Revalidation of the isobaric multiplet mass equation at A = 53, T = 3/2

The T=3/2T=3/2 isobaric analog state (IAS) in 53Co is firmly established through a comprehensive measurement of β-delayed γ and proton decay of 53Ni. The determined excitation energy of 53Co IAS combined with the mass of 53Co generates a precise mass excess of −38333.6(27) keV for the 53Co IAS, which is 70(18) keV lower than the previously adopted value. The new result solves a problem raised by incorrect assignments of the 53Co IAS of unexpected deviation from the isobaric multiplet mass equation (IMME) at A=53A=53, T=3/2T=3/2.