Copyright: ESA, Airbus DS
Gaia was launched on 19 December 2013 from ESA's spaceport in French
Guiana. On 14 January 2014, Gaia finalised its entry into operational
orbit around the Lagrange point L2, a gravitationally stable virtual
point in the Sun-Earth (with Moon) system, located 1.5 million km from
our planet. From this vantage point, Gaia will survey the sky
continuously for the next five years.
On 8 January, en route to L2, Gaia completed another milestone by observing its first batch of stars – about 18 000
in less than 3 hours. These observations were performed while the
satellite was in near-operational mode for the first time, although
attitude system control and optical system calibration are yet to be
finely tuned as part of the routine planned commissioning activities.
Hipparcos data give a parallax value for Sadalmelik, also known as
Alpha Aquarii, of 6.23 ± 0.19 mas, corresponding to a distance of 161 ± 5
pc. The Gaia error bar will be 30 times smaller, resulting in a
distance measurement that will be 30 times more precise.
Sadalmelik was one of the first stars to be observed and processed.
This image, while being saturated at the centre and showing that the
mirrors are not yet focussed, gives us a first taste of the massive
census of stars that Gaia is about to perform.
