The distance to Supernova 1998aq in NGC 3982
1 Its membership has been questioned by some (e.g. Tully et al. 1996).
3 Enforcing a lower period cut of 25 d reduces the Cepheid sample from 32 to 20, the unweighted mean true modulus for which is , consistent with our favoured result of . This suggests that PL bias of the magnitude encountered for some galaxies (see section 3.4 of Freedman et al. 2001) does not afflict our NGC 3982 data set, and so we employ the full set of 32 Cepheids in our quoted final result.
Abstract
The distance to NGC 3982, host galaxy to the Type Ia supernova SN 1998aq, is derived using 32 Cepheids discovered in archival multi-epoch Hubble Space Telescope observations. Employing recent Large Magellanic Cloud Cepheid period–luminosity relations and absolute zero-point, we find a distance to NGC 3982 of
, including both random (r) and systematic (s) uncertainties, and ignoring any metallicity dependence in the Cepheid period–luminosity relation. Still unpublished light curve photometry promises to make SN 1998aq one of the most important calibrators for the Type Ia supernova decline rate–peak luminosity relationship.
