P & Pdot

[nicksauce]

Often I will hear quoted such and such Pulsar has a period of X and a Pdot of Y. However this is somewhat ambiguous to me. If the period is changing, then how does one quote its period? Obviously, by using some unambiguous standard that I am unsure of. Is the reported period (in a paper about an observation, say) the period at the start of the observation?

[George Jones]

Often I will hear quoted such and such Pulsar has a period of X and a Pdot of Y. However this is somewhat ambiguous to me. If the period is changing, then how does one quote its period? Obviously, by using some unambiguous standard that I am unsure of. Is the reported period (in a paper about an observation, say) the period at the start of the observation?

The date of the measurement is usually given. For example, in his book Was Einstein Right?, Clifford Will writes
Because the pulsar period changes by the quoted amount in the last three digits each year, the measured pulsar period is usually referred to a specific date, in this case, July 7, 1984.

Another example: the fourth column of Table 2 of the pulsar survey paper

http://arxiv.org/abs/astro-ph/0303473

gives the date (Modified Julian Date) of each observation.

[nicksauce]

But just to be clear... does the reported Period correspond to the period at the start of the observation, or the end of the observation or what?

[George Jones]

But just to be clear... does the reported Period correspond to the period at the start of the observation, or the end of the observation or what?

I'm not sure. A date is given for each observation, so that narrows things down to a twenty-four hour interval. Do pulsar periods change noticeably over twenty-four hours?