We present X-ray observations of the new transient magnetar Swift J1834.9–0846 , discovered with Swift BAT on 2011 August 7 .
The data were obtained with Swift , RXTE , CXO , and XMM-Newton both before and after the outburst .
Timing analysis reveals single peak pulsations with a period of 2.4823 s and an unusually high pulsed fraction , 85 \% \pm 10 \% .
Using the RXTE and CXO data , we estimated the period derivative , \dot { P } = 8 \times 10 ^ { -12 } s s ^ { -1 } , and confirmed the high magnetic field of the source , B = 1.4 \times 10 ^ { 14 } G. The decay of the persistent X-ray flux , spanning 48 days , is consistent with a power law , F \propto t ^ { -0.5 } .
In the CXO /ACIS image , we find that the highly absorbed point source is surrounded by extended emission , which most likely is a dust scattering halo .
Swift J1834.9–0846 is located near the center of the radio supernova remnant W41 and TeV source HESS J1834–087 .
An association with W41 would imply a source distance of about 4 kpc ; however , any relation to the HESS source remains unclear , given the presence of several other candidate counterparts for the latter source in the field .
Our search for an IR counterpart of Swift J1834.9–0846 revealed no source down to K _ { s } \sim 19.5 within the 0 . ^ { \prime \prime } 6 CXO error circle .