Increasing of new GEO/HEO space debris discovery rate with ISON optical network

International Scientific Optical Network (ISON) represents one of largest systems specializing in observation of space objects. ISON provides permanent monitoring of the whole GEO region, regular surveying of Molniya type orbits, and tracking of objects at GEO, GTO, HEO and LEO. ISON project is continuously developing and is joining now the 37 observation facilities in 16 countries with 86 telescopes of different class (aperture from 12.5 cm to 2.6 m). 15.4 millions measurements in 2.1 millions of tracklets for about 5000 objects are collected by KIAM in 2015. 339 new space objects have been discovered, 307 previously lost objects have been rediscovered. For comparison, 160 new objects have been discovered in 2014, and 250 in 2013. 2014 was devoted to putting into operation of small survey and follow up telescopes (including new subsystem for extended GEO surveys to determine more precise orbits for conjunction analysis). This caused some decreasing of new space debris discovery rate in 2014. During 2015 and 2016 a lot of the telescopes of 40 cm – 80 cm apertures has been putted into operation. In addition, the methodology of quick identification and follow up of new space objects has been adjusted in part of ISON observatories. This resulted significant increasing of GEO/HEO space debris discovery rate. Achieved parameters of the above mentioned telescopes and obtained results will be presented and discussed. It is planned to start the printing of KIAM monthly bulletin with orbits of new discovered space debris

2014 WZ120

International audienceAvailable from the Minor Planet Center

2014 WZ120

International audienceAvailable from the Minor Planet Center

Repetitive patterns in rapid optical variations in the nearby black-hole binary V404 Cygni

ブラックホール近傍から出る規則的なパターンを持つ光の変動を可視光で初めて捉えることに成功 -ブラックホールの「またたき」を直接目で観測できる機会に期待-. 京都大学プレスリリース. 2016-01-07.How black holes accrete surrounding matter is a fundamental yet unsolved question in astrophysics. It is generally believed that matter is absorbed into black holes via accretion disks, the state of which depends primarily on the mass-accretion rate. When this rate approaches the critical rate (the Eddington limit), thermal instability is supposed to occur in the inner disk, causing repetitive patterns of large-amplitude X-ray variability (oscillations) on timescales of minutes to hours. In fact, such oscillations have been observed only in sources with a high mass-accretion rate, such as GRS 1915+105 (refs 2, 3). These large-amplitude, relatively slow timescale, phenomena are thought to have physical origins distinct from those of X-ray or optical variations with small amplitudes and fast timescales (less than about 10 seconds) often observed in other black-hole binaries--for example, XTE J1118+480 (ref. 4) and GX 339−4 (ref. 5). Here we report an extensive multi-colour optical photometric data set of V404 Cygni, an X-ray transient source containing a black hole of nine solar masses (and a companion star) at a distance of 2.4 kiloparsecs (ref. 8). Our data show that optical oscillations on timescales of 100 seconds to 2.5 hours can occur at mass-accretion rates more than ten times lower than previously thought. This suggests that the accretion rate is not the critical parameter for inducing inner-disk instabilities. Instead, we propose that a long orbital period is a key condition for these large-amplitude oscillations, because the outer part of the large disk in binaries with long orbital periods will have surface densities too low to maintain sustained mass accretion to the inner part of the disk. The lack of sustained accretion--not the actual rate--would then be the critical factor causing large-amplitude oscillations in long-period systems