English

The Position of Sgr A$^*$ at the Galactic Center

Astrophysics 2009-10-31 v1

Abstract

The absolute position of the compact radio source at the dynamical center of the Galaxy, Sgr A^*, was known only to an accuracy of 0.20.2'' in spite of its accurate location with respect to near-IR stellar sources to within 30 milliarcsecond (mas). To remedy this poor positional accuracy, we have selected 15 high-resolution, high-frequency VLA observations of Sgr A^* carried out in the last 13 years and determined the weighted average position with the average epoch 1992.4 to be at α\alpha, δ\delta[1950] = 17h42m17^{\rm h} 42^{\rm m} 29\dsec3076±0.0007\pm0.0007, 285918.484±0.014-28^\circ 59^\prime 18.484\pm0.014^{\prime\prime}, or α\alpha, δ\delta [2000] = 17h45m17^{\rm h} 45^{\rm m} 40\dsec0383±0.0007\pm0.0007, 290028.069±0.014-29^\circ 00^\prime 28.069\pm0.014^{\prime\prime} which agrees with earlier published values to within the 0.20.2'' error bars of the earlier measurements. An accurate absolute position of Sgr A^* can be useful for its identification with sources at other wavelengths, particularly, in soft and hard X-rays with implications for the models of a massive black hole at the Galactic center.

Keywords

Cite

@article{arxiv.astro-ph/9904142,
  title  = {The Position of Sgr A$^*$ at the Galactic Center},
  author = {F. Yusef-Zadeh and D. Choate and W. Cotton},
  journal= {arXiv preprint arXiv:astro-ph/9904142},
  year   = {2009}
}

Comments

11 pages, one figure and one table. ApJL (in press)