Install and Set Up PixInsight: A Beginner’s Guide

You will need a PixInsight account with a valid commercial or trial license, a compatible computer, a reliable internet connection, and room for the application and its database downloads. Check the current system requirements and installation notes in the official download portal before choosing an installer.

This guide covers initial setup, rather than a complete image-processing workflow. Menu names may differ between releases. The public sources were reviewed on October 25, 2026; the account-only download list and installation screens have not been independently checked. Use the portal’s current filenames, sizes, and platform instructions whenever they differ from this guide.

Allow extra time for downloading. Check the total size of your selected datasets before starting, and leave additional room for your images and working files. You do not need third-party processing plug-ins to complete this setup.

Choose the instructions for your operating system. Keep the database files separate from the application installation.

Application installers and in-app updates are separate parts of maintenance. Follow the current release notes when a new core installer is required.

A database is a reference library that PixInsight reads when it needs information about the sky. Downloading it does not automatically tell PixInsight where to find it.

Create a folder called PixInsight Databases on a local drive that stays connected. Inside it, create three folders: Gaia DR3, Gaia DR3 SP, and MARS DR2. On Windows, for example, you could use D:\Astro\PixInsight Databases if you have a D: drive; otherwise choose a suitable folder on your own drive. On macOS or Linux, use a permanent folder in your home directory or on an always-connected data drive.

Keep these folders outside the PixInsight application folder and outside temporary downloads. Moving files later will require updating their paths in PixInsight. If you use an external drive, connect it before opening the tools that need it.

Gaia DR3 → ImageSolver: star positions used for plate solving, which identifies the patch of sky in your photograph and adds coordinates to the image.

Gaia DR3/SP → SpectrophotometricColorCalibration (SPCC): stellar spectral information used for color calibration. Register it separately from DR3; the two selections are not interchangeable.

MARS DR2 → MultiscaleGradientCorrection (MGC): sky-reference data used for gradient correction. MARS means Multiscale All-Sky Reference Survey; it is not a database about the planet Mars. PixInsight’s DR2 announcement says it replaces DR1.

In the official portal, find the Gaia XPSD database downloads and the MARS database downloads. Gaia files use the .xpsd extension; MARS uses .xmars. Download each dataset into its matching folder and wait for every selected file to finish.

For Gaia DR3/SP, use the small set if the portal offers it and its stated depth suits your images. Deeper fields may need more stars from the full set. For Gaia DR3, the numbered files are ordered by stellar magnitude, so use a consecutive set starting with the first file and follow the portal’s coverage guidance. Do not choose random numbered files or mix small-set and full-set alternatives unless the official instructions say to do so.

Use the Gaia process’s Preferences dialog to register the downloaded files. Selecting a catalog in the main process window alone does not configure its file locations.

Repeat the configuration for the spectral catalog. Keep the files under their matching Data release entry.

MARS has its own configuration in MultiscaleGradientCorrection. Adding it to Gaia Preferences will not make it available to MGC. Use the files explicitly identified as DR2 in the current download portal, rather than following an older guide’s DR1 filename or download size.

Use a duplicate of a calibrated, stacked deep-sky image with plenty of stars. For the color checks, use a linear RGB image: one that has not had a permanent stretch applied. ScreenTransferFunction (STF) can brighten its display without changing the underlying pixel values.

Plate solving: open Script → Image Analysis → ImageSolver, or its equivalent in your version. Supply the target’s approximate coordinates, image scale (or focal length and pixel size), and observation information if they are missing. Select the local Gaia DR3 catalog. Run the solver and confirm that it reports a successful astrometric solution with no missing-database errors.

Color calibration: on a solved linear RGB duplicate, open SpectrophotometricColorCalibration and select Gaia DR3/SP. Choose the camera response and filters appropriate to the data, using the process help when unsure. Run it and inspect the console for a completed calibration and matched stars. A successful run checks catalog access; it does not prove every camera or filter choice was correct.

MARS: first confirm that MGC’s active XMARS list points to your DR2 files. A processing test also requires suitable image metadata and settings. On a fresh solved linear duplicate, follow the current MGC help for flux calibration with SpectrophotometricFluxCalibration (SPFC) before running MGC. Do not treat an SPCC test as a substitute for that prerequisite. A completed MGC run without file-access errors verifies that the selected database can be read; inspect the result for artifacts before keeping it.

Save your test results under new filenames. Keep the original image untouched, and record your application version and database folder locations for future troubleshooting.

“No database files selected” for Gaia DR3: reopen Gaia Preferences, choose Gaia DR3, and select its files. Having DR3/SP configured does not populate the separate DR3 entry.

SPCC cannot find the spectral catalog: check the Gaia DR3/SP entry, confirm every selected download is complete, and verify that SPCC is using that catalog. Installing DR3 alone does not complete this step.

The solver tries to connect to an online service: check the solver’s catalog setting. Registering a local database does not necessarily switch an existing process instance away from its online catalog.

A path no longer exists: reconnect the external drive or reselect the files at their new location. On Windows, check whether the drive letter changed. Do not delete the database files after registering them; PixInsight still reads them from that location.

Gaia works but solving fails: verify target coordinates, focal length, pixel size, image scale, and star quality. Missing or incorrect image information can prevent solving even when the database is installed correctly.

MGC reports missing metadata or fails on a target: check the image’s astrometric solution, SPFC prerequisites, DR2 file access, and the current MGC help for coverage and data requirements. A database installation does not guarantee that every image is suitable.

A process or catalog option is missing: finish official updates and check the release notes for a required core upgrade. When requesting help, include your operating system, PixInsight version, selected catalog, and the exact console error.

PixInsight opens and its official updates are complete. Your databases live in permanent folders outside the application. Gaia Preferences lists DR3 and DR3/SP under separate matching entries. MGC’s active database list points to MARS DR2.

A test image solves with the local Gaia DR3 catalog, and a solved linear RGB image completes SPCC with DR3/SP. For MGC, you have checked its current help, prepared the required metadata, and confirmed database access on suitable data. You are ready to move on to an image-specific processing tutorial.

Sources below support this original StellarPix guide. Use PixInsight’s current release notes and built-in process documentation as the final reference for version-specific behavior. The linked community forum replies describe configuration details; they are not all written by PixInsight staff.