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Accurately determining the black hole mass ($M_\mathrm{BH}$) in activegalactic nuclei (AGN) is crucial to constraining their properties and tostudying their evolution. While direct methods yield reliable measurements of$M_\mathrm{BH}$ in unobscured type 1 AGN, where the dynamics of stellar or gascomponents can be directly observed, only indirect methods can be applied tothe vast majority of heavily absorbed type 2 AGN, which represent most of theAGN population. Since it is difficult to evaluate the accuracy and precision ofthese indirect methods, we utilize the nearby X-ray bright Seyfert galaxy NGC4151, whose $M_\mathrm{BH}$ has been tightly constrained with severalindependent direct methods, as a laboratory to assess the reliability of threeindirect methods that have been applied to obscured AGN. All three, the X-rayscaling method, the fundamental plane of black hole activity, and theM-$\sigma$ correlation, yield $M_\mathrm{BH}$ values consistent with thoseinferred from direct methods and can therefore be considered accurate. However,only the X-ray scaling method and the M-$\sigma$ correlation are precisebecause the substantial scatter in the fundamental plane of BH activity allowsonly for crude estimates. Of the four M-$\sigma$ correlations we used, only theone from Kormendy and Ho yields a value consistent with the dynamicalestimates. This study suggests that the best approach to estimating the blackhole mass in systems where direct dynamical methods cannot be applied is toutilize a combination of indirect methods, taking into account their differentranges of applicability.

Assessing indirect methods to determine black hole masses using NGC 4151