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Description
We report new color-magnitude diagrams for Fornax globular clusters 1 and 5 where our data reaches V=24, below the horizontal branch. Using the index B-R/(B+V+R), a measure of the horizontal branch color, we find cluster 1 has a red (-0.50+/-0.10) and cluster 5 an intermediate color (-0.09+/-0.12) horizontal branch confirming the first extragalactic second parameter pair. The HB types are markedly redder than the Galactic globular clusters at [Fe/H]=-2. In globular cluster 1, we find 21 possible variable stars out of 41 horizontal branch stars. Cluster 1 has an anomalously low ratio of horizontal branch to red giant stars, which formally gives a helium abundance of 0.16<Y<0.22, depending on the assumptions used. For both clusters 1 and 5, and for the red horizontal branch in the field adjacent to cluster 5, V_HB = 21.25 +/- 0.05. We give calibrated surface brightness profiles and measure new core and tidal radii for cluster 1 of 17.6" and 104" and for cluster 5 of <2" and 91", respectively.
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