From: "Mati Morel" <morel@ozemail.com.au> Subject: [vsnet-chat 4969] V644 Cen sequence I have prepared a V sequence for V644 Cen recently, based on Tycho2 data. The sequence is below. V sequence for V644 Cen. ================== HD/HDE GSC RA 2000 DEC 2000 V B-V 306985 8972.00906 11h41m23.8s -60o40'46" 10.22 0.11 306987 8972.00710 11 42 00.9 -60 45 30 10.50 0.38 306998 8973.01150 11 43 39.7 -60 54 41 10.33 0.04 306994 8973.00940 11 43 39.2 -60 49 56 10.48 0.02 306995 8973.00899 11 43 16.5 -60 47 03 10.58 -0.03 306983 8973.00021 11 43 00.3 -60 33 53 10.56 0.23 306997 8973.00137 11 43 31.7 -60 55 13 9.60 0.99 306999 8973.00632 11 44 46.7 -60 55 12 9.76 0.67 101825 8972.01940 11 42 47.6 -60 40 42 9.58 -0.00 101600 8972.00496 11 41 01.3 -60 36 48 8.56 0.00 101793 8972.00816 11 42 30.8 -60 40 48 8.74 -0.03 101850 8973.00429 11 42 59.4 -60 39 12 9.23 -0.07 HD 101825 = NSV 5303 (variability doubted) HD 101850 = NSV 5305 (variablity doubted) The report of the discovery (by D.J.K. O'Connell) appears in MNRAS 111,111 (1951). He discovered the long minimum from 1931-1950, which resembled a typical flat-bottom Algol-type minimum. Possible periods of 65y and 200y were mentioned. Between 1964-1975 the star was observed at maximum on the Bamberg sky survey plates, at 8.86p. In IBVS 3006 another fading was reported. Between 1981 May 17 and 1984 April 18 V644 Cen experienced another decline, from 9.91V (JD 2444742.327) to 10.213V (JD 2445809.459). When the Hipparcos/Tycho mission was aloft in the early 1990s the minimum was still apparently in progress, as it measured V = 10.22 Refer to IBVS 3006 (3 April 1987) for other historical observations. Regards, Mati Morel morel@ozemail.com.au http://vsnet.ozemail.com.au/~morel