[time-nuts] GSP clock stabilitiy, Rb vs Cs

Attila Kinali attila at kinali.ch
Sun May 5 04:17:49 EDT 2013

On Sat, 04 May 2013 21:53:00 -0700
Hal Murray <hmurray at megapathdsl.net> wrote:

> Radio astronomers use H-masers.  Can I assume that they are mid-term and that 
> H-masers are better than Rb (at mid-term)?

Disclaimer: I'm not into astronomy. What i write below is solely based
on what i've stumbled upon in the last years. It is probably inacurate
and maybe even wrong.

Modern H-Masers outperform both Cs beams and Rb Vapor Gas Cells
siginificantly up to a couple of days to a couple of months.

Which stability (short term or mid term) is exactly used for astronomy
depends on the phenomena they want to observe and how often they
can synchronize their clocks. The three most demanding applications
are probably large antenna arrays, VLBI and pulsar rate measurement.
Large antenna arrays mostly need short term stability, up to a couple
of hours (the length of one observation). VLBI can take multiple
days, depending on the setup. And pulsar rate measurement spans
many months to a couple of years.

			Attila Kinali

The people on 4chan are like brilliant psychologists
who also happen to be insane and gross.
		-- unknown

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