Let $X$ be a smooth and proper variety over $\mathbb{C}$. Let $F$ be an $\mathbb{A}^1$ family of $\mathbb{G}\_m$ gerbes over $X$. Suppose the fibers over every point away from 0 in $\mathbb{A}^1$ are all isomorphic. Must the fiber over zero be isomorphic to the general fiber $F\_t$ ? This is certainly true for line bundles. I could think of stronger results that might be true, but my general ignorance of the subject leads me to pose the question I am interested in. Sorry also if this question belongs on math.stackexchange. 



family of gerbes over smooth and proper algebraic varieties 
By a family of gerbes you mean, I suppose, a gerbe over $X \times \mathbb A^{1}$. In any case, it has a class in $\mathrm H^0(\mathbb A^1, \mathrm R^2 \mathrm{pr}\_{2\*}\mathbb G\_{\rm m})$. Since $\mathrm R^2 \mathrm{pr}\_{2\*}\mathbb G\_{\rm m}$ is a torsion sheaf, this class comes from $\mathrm H^0(\mathbb A^1, \mathrm R^2 \mathrm{pr}\_{2\*}\mu\_{n})$ for some $n$; and $ \mathrm R^2 \mathrm{pr}\_{2\*}\mu\_{n}$ is a constant sheaf on $\mathbb A^1$. Hence any family of gerbes is in fact constant along the fibers.


And I don't think that your question, or any question about gerbes, belongs in <https://math.stackexchange.com/>.


