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.

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 <hmurray@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.

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 <kb8tq@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 <hmurray@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. >

			Attila Kinali

On Fri, 17 Nov 2017 17:54:51 -0800 Hal Murray <hmurray@megapathdsl.net> wrote: > 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. I was wondering about those limits, when i saw the plots. Though, is it really the time/frequency source that defines the detection limit? > 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. I think going with a 2-4 5071s and a Cs or Rb fountain to keep them on frequency would be the easier thing to do. For additional short term performance, throw in an active H-maser. Attila Kinali -- You know, the very powerful and the very stupid have one thing in common. They don't alters their views to fit the facts, they alter the facts to fit the views, which can be uncomfortable if you happen to be one of the facts that needs altering. -- The Doctor

On 11/18/2017 12:16 PM, Attila Kinali wrote: > On Fri, 17 Nov 2017 17:54:51 -0800 > Hal Murray <hmurray@megapathdsl.net> wrote: > >> 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. > > I was wondering about those limits, when i saw the plots. > Though, is it really the time/frequency source that defines > the detection limit? If your laser bounces 100000 times in a 4 km tunnel to detect things, speed of light will limit the effective bandwidth. Thermal noise plucking the silica fibre suspension creates a noise floor. There is no cesium or H-maser at LIGO, they use GPS, we sure asked. Cheers, Magus