Everything you need to know to use this log, whether you are ticking off objects for the fun of it or building a complete record for the Astronomical League Messier Club certificate.
This log is designed to serve two kinds of observers. You can use it for one, the other, or both — many observers start casual and add full records as their interest in the AL program grows.
When you open the site for the first time, a Quick Start Guide appears automatically explaining both use cases and linking to this page. Tick "Don't show again" before dismissing it to suppress it on future visits, or leave it unticked to see it again on any browser where no data has been saved yet.
Check off objects as you observe them, jot a brief note in the inline field, and watch the progress bar advance. Use Night Mode (🌙 toggle, top right) at the telescope — red-on-black preserves your dark adaptation. Export your log as a CSV any time from the ☰ Log menu. That's all you need to do.
Click the ✎ button on any object to open the full observation record — date, time, site, seeing, transparency, limiting magnitude, telescope, eyepiece, and a written description. Use ☰ Log → Session Setup to set location and equipment once per night so every record auto-fills. Generate your submission PDF from ☰ Log → Generate AL Report.
The 🌙 / ☀ toggle in the top-right corner switches between two display themes. Your preference is saved automatically and restored every time you open the page.
| Mode | Appearance | When to use |
|---|---|---|
| 🌙 Night | Near-black background, red-spectrum text and controls | At the telescope. Red light does not constrict the pupil or bleach the rods, so your dark adaptation is fully preserved. |
| ☀ Day | Warm parchment background, dark ink, maroon accents | Planning sessions indoors, filling in full AL records, generating reports. |
All 110 Messier objects are listed in marathon search order — the sequence that gives the best statistical chance of seeing all 110 in a single night, running west to east from objects visible just after dusk to objects rising just before dawn. This is different from Messier number order.
| Column | Description |
|---|---|
| # | Marathon sequence position (1–110) |
| Object | Messier designation — click to open the image lightbox |
| Type | Object type with a colour-coded dot. See the legend panel below the toolbar. |
| Con | IAU constellation abbreviation |
| Mag | Visual magnitude |
| RA / Dec | J2000.0 equatorial coordinates |
| PSA Pg | Pocket Sky Atlas page reference (Roger Sinnott, Sky & Telescope) |
| ✓ | Observation checkbox — records a hidden timestamp when ticked |
| Field Notes | Brief inline note field + ✎ full AL record button |
Checking an object dims its row, advances the progress bar, and silently records the exact timestamp of the observation. This timestamp flows into the full AL record and the CSV export as "Date Observed." Unchecking removes it.
Field Notes ↔ AL Description sync: the inline Field Notes field and the Description field in the full AL record modal are kept in sync automatically. When you open the AL record, any text in Field Notes seeds the Description so you are never starting from scratch. When you save the AL record, the Description is written back to Field Notes so the table always shows your latest observation text. You can type a shorthand note at the telescope and expand it properly in the AL form later — the table cell updates when you save.
Filter buttons above the table narrow the display to one object type, or to unobserved objects only. Click All to reset. The Unobserved filter is especially useful during a session to see only what remains.
Search filters by any text matching the M-number, type name, or constellation abbreviation. For example: Sgr shows only Sagittarius objects; glob shows globulars; M4 shows M4, M40, M41 and so on. The × button clears the field instantly. Filters and search combine — you can filter to Globular Cluster and then type Her to show only Hercules globulars.
Click any M-number in the Object column to open the lightbox modal for that object.
images/ folder. A placeholder is shown if the image is absent.charts/M[n].png if present.Escape or click outside to close.Open ☰ Log → Session Setup at the start of each observing session to set defaults that auto-fill blank fields in every full observation record you open that night. Existing saved data is never overwritten — session values only fill gaps.
Fields you can set as session defaults: observing site, seeing (Antoniadi scale), transparency, limiting magnitude, telescope / instrument, aperture, eyepiece, magnification.
The 📍 Locate button requests your GPS coordinates from the device (browser permission required; works on HTTPS or localhost). Once obtained, the site calls OpenStreetMap Nominatim to reverse-geocode the coordinates into a place name and fills it into the Site field automatically. Raw coordinates are also stored in the session.
A pulsing Session active indicator appears in the toolbar while any session default is set. Use ↺ Clear Session inside the modal to remove all defaults without affecting any saved records. Session data lives in mm_session localStorage and survives page refreshes.
The ✎ button at the right edge of every object's notes cell opens the full observation record form. The icon is outlined and dim when no record is saved; it fills with a solid red background when a record exists — giving an at-a-glance status across the whole table.
Auto-fill priority when opening a blank record: existing saved data → session defaults → checkbox timestamp (for date/time) → current date and time. The description field pre-populates from any brief inline note already typed.
| Section | Field | Notes |
|---|---|---|
| When & Where | Date | Pre-filled from checkbox timestamp or current date |
| Time (local) | Pre-filled similarly | |
| Observing site | Pre-filled from session default | |
| Sky Conditions | Seeing — Antoniadi scale | I Perfect · II Slight undulations · III Moderate · IV Poor · V Very bad |
| Transparency | 5 Excellent → 1 Very poor | |
| Limiting magnitude | Faintest naked-eye star visible | |
| Equipment | Telescope / instrument | e.g. 8″ Dobsonian f/6 |
| Aperture (mm) | e.g. 203 | |
| Eyepiece | e.g. 24mm Panoptic | |
| Magnification | e.g. 50× | |
| Observation | Description | Required for AL certificate. Describe size, shape, brightness, structure, whether averted vision was needed, notable features. |
| Sketch notes | Orientation, field stars noted, anything relevant to a sketch made at the eyepiece |
Click Save Record to store. If all fields are blank when you save, the record is deleted. The ✎ button indicator updates immediately in the main table.
The ☰ Log ▼ button in the toolbar opens a dropdown with all data management functions.
| Item | What it does |
|---|---|
| Applies a clean black-on-white print stylesheet and opens the browser print dialog. Use Print to PDF to save a snapshot of the current table. | |
| ⬇ Export CSV | Saves a timestamped CSV with marathon order, catalog data, observed status, date observed, and field notes for all 110 objects. |
| ⬆ Import CSV | Reads a previously exported CSV back in. Shows a conflict summary and asks you to choose Merge (fill blanks only) or Overwrite (replace all). |
| ⬇ Export AL Records | Saves a timestamped JSON file containing all full observation records plus observation timestamps. Export this after every session. |
| ⬆ Import AL Records | Merges an exported JSON back in. Shows new-vs-conflict counts before confirming. Useful for moving data between devices. |
| 📄 Generate AL Report | Opens a dialog to enter your name and club, then generates a multi-page PDF in the browser — cover, index table, and one full page per record. |
| ⚙ Session Setup… | Opens the session defaults modal (see above). |
| ↺ Reset All Data… | Shows counts of saved data before asking for confirmation. Clears all mm_* localStorage keys permanently. Export first. |
When you are ready to submit for the AL Messier Club certificate, go to ☰ Log → Generate AL Report. Enter your name and an optional club or location subtitle, then click Generate PDF. The PDF is built entirely in the browser — no internet connection needed — and saved to your Downloads folder.
The report contains three sections:
al_report.py) is also available in the repository for observers who prefer to generate the PDF from the command line, or who want to customise the layout further.All data is stored in your browser's localStorage — a private, local database that is never transmitted to any server. Nothing leaves your device.
| Key | Contents |
|---|---|
| mm_checks | Which objects you have observed |
| mm_notes | Brief inline notes per object |
| mm_times | Observation timestamps per object (ISO string) |
| mm_fullnotes | Full AL record data per object (structured JSON) |
| mm_session | Current session defaults including GPS coordinates |
| mm_theme | Night or day mode preference |
| mm_visited | Set to "1" when "Don't show again" is ticked in the Quick Start guide |
The log works fully without any local media files, but the lightbox is much richer with them. Place files alongside index.html in the following folders:
| Folder | Contents | Naming |
|---|---|---|
| images/ | Object photographs (JPEG) | M1.jpg … M110.jpg. A batch download script for SEDS Messier Catalog photos is in the README. |
| charts/ | Finder chart images (PNG) | M1.png … M110.png. The generate_charts.py script produces red-on-black night-vision charts for all 110 objects. |
| fonts/ | Self-hosted typefaces (TTF) | Seven files — see README for the full list and Google Fonts download links. The site falls back to system fonts if the folder is absent. |
After the page has loaded once, the following all work without internet: the full table, filtering, search, progress bar, checkboxes, notes, full AL record forms, image lightbox (with local images and charts), CSV and JSON export / import, AL Report PDF generation, and printing.
The only features that require internet: 📍 Locate (reverse geocoding via OpenStreetMap) and 🔭 Stellarium Web (external site). Both degrade gracefully — Locate shows an error message; Stellarium simply doesn't open.
The log is a small family of pages, all sharing the same fonts, theme toggle, and design system.
| Page | Purpose |
|---|---|
| index.html | Main observation log — the tool itself |
| faq.html | Common questions about the Messier Marathon, AL program, and how the log works |
| docs/user-guide.html | This page |
| resources.html | Curated external links — databases, observing guides, marathon planners, and printable logbooks |
All pages carry a footer nav: ← Back to Log · FAQ · User Guide · Resources.
The Astronomical League Messier Observing Program is one of the most popular observing certificates in amateur astronomy. To earn it, observe all 110 Messier objects and submit a structured log to an AL member club coordinator.
Required data per object: date and time, observing site, seeing and transparency, telescope aperture, magnification used, and a written description of what you saw through the eyepiece. This log captures all of these fields. The generated PDF report is designed to serve as your submission document.
The AL program explicitly requires you to find each object yourself using a chart or atlas — GoTo telescopes, digital setting circles, and phone apps that point you to objects are not permitted. The intent is to teach real sky navigation.
For further detail on program rules and submission, see the FAQ page or the official AL website above.