Last updated: 2026-07-27

Need help with Meridian? This guide covers common issues, troubleshooting steps, and how to contact support effectively.

Getting Help

Before contacting support, try these resources:

  1. Re-scan your archive. Many issues resolve after a fresh scan. Press Cmd+Shift+R to force a full rescan of all watched folders.
  2. Check your FITS/XISF headers. Meridian relies on standard header keywords (OBJECT, RA, DEC, INSTRUME, TELESCOP, FILTER, EXPTIME, DATE-OBS). Missing or non-standard headers are the most common cause of cataloging issues.
  3. Check the Source Files view. It shows every file Meridian found, including the ones it skipped and the reason why. If something is missing from your catalog, that is usually where the answer is.
  4. Review this page. The Common Issues section below covers the most frequently reported problems.

If you're still stuck, I'm here to help. The most effective support requests include:

  • A clear description of the problem
  • The target or file(s) involved
  • Your Meridian version (shown in Meridian > About Meridian)
  • Screenshots if the issue is visual

Common Issues

Files Not Found During Scan

Symptoms: Meridian finishes scanning but is missing files you know are there.

Try:

  1. Confirm the folder is added as a watched folder in Settings. Meridian only scans folders you've explicitly granted access to
  2. Check that files have .fits, .fit, .fts, or .xisf extensions. Other formats are not scanned as light frames
  3. If files are on an external drive, make sure the drive is mounted before scanning
  4. If using iCloud Drive, offloaded (cloud-only) files cannot be scanned. Download them to your Mac first
  5. If the files are present on disk but absent from the Catalog, they were probably skipped rather than missed. See the next section

Files Were Skipped, and I Disagree

Symptoms: Frames you consider genuine light frames don't appear in the Catalog or count toward integration time.

Meridian classifies every file it finds, and it deliberately skips things that look like calibration masters, stacked results, or intermediate files from processing software. That heuristic is right most of the time and wrong some of the time, most often with RAW frames converted through a processing tool, which can inherit headers that make them look like stacked output.

Try:

  1. Open the Source Files view. Skipped files are listed there along with the reason each one was skipped
  2. Right-click any file to reclassify it. Your override is remembered, so a rescan will not undo it
  3. If a whole folder was misclassified, you can apply the override at the folder level rather than file by file
  4. Overrides are visible and editable in Settings if you later change your mind

If you find a pattern Meridian gets consistently wrong, please email me a sample file. Several classification improvements have come directly from users doing exactly that.

Target Not Identified Correctly

Symptoms: A target shows up with the wrong name, an obscure catalog designation (for example LBN instead of the common name), or as "Unidentified."

Try:

  1. Meridian identifies targets from the pointing coordinates in your headers first, and falls back to the OBJECT keyword and then the folder name. If a frame has no usable coordinates and a non-standard OBJECT name, it has little to work with
  2. If the designation is correct but obscure, Meridian uses a popularity-ordered catalog search (Messier, then NGC, IC, Caldwell, then specialized catalogs). You can rename any target in the Catalog view via right-click
  3. For frames with no coordinates at all, plate solving can recover them. See the plate solving section below
  4. For very obscure objects, enable the optional SIMBAD online lookup in Settings to attempt resolution against the full astronomical database

Everything Merged Into One Giant Target

Symptoms: Instead of individual objects, your Catalog contains one target named after a telescope, a category, or something else that isn't an astronomical object, and it contains everything.

This is a folder structure issue, and it is the one arrangement Meridian genuinely cares about. Meridian steps over any folder named for a year, then treats the next folder down as a single target and reads everything beneath it. So if your archive is sorted like 2026/Redcat/M90/ or 2026/Galaxies/M90/, then "Redcat" or "Galaxies" becomes the target and every object underneath merges into it.

Try:

  1. Restructure so the first folder below any year folder is an object: 2026/M90/, 2026/NGC 3718/, and so on
  2. Everything inside the object folder is up to you. Subfolder names are invisible to Meridian, so Light, Subs, Raw, or one folder per filter all work identically, at any depth
  3. If you want to group by telescope or by object type, do it above the year rather than below it. You don't need equipment folders anyway, since Meridian tracks your gear from the headers and lets you filter by it
  4. After restructuring, force a rescan with Cmd+Shift+R

Duplicate Targets in Catalog

Symptoms: The same object appears as two or more separate entries (for example "M42" and "NGC1976", or two entries both named "M31").

Try:

  1. Right-click either entry and choose Merge to combine them manually
  2. Duplicates often arise from inconsistent OBJECT headers across sessions or capture software. Meridian normalizes most common variations automatically, but unusual spellings may slip through
  3. If coordinates differ significantly between data sets, Meridian may treat them as separate fields of the same region. This is by design for mosaic panels

Equipment Shows as "Unknown Telescope" or "Unknown Camera"

Symptoms: A data set has no equipment attached, and renaming it appears to do nothing.

Meridian builds equipment profiles from the TELESCOP and INSTRUME keywords in your headers. If neither is present in a file, there is no profile to attach a name to, and the rename has nothing to act on. This is the one place where Meridian genuinely needs something from your capture software.

Try:

  1. Configure your capture software to write telescope and camera names into the FITS headers. Every session from then on will be attributed automatically
  2. For sessions that do have at least one of the two, you can rename the telescope and camera independently on any data set card, and choose whether the change applies everywhere that profile is used or only to that session
  3. Existing sessions with neither keyword cannot be attributed retroactively, since there is nothing in the files to attach the name to

Duplicate Equipment Entries

Symptoms: The same telescope or camera appears multiple times with slightly different names.

Try:

  1. This usually happens when firmware updates or capture software changes cause small header variations (for example "ZWO ASI2600MM Pro" versus "ASI2600MM Pro")
  2. Select the duplicate entry, right-click, and choose Merge to combine it with the correct equipment profile
  3. Small focal length differences between sessions do not fragment your equipment list. Meridian applies a tolerance for rigs that report slightly different values night to night
  4. Rename equipment entries to human-readable names for easier identification

Thumbnails Not Generating

Symptoms: Targets show a placeholder image instead of an auto-stretched preview.

Try:

  1. Thumbnails generate in the background after the initial header scan completes. Check if the scan is still running in the toolbar
  2. If you quit Meridian during thumbnail generation, it picks up where it left off on next launch
  3. Tiled Rice/GZIP compressed FITS files (ZCMPTYPE header) are not currently supported for thumbnails. Standard FITS and XISF files work fine
  4. Extremely large files or unusual bit depths may take longer to process

My Sky View Not Loading Map Tiles

Symptoms: The sky map appears black or shows only your target overlays without background imagery.

Try:

  1. Map tiles are loaded from the CDS (Centre de Données astronomiques de Strasbourg) and require an internet connection
  2. Your target overlays, coordinates, and catalog browsing all work offline. Only the background survey imagery needs a connection
  3. Try switching to a different survey (DSS2, 2MASS, Mellinger) using the survey selector. Some surveys may load faster depending on your connection
  4. If you're behind a firewall or VPN, ensure access to alasky.cds.unistra.fr is not blocked

Plate Solving Not Working

Symptoms: Frames without coordinates aren't being resolved to targets, or the solver queue isn't producing results.

Meridian uses a two-stage solver. It tries ASTAP locally first, which is free, fast, and keeps your data on your own machine. If a frame fails locally, it can optionally be sent to Astrometry.net for cloud rescue. The cloud path is off by default and strictly opt-in: entering an API key alone does not authorize uploads.

Try:

  1. If nothing is solving locally, check that ASTAP is installed and that you've pointed Meridian at it in Settings. ASTAP is a separate free download. Without it, local solving is unavailable and every frame falls through to the cloud path
  2. ASTAP also needs its own star database installed to solve. If ASTAP is found but every solve fails, that's the usual reason
  3. If you're using cloud rescue, confirm you've both entered a valid Astrometry.net API key and enabled cloud solving. Both are required
  4. Cloud solving needs an internet connection, and frames are uploaded one at a time through a background queue. A large batch takes a while
  5. Very wide-field or very narrow-field images may take longer to solve or fail entirely. This is a limitation of plate solving generally, not of Meridian
  6. Results are cached locally, so a previously solved image won't be re-submitted

Most archives never need plate solving at all. If your capture software writes coordinates into your headers, Meridian uses those directly.

Visibility Data Looks Wrong

Symptoms: Rise/set times, transit times, or altitude charts don't match your expectations.

Try:

  1. Check your observer site coordinates in Settings. All visibility calculations are driven by your active observing location
  2. If using Core Location, ensure Meridian has location permission in System Settings > Privacy & Security > Location Services
  3. You can configure multiple observing sites and switch between them. Make sure the correct site is active
  4. Visibility is calculated for the current date by default

Missing Files Indicator

Symptoms: Files show a "?" indicator in the Source Files view.

This is expected behavior. Meridian never silently removes records when files go missing. Common causes:

  • An external drive is disconnected
  • Files were moved or deleted outside of Meridian
  • iCloud Drive offloaded files to the cloud

Reconnect the drive or restore the files, then rescan. Meridian will re-link them automatically.

Quick Look Extension Not Working

Symptoms: Pressing Space on a FITS or XISF file in Finder doesn't show a preview.

Try:

  1. The Quick Look extension installs alongside Meridian but may need to be enabled in System Settings > Extensions > Quick Look
  2. Restart Finder (Option+right-click the Finder icon in the Dock, then Relaunch)
  3. If another app has registered a Quick Look handler for FITS files, there may be a conflict

iCloud Drive Triggering Mass Downloads

Symptoms: Adding an iCloud Drive folder as a watched folder causes macOS to begin downloading all offloaded files.

Meridian scans local files only and does not intentionally trigger downloads of offloaded content. However, macOS may begin downloading files when any app accesses an iCloud-backed folder. If this is a concern, consider pointing Meridian at a local copy of your archive rather than an iCloud-synced folder.

Keyboard Shortcuts

Shortcut Action
Cmd+K Universal search across all views
Cmd+F Sidebar filter for current view
Cmd+1 / 2 / 3 / 4 Switch between Catalog, Source Files, My Sky, and Wish List views
Cmd+Shift+R Force rescan all watched folders
Cmd+Z / Cmd+Shift+Z Undo / Redo

System Requirements

  • macOS 14 (Sonoma) or later
  • Apple Silicon or Intel Mac (Meridian ships as a universal binary)
  • No internet connection required for core features

Meridian is available on the Mac App Store as a one-time purchase.

Contact Support

If you've tried the troubleshooting steps and still need help, get in touch:

Email: support@macobservatory.com

Please include:

  • Your problem description and steps to reproduce
  • Meridian version (from Meridian > About Meridian)
  • The target name or files involved, if applicable
  • Screenshots if the issue is visual

I typically respond within one to two business days.