| Abstract
| - Using CGS4 on UKIRT, we have obtained a 1.95-2.45 μm infrared (IR) spectrum of the primary candidate counterpart to the bright Z LMXB GX5-1.IR photometry by Naylor, Charles & Longmore and the astrometry of Jonker et al.had previously identified this star as the most likely counterpart to GX5-1.The spectrum presented here clearly shows Brackett γ and He lines in emission, for the first time confirming the identity of the counterpart.Similar to our previous spectroscopy of the Z source LMXBs Sco X-1 and Sco X-2 (), the K-band spectrum of GX5-1 shows emission lines only.We briefly discuss the implications of this spectrum for the nature of the Z sources.
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