ART-XC, the telescope on Spektr-RG, monitors the weather at the Lagrange point L2

During periods of increased solar activity, coronal mass ejections occur. They can reach around the Earth and distort the magnetosphere, especially by causing disturbances in the magnetic “tail”, which greatly increases the flow of solar wind particles in the area where the Spektr-RG observatory and other spacecraft.

The SRG / ART-XC telescope “Pavlinsky” has unique sensitive detectors for detecting X-rays, and charged particles are a harmful background for it. Therefore, the developers of the telescope took a long time to record and then “remove” such events associated with the entry of charged particles into the detectors. It turns out that it can also be used to monitor “space weather”.

Almost a year ago, on October 28, 2021, after 7:00 pm Moscow time, the detectors of the ART-XC telescope recorded a fourfold increase in the background noise, caused by a series of solar flares. After this event, it was decided to create a monitor of the radiation situation at the Lagrange point L 2 to record the powerful solar flares that began to occur at the beginning of solar maximum.

The L-point 2 provides unique opportunities for the location of large astrophysical features, therefore, the collection and analysis of the radiation situation in this area is necessary for the competent design of highly sensitive scientific instruments and to ensure the reliable operation of the systems of tracking. promising spacecraft service.

The monitor of the radiation situation near the Lagrange point L2 can be found on the public official Internet resource of the Spektr-RG observatory

After the daily communication session with the spacecraft and the reception of measurement data for the previous day, specially developed software processes the received data and sends information about the radiation situation to the project website. So, the data is displayed with an offset of 1 day.

The SRG/ART-XC monitor provides data on the radiation situation in the form of a light curve (ie count rate) from the telescope’s detectors in the energy range of 60 to 120keV. This range reflects only the radiation situation and is almost unaffected by astrophysical sources, except for bright gamma-ray bursts.

The site allows you to interactively view the light curve at different time intervals and with different averaging intervals, from 10 minutes to a day, that are automatically selected. The user can also download the light curve to their personal computer for further study.


The Spektr-RG spacecraft, developed by JSC NPO Lavochkin (part of Roscosmos), was launched on July 13, 2019 from the Baikonur Cosmodrome. It was created with the participation of Germany within the framework of the Federal Space Program of Russia on the order of the Russian Academy of Sciences. The observatory is equipped with two unique X-ray mirror telescopes: ART-XC (IKI RAS, Russia) and eROSITA (MPE, Germany), which work on the principle of oblique incidence X-ray optics. The telescopes are installed on the Navigator space platform (NPO Lavochkine, Russia), which is suitable for project tasks. The main objective of the mission is to map the entire sky in the soft (0.3 to 8 keV) and hard (4 to 20 keV) ranges of the X-ray spectrum with unprecedented sensitivity. The observatory must operate in space for at least 6.5 years.

  • Scientific director of the orbital X-ray observatory “Spektr-RG” Academician Rashid Sunyayev .
  • Scientific advisor for the ART-XC telescope named after MN Pavlinsky (Russia): corresponding member of the Russian Academy of Sciences, professor of the Russian Academy of Sciences Alexander Lutovinov .
  • Supervisor of the eROSITA telescope (Germany): Dr Andrea Merloni

Source and graphic credit: IKI RAS

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