far as I can tell, recent research has not demonstrated significant energy saving for DST in Japan. Admittedly I am hampered by the language barrier as I don’t read Japanese; that being said, I looked for publications in Japanese or English and found only two, cited below: one suggests DST would waste electricity and the other suggests DST would save electricity, and both studies are of course merely simulations, not empirical results. For what it’s worth, the Havranek meta-analysis attempted to assess research study quality, and reported “The difference in implied DST savings between a study from a journal with a zero impact factor and an impact factor of one is 0.96; better journals publish more pessimistic estimates of DST savings.” The two studies I mentioned are consistent with this finding.
Havranek T, Herman D, Irsova Z. Does Daylight Saving Save Electricity? A Meta-Analysis. Energy J. 2018;39(2). https://doi.org/10.5547/01956574.39.2.thav with preprint at https://meta-analysis.cz/dst/dst.pdfyo
That last URL should be: https://meta-analysis.cz/dst/dst.pdf The two studies I mentioned above are: Fong W, Matsumoto H, Lun Y, Kimura R. Energy savings potential of the summer time concept in different regions of Japan from the perspective of household lighting. J Asian Arch Build Engr. 2007;6:371-8. https://doi.org/10.3130/jaabe.6.371 Shimoda Y, Asahi T, Taniguchi A, Mizuno M. Evaluation of city-scale impact of residential energy conservation measures using the detailed end-use simulation model. Energy. 2007;32(9):1617-33. https://doi.org/10.1016/j.energy.2007.01.007
participants (6)
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aya sekido
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horonet@ml.nict.go.jp
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Michael H Deckers
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Paul Eggert
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Paul Ganssle
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Phake Nick