[time-nuts] Q/noise of Earth as an oscillator

[Azelio Boriani]

What about an ADEV/TDEV plot of the pulsar J0437-4715?

On Fri, Jul 29, 2016 at 12:39 AM, Jim Palfreyman <jim77742 at gmail.com> wrote:
> Hi All,
>
> Tom gave me a nudge to look here - I hadn't been following this thread.
>
> For those that don't know, I study pulsars and so the way we measure what
> pulsars do could be relevant to this discussion.
>
> First, I have never heard of a Q measure when referencing a pulsar. I think
> the key here is that it's not resonating as such. Rotating yes, resonating
> no.
>
> Pulsars spin and slow down due to giving off energy (magnetic dipole
> radiation). So in the pulsar world we mainly refer to spin frequency (F0)
> and frequency derivative (F1). With some of the younger and more "erratic"
> pulsars, F2 (and further) can be modelled.
>
> Here's some data on the Vela pulsar (hot off the presses - measured just
> now):
>
> F0              11.1867488542579
> F1              -1.55859177352837e-11
> F2              1.23776878287221e-21
>
> Vela is young and erratic. Millisecond pulsars are outstanding clocks.
> Here's the data for J0437-4715 - one of the most stable pulsars we know
> about:
>
> F0              173.6879458121843
> F1              -1.728361E-15
>
> I'm sure the "Q" of Vela would be pretty decent - but I can tell you now,
> as a time-keeper, she's useless.
>
>
> Jim Palfreyman
>
>
>
> On 28 July 2016 at 20:50, Tony Finch <dot at dotat.at> wrote:
>
>> Neville Michie <namichie at gmail.com> wrote:
>>
>> > The conical pendulum has a simple form of a weight on a string, instead
>> > of oscillating in one plane as a conventional pendulum, it swings around
>> > in a circular orbit in the horizontal plane. It has a definite resonant
>> > frequency.
>>
>> I don't think it does have a resonant frequency, any more than the Earth
>> does: the angular velocity of the pendulum is sqrt(g/h) where h is the
>> height of the pendulum; give it more energy, it swings higher, so h is
>> smaller, so the frequency is higher.
>>
>> Tony.
>> --
>> f.anthony.n.finch  <dot at dotat.at>  http://dotat.at/  -  I xn--zr8h
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