A VERY METAL-POOR H-II REGION IN THE OUTER DISK OF M101

We present new spectroscopic observations of an H II region in the ext reme outer disk of the spiral galaxy M101, more than 32 kpc from the n ucleus, or 25% farther out than the well-studied giant H II region NGC 5471. From a derived [O III] electron temperature of 13,900 K, we der ive log O/H = -4.1, only 10% of the solar value, and smaller than the abundance measured in NGC 5471. Log N/O = -1.49, similar to the values seen in metal-poor dwarf galaxies, while log S/O = - 1.74, essentiall y identical to the solar value, confirming the trend of constant S/O o bserved in earlier studies. With the inclusion of this new object, the composition gradient in M101 from published spectroscopic observation s shows no evidence for either a break in the gradient from 4 to 33 kp c, or a rise in the abundances in the outer parts of the disk.