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The southern hypergiant HD 97671 turns out to be a conspicuous variable star. A webpage with lightcurves: http://ar.geocities.com/varsao/Curva_HD_97671.htm It was first reported in Humphreys et al. (1972), which gives V= 8.39, B-V 2.52. This star is compared to VY CMa and VX Sgr in that paper due to a large excess over the entire long-wave region. Since the Tycho-2 catalogue gives V= 8.82, I suspected something was wrong. I downloaded ASAS-3 data and it turned out to be a large amplitude bright variable!! I also used Tycho-1 Epoch data (with Bessell's transformations aplying a linear trend following the 2.0 final values in his table since this star is reddder!! I used the mean magnitudes from the catalogue to obtain a convertion value. This is 0.30 for a Bt-Vt of 2.66 which turns into V= 8.74 and B-V= 2.17 ) and found that the mean magnitude is also variable. It's difficult to understand how such variability was not noted before. Both sets of data show a period in the order of 600-700 days. I applied a 6th order polynomial to find an average magnitude for the noisy Tycho data and found a range from 8.4 to 9.1. There has been an increase in mean magnitude since the early 90's and the present ASAS-3 data. ASAS-3 data range from V= 7.65 and 8.79. Unfortunately, Humphreys at al. datapoint from February-March 1971 is an isolate measure that don't offer the chance to know what the mean magnitude was by then. Ducati, 2002 gives V= 10.10 but I can't trust in such an isolate and discrepant measure. Although.... ;-)) Star: HD 97671 Type: SRc Spectral type: M3Ia+ V= 7.6 - 9.1 (at least, lightcurve indicates that the amplitude is even higher) Period: ~620 days Mean magnitude seems to be on the rise, so in the next maximum around October 2004 it will probably be an easy binocular object. References: Humphreys, R.M., Strecker, D.W., and Ney, E.P., Spectroscopic and photometric observations of M supergiants in Carina, 1972, ApJ 172, 75-88 Perryman, M.A.C., et al., 1997, The Hipparcos and Tycho Catalogues, ESA SP-1200 Pojmanski, G. 2002, Acta Astronomica, 52,397
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