Corrections for the Lutz-Kelker Bias for Galactic Masers

Based on published data, we have collected information about Galactic maser sources with measured distances. In particular, 44 Galactic maser sources located in star-forming regions have trigonometric parallaxes, proper motions, and radial velocities. In addition, ten more radio sources with incomplete information are known, but their parallaxes have been measured with a high accuracy. For all 54 sources, we have calculated the corrections for the well-known Lutz-Kelker bias. Based on a sample of 44 sources, we have refined the parameters of the Galactic rotation curve. Thus, at R_0=8 kpc, the peculiar velocity components for the Sun are (Uo,Vo,Wo)=(7.5,17.6,8.4)+\-(1.2,1.2,1.2) km s^-1 and the angular velocity components are ω_0=-28.7+\-0.5 km s^-1 kpc^-1, ω'_0=+4.17+\-0.10 km s^-1 kpc^-2, and ω''_0=-0.87+\-0.06 km s^-1 kpc^-3. The corresponding Oort constants are A=16.7+\-0.6 km s^-1 kpc^-1 and B=-12.0+\-1.0 km s^-1 kpc^-1; the circular rotation velocity of the solar neighborhood around the Galactic center is V_0 = 230+\-16 km s^-1. We have found that the corrections for the Lutz-Kelker bias affect the determination of the angular velocity ω_0 most strongly; their effect on the remaining parameters is statistically insignificant. Within the model of a two-armed spiral pattern, we have determined the pattern pitch angle i=-6.5^\circ and the phase of the Sun in the spiral wave χ_0=150^\circ.

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