Constraints on forbidden Fe X emission from the Perseus cluster of galaxies

We report results of a deep search for [Fe X] λ6374 emission associated with NGC 1275, the central galaxy in the Perseus cluster. Emission of this coronal feature is expected from intermediate temperature gas ({TAU} ~ 10^6.3^ K), with a total luminosity in proportion to the true rate that mass cools out of the hot intracluster plasma. After excision of the nucleus of NGC 1275, which may exhibit coronal emission associated with Seyfert activity, our spectra show no indication of the [Fe X] feature to limiting surface brightnesses that represent a factor of 5-10 improvement over previous limits. The new upper bounds remain consistent with mass accretion rates inferred from x- ray observations. The present observations suggest that the Perseus cooling flow, if transonic, features a sonic radius within 2.3" (1.2 kpc, H_0_ = 50 km s^-1^ Mpc^-1^) of the nucleus. If the optical nebulosity in NGC 1275 is photoionized by the cooling intracluster medium, the limits found in this study preclude a close spatial association between the nebular and coronal phases.