Tenmon misso (天文密奏)

Tenmon misso was a practice in ancient East Asia whereby observation of unusual astronomical phenomenon was confidentially reported to the monarch along with observations and astrological divination (prediction.)
It is also referred to as Tenmon so.

In ancient China, it was believed that the stars in the heavens symbolize the nations on the earth and that unusual movements of stars were portent of political upheaval (上天思想.)
Based on that idea, it was considered that the monarch should be informed of such movements as soon as possible because it was vital to the management of the national administration.
The Astronomical Chapter of "Jin shu" (History of the Jin Dynasty) -- which was also used as a textbook of tenmondo (ancient horoscopy) and rekido (calendrical study) in Japan -- described that 'some of the unusual movement of starts were good omens, but most of them were bad omens of natural disasters.'
For that reason, it was imperative that an unusual astronomical phenomenon should be reported to the monarch by those well versed in astronomy and astrology together with observations and astrological divination. This was Tenmon misso.

In Japan, it was decided that upon observing an unusual astronomical phenomenon, tenmon hakase (a master of astronomy) or a person who was well versed in astrology and astronomy and had received an imperial decree constituting the mission as the medium of tenmon misso should draw up a document stating what it symbolized by taking into account the divination and similar cases in the past, and observations; seal it; and directly submit it to the emperor through Onmyo no kami (Director of Onmyoryo, or Bureau of Divination) at once.
The article 'hisho gensho no jo' in Zoryo (the Law on Miscellaneous Matters) of Yoro ritsuryo code (code promulgated in the Yoro period) states that 'Onmyoryo should report a good omen or bad omen observed, to the emperor. The reported documents should be gathered for each season, sealed, sent to the Ministry of Central Affairs, and recorded for national history.'
In later ages, a procedure was established such that ichinokami (the ranking Council Member) of Daijokan (Grand Council of State or Sekkan - regents and advisers) confirmed the contents in advance, sealed the documents again, and returned them to tenmon hakase, and then the documents were submitted to Onmyo no kami (according to "Saikyuki" - record of court practices and usage, written by MINAMOTO no Takaaki in Chinese style), "Shingishiki" (New Procedures in Administration.)
It was decided that since the prediction was a top secret, it should be excluded from the record of national history (under the command of naiki - secretary of the Ministry of Central Affairs).)

As the books used for divination at this time, "Tenmon yoroku" (astrological digest), "Shinsen Onmyo sho" (New edition of the book of Onmyo), "Teiran", "Tenmon roku" (astronomical records), "Tenchi zuisho shi," "Shishosukuyokyo," "Senji ryakketsu," and "Rekirin" were known.

After kurodo dokoro (the Chamberlain's Office) was established, tenmon hakase and others began to submit misso to kurodo (chamberlain), bypassing Onmyo no kami, and the kurodo mediated the misso to the emperor (due to the nature of the matter, the misso often took place in the middle of the night or in the early morning, in which case the tenmon hakase was exceptionally allowed to report the misso directly to the emperor.)
After the mid Heian period, such direct access to the emperor was only allowed to the Abe clan whose hereditary occupation was tenmon hakase and the Nakahara clan which was kyokumu (the chief secretary of the Daijokan, or Grand Council of State); incidentally, the Nakahara clan had assumed the role of tenmon misso from Mochitada NAKAHARA in the tenure of Emperor Daigo (afterwards in 972, he was granted the family name of NAKAHARA along with Uzo NAKAHARA [中原有象] of the head family and originated the clan), allegedly because, besides the clan's hereditary occupation of Geki [Secretary of the Grand Council of State], it inherited the family learning of Myogo-do [the study of Confucian classics] and used many Chinese classics as source books, many of which contained elucidation of astronomical phenomena so that the clan produced many persons well versed in tenmondo. In the Muromachi period, an imperial decree constituting the mission as the medium of tenmon misso was issued to the Kamo clan, which was reki hakase (master of reki [calendar]).
According to "Azuma Kagami" (The Mirror of the East; a chronicle of the early history of the Kamakura Bakufu), the Kamakura bakufu (Japanese feudal government headed by a shogun) also invited Onmyoji who was well versed in tenmondo from Kyoto to Kamakura to constitute him the mission as the medium of tenmon misso to seii taishogun (literally, "great general who subdues the barbarians") (Since the misso could not have been available for the emperor in that situation, it was considered that the imperial decree of the misso meant no more than qualifying a person as tenmon hakase or the like.)

Tenmon misso was not performed for all the unusual astronomical phenomena but only for phenomena which had been divined by tenmon hakase or those who had received the imperial decree constituting the mission as the medium of tenmon misso as an omen of a great calamity -- the phenomena which tenmon hakase and those who had received the imperial decree constituting the mission as the medium of tenmon misso had failed to observe were not reported as tenmon misso either. According to the entry of "Gonijo Moromichi ki" (Diary of FUJIWARA no Moromichi) for September 8, 1096, people were terribly frightened at the sight of a meteor streaking across the night sky in August, yet no tenmon misso was done. Then, kanpaku (chief adviser to the Emperor) FUJIWARA no Moromichi and others summoned NAKAHARA no Moroto, who had received the imperial decree constituting the mission as the medium of tenmon misso, and tenmon hakase ABE no Chikamune -- Moroto confessed that he could not have done misso because he was not aware of the meteor and failed to observe it; but Chikamune explained that since the meteor was not an extraordinary astronomical phenomenon, it needed not to be reported as tenmon misso.

It was considered that tenmondo and rekido in those days provided relatively highly accurate prediction of solar eclipse, but that since their personnel and equipment were only enough for keeping their standard time observation from eight to ten p.m. and from four to six a.m. and not enough for observing other phenomena, tenmon hakase and others were not guaranteed to observe unusual astronomical phenomenon without fail -- therefore, great many of unusual astronomical phenomena might have been left out of the tenmon misso.

At the end of Heian period, the Abe clan began to monopolize the roles of tenmon hakase and that received the imperial decree constituting the mission as the medium of tenmon misso, however, both the Abe clan's deep involvement in Onmyodo, the other family learning of the clan and the internal strife within the clan confused tenmon misso. There was a dispute between the ABE no Suehiro brothers who performed the misso and the other members of the ABE clan over the sekki phenomenon (low-latitude aurora) observed on February 9, 1185. The former argued that it was a comet, and the latter objected that it was shiyuki (a star that is a portent of war). When inquired by the Udaijin (Minister of the Right) Kanezane KUJO, Suehiro stated that when the similar phenomenon was observed in 1177, his deceased father ABE no Yasuchika said that it was a comet, but he objected to that; then his father asked Heaven to give them judgment by punishing the wrong one, and consequently, Suehiro fell seriously ill, thereby they confirmed that it was a comet -- therefore, it could be concluded that actual movement of stars did not matter (the entry of "Gyokuyo" [the diary of Kanezane KUJO] for February 4, 991). That was considered to be an example of a transition of tenmondo and tenmon misso from the prediction originated from China, which was made according to the actual movement of stars based on 上天思想, to the divination based on Onmyodo, which was a divination technique originally developed in Japan. In 1234, there was a case contrary to the general rule such as that ABE no Ieuji -- who had not received the senji (imperial decree) -- reported on the appearance of a guest star, and was appointed to tenmon hakase in recognition of the services (the entry of "Meigetsuki" [the diary of FUJIWARA no Sadaie] for April 22, 1235).