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		| Paper: | On the Systematic Errors of Quantitative Spectroscopy of O Stars |  
		| Volume: | 465, Four Decades of Massive Star Research - A Scientific Meeting in Honor of Anthony J. Moffat |  
		| Page: | 260 |  
		| Authors: | Sabín-Sanjulián, C.; Simón-Díaz, S.; García, M.; Herrero, A.; Puls, J.; Castro, N. |  
		| Abstract: | We use the IACOB grid-based automatic fitting algorithm to evaluate the effects 
 that uncertainties associated to rotational velocities and the presence of nebular 
 emission lines in H and He profiles could introduce in the analysis of O stars. 
 We find that the derived stellar and wind parameters can be biased 
 when clipping the nebular lines 
 because of loss of information due to nebular contamination
 and that variations of ∼ 30% in rotational velocities 
 may lead to uncertainties of ∼ 20% in the derived stellar masses. |  
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