international observatory usually known russian soviet later russian space observatory developed collaboration france denmark bulgaria launched december aboard rocket placed highly eccentric day orbit devoted observations operated years september nearly years directed observations gas supply attitude control exhausted observatory placed non directed survey mode finally ceased november seven different instruments board designed observe universe energies ranging ray gamma ray main instrument capable imaging hard ray soft gamma ray sources instrument meant study gamma ray bursts sources experiments intended image sources range instrument watch designed monitor sky continuously alert instruments new interesting sources art covered ray energy range experiments covered ray gamma ray spectrum spacecraft axis stabilized spacecraft class spacecraft produced similar observatory functional reason spacecraft originally known weighed metric tons carried metric tons international scientific instrumentation stood tall total span solar power available scientific instruments approximately launch orbit spacecraft launched december aboard rocket placed highly eccentric hour orbit initial respectively degrees meant solar lunar significantly increase reducing orbit near circular time completed directed observations september increased september degrees days day orbit devoted observations years orbit observatory finally earth atmosphere instrumentation hard ray low energy gamma ray collaboration covered energy range effective area cm2 maximum sensitivity field view maximum angular resolution energy resolution imaging capabilities derived association coded mask position sensitive based anger camera principle responsibility moscow instrument covered energy range imaging timing identical consisting position sensitive multi wire proportional counter coded mask module effective area approximately producing field view angular resolution temporal energy resolutions respectively instrument achieved sensitivity crab source hour exposure maximum time resolution built covered energy range field view instrument consisted based making effective area time resolution experiment designed record high energy events range consisted independent associated electronics consisted crystal diameter thick surrounded plastic anti coincidence jacket arranged spacecraft observe burst mode triggered count rate energy range exceeded background level seconds energy channels watch starting january watch instruments designed operation observatory instruments bright sources range rotation taken instruments fields view covered approximately sky energy resolution quiet periods count rates energy bands accumulated seconds depending onboard computer memory availability burst event count rates accumulated time resolution second energy channels instrument designed consisted seven distributed spacecraft responded energy consisted crystals diameter thick entrance window surfaces protected thick lead layer burst detection threshold square meter depending burst spectrum rise time taken channel pulse height measured time resolution remaining variable time resolutions depending count rate range resolutions covered instrument operated december february period time experiment days solar cosmic gamma ray bursts detected french instrument consisted proportional optical proportional detected field view visible field view instrument designed look optical counterparts high energy burst sources performing analysis high energy events science results initial years directed observations observed extra ray sources emphasis deep imaging center broad band observations black hole candidates ray observatory switched survey mode carried sensitive sky survey energy band highlights included deep imaging million seconds duration center region discovery electron lines ray nova study time black hole candidates years observations discovered new ray sources candidate black holes stars consequently designations begin meaning source examples discovered galaxy impact dissolution soviet_union end soviet_union problems arose project nature main spacecraft control center located facility region control center significant soviet space program country equipped dish antenna breakup union region populated ethnic russians found newly independent ukraine center ukrainian national control prompting new political main urgent problem finding funds support continued operation spacecraft amid spending post soviet russia french space agency having contributed significantly project scientifically financially took fund continuing operations directly
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