Chris (preliminary): There is a hint of an OII line at 4856 Angstroms (z=0.3), but we cannot see a type Ia in this data.
Lifan (preliminary): SNmatch showed it to be a 91T a week before max, at z = 0.3-0.31. A bluer spectrum would help a lot.
For R_B = 4.1, I derived A_v around 2. But I would not bet heavily on that considering slit losses and other uncertainties. The 5000A feature Peter mentioned might be there, but with low S/N.
Peter (preliminary): 91T-like Ia's and Ib/c's do look a lot like each other. Unfortunately it doesn't look like there is a lot of extinction for this SN, the spectrum looks too blue. Also t is missing a prominent 91 feature at 5000 Ang restframe. As Lifan said a bluer spectrum would be nicer to figure this out. Given how faint it is I doubt it's a 91T since I don't see the extinction. Another spectrum would be nice but I don't know if we have the time to do that.
It is 1.0 mag fainter at this epoch than 91T would be at this z. I wouldn't bother with more obs, other than the rolling photometry, unless we have time to kill.
Andy (preliminary): I also get SN 1991T as the best fit, but I am not convinced because I don't see the feature at 5600A (observed) in our spectrum.