87 :.-'.!NA_,_,_TU=R:.::...E..:...::VO=L...::.:32:::_5 _,_,IJ=AN=UA=R,_,_Y =19=87 _____ MATTERS ARISING------=..:.

The colour of apparently indicates the time when the time, and their depicted orientation to the in the sixth century reaches the position that the Sun would horizon as a and {3 Canis minoris, we can attain at the given of the day, that determine 'Quinio's LSTr. Lastly, we must ON the basis of Gregory of Tours' descrip­ is, so many after the star rises. These not ignore the depiction of'Quinio', which tion of the star called 'Rubeola' or two sections employ general terms rather matches the pattern of Sirius and its com­ 'Robeola' in his 'De cursu stellarum than exact measurements and are not fully panions at their rising'.4. 1 4 5 ratio' - , Schlosser and Bergmann have consistent; it therefore seems wisest to Comparing the limits thus obtained with proposed that Sirius appeared red in the consider all the available evidence rather the positions of the . computed for sixth century, an appearance which w.ould than a selected set. AD 600 at the latitude of Tours (Table 1). raise serious astrophysical questions. From the fact that 'Rubeola' is twice It is apparent that 'Quinio' is Sirius and From close examination of the text, the described as rising heliacally in September 'Rubeola' is most likely Arcturus, a star identification of Sirius with 'Rubeola' can­ and is also visible for an hour after sunset widely noted for its ruddy colour. The not be supported. the same evening, we can compute limits importance of Arcturus for monastic Gregory's treatise appears in eight for right ascension and declination. From timekeeping is reinforced by its appear­ manuscripts, two of which 1·2 include the the contradictory data for a maximum visi­ ance as one of seven bright stars in an astronomical portions, and two printed bility of 8 hours from December through eleventh-century monastic timetable from 3 4 editions • , both of which include iden­ February, which I would question on northern France, in which Sirius does tifications of the constellations by the textual grounds, alternative limits can be not appear9. Gregory's description of astronomer, J. F. Galle. Galle identified computed (W. Schlosser and W. Berg­ 'Rubeola' cannot be added to the ancient 'Rubeola' as Arcturus, a nearby com­ mann, personal communication). reports of a reddish Sirius10. panion as T/ Boo, and the central star of The Local Sidereal Time of rising (LSTr) Gregory's constellation 'Quinio' (the five) can be computed from 'Rubeola's rising STEPHEN C. MCCLUSKEY as 'undoubtedly Sirius'. He considered one month before 'Stefadium' (Corona Program in the History 'Rubeola' to be Arcturus because of its Borealis), from the duration of visibility of Science and Technology, colour (which we should not take into each month between its rising and sunrise, West Virginia University, account) and its monthly appearances as and from the number of psalms that can Morgantown, recounted by Gregory. be sung after its rising or after its appear­ West VirKinia 26506, USA There are several independent sources ance at a given place in the sky. The Local of evidence in 'De cursu stellarum ratio'. Sidereal Time of setting (LSTs) can be I. Bamberg, Staatsbibliothek, patres 61 (HJ.IV.15), fl. 75.- In the first section Gregory describes a determined in like manner from the dur­ 82 •. number of constellations, giving their ation of visibility each month between 2. Vatican City, Biblioteca Apostolica Vaticana, ms Urbinas lat. 67, fl. !20v-126v. month-by-month visibility from heliacal sunset and the star's setting. Positions were 3. Gregorii Turonensis, ·De Cursu Stellarum Ratio' (ed. rising to heliacal setting, depicting (in the adjusted for precession and proper Haase, F.) (Max, Vratislaviae, 1853). eighth-century Bamberg MS) the con­ motion; times of rising and setting were 4. Gregorii Turonensis, Opera, pars II, Miracula et Opera Minora (eds Arndt, W. & Krusch, B.) (MGH, Scr. rer. stellations as they appear rising on the computed for the latitude of Tours merov., 1), (Hahn, Hanover, 1885). eastern horizon, and in some cases (47.3° N) without corrections for refrac­ 5. Schlosser, W. & Bergmann, W. Nature 318, 45-46 (1985). 6. de Vogue, A. (ed. trans!.) La Regie du Maitre Vol. 2, expressing their declination in terms of the tion. First nighttime visibility is taken as 168-187 (du Cerf, Paris, 1964). 8 path that the Sun takes in a given month. when a bright star is on the horizon . 7. Fry, T. (ed. trans!.) The Rule of Saint Benedict 202-205 (Liturgical Press, Collegeville, Minnesota, 1981). In the second section Gregory uses these Turning to the constellation 'Quinio', 8. Bruin, F. Proc. ned. A/cad. Wet. 882, 385-410 (1979). 3 constellations to time the pre- office which has also been identified as Sirius , 9. Poole, R. J. theol. Stud. 16, 98-104 (1914). 6 7 10. Brecher, K. in Astronomy of the Ancients (eds Brecher, K. of matins • for each month, telling the we can determine its declination because & Feinag, M.) 95-102 (MIT Press, Cambridge, 1979). reader the number of psalms to be it follows the path that the Sun does in chanted, beginning when a star rises or February. Because it rises one hour after more commonly when it reaches a given a pair of stars that can be identified on SCHLOSSER and Bergmann1 (hereafter hour of the day. The latter expression the basis of their declination, their rising SB) have recently presented new evidence apparently corroborating the well-known Greek-Roman and Babylonian references 3 Table I Positions of 'Rubeola' and 'Quinio' to a red-coloured Sirius in antiquitl· • The purpose of this letter is to show that they From 'De cursu ste/larum ratio' 'Rubeola' Sirius Arcturus have erroneously confounded Sirius with Arcturus (a Boo), a star which is indeed September heliacal rising reddish (B- V = 1.2). SB based their Dec. (deg.) >14.3 -15.75 26.95* RA (h:min) 10:47-12:32 5:43 13:12 analysis on 'De cursu stellarum ratio' (hereafter CS), a text written sometime December (doubtful) between 575 and 582 by Georgius Floren­ Dec. (deg.) <0 -15.75* 26.95 tius Gregori us, Bishop of Tours. This text RA (h:min) 4:40-10:50 5:43* 13:12 was published twice in the previous cen­ Appears one month before 'Stefadium' tury by Haase4 and Krusch5 (hereafter H LST, (h : min) 0:56-4:51 0:55 4:58 and K). The text (CS 20, 36-39) refers to Monthly visibilities a 'stella splendida', named 'Robeola' LST, (h : min) 3:18-7:16 0:55 4:58* (=reddish). According to the editions of

LST5 (h : min) 12:02-19:07 10:32 21:26 H and K, 'Robeola' =Arcturus, but SB Times for Nocturnal Psalms (without even acknowledging the earlier LST, (h: min) 2:19-4:57 0:55 4:58 work of HK) argue rather that 'Robeola' = 'Quinio' Sirius. Dec. (deg.) -7.0 to -16.6 -15.75* 26.95 Their novel identification is partly based LST, (h : min) 23:57-1:22 0:55* 4:58 on the singular description of 'Robeola' as a 'stella splendida', which, as SB argue, * Star within the range computed for the constellation. can apply only to the brightest star in the