---
title: Image Annotator
description: "The Annotator answers “what exactly is in my image?” – plate solve the frame, overlay professional catalogs, identify every smudge, and export a labeled version worth sharing. ### Step 1-2: Load & Plate Solve Open a FITS/XISF/TIFF, then solve it…"
url: "https://astro-pm.com/docs/image-annotator/"
updated: "2026-07-12"
category: "Astro PM App Guide / Analysis Tools & Calculators"
---

# Image Annotator

The Annotator answers “what exactly is in my image?” – plate solve the frame, overlay professional catalogs, identify every smudge, and export a labeled version worth sharing.

### Step 1-2: Load & Plate Solve

Open a FITS/XISF/TIFF, then solve it with your choice of engine:

- **ASTAP** – local and fast (path configured in Settings).
- **astrometry.net** – remote solve via nova.astrometry.net (API key in Settings); slower but works when ASTAP is stumped.
- **SIMBAD / VizieR / Aladin Lite** – quick lookups of the field center in the professional databases and the Aladin web viewer.

A successful solve reports center RA/Dec and plate scale, and georeferences the cursor – from here on, hovering the image reads out sky coordinates.

### Step 3: Fetch Catalogs & Annotate

Pick catalogs from the middle column (Gaia, 2MASS, SDSS, SIMBAD, and more – All on / All off shortcuts), then **Fetch Catalogs & Annotate**. Astro PM downloads the objects inside your field and labels the image. Display options:

- **Max labels** slider (20-3000, default 500) to keep dense fields readable.
- **Show RA/Dec grid**, **object names**, **markers**, **angular-size circles**, **magnitudes**, and **catalog source** – each independently toggleable.
- **Alignment correctors** – flip horizontally/vertically and rotate (±180°) for optical trains that mirror or rotate the field.

[![](https://astro-pm.com/wp-content/uploads/2026/07/Screenshot-2026-07-12-131743.png)](https://astro-pm.com/wp-content/uploads/2026/07/Screenshot-2026-07-12-131743.png)

### Exploring the Annotated Image

Click any label for its info card: name, object type, coordinates, angular size, magnitude – and for stars, the **peak ADU in your image**. From the card you can pin the label permanently, open the object in SIMBAD, or add the star to your calibration set. The same freehand drawing tools as the analysis panel are available for your own marks.

### Calibration Stars

The **Star Calibration** workflow pairs catalog magnitudes with measured ADU in your frames – building an empirical sensitivity model of your rig that sharpens Astro PM’s exposure recommendations (including the exoplanet/point-source exposure calculator). Highlight the calibration set on the image with one checkbox; add promising stars from any info card.

### Step 4: Save

**Save Annotated Image** exports the labeled frame as PNG or JPG – ready for a forum post, an observing log, or showing a friend exactly which faint fuzzy photobombed your galaxy.