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Repetitive Observations

Document Version: 1.0 | Last Updated: March 2026

Repetitive observations let you schedule a series of recurring observations of the same target — automatically creating new executions at defined intervals without manual resubmission.

When to Use Repetitive vs Monitoring

The Science Scheduler offers two ways to observe a target repeatedly:

Feature Repetitive Observations Monitoring (Cadence)
Created via Repetitive observation form Standard observation with cadence settings
Interval Days + hours (down to 6 minutes) Days between observations
Execution windows Configurable start/end windows Based on cadence eligibility
Series management Pause/resume, execution history, statistics Basic cadence tracking
Best for Structured campaigns with precise timing Simple "observe every N days" programs

Use repetitive observations when you need precise interval control, execution windows, series statistics, or pause/resume capability. Use monitoring for simpler cadence-based programs where you just want the target re-observed periodically.

Creating a Repetitive Observation

Observation Data

Configure the observation exactly as you would a standard observation:

  • Target coordinates and name
  • Exposure plan (filters, exposure time, count, binning)
  • Constraints (altitude, airmass, moon distance, twilight)
  • Priority
  • Observatory assignment

See Creating Observations for details on these fields.

Repetition Configuration

Field Description Constraints
Interval (days) Days between executions Combined with hours, minimum total interval is 0.1 hours (6 minutes)
Interval (hours) Hours between executions Combined with days
Start Date When the series begins Required
End Date When the series ends Optional (defaults to 1 year from start)
Max Executions Maximum number of times to execute Optional (default cap: 1,000)
Window Hours How long the execution window stays open Optional

Example configurations:

Campaign Interval Duration Max
Supernova follow-up 3 days 2 months —
Asteroid lightcurve 0 days, 4 hours 1 week 42
Variable star monitoring 1 day 6 months 180
Rapid transient follow-up 0 days, 0.5 hours 3 days 144

Rise-to-Set Mode

For targets where you want to observe the entire visibility window each night, repetitive observations support rise-to-set mode:

  • The system calculates when the target rises and sets each night, accounting for your observatory's location
  • Rise and set times shift by approximately 4 minutes per day due to Earth's orbital motion
  • The execution window is dynamically recalculated for each iteration
  • A minimum observing time of 90% of the calculated window is applied
  • Fill-time mode is automatically enabled — the plugin takes continuous exposures throughout the window

Rise-to-set repetitive observations are ideal for comprehensive lightcurve campaigns where you need maximum coverage each night.

Execution Windows

Each iteration of a repetitive observation has an execution window:

Field Description
Ideal Time The target time for execution (e.g., transit time)
Window Start Earliest the execution can begin
Window End Latest the execution can begin
Iteration Number Which execution in the series this is

The scheduler will attempt to execute the observation within the window. If the window passes without execution (weather, no available observatory), the execution is recorded as skipped and the next window is calculated.

Series Statistics

The system automatically tracks series progress:

Metric Description
Total Planned Number of executions planned for the series
Total Completed Executions that finished successfully
Total Failed Executions that encountered errors
Total Skipped Windows that passed without execution
Success Rate Completed / (Completed + Failed + Skipped)

Pause and Resume

You can temporarily halt a repetitive series:

  1. Open the observation detail page
  2. Click Pause Series
  3. The observation enters a paused state — no new executions are scheduled

To resume:

  1. Open the paused observation
  2. Click Resume Series
  3. The next execution window is recalculated from the current date

Note

Pausing does not cancel any execution currently in progress. It only prevents future executions from being scheduled.

Viewing Upcoming Executions

The observation detail page shows the next scheduled execution:

  • Next execution — when the next iteration is scheduled

Execution History

The execution history tab shows every iteration in the series:

Column Description
Iteration Execution number in the series
Scheduled For When the execution was planned
Status Completed, failed, or skipped
Observatory Which observatory executed (if applicable)
Reason Why an execution was skipped (if applicable)

This history provides a complete record for data analysis — you can see exactly which nights produced data and which were missed due to weather or other factors.

Background Scheduling

A background service runs every 60 seconds to manage repetitive observation windows:

  1. Checks for observations with expired execution windows
  2. Records skipped executions when windows pass without execution
  3. Calculates the next execution window using astronomy-aware scheduling (target visibility, rise/set times)
  4. Marks series as complete when max executions are reached or the end date passes

This is fully automatic — you don't need to take any action to advance the series.