Cairo solar-time corpus associated with Ibn Yunus

A Cairo corpus of spherical tables deriving time and azimuth from the Sun, associated with Ibn Yunus and later contributors. Listing him as an author records a documented contribution, not sole authorship of all contents. King explicitly notes difficulty determining how many tables he computed; TDV describes Ghayat al-intifa as a later title for this material ^{1 2}.

King describes about200pages, most with180entries each, and three principal sets exceeding10,000entries apiece. They give time since sunrise, time until noon and azimuth from solar altitude and longitude at one-degree intervals in both arguments. These are King's approximate aggregate descriptions, not an independent census or attribution of every entry to one person ³.

His description gives Cairo latitude30degrees and obliquity23degrees35minutes. Historical parameters do not make an unmodified timetable usable everywhere and always. Other spherical tables include prayer-related functions: a historical use account, not issued prayer times or a ruling ⁴.

Some additions date from the13thand14thcenturies; TDV names al-Maqsi among later contributors. Ibn Yunus's lifetime endpoint cannot date the entire corpus. The contribution record explains this rather than selecting every surviving table as his own ^{5 2}.

The Hakimi Zij is another, broader handbook covering observations, calendars and planets. MacTutor's lunar tables are separate and have attribution qualifications. The nonlinear-interpolation suggestion does not establish a particular historical algorithm; the original1973 study was not read here ⁶.

King describes important Dublin and Cairo manuscripts and many witnesses with differing arrangements and selections, use into the nineteenth century and inspiration for Yemeni and Syrian work. This is not our inspection of every copy, nor does continued use mean unchanged values ⁷.

No manuscript cells were inspected or transcribed in this run. Defined scholarly sources were read completely, and the invention page's calculation remains an explicitly modern model. This preserves the corpus's historical value without claiming a new edition or generating a contemporary timetable.