asteroid-scheduler identifies when and where uncovered phase intervals (gaps) in an asteroid rotational lightcurve are observable across a network of ground-based sites. Given a rotation period, epoch (BJD_TDB with light travel time correction per Eastman et al. 2010), and gap phase boundaries, the tool queries live ephemerides from the Minor Planet Center, computes per-night dark windows from dynamically calculated astronomical twilight (pyephem, Sun at −18°), and intersects them with gap occurrence times at each site. Lunar sky brightness is evaluated via the physical model of Krisciunas & Schaefer (1991), accounting for moon phase, angular separation, and site extinction. Output includes console display, CSV tables of observing windows with moon metrics, and optional iCalendar export. The tool also operates without lightcurve parameters as a standalone multi-site visibility calculator. Developed and validated against a photometric campaign on asteroid 7605 Cindygraber (MPC I12, Phillips Academy Observatory).