ART-XC telescope onboard Spectrum-RG continues to monitor the Galactic center region after reports on Sgr A* flaring activity (ATel #13007, #12768).
Recent ART-XC observations of Sgr A* on August 15-16 (2019-08-14T23:40 – 2019-08-15T14:00 and 2019-08-15T23:40 – 2019-08-16T14:00, UTC) with total exposure of 50 ks each, demonstrate source average 5-16 keV flux at the level of 1.6×10-11 erg cm-2 s-1, which corresponds to the luminosity of 1.4×1035 erg s-1 , assuming a distance of 8.5 kpc. This measurement of the source luminosity is comparable to that observed with ART-XC on August 12 (ATel #13023). We also see a small flux variability at the level of 15% on the timescale of a few hours. More detailed information will be provided in the corresponding publication, which is under preparation.
Multi-wavelength observations are encouraged; next time when ART-XC will observe Sgr A* is between 2019-08-22T05:46 and 2019-08-22T15:20 UTC.
Following the recent report on Sgr A* flaring activity (ATel #13007, #12768) ART-XC telescope onboard Spektr-RG observed the Galactic center region for 50 ks during the period between 2019-08-11 22:27:50 UTC and 2019-08-12 13:19:12 UTC
We found Sgr A* in unusually active state: using absorbed power-law spectral model (slope Γ=2, following Zhang+17) we estimated mean flux in 5-16 keV band as (1.6±0.2)x10-11 erg cm-2 s-1, which corresponds to the unabsorbed bolometric luminosity of 2×1035 erg s-1 (0.1-20 keV), assuming a distance of 8.5 kpc.
We also noticed variability on timescale of few kiloseconds.
Because of preliminary calibration status of ART-XC more accurate details will be provided in the following article.
Multi-wavelength observations are encouraged; ART-XC will observe Sgr A* between 14.08.2019 23:40 and 15.08.2019 15:20 UTC
One of the most exciting times in the life of any astronomical observatory is achieving “first light“, the first time a telescope produces an image of an astronomical object. For space-based observatories, this can be a time that’s especially nerve-wracking, given the remote nature of the science and the fact that it can be difficult to address problems in deep space. As capabilities grow, and observatories are placed farther from earth, problems encountered are ever harder to resolve. The Spektr-RG observatory (or SRG as it’s more commonly known) is a Russian-German X-ray observatory, launched on July 13, and currently on a journey to its final staging point, a region of precarious orbital stability in the earth-Sun system called “L2”, about a million miles from earth along the earth-Sun line. Once it arrives at L2, SRG will survey the entire sky every six months over the next four years. SRG consists of two observing instruments. The Astronomical Roentgen Telescope X-ray Concentrator (ART-XC) instrument consists of 7 individual telescopes whichwill generate images of the X-ray sky in the energy band from 5 kilo-electronvolts up to 30 kilo-electronvolts, which is about 3 times higher in energy than most other imaging X-ray observatories, like Chandra, XMM-Newton and Swift. ART-XC was developed by the Russian Academy of Sciences’ Space Research Institute, in cooperation with the Russian Federal Nuclear Centre; NASA’s Marshall Space Flight Center provided ART-XC’s X-Ray mirrors. The image above is the first light image from the 7 ART-XC telescopes, obtained on July 30, 2019. This image shows the well-known X-ray pulsar Cen X-3, a binary system in which a spinning neutron star (rotating once every 4.8 seconds) is in a 2-day orbit around Krzeminski’s star, a massive star about 20 times the mass of the Sun. ART-XC can also measure the time variation of the observed X-rays, and the plot on the bottom of the image clearly shows the 4.8 second X-ray variation of the pulsar as measured by ART-XC. eROSITA, developed by Germany’s Max Planck Institute, is the second instrument on SRG, and is expected to achieve first light in the coming weeks.
During the ART-XC calibration observations on August 3, the collaboration received a new scientific image:
As of August 7, 2019, the Spektr-RG spacecraft was continuing its flight to the L2 Sun – Earth system libration point area, the onboard equipment being adjusted. The ART-XC telescope creators expect to receive the images from the second telescope, eROSITA, to collate the fields of view of both telescopes.
eROSITA, the second telescope of the project was created in Germany. The spacecraft has already opened the lid used to cover the mirror systems entrance openings. eROSITA is expected to send its first images in mid-September.
Spektr-RG is a Russian-German joint project to create a space astrophysical observatory aimed to explore the Universe in the X-Ray electromagnetic radiation spectrum around the Sun – Earth system L2 point. The spacecraft was launched on July 13 2019 from the Baikonur Cosmodrome.
31 July 2019 INTEGRAL is currently observing the High Mass X-ray Binary Cen X-3. The source is the target selected for the first light of the ART-XC detector onboard the Spektr-RG mission.
INTEGRAL observations will provide complementary information of the source at hard X-rays and will help to characterise the performance of the ART-XC detector in space. Spektr-RG was launched from the Baikonur Cosmodrome on 13 July 2019. We wish sucessful operations to our Spektr-RG colleagues.
On July 30, 2019 the first images of Cen X-3 X-ray pulsar have been obtained with ART-XC telescope onboard Spectrum-RG mission.
Quick-look data analysis demonstrated a strong pulsations with known period of 4.8 seconds.
Images of the X-ray pulsar Cen X-3 obtained with seven ART-XC telescope modules.The location of the images corresponds to the location of the telescope modules. Bottom panel: the pulse profile of Cen X-3 folded with the period of about 4.8 s, registered by the ART-XC telescope from this source.
More detailed investigations will be later presented in official press release.
Last, but not the least, there is a little film, showing how brightness of the pulsar changes – through the eyes of ART-XC
During the last few days Spectrum-RG spacecraft was observed by many Russian optical telescopes. These observations are needed to improve SRG orbit parameters measurements. The improved orbital solution will allow to apply more accurate orbit correction, which is planned on July 22. More accurate orbit correction will allow to save fuel aboard SRG spacecraft during its fly to the second Lagrange point (L2) of the Sun-Earth system. In future it will help to extend the mission lifetime.
These optical observations were done with Russian-Turkish 1.5-m telescope, Zeiss-1000 of Special Astrophysical Observatory of RAS, 1.6-m Sayan observatory telescope of Institute of Solar-Terrestrial Physics of SB RAS, 0.6-m telescope of Institute of Astronomy of RAS at Terskol observatory, telescopes of Crimean Astrophysical Observatory and others.
The SRG spacecraft is now located at the distance about 700 km from the Earth, in the direction of Aquila constellation and is moving to the Lagrange L2 point with the velocity around 800 m/s relative to Earth.
The image above shows the launch of Spectrum-Roentgen-Gamma from the Baikonur Cosmodrome in the Republic of Kazakhstan on July 13, 2019. Spectrum-Roentgen-Gamma (also called Spektr-RG, or SRG for short) is a Russian-German space observatory (with contributions from NASA), which will explore the entire high-energy X-ray Universe. The primary instrument on SRG is the “extended ROentgen Survey with an Imaging Telescope Array” telescope, better known as eROSITA. eROSITA will perform an unprecedented, 4-year long survey of the entire X-ray sky, greatly improving upon the only prior imaging all-sky X-ray survey, obtained by the German-US-UK ROSAT observatory in the early 1990s. The eROSITA survey will be obtained over a 5-times wider X-ray energy band, extending from 0.2 keV up to 10 keV, and to a much higher sensitivity than achieved by the ROSAT All-Sky Survey. The Astronomical Roentgen Telescope – X-ray Concentrator (or ART-XC) on SRG will expand the energy range of SRG to even higher energies, up 30 kilo-electron volts. One of the primary goals of SRG is to detect tens of thousands of distant galaxy clusters to determine the large scale structure in the Universe and test our understanding of the mysterious dark energy which drives the Universe apart. SRG will observe the Universe from a parking orbit at the Sun-Earth L2 point, a region of gravitational stability about a million miles behind Earth along the Sun-Earth axis. SRG will execute its 4-year all-sky survey by orbiting around the Sun-Earth axis every 4 hours. After this survey, SRG will spend 3 years taking detailed observations of individual celestial objects including galaxy clusters, active galactic nuclei, stars, neutron stars and black holes.
The first passage of the Spectr-RG space observatory over the territory of Russia from 21:18 to 02:40 MSK was observed by the head of the Kuban State University Observatory (KubSU) Alexander Ivanov with a 254 mm / 1200 mm Maksutov–Cassegrain telescope installed at the KubSU observatory. The video shows the passage of the upper stage DM-03 and the Spektr-RG observatory, moving along the constellation Vulpecula, a densely populated part of the Milky Way:
Averaged image of the DM-03 upper stage and Spectr-RG on July 13, 2019 from 21:18 to 02:40 MSK: