Testing SNe Ia distance measurement methods with SN 2011fe. (arXiv:1207.4310v1 [astro-ph.CO])

Testing SNe Ia distance measurement methods with SN 2011fe. (arXiv:1207.4310v1 [astro-ph.CO]):
The nearby, bright, almost completely unreddened Type Ia supernova 2011fe in
M101 provides a unique opportunity to test both the precision and the accuracy
of the extragalactic distances derived from SNe Ia light curve fitters. We
apply the current, public versions of the independent light curve fitting codes
MLCS2k2 and SALT2 to compute the true distance modulus of SN 2011fe from
high-precision, multi-color (BVRI) light curves. The results from the two
fitting codes confirm that 2011fe is a "normal" (not peculiar) and only
slightly reddened SN Ia. New unreddened distance moduli are derived as 29.21
+/- 0.07 mag (D \sim 6.95 +/- 0.23 Mpc, MLCS2k2), and 29.05 +/- 0.07 mag (6.46
+/- 0.21 Mpc, SALT2). Despite the very good fitting quality achieved with both
light curve fitters, the resulting distance moduli are inconsistent by 2 sigma.
However, both are marginally consistent (at \sim 1 sigma) with the HST Key
Project distance modulus for M101. The SALT2 distance is in good agreement with
the recently revised Cepheid- and TRGB-distance to M101 by Shappee & Stanek
(2011). Combining all SN- and Cepheid-based estimates, the absolute distance to
M101 is \sim 6.6 +/- 0.5 Mpc.