Abstract
We report Swift-UVOT observations of GRO J1655-40 during the recent outburst. GRO J1655-40 has been observed with Swift for 9 times since April and the Ultra-Violet/Optical telescope (UVOT) obtained images through the U, B, V, UVW1, and UVW2 filters during 3 of the observations. GRO J1655-40 was clearly detected and we derived the following magnitudes: 2005 Apr 10: U=16.51+/-0.16, B=16.60+/-0.09, V=15.12+/-0.09, UVW1=18.12+/-0.24, UVW2=19.15+/-0.28 2005 May 14: U=17.38+/-0.18, B=17.47+/-0.11, V=15.86+/-0.10, UVW1=18.90+/-0.27, UVW2=20.18+/-0.33 2005 May 16: U=18.08+/-0.18, B=17.91+/-0.10, V=16.32+/-0.10, UVW1=19.52+/-0.28, UVW2=20.27+/-0.32 The bandpass of the UVW1 and UVW2 filters is centered at 251nm (width=70nm) and 188nm (width=76nm), respectively.