PSR J1907+0918: A young radio pulsar near SGR 1900+14 and G42.8+0.6

We have extensively searched for periodic signals from the soft gamma repea ter SGR 1900+14 at 430 and 1410 MHz with the Arecibo Telescope. Our observa tions did not reveal the 5.16 s periodicity discovered at X-ray wavelengths by Hurley and coworkers. We place pulsed flux-density upper limits of 150 and 30 mu Jy at 430 and 1410 MHz, respectively. In the course of the 1410 M Hz search we discovered a 226 ms radio pulsar, PSR J1907+0918. Its period d erivative implies that the age of J1907+0918 is only 38 kyr, making it one of the youngest members of the known pulsar population. Independent lines o f evidence in support of this apparent youth are the unusually high degree of circular polarization and a relatively flat radio spectrum. The close pr oximity of this young radio pulsar to the supernova remnant G42.8+0.6 poses a problem for the proposed association between the G42.8+0.6 and SGR 190014.