Approximately 6% of pulsars "glitch" and yes these (typically young) pulsars are poor time standards. The glitching is most likely caused by unpinning of vortices in the superfluid outer core. This causes a momentum transfer from the core to the crust - and a speed-up. The Vela pulsar (freq of ~11 Hz) is the most famous of the glitching pulsars as it glitches regularly (approximately every three years). The last glitch of Vela (Dec 2016) had a deltaF/F of about 1.4E-6.
However millisecond pulsars are completely different. They spin at hundreds of Hz, typically don't glitch, and PSR J0437-4715 will give many atomic clocks a run for their money. It has an error in its period (5.75 ms) of 9.9E-17 and an error in its period derivative of 9E-26. The idea was to monitor an array of millisecond pulsars and use this to detect gravitational waves. For many years it was a race between LIGO and the pulsar array to find GW. LIGO won. Incidentally, LIGO has looked for GW coming from a pulsar. Vela was chosen as its frequency is in the LIGO sweet spot. Nothing was found however ( https://arxiv.org/pdf/1104.2712.pdf) - but this was 7 years ago. Jim On 18 November 2017 at 13:24, Bob kb8tq <kb...@n1k.org> wrote: > Hi > > There are a number of papers on pulsars as time standards. The gotcha > in the observed data (that has been measured over long time periods) has > been random frequency jumps. Put another way, 10 million seconds and > beyond *is* the problem. It’s going to take a *lot* of monitoring for a > very long > time to convince people that a specific pulsar is a good idea. > > Bob > > > On Nov 17, 2017, at 8:54 PM, Hal Murray <hmur...@megapathdsl.net> wrote: > > > > > > Context is the what-next portion of a recent LIGO talk. For those of you > > that missed it (or didn't pay enough attention), on Aug 17th, they got > good > > data from a pair of neutron stars. 1.7 seconds later, the Fermi > satellite > > got a gamma ray burst. Within a day, the optical guys had found a new > spot. > > Over the next days and weeks, they got data over the whole spectrum, > radio to > > X-rays. (There were 70 observatories lined up to pounce. Everybody > wanted > > in on the action.) > > > > LIGO only works for roughly the audio spectrum. At the low and high > ends, > > the noise goes up. Lots of people are working on how to build gear that > will > > work at other wavelengths. > > > > One proposal is to monitor pulsars. There might be stuff leftover from > the > > big bang with a period of a year or so. If you can get good timing from > a > > pulsar, you might be able to see it. I suspect that will take "good" > timing > > to a scale that would astonish most time-nuts. > > > > > > > > -- > > These are my opinions. I hate spam. > > > > > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.