We report unsuccessful searches for pulsations from the neutron star RX J1836.2+5925 identified with the EGRET source 3EG J1835+5918 .
A 24-hr observation with the NRAO Green Bank Telescope at 820 MHz placed an upper limit on flux density of 17 \mu Jy for P \gtrsim 10 ms , and gradually increasing limits for 1 \lesssim P \lesssim 10 ms .
The equivalent luminosity is lower than that of any known pulsar with the possible exception of the radio-quiet \gamma -ray pulsar Geminga .
A set of observations with the Chandra X-ray Observatory HRC totaling 118 ks revealed no pulsar with 1 ms \leq P \leq 10 s. The upper limit on its pulsed fraction is 35 % assuming a sinusoidal pulse shape .
The position of RX J1836.2+5925 in Chandra observations separated by 3 years is unchanged within errors , leading to an upper limit on its proper motion of < 0.14 ^ { \prime \prime } yr ^ { -1 } , or v _ { t } < 530 km s ^ { -1 } at d = 800 pc , a maximum distance estimated from its thermal X-ray spectrum .
With these null results , the properties of 3EG J1835+5918 and its X-ray counterpart RX J1836.2+5925 are consistent with a more distant or older version of Geminga , or perhaps a recycled pulsar .
Having nearly exhausted the capabilities of current instrumentation at all wavelengths , it will likely fall to the Gamma-ray Large Area Space Telescope to discover pulsations from 3EG J1835+5918 .