Two philosophies of dividing a night, plus a set of tie-breakers and guards. This page explains what the scheduler is actually doing so its decisions never feel like a black box.
Proportional Time #
The default. Every active project gets a fair share of the usable night, weighted by how much work it has remaining and constrained by when it is visible and which filters are moon-safe at each moment. Projects that are setting soon, or that have only narrow windows, receive protective preference so they are not starved by targets that are up all night. Over a season this converges every project toward completion together.
Manual Priority #
You rank projects (Priority 1, 2, 3…) and the scheduler serves them strictly in order: Priority 1 gets everything it can use tonight up to its requested sub counts, then Priority 2, and so on. A finished or capped priority does not hog slots – the moment its requested work is satisfied, time flows to the next project.
Exoplanet Transits: Time-Critical Interrupts #
Exoplanet transit projects (created in the Exoplanet Targets panel and pushed to NINA) play by different rules than everything above. A transit is an appointment, not a queue entry – the event happens at a fixed time whether your schedule is ready or not. The engine therefore prioritizes transits above regular astrophotography: as the capture window approaches (including the out-of-transit baseline before ingress), the scheduler interrupts the imaging target currently running, slews to the host star, and holds it through baseline, ingress, the full transit, egress, and the trailing baseline. When the window completes, the scheduler returns to regular astro targets automatically and re-plans the remainder of the night around the time that was spent. Neither Proportional Time nor Manual Priority can preempt a transit window – a light curve with a hole in it is worthless, so the appointment always wins.
The Scheduling Priority Chain #
When multiple targets compete for the same time slot, the drag-to-reorder chain breaks the tie. Criteria include:
- Setting Soonest – favor targets about to be lost for the night (or season).
- Constrained Windows – favor targets with the least usable time.
- Most Remaining Work – favor projects farthest from completion.
- Most Moon-Limited Work – favor work that can only happen in moon-safe windows.
- Lowest Peak Altitude – favor targets that never get high, when they are at their best.
- Mosaic Grouping and User Card Order.
The order of the chain is yours to set per rig; the defaults work well for most fleets.
Filter Switching & Tolerance #
With filter switching on, the scheduler rotates through a target’s filters every N subs instead of finishing one filter before starting the next – keeping channels balanced if a night is cut short. The tolerance is a runway guard: a switch may only start a filter that still has time to capture at least that fraction of a full batch before the block ends or its moon window closes. Higher tolerance = fewer switches near window edges.
Dithering & Bonus Images #
Dither every N subs is planned into the schedule (and NINA executes it between the right exposures). Bonus images lets a completed project keep collecting extra subs when nothing else can use the time – free signal instead of idle minutes; bonus subs are marked as such in the log.
Guards You Get for Free #
- Minimum time on target – the scheduler will not slew somewhere for a uselessly short block; each allocation must meet the minimum-imaging-time bar.
- Gap-fill – a few spare minutes at the end of a block become one more sub on the current target rather than an early slew.
- Moon-down priority – projects that can only shoot when the moon is down get first claim on those scarce dark hours before moon-flexible projects take them.
- End-of-target completion – the final remnant of a nearly finished project gets scheduled instead of being stranded below the minimum-block rule forever.