## Testing of General Relativity with Geodetic VLBI

Transactions of IAA RAS, issue 40, 22–27 (2017)

**Keywords**:
VLBI, Astrometry, General Relativity, IVS

### Abstract

The geodetic VLBI technique is capable of measuring the Sun’s gravity light deflection from distant radio sources around the whole sky. This light deflection is equivalent to the conventional gravitational delay used for the reduction of geodetic VLBI data. While numerous tests based on a global set of VLBI data have shown that the parameter gamma of the post-Newtonian approximation is equal to unity with a precision of about 0.02 percent, more detailed analysis reveals some systematic deviations depending on the angular elongation from the Sun. In this paper a limited set of VLBI observations near the Sun were adjusted to obtain the estimate of the parameter gamma free of the elongation angle impact. The parameter gamma is still found to be close to unity with precision of 0.06 percent, two subsets of VLBI data measured at short and long baselines produce some statistical inconsistency.

### Citation

`O. Titov. Testing of General Relativity with Geodetic VLBI // Transactions of IAA RAS. — 2017. — Issue 40. — P. 22–27.`

```
@article{titov2017,
abstract = {The geodetic VLBI technique is capable of measuring the Sun’s gravity light deflection from distant radio sources around the whole sky. This light deflection is equivalent to the conventional gravitational delay used for the reduction of geodetic VLBI data. While numerous tests based on a global set of VLBI data have shown that the parameter gamma of the post-Newtonian approximation is equal to unity with a precision of about 0.02 percent, more detailed analysis reveals some systematic deviations depending on the angular elongation from the Sun. In this paper a limited set of VLBI observations near the Sun were adjusted to obtain the estimate of the parameter gamma free of the elongation angle impact. The parameter gamma is still found to be close to unity with precision of 0.06 percent, two subsets of VLBI data measured at short and long baselines produce some statistical inconsistency.},
author = {O. Titov},
issue = {40},
journal = {Transactions of IAA RAS},
keyword = {VLBI, Astrometry, General Relativity, IVS},
pages = {22--27},
title = {Testing of General Relativity with Geodetic VLBI},
url = {http://iaaras.ru/en/library/paper/1674/},
year = {2017}
}
```

```
TY - JOUR
TI - Testing of General Relativity with Geodetic VLBI
AU - Titov, O.
PY - 2017
T2 - Transactions of IAA RAS
IS - 40
SP - 22
AB - The geodetic VLBI technique is capable of measuring the Sun’s gravity
light deflection from distant radio sources around the whole sky.
This light deflection is equivalent to the conventional gravitational
delay used for the reduction of geodetic VLBI data. While numerous
tests based on a global set of VLBI data have shown that the
parameter gamma of the post-Newtonian approximation is equal to unity
with a precision of about 0.02 percent, more detailed analysis
reveals some systematic deviations depending on the angular
elongation from the Sun. In this paper a limited set of VLBI
observations near the Sun were adjusted to obtain the estimate of the
parameter gamma free of the elongation angle impact. The parameter
gamma is still found to be close to unity with precision of 0.06
percent, two subsets of VLBI data measured at short and long
baselines produce some statistical inconsistency.
UR - http://iaaras.ru/en/library/paper/1674/
ER -
```