We present the analysis of RXTE monitoring data obtained during the January 2009 outburst of the hard X-ray transient 1A 1118 - 61 .
Using these observations the broadband ( 3.5–120 keV ) spectrum of the source was measured for the first time ever .
We have found that the broadband continuum spectrum of the source is similar to other accreting pulsars and is well described by several conventionally used phenomenological models .
We have discovered that regardless of the applied continuum model , a prominent broad absorption feature at \sim 55 keV is observed .
We interpret this feature as a cyclotron resonance scattering feature ( CRSF ) .
The observed CRSF energy is one of the highest known and corresponds to a magnetic field of B \sim 4.8 \times 10 ^ { 12 } G in the scattering region .
Our data also indicate the presence of an iron emission line presence that has not been previously reported for 1A 1118 - 61 .
Timing properties of the source , including a strong spin-up , were found to be similar to those observed by CGRO /BATSE during the previous outburst , but the broadband capabilities of RXTE reveal a more complicated energy dependency of the pulse-profile .