press release #35
First Forbush decrease of the 24th Solar Activity Cycle registered by Aragats Neutron Monitors
After long absolutely calm period, Sun started to presentfirst signs of activity. A shock detected by the Ace Spacecraft at 3August indicated the arrival of at least one CME (Coronal Mass Ejection) causedby the long duration C3 flare on August 1.
CME hit Earth's magnetic field on August 3rd at 17:40 UT. TheKp-index reached 6 (DST index -70nT) and this indicates a G2 Level GeomagneticStorm, lasted nearly 12 hours. Correspondingly Neutron monitors demonstratecoherent changes of the hourly count rates as seen in the Figure 2. Thestrength of the geomagnetic storm was not very large and cosmic ray intensity depletion (so calledForbush decrease) do not enhance 2.5%; however very similar pattern of theintensity changes demonstrate by remote monitors do not leave any doubts thatthey are caused by the disturbances of the geomagnetic field due to arrivedhuge clouds of magnetized solar plasma. Other ASEC monitors as well as worldwidenetwork of SEVAN monitors did not register event due to higher cutoff rigidity.
Figure 2.Geomagnetic storm index (planetary DST index) and count rates of 2 Aragats(ArNM and NANM)and Alma-Ati (AATB)Neutron Monitors
last 10 press releases:
- Armenia become member of SCOSTEP!
- A.Alikhanyan national lab purchase high purity germanium gamma-detector for nuclear physics research and isotope production
- KHEBR laser technological complex, which is unique with its power is launched in AANL
- Ground Breaking ceremony of Nuclear Medecine Center, October 30, 2012
- Visit in Dubna, 3-4 May 2012
- National Scientific laboratory after A. I.Alikhanyan young scientist Artyom Hovhanisyan “Haykyan” award-winner.
- The prime minister visited the National Scientific laboratory after A. I.Alikhanyan
- Center for Cosmology and Astrophysics is established in A.Alikhanyan National Laboratory (AANL)
- The workshop “Low dimensional physics and gauge principles”
- Launching of the detector in Yerevan