This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
The Maragheh Observatory was financed through waqf, the Islamic charitable endowment, an arrangement that let it keep operating for more than fifty years after Tusi's own death in 1274, well beyond the working life of any single patron or director. Tusi's son supervised the observatory in that period, continuing the institution his father had built rather than letting it lapse the moment its founding astronomer was no longer there to direct it personally.
The observatory nonetheless fell out of active use by the end of the thirteenth century, and it survives today only as ruins, a site whose scholarly output outlasted the physical institution that produced it by many centuries. Whatever administrative or political changes ended its working life, the mathematical tables its astronomers compiled under Tusi's direction continued circulating and being used long after the instruments that produced them had fallen silent and the buildings that housed them had begun to fall into ruin.
The waqf endowment structure itself is worth naming as a deliberate institutional choice rather than an incidental funding detail: by tying the observatory's upkeep to a charitable endowment rather than to the ongoing goodwill of a single ruling patron, Tusi and Hulagu built in a source of continuity that let the observatory's work outlast both of their own lifetimes, even though it could not, in the end, outlast the political and administrative changes that eventually let the institution itself lapse.