Instrumental profiles (IPs) of NIRSPEC for two different observing epochs of vB10. On 2001-06-15, a broader slit was used (0.576′′; solid line) than for the reference epoch (0.432′′; 3007-06-25; dashed line). To visualize the asymmetries between both IPs, we calculated the ratio between both IPs and scaled the resulting function for better visibility (dotted line). ZO09 did not account for these asymmetries between both IPs, which led to a spurious RV shift of about 1 km s^-1 for the 2001-06-15 measurement in their data analysis.