[time-nuts] The forbidden question

[Michael Wouters]

My radio astronomer colleagues tell me that there is about a 20 minute
limit to VLBI observing runs because of atmospheric instability so this
limits improvements to be had from better clocks. My recollection is that a
maser is still sufficient out to 100 GHz. There is a paper about this that
I will dig out later.

Cheers
Michael

On Thu, 6 Jun 2019 at 12:01 pm, Joseph B. Fitzgerald <
jfitzgerald at alum.wpi.edu> wrote:

>
> Regarding Dana's remarks on VLBI, consider the recent black hole image
> released by the Event Horizon Telescope.    Measurements were taken at 230
> GHz, and they would like to begin measurements at 345 GHz.    Hydrogen
> masers were used at each telescope.    I am no expert, but I strongly
> suspect that a better clock would result in longer/better observations.
> The H maser only runs at 1.42 GHz ... the astrophysicist wizards are
> proposing to do their measurements at about 250 times higher in frequency!
>
>
> -Joe
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