Precise Chandra localization of the soft gamma-ray repeater SGR 1806-20

D. L. Kaplan, D. W. Fox, S. R. Kulkarni, E. V. Gotthelf, G. Vasisht, D. A. Frail

Research output: Contribution to journalReview articlepeer-review

34 Scopus citations


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 s.32 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.

Original languageEnglish (US)
Pages (from-to)935-940
Number of pages6
JournalAstrophysical Journal
Issue number2 I
StatePublished - Jan 10 2002

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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