Astronomy
Telescope Observation Timing Calculator
Estimate exposure cycle, subexposures per usable night, integration per usable night, usable nights required, expected planned integration, and any integration gap.
Exposure cycle including overhead (minutes)-
Usable imaging time per night (minutes)-
Whole subexposures per usable night-
Integration captured per usable night (hours)-
Usable nights required for target-
Expected usable nights in calendar plan-
Expected integration from planned nights (hours)-
Calendar nights implied by weather probability-
Target minus expected integration (hours)-
Decision view
Telescope observation calendar progress
Telescope observation calendar progressWhole subexposures per usable night and weather-adjusted calendar progress reconcile to the target integration.
Exact scenario comparisonPlanned calendar nights changes while all other entered assumptions remain constant.
| Planned calendar nights | Exposure cycle including overhead (minutes) | Usable imaging time per night (minutes) | Whole subexposures per usable night | Integration captured per usable night (hours) | Usable nights required for target | Expected usable nights in calendar plan | Expected integration from planned nights (hours) | Calendar nights implied by weather probability | Target minus expected integration (hours) |
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How to use Telescope Observation Timing Calculator
- Enter usable target window, subexposure length, overhead, and setup time.
- Enter the target integration and weather probability.
- Use the calendar/timeline view to see whether the plan reaches the target.
Calculator guide
Understanding Telescope Observation Timing Calculator
Observation timing depends on usable target window, overhead, whole subexposure count, and weather probability; the calendar plan should not hide those pieces.
Calculation method
How the calculation works
Deduct setup and per-exposure overhead from the usable target window, count whole subexposures, and apply weather probability only to calendar-night planning. Convert overhead seconds to minutes, deduct setup time from the nightly window, count whole exposures, then apply weather probability to planned calendar nights.
Detailed calculation process
Translate nightly window and weather into expected integration
The default uses a 5.5 hour target window, 3 minute subexposures, 28 seconds overhead, 45 minutes setup/teardown, a 12 hour integration target, 65% usable-night probability, and 6 calendar nights.
General formula: c = s+o/60W = 60h-qN = floor(W/c)I_n = Ns/60U = T/I_nE_n = d r/100E_I = E_n I_nC = U/(r/100)G = max(T-E_I,0) Each exposure consumes exposure time plus overhead, so only whole cycles fit in the available window. Weather probability is applied to calendar nights after the per-usable-night integration is known.
What each symbol means
Worked substitution with the default inputs
The default captures 4.100 hours per usable night and expects 15.990 hours across the six-night calendar plan.
Purpose-built visual
Observation calendar progress
A time-based plan shows the nightly exposure blocks and the expected progress toward the integration target.
Worked situations
Practical examples
- The default uses a 5.5 hour target window, 3 minute subexposures, 28 seconds overhead, 45 minutes setup/teardown, a 12 hour integration target, 65% usable-night probability, and 6 calendar nights.
- The default captures 4.100 hours per usable night and expects 15.990 hours across the six-night calendar plan.
Better inputs
Useful tips
- Build one exposure cycle from exposure, readout, dither, filter-change, and other overhead before multiplying by frame count.
- Use the actual astronomical window after twilight, altitude, moon, and target-visibility constraints rather than the full clock night.
- Compare required session time with usable window time and leave a weather or reacquisition reserve outside the ideal sequence.
Before relying on the result
Limitations and common mistakes
- Moon, twilight, target altitude, meridian flips, guiding, autofocus, equipment failure, travel, and target season are not modeled.
- Weather is treated as one average usable-night probability.
- Only whole subexposures are counted.
Reference
Key terms
- Exposure cycle
- One subexposure plus its overhead.
- Usable night
- A night that satisfies the entered weather and observing assumptions.
- Integration gap
- Target hours not expected to be captured by the planned calendar nights.
Important note
Calculated from the entered values using the displayed astronomical model. Use current ephemerides and qualified references for observation or mission decisions.
Frequently asked questions
Why use floor for subexposures?
A partial exposure cycle cannot be captured as a complete subexposure.
Does weather reduce every night equally?
It is an average planning probability, not a forecast for specific dates.
Why can expected integration exceed the target?
The plan uses whole nights, so the expected total can overshoot.
Is setup time applied per exposure?
No. Setup and teardown are entered once per night.