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GRAVITATIONAL REDSHIFT EXPERIMENT WITH THE SPACE

RADIO TELESCOPE RADIOASTRON

Dmitry Litvinov1, Norbert Bartel 2, Alexander Biriukov3, Vladimir Kauts3, Victor Kulagin1, Valentin Rudenko1
1

Sternberg Astronomical Institute, Russia
2 3

York University, Canada

Astro Space Center, Russia

Journees 2014, Saint-Petersburg, 22-24 September 2014


GRAVITATIONAL REDSHIFT

Einstein, 1911:

Pound, Rebka, 1960: laboratory test
Journees 2014, Saint-Petersburg, 22-24 Septem ber 2014 2


ATOM

IC FREQUENCY STANDARDS

Caesium fountain clock FOCS 1, Switzerland
Journees 2014, Saint-Petersburg, 22-24 Septem ber 2014 3


ATOM

IC FREQUENCY STANDARDS

Tiny caesium clock

VCH-1010 Hydrogen maser frequency standard of the space radio telescope "RadioAstron"
Journees 2014, Saint-Petersburg, 22-24 Septem ber 2014 4


ATOM

IC FREQUENCY STANDARDS: ACCURACY AND STABILITY

accurate and stable

accurate but unstable

inaccurate but stable

inaccurate and unstable

f

f

f

f

f

0

f

0

f

0

f

0

time

time

time

time

Journees 2014, Saint-Petersburg, 22-24 Septem ber 2014

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AB

SOLUTE MEASUREMENT OF THE GRAVITATIONAL FREQUENCY SHIFT

3105 km
710-10

H-maser Frequency accuracy, Df / f 310-13

Cs-fountain ~110-16

e-parameter error, de

410-4

1.410-7
Journees 2014, Saint-Petersburg, 22-24 Septem ber 2014 6


M

ODULATION MEASUREMENT OF THE GRAVITATIONAL FREQUENCY SHIFT

1103 km
210-10

3105 km
710-10

H-maser
Frequency stability at ~1 day, Df / f 410-15

Cs-fountain
~110-16

e-parameter error, de (after 100 orbits)

110-6

310-8
Journees 2014, Saint-Petersburg, 22-24 Septem ber 2014 7


FR

EQUENCY METHOD: CLOCK MOTION

,
orbit

meteo data + model
Journees 2014, Saint-Petersburg, 22-24 Septem ber 2014 8


G

RAVITATIONAL REDSHIFT EXPERIMENT WITH THE

SRT "RADIOAS

TRON

"

Journees 2014, Saint-Petersburg, 22-24 Septem ber 2014

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GRAVITATIONAL REDSHIFT EXPERIMENT WITH THE SRT "RADIOASTRON"
Contributions to the total frequency shift of the 8.4 GHz signal. Puschino TS, Oct 2012

Journees 2014, Saint-Petersburg, 22-24 Septem ber 2014

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GRAVITATIONAL REDSHIFT EXPERIMENT WITH THE SRT "RADIOASTRON"
Contributions to the total frequency shift of the 8.4 GHz signal. Puschino TS, Oct 2012

Journees 2014, Saint-Petersburg, 22-24 Septem ber 2014

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GRAVITATIONAL REDSHIFT EXPERIMENT WITH THE SRT "RADIOASTRON"

Residual frequency of the 8.4 GHz signal. Puschino TS, Oct 2012 geocentric distance residual frequency

Distance, 103 km

Frequency, Hz

Date (October)
AGREEM
ENT BETWEEN THEORY AND EXPERIMENT:

3%

Journees 2014, Saint-Petersburg, 22-24 Septem ber 2014

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TIMING

METHOD
Daily time dilation, due to gravitation gravitaiton and kinematics GPS 45 ms RadioAstron 58 ms

38 ms

57 ms

Journees 2014, Saint-Petersburg, 22-24 Septem ber 2014

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GRAVITATIONAL REDSHIFT EXPERIMENT WITH THE SRT "RADIOASTRON":
TIMING METHOD

Gravitational time dilation. Puschino tracking station, 18 March 2013

Time dilation, ms

Time, UTC observed calculated (general relativity)
Journees 2014, Saint-Petersburg, 22-24 Septem ber 2014 14


GRAVITATIONAL REDSHIFT EXPERIMENT WITH THE SRT "RADIOASTRON":
TIMING METHOD

Gravitational time dilation: observed ­ calculated (general relativity). Puschino tracking station, 18 March 2013

Time dilation, ms

Time, UTC
AGREEM
ENT BETWEEN THEORY AND EXPERIMENT:

1.5%
Journees 2014, Saint-Petersburg, 22-24 Septem ber 2014 15


G

RAVITY

PR

OBE

A

EXPERIMENT

(1976)

Flight duration Apogee
Gravitational potential difference DU / c2 H-maser stability sy

1 h 58 min 10,000 km
410 110
-10

-14

at 100 s

Gravity Probe A project leaders R. F. C. Vessot (right) and M. Levine (left) beside the mission's H-maser

Journees 2014, Saint-Petersburg, 22-24 Septem ber 2014

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G

RAVITY

PR

OBE

A

EXPERIMENT

(1976)

Journees 2014, Saint-Petersburg, 22-24 Septem ber 2014

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SRT RADIOAS

TRON ON-BOARD HARDWARE SYNCHRONIZATION

"COHERENT" MODE

"H-MASER" MODE

Journees 2014, Saint-Petersburg, 22-24 Septem ber 2014

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SRT RADIOASTRON ON-B "SEMI-COHERENT" MODE

OARD HARDWARE SYNCHRONIZATION

:

Biriukov et al. 2014, Astron. Rep. 58, p.783 (in print)

Journees 2014, Saint-Petersburg, 22-24 Septem ber 2014

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SRT RADIOASTRON ON-B "SEMI-COHERENT" MODE

OARD HARDWARE SYNCHRONIZATION

:

Spectrum of the 15 GHz signal, transmitted data is noise-like

Normalized spectral power density, dB

Frequency, Hz
Journees 2014, Saint-Petersburg, 22-24 Septem ber 2014 20


SRT RADIOASTRON ON-B "SEMI-COHERENT" MODE

OARD HARDWARE SYNCHRONIZATION

:

Spectrum of the 15 GHz signal, transmitted data is 010101...

Normalized spectral power density, dB

Frequency, Hz

Journees 2014, Saint-Petersburg, 22-24 Septem ber 2014

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SRT RADIOASTRON ON-B "SEMI-COHERENT" MODE

OARD HARDWARE SYNCHRONIZATION

:

Select components of the 16 GHz signal spectrum 31 Aug 2014, Puschino TS, 08:20:00 UTC, mode: "Test-2" 18 MHz

Journees 2014, Saint-Petersburg, 22-24 Septem ber 2014

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GR

AVITATIONAL REDSHIFT TESTS

Mission

Launch/ status 1976 completed
2011 active

Frequency standard

Achieved/ planned accuracy 1.410
-4

Gravity Probe A

H-maser

RadioAstron

H-maser

110

-5

ACES

2016

Cs-fountain + H-maser

210

-6

STE-Quest

2026

?

210

-8

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