Observations of the recent SN 1997cn in the elliptical galaxy NGC 5490 show that this objects closely resembles , both photometrically and spectroscopically , the faint SN Ia SN 1991bg .

The two objects have similar light curves , which do not show secondary maxima in the near IR as normal type Ia supernovae .
The host galaxy , NGC 5490 , lies in the Hubble flow .
Adopting for SN 1997cn a reddening E ( B - V ) = 0 , the absolute magnitude is faint : M _ { V } = -17.98 using H _ { o } = 65 and M _ { V } = -17.40 using H _ { o } = 85 km s ^ { -1 } Mpc ^ { -1 } .
The latter value is in close agreement with the absolute magnitude of SN 1991bg on the SBF–PNLF–TF distance scale .
The photospheric spectra of the two SNe show the same peculiarities , the deep \ion Ti2 trough between 4000 and 4500A , the strong \ion Ca2 IR triplet , the narrow absorption at about 5700A and the slow expansion velocity .

In analogy to SN 1991bg the observed spectrum of SN 1997cn has been successfully modeled by scaling down the W7 model by a factor of 2 , assuming a rise time to B maximum of 18 days , a photospheric velocity and an effective temperature low compared to normal SNIa .
The influence of the distance scale adopted on the input parameters of the best fit model is also discussed .

These data demonstrate that peculiar SNIa like SN 1991bg are not once–in–a–lifetime events and that deep SN searches can be contaminated by underluminous SN Ia in a fairly large volume .