Moon-year quirk.

Seta Village was on the southern shore of Lake Biwa [so near Kyôto . . . ].
Bashô's Abode of Illusion overlooked Lake Biwa and the Seta River:

The Harvest Moon --
ah, this Moon-year two passing
the Moon over Seta.


[白狐]

[Matsuo Bashô # 743, autumn 1691.]

meigetsu wa / futatsu sugite mo / seta no tsuki.

"famous-Moon" (nom.) // two(-things) passing ah!! // Seta's Moon."
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NOTES SO AS TO BETTER APPRECIATE THIS HAIKU:

Nov. 1, 1690 New Moon in Scorpio / Nov. 16, 1690, Full Moon in Taurus /
Nov. 30, 1690, New Moon in Sagittarius. >> That makes 13 New Moons
in 1690, corrected with an intercalary ("extra") ninth Moon-month.

Jane Reichhold says: "In 1691 August (??) occurred twice(??) . . . "

That is the ninth Moon-month of 1691
in the (eighth) Solar-month of August
and again in the (ninth) Solar-month of September, . . .

so the Harvest Moon was celebrated on the night of Solar-August 9
and again on the night of Solar-September 7.


>> Harvest Moon -- the Full Moon closest to autumnal equinox >>
Sept. 7 and Oct. 7 are equally close to Sept. 22, but
Aug. 9 is closer to Aug. 23 than Sept. 7.

So, that Moon viewing party Bashô held at his Abode of Illusion
[see: Gifts for Master Bashô -- MB739.]
must have been on the first Harvest Moon of August 9, 1691.


Dec. 30, 1690 New Moon //
1691 New Moons: Jan. 29 / Febr. 28 / March 29 /April 28 / May 27 / June 26 /
July 25 / Aug. 23 / Sept. 22 / Oct. 21 / Nov. 20 / Dec. 19.

1691 Full Moons: Jan. 14 / Febr. 12 / March 14 / Apr. 12 / May 12 / June 10 /
July 10 / Aug. 9 / Sept. 7 / Oct. 7 / Nov. 6 / Dec. 5. //
Jan. 4, 1692, Full Moon.
_ _ _

Source: "Bashô - The Complete Haiku", translated by Jane Reichhold.