We present observations of the soft γ-ray repeater SGR 1806-20 taken with the Chandra X-Ray Observatory. We identify the X-ray counterpart of SGR 1806-20 based on detection of 7.5 s pulsations. Using three unrelated X-ray sources (and USNO stars) as position references, we are able to determine that the SGR is at α2000=18h08m39.32s and δ2000=-20°24'39.5", with rms uncertainty of 0.3" in each coordinate. We find that SGR 1806-20 is located within the 1 σ error region determined by Interplanetary Network data and is 14"+/-0.5" distant from the nonthermal core of SNR G10.0-0.3, excluding SGR 1806-20 as the origin of the core. We see evidence of a significant deviation of the spin-down of SGR 1806-20 from its long-term trend, demonstrating erratic spin-down behavior in this source similar to that seen in other SGRs. Finally, we show that there is a broad X-ray halo surrounding SGR 1806-20 out to radii ~1' due to scattering in the interstellar medium.
The Astrophysical Journal
- Pub Date:
- January 2002
- Stars: Pulsars: Individual: Alphanumeric: SGR 1806-20;
- Stars: Neutron;
- X-Rays: Stars;
- 16 pages, 4 figures, accepted by ApJ