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Anomalously high K-band surface brightness fluctuations (SBF) have beenreported in NGC 4489 by Pahre & Mould (1994), Jensen et al. (1996) and Jensenet al. (1998). However, these conclusions were uncertain because of relativelylow signal-to-noise data. New high signal-to-noise data for NGC 4489 have beenobtained at the NOAO/KPNO 2.1m and the ESO/La Silla 3.5m NTT telescopes.Adopting the I-band SBF distance modulus determined by Tonry et al. (1990) andthe M_I versus (V-I) calibration of Tonry et al. (2000), a value of M_K =-6.18+/-0.09 mag was derived. Relative to the average empirical M_K derived forgiant ellipticals by Jensen et al. (1998) (M_K=-5.61 +/- 0.12 mag), thedetection of an anomalous K-band SBF in NGC 4489 is confirmed at the two sigmalevel. Such anomalous fluctuations could be caused by an extended giant branch,consisting of either intermediate-age AGB stars above the tip of thefirst-ascent giant branch or high-metallicity first-ascent giants, or by lackof a full understanding of the K-band SBF calibration. This result raisesquestions about the accuracy of K-band SBF distance measurements for ellipticalgalaxies with unknown stellar composition and underscores the need for M_Kmeasurements over a larger range of color and luminosity.Comment: A&A, in pres

Anomalous surface brightness fluctuations in NGC 4489