Sunspot transition region oscillations in NOAA 8156

Based on observations obtained with the Solar and Heliospheric Observatory joint observing program for velocity fields in sunspot regions, we have detected 3 minute transition region umbral oscillations in NOAA 8156. Simultaneous recordings of O v lambda 629 and N v lambda 1238, lambda 1242 with the SUMER instrument give the spatial distribution of power in the 3 minute oscillations, both in intensity and in line-of-sight velocity. Comparing loci with the same phase, we find that the entire umbral transition region oscillates. The observed maxima in peak line intensity are nearly in phase with the maxima in velocity directed toward the observer. We discuss the suggestion that the waves are upward-propagating acoustic waves.