The primary goal of this paper is to study the geometry of the p-adic eigencurve at a point f corresponding to a weight one theta series θ ψ irregular at p. We show that f belongs to exactly three or four irreducible components and study their mutual congruences.In particular, we show that the congruence ideal of one of the CM components has a simple zero at f if, and only if, a certain L -invariant L-(ψ-) does not vanish. Further, using Roy's Strong Six Exponential Theorem we show that at least one amongst L-(ψ-) and L-(ψ −1 -) is non-zero. Combined with a divisibility proved by Hida and Tilouine, we deduce that the anti-cyclotomic Katz p-adic L-function of ψ-has a simple (trivial) zero at s = 0, if L-(ψ-) is non-zero, which can be seen as an anti-cyclotomic analogue of a result of Ferrero and Greenberg. Finally, we propose a formula for the linear term of the two-variable Katz p-adic L-function of ψ-at s = 0 thus extending a conjecture of Gross.