---
title: The Nightly Simulator
description: "The simulator is the heart of Astro PM: it takes every active project on a rig and builds tonight’s minute-by-minute plan – which target, which filter, which exposure, in what order, from dusk to dawn. What you see here is…"
url: "https://astro-pm.com/docs/nightly-simulator/"
updated: "2026-07-12"
category: Astro PM App Guide / NINA Tools
---

# The Nightly Simulator

The simulator is the heart of Astro PM: it takes every active project on a rig and builds tonight’s minute-by-minute plan – which target, which filter, which exposure, in what order, from dusk to dawn. What you see here is exactly what NINA will execute.

### Step 1: Strategy & Settings

The settings row at the top controls how the schedule is built:

- **Strategy** – Proportional Time or Manual Priority (see [Scheduling Strategies](/docs/scheduling-strategies/)).
- **Playback** – how NINA follows the plan after delays (see [Playback Modes](/docs/playback-modes/)).
- **Scheduling priority** – the drag-to-reorder sort chain used to break ties.
- **Bonus images** – keep shooting a finished target if time remains.
- **Prefer finishing mosaic panels**.
- **Dither** every N subs.
- **Filter switch** every N subs, with a tolerance guard.
- **Enable Flats Sequence** – end-of-night automated flats in NINA.

All of it is stored per imaging system and pushed to the cloud, so NINA builds its schedule with the same knobs.

[![](https://astro-pm.com/wp-content/uploads/2026/07/Screenshot-2026-07-12-130856.png)](https://astro-pm.com/wp-content/uploads/2026/07/Screenshot-2026-07-12-130856.png)
Step 1: Settings & Strategy

### Running a Simulation

![](https://astro-pm.com/wp-content/uploads/2026/07/Screenshot-2026-07-12-130938.png)
Step 2: Running the Simulation with Target Cards

Pick the imaging system and date, and run. The engine allocates the night across projects and produces three synchronized views: the **graph**, the **schedule log**, and per-target **allocation cards**.

### Reading the Graph

The graph shows each target’s altitude arc with the scheduled time painted on it, color-coded by target. Twilight and moon events are marked. Drag the scrubber to any time of night to see what the rig will be doing at that moment.

[![](https://astro-pm.com/wp-content/uploads/2026/07/Screenshot-2026-07-12-131018.png)](https://astro-pm.com/wp-content/uploads/2026/07/Screenshot-2026-07-12-131018.png)
Step 3: NINA Simulation Plan

### The Schedule Log

The log is the canonical schedule – every slew, filter change, exposure, and dither with its timestamp. It is exactly what NINA consumes, so if you want to know precisely what happens at 2:14 AM, the log is the answer.