Decan


The decans are 36 groups of stars used in ancient Egyptian astronomy to conveniently divide the 360 degree ecliptic into 36 parts of 10 degrees each, both for theurgical and heliacal chronometrical purposes. The decans each appeared, geocentrically, to rise consecutively on the horizon throughout each daily Earth rotation. The rising of each decan marked the beginning of a new decanal "hour" of the night for the ancient Egyptians, and they were used as a nocturnal beginning by at least the Ninth or Tenth Dynasty of Egypt in the 21st century BC.
Because a new decan also appears heliacally every ten days, the Greeks called them dekanói or "tenths".
Decans gave way to a lunar division of 27 or 28 lunar stations, also known as manzil, lunar stations, or nakshatras and thence to a zodiac of twelve signs, based on an anthropomorphic pattern of constellations, and their use can be seen in the Dendera zodiac dated to circa 50 BCE.

Ancient Egyptian origins

Decans first appeared in the First Intermediate Period of Egypt on coffin lids. The sequence of these star patterns began with Sirius, and each decan contained a set of stars and corresponding divinities. As measures of time, the rising and setting of decans marked 'hours' and groups of ten days, which comprised an Egyptian year. The Book of Nut covers the subject of the decans.
There were 36 decans, plus five added days to compose the 365 days of a solar-based year. Decans measure sidereal time and the solar year is six hours longer; the Sothic and solar years in the Egyptian calendar realign every 1460 years. Decans represented on coffins from later dynasties, such as Pharaoh Seti I, compared with earlier decan images, demonstrate the Sothic cycle shift.
According to Sarah Symons,

Later developments

These predictable heliacal re-appearances by the decans were eventually used by the Egyptians to mark the divisions of their annual solar calendar. Thus the heliacal rising of Sirius marked the annual flooding of the Nile.
This method led to a system of 12 daytime hours and 12 nighttime hours, varying in length according to the season. Later, a system of 24 "equinoctial" hours was used. After Hellenistic astrology arose in Alexandria, recorded principally in the work of Ptolemy and Vettius Valens, various systems attributing symbolic significance to decans arose and linked these to the classical planets: the "wandering stars" Mercury, Venus, Mars, Jupiter and Saturn and the "lights", the sun and moon. Decans were connected, for example, with the winds, the cardinal directions, the sect male and female, as well as the four humours also these were hermetically considered linked with various diseases and with the timing for the engraving of talismans for curing them; with decanic "faces", a system where three decans are assigned to each zodiacal sign, each covering 10° of the zodiac, and each ruled by a planetary ruler ; and correlated with astrological signs.

Descriptions of the decans

Decans are named in various Greco-Egyptian sources, many Hermetic writings, the Testament of Solomon, the Tabula Aristobuli attributed to Aristobulus of Paneas, and the writings of Julius Firmicus Maternus, Cosmas of Maiuma, Joseph Justus Scaliger, and Athanasius Kircher.
Images of the decans are described in Hermetic writings, by the Indian astrologer Varāhamihira, in the Picatrix, and in Japanese writings. Varāhamihira's images of the decans was influenced by Greco-Egyptian, if not Hermetic, depictions of the decans by way of the Yavanajataka. Their role in Japanese astrology may have derived from an earlier Chinese or Indian form possibly from adding the twelve animals of the Chinese zodiac to a list of twenty-four hour stars. They were most common between the Kamakura and Edo periods.
The first original decan position due to the precession in ancient times started at 0° of Cancer when the heliacal rising of Sirius before sunrise marking the Egyptian New Year which fell at 0° of Leo at July 20 in the Julian calendar, that is July 22/23 on the Gregorian calendar.
Western ZodiacDecanOriginal Decan Position due to the Precession in Ancient TimesAncient Egyptian
Greco-EgyptianTestament of SolomonAristobulus's namesGreek HermeticismLatin HermeticismFirmicusCosmasScalingerKircher
Aries128W17-Xr:r-w-sbA Khent-kheruW17-pt:sbA ⲭⲟⲛⲧⲁⲣⲉ
Χont-har		Rhyax or RuaxBendoncChenlachoriAulathamasSenator or AsiccanAidoneusAsiccanArueris
Aries229P11-d:nw-sbA QeṭW17-Xr:r-sbA ⲭⲟⲛⲧⲁⲭⲣⲉ
Xont-χre		BarsafaelMensourChontaretSabaothSenacher or AsenterPersephoneSenacherAnubis
Aries330zA-zA-P11-d:nw-sbA*sbA:sbA*sbA*sbA SasaqeṭzA-P11-sbA ⲥⲓⲕⲉⲧ
Si-ket		Artosael or ArôtosaelCarexonSiketDisornafaisSentacher or AsentacerErosAcentacerHorus
Taurus431a:r:t-sbA:sbA ĀrtxA-w-sbA ⲭⲱⲟⲩ
Xau		HoropelGisanSoouJausSuo or AsicatCharisAsicathSerapis
Taurus532xA*xA*xA-sbA Khaua:r-i-t:sbA ⲉⲣⲱ, ⲁⲣⲟⲩ
Arat		Kairoxanondalon or IudalTourtourAronSarnotoisAryo or Asondie HorenViroasoHelitomenos
Taurus633D41:n-Hr:r-w-O28-Z1-D63-Z1:sbA Remen-ḥeru-an-SaḥD41:pt-sbA ⲣⲉⲙⲉⲛⲁⲁⲣⲉ
Remen-hare		SphendonaelBallatRhomenosErchmubrisRomanae or ArfaLitaiAharphApopis
Gemini734ms-s-M36-F21-D63-sbA Mestcher-SaḥS24:z-V12:sbA ⲑⲟⲥⲟⲗⲕ
Θosalk		SphandorFarsanXochaManuchosThesogar or TensogarThetysThesogarTautus
Gemini835D41:n-Xr:r-D63-sbA Remen-kher-SaḥZ7:a-r:t*sbA ⲟⲩⲁⲣⲉ
Uaret		BelbelVaspanOuariSamuroisVer or AsuaeKybeleVerasuaCyclops
Gemini936a:Z1-D63-sbA A-Saḥtp:a-D63-M44-t:sbA
Phu-hor		Kourtael or KurtaêlParquiaPepisothAzuelTepis or AtosoaePraxidikeTepisatosoaTitan
37D63-sbA Saḥ
Cancer101 M44-t:sbA Sepṭetⲥⲱⲑⲓⲥ
Sopdet		MetathiaxPanemSotheirSeneptoisSothis or SociusNikeSothisApollun
Cancer112tp:a-k:n-mwt-t:sbA Ṭepā-KenmutS:tA-I2 ⲥⲓⲧ
Seta		KatanikotaelCatarnoOuphisitSomachalmaisSithHeraklesSythHecate
Cancer123k-S3-mwt-t:sbA Kenmutk:n-F45A-sbA ⲭⲛⲟⲩⲙⲓⲥ
Knum		Saphthorael or SaphathoraélHellorsChnouphosCharmineThiumis or ThumusHekateThuimisMercophta
Leo134Xr:r-K23-k:n-mwt-t:sbA Kher-khept-KenmutXr:r-x:t-p:y-k:n:Aa15-sbA ⲭⲁⲣⲭⲛⲟⲩⲙⲓⲥ
Χar-Knum		Phobothel or BobêlJareaChnoumosZaloiasCraumonis or AfruicoisHephaistosAphruimisTyphon
Leo145HAt-DA-t:sbA Ḥā-tchatHAt-DA-sbA ⲏⲧⲏⲧ
Ha-tet		Leroel or KumeatêlEffraaIpiZachorSicIsisSithacerPeroeus
Leo156pH:y-DA-t:sbA Peḥui-tchatpH:y-DA-sbA ⲫⲟⲩⲧⲏⲧ
Phu-Tet		SoubettiHayasPhatitiFrichFutile or EisieSarapisPhuonisieNephthe
Virgo167T-mA:t-Hr:r:t-sbA Themat-ḥertt:mA-sbA ⲧⲱⲙ
Tom		Katrax or AtraxAngafAthoumZamendresThumis or ThinnisThemisThumiIsis
Virgo178T-mA:t-Xr:r:t-sbA Themat-khertZ7-M8-U33-bA-kA:sbA ⲟⲩⲉⲥⲧⲉ—ⲃⲓⲕⲱⲧⲓ
Uste-bikot		Jeropa or IeropaêlBethapenBrysousMagoisTophicus or TropicusMoiraiThopitusPiosiris
Virgo189G42-U33-i-sbA Usthȧi-p:z-t:sbA ⲁⲫⲟⲥⲟ
Aposot		Modobel or BuldumêchBarocheAmphathamMichulaisAfut or AsuthHestiaAphutCronus
Libra1910B2-U33-i-sbA Bekathȧs-b-X:z-sbA ⲥⲟⲩⲭⲱⲥ
Sob‿χos		Madero or NaôthZercurisSphoukouPsineusSeuichut or SenichutErinysSerucuthZeuda
Libra2011tp:a-W17-t:t-sbA Ṭepā-khentettp*Z1:a-Z1-W17-sbA ⲧⲡⲏⲭⲟⲛⲧⲓ
Tpa-χont		Nathotho or MarderôBahamNephthimesChusthisisSepisent or AtebenusKairosAterechinisOmphta
Libra2112W17-t:t-Hr:r:t Khentet-ḥertW17-pt:sbA ⲭⲟⲛⲧⲁⲣⲉ
Xont-har		AlathPieretPhouPsamiatoisSenta or AtepitenLoimosArpienOphionius
Scorpio2213W17-t:t-Xr:r:t-sbA Khentet-khertW17-Xr:sbA ⲭⲟⲛⲧⲁⲭⲣⲉ
Spt-χne		AudameothHazizaNameNecbeuosSentacer or AsenteNymphsSentacerArimanius
Scorpio2314T-Y4-s-n-W17-t*t:sbA Themes-en-khentetT-ms-s-n-W17-sbA......
Sesme		NefthadaNacyOustichosTurmantisTepsisen or AsentatirLetoTepiseuthMerota
Scorpio2415Aa18-p:t-x:n:nw-N21:N21-sbA Sapt-khennus-p:t-x:n-T19-sbA ⲥⲡⲧⲭⲛⲉ
Si-sesme		AktonAlleinacAphebisPsermesSentineu or AterceniKairos SenicerPanotragus
Sagittarius2516Hr:Z1-ib-P1-sbA Ḥer-ab-uȧaHr:Z1-ib-P1-sbA ʿⲣⲏⲟⲩⲱ
Hre-ua		AnatrethOrtusaSebosClinothoisEregbuo or ErgbuoLoimos EregbuoTolmophta
Sagittarius2617P6-W8:??:W10-V17-Ba16-S-s-m-w-sbA-Ba16a Shesmuz:S-mw-sbA ⲥⲉⲥⲙⲉ, ⲥⲓⲥⲉⲥⲙⲉ
Sesme		Enautha or EnenuthDahaTeuchmosThursoisSagonKoreSagenTomras
Sagittarius2718k:n-m-w-sbA Kenmuk:n-Aa15:sbA ⲕⲟⲛⲓⲙⲉ
Konime		Axesbyth or PhêthSatanChthisarRenethisChenene or ChenemAnankeChenenTeraph
Capricorn2819s-m-d:t*sbA Semṭets-Aa15:t*sbA ⲥⲙⲁⲧ
Smat		Hapax or HarpaxEractoTairRenpsoisThemesoAsklepiosThemesoSoda
Capricorn2920tp:a-s-m-d:sbA Ṭepā-semṭtp:a-s-Aa15:t*sbA........
Srat		AnosterSalacEpitekManethoisEpiemu or EpimenHygieiaEpimaRiruphta
Capricorn3021z:r:t-E11-sbA Sertz:r-t:sbA ⲥⲣⲱ
Si-srat		Physikoreth or AlleborithSerosEpichnausMarcoisOmotTolmaHomothMonuphta
Aquarius3122zA-zA-z:r:t-sbA Sasa-sertzA-z:r:t*sbA ⲥⲓⲥⲣⲱ
Tpa-χu		Aleureth or HephesimirethTonghelIsiUlarisOro or AsoerDikeOroasoerBrondeus
Aquarius3223Xr:r-K23-z:r:t*sbA Kher-khept-sertXr:r-x*p:t-z:r:sbA........
Xu		IchthionAnafaSosomoLuxoisCratero or AstiroPhobosAstiroVucula
Aquarius3324Ax-Ax-sbA Khukhutp:a-N8-sbA ⲧⲡⲏⲭⲩ
Tpa-Biu		Achoneoth or AgchoniônSimosChonoumousCrauxesTepis or AmasieroOsirisTepisatrasProteus
Pisces3425bA-bA BabaN8-w-ra-sbA ⲭⲩ
Biu		Autoth or AutothithAchafTetimoFambaisAcha or AtapiacOkeanosArchatapiasRephan
Pisces3526W17-Hr:r-w-sbA Khent-ḥerutp:a-G30-sbA ⲧⲡⲏⲃⲓⲟⲩ
Xont-Har		Phtheneoth or PhthenothLarvataSopphiFlugmoisTepibui or TepabiuDolusThopibuiSourut
Pisces3627Hr:Z1-ib-W17-n:t*w-sbA Ḥer-ȧb-khentu-G30-Z3-sbA- ⲃⲓⲟⲩ, ⲧⲡⲓⲃⲓⲟⲩ
Tpi-biu		BianakithAjarasSyroPiatrisUiu or AatexbuiElpisAtembuiPhallophorus