Half a year ago, on July 13, 2019, the SRG astrophysical observatory was launched from the Baikonur Cosmodrome. These six months have been full of events: orbit corrections, switch-on and the “first light” of the ART-XC and eROSITA telescopes, their tuning and calibration, the first scientific observations, entry into the operating orbit around the L2 point, and, finally, the long-awaited beginning of the all-sky X-ray survey.
In the course of the calibration and performance verification phase, during daily communication sessions a total of 360 gigabytes of scientific data were received by three ground stations. The first results of these observations were presented at the all-Russian conference “High-energy astrophysics today and tomorrow – 2019”, which was held in December at the Space Research Institute of the Russian Academy of Sciences in Moscow.
On December 8, 2019, the SRG observatory began its all-sky survey. Completing six revolutions per day around the spacecraft’s axis pointed at the Sun, the telescopes of the observatory will complete the first scan of the whole sky already by June 2020, and a total of 8 such surveys are planned to be carried out over 4 years. The illustration shows (in Galactic coordinates) the one sixth of the sky for which data have been obtained during the first month of the survey. During this period, the ART-XC telescope has detected more than 3 million hard X-ray photons (with energies between 4 and 30 keV) from the distant Universe. It is these photons which are shown on the map.
To demonstrate the huge scientific potential of these data, two small fragments of the map are shown on a much larger scale. In the first of them, one can see an extended object – the hot remnant of the Cassiopeia A supernova, which exploded about 300 years ago in our Galaxy (the colors show the image obtained with ART-XC in hard X-rays, while the contours show for comparison an image obtained previously in soft X-rays with the German ROSAT observatory). In the second field, three point-like sources are clearly visible: two X-ray binary systems,
V395 Car and MAXI J0911-655, in our Galaxy, in which matter from a normal star is flowing onto a neutron star (in the latter case, a strongly magnetized neutron star is spinning 340 times per second), and a Seyfert galaxy, IRAS 09149-6206, at a distance of 840 light-years from us, where accretion of interstellar medium onto a supermassive black hole takes place.
The service systems of the SRG spacecraft and all 14 units of the ART-XC and eROSITA telescopes continue to operate in nominal regime, providing the scientists with new data on a daily basis. The unique all-sky X-ray survey is going on!