{'fraction_non_alphanumeric': 0.027704485488126648, 'fraction_numerical': 0.06200527704485488, 'mean_word_length': 4.128378378378378, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
The Proper Motion, Age, and Initial Spin Period of PSR J0538+2817 in S147

We present results of the timing observations of the 143 ms pulsar PSR J0538+2817 that provide a proper-motion measurement clearly showing an association of the pulsar with the supernova remnant S147. We measure a proper motion of 67 mas yr-1, implying a transverse velocity of v = 385 km s-1. We derive an age of the pulsar and S147 of only 30 ± 4 kyr, which is a factor of 20 times less than the pulsar's characteristic age of τc = 620 kyr. This age implies an initial spin period of P0 = 139 ms, close to the present pulse period and a factor of several larger than what is usually inferred for birth periods. Implications for recent X-ray detections of this pulsar are discussed.