The M31 globular cluster candidate 037–B327 has long been known to be an extremely red , non-stellar object .
The first published spectrum of this object is used to confirm that it is a globular cluster belonging to M31 , with rather typical values of v _ { r } = -338 \pm 12 { ~ { } km~ { } s } ^ { -1 } and { [ Fe / H ] } = -1.07 \pm 0.20 dex .
Using the spectroscopic metallicity to predict the intrinsic colours , we derive a reddening value of E ( B - V ) = 1.30 \pm 0.04 , in good agreement with the value obtained using reddening-free parameters .
The extinction-corrected magnitude of 037–B327 is V _ { 0 } = 12.73 ( absolute magnitude M _ { V } = -11.74 ) , which makes it the most luminous globular cluster in M31 .
We examine van den Bergh ’ s ( 1968 ) argument regarding the brightest and most-reddened globular cluster in in M31 ; we find that the brightest clusters are more heavily-reddened than average , but this can be explained by selection effects rather than a different R _ { V } in M31 .