2004IAUC.8385....2M

J. Maiz-Apellaniz, Space Telescope Science Institute (STSI), writes that Sandage's star 96 appears to be pointlike in the H_alpha image (not continuum-subtracted) obtained by Matonick et al. (1997, Ap.J. Suppl. 113, 333, Fig. 5a) but was not identified as an H II region by Sivan et al. (1990, A.Ap. 237, 23), indicating that Matonick et al. simply detected the R-band continuum. Based on these data and on a distance to NGC 2403 of 3.30 Mpc (Karachentsev et al. 2004, A.J. 127, 2031), star 96 appears to be a very bright (M_V < -9.3) blue supergiant. Alternatively, the progenitor could have been a red supergiant, in which case it must have been a member of a multiple system or a very compact cluster that included very bright blue stars. If the progenitor is indeed a late-B/early-A supergiant, the color (B-V = +0.24) measured by Sandage would be compatible with the value E(B-V) about 0.18 measured by Patat et al. (IAUC 8378).