User Guide
Complete Feature Reference
Every panel, control, and workflow in OpenSkyLab explained. All features described here are included in the free, open-source core unless marked with a PRO badge.
Interactive Sky Map
The sky map is a WebGL-rendered 3D sky view powered by Three.js. It displays over 100 million stars, 530+ deep-sky objects, 35 constellations, planets, and the Milky Way — all rendered in real-time.
Embedded Catalogs (Offline)
| Catalog | Objects | Details |
|---|
| Messier | 110 | All objects with popular names |
| Caldwell | 109 | Complete Caldwell catalog |
| NGC | 210+ | Notable NGC, mag 11.5 and brighter |
| IC | ~100 | Notable IC objects |
| Named Stars | ~240 | Hipparcos J2000 coordinates |
| Constellations | 35 | IAU stick-figure lines |
Unified Search
Search by catalog number (M42, NGC 2903), popular name (Orion Nebula), or star name (Sirius, Vega). Supports multi-language aliases for solar system objects (Sol, Lua, Marte in Portuguese).
Time Travel
Scrub through time with date picker, hour slider (1-minute steps), and step buttons (+-1h, +-1d, +-1y). See where objects will be at any point in the future or past. Reset to current time with one click.
HiPS Background
Download sky survey tiles (HiPS) for background imagery. 5 detail levels cached locally for offline use. Pre-download regions centered on your targets.
Camera Control
Full camera control with exposure, gain, offset, binning, ROI, and cooler management. Supports INDI, ASCOM Alpaca, and DSLR/Mirrorless cameras (CR2, CR3, ARW via libraw).
Exposure Controls
Set duration (0.001s to 3600s), gain, offset, binning (1x1 to 4x4), and frame type (Light, Dark, Flat, Bias). ROI support for faster readout on high-resolution sensors.
Cooler Management
Set target temperature, monitor current temperature, and power percentage. Visual indicator shows cooling progress and stability.
Frame Browser
Table view of all captured frames with HFR, FWHM, star count, and file path. Click any frame to open it in the FITS Viewer.
Flat Wizard
Automatically finds the optimal exposure time for flat frames by targeting a specific ADU value. Iterative algorithm converges in 3-5 iterations.
Mount & GoTo
Control your mount with GoTo, sync, tracking modes, park/unpark, and meridian flip management.
GoTo
Enter RA/DEC coordinates manually or click any object on the Sky Map. The mount slews to the target and tracking begins automatically.
Tracking Modes
Sidereal (stars), Lunar, Solar, or Off. Switch modes for different target types.
Meridian Flip
Configurable hour angle limit and direction. When the limit is reached during a sequence, the system automatically flips, re-solves, re-centers, and re-starts guiding.
Pointing Model
Build a multi-star alignment model. Add alignment points (solved positions vs. reported positions) to improve GoTo accuracy across the sky.
Sequencer
The sequencer engine automates multi-target, multi-filter imaging sessions with dithering, autofocus triggers, and checkpoint recovery.
Sequence Steps
Each step defines: filter, exposure time, gain, offset, binning, frame count, dither interval, and focus offset. Steps execute in order with automatic filter changes.
Advanced Conditions & Triggers
Define conditions for step execution (altitude limits, time windows) and triggers (autofocus every N frames, temperature drift threshold).
Checkpoint Recovery
If power is lost or the daemon crashes, the sequencer saves progress to disk. On restart, resume from the exact frame where you left off.
Templates
Save and share sequence configurations as templates. Create, edit, clone, and apply templates from the Template Browser.
Autoguiding (PHD2)
Integrated with PHD2 via JSON-RPC. Real-time RMS statistics, dither control, guide star monitoring, and calibration — all from within the OpenSkyLab UI.
Guide Graph
High-performance uPlot chart showing RA and DEC corrections in real time. RMS values displayed with color-coded quality indicators.
Dithering
Configurable dither amount (pixels) and settle time. Dithering integrates with the sequencer — dither every N frames automatically.
Autofocus (V-Curve)
Automated V-curve focusing with HFR measurement. The algorithm captures frames at different focus positions, fits a V-curve, and moves to the minimum HFR position.
Configuration
Step size, number of steps (typically 9), tolerance threshold, and backlash compensation. Per-filter focus offsets are applied automatically when the filter changes.
Temperature Compensation
Optional coefficient-based compensation that adjusts focus position based on temperature drift from the focuser's temperature sensor.
Target Scheduler
Multi-night observation planner. Define targets with constraints, and the scheduler automatically picks the best target based on altitude, moon distance, and priority.
Target Constraints
Minimum altitude, moon separation distance, time window (start/end), maximum airmass. Targets that don't meet constraints are skipped.
Automated Workflow
For each target: slew, plate solve, sync, start guiding, run sequence. On completion, move to the next best target. Auto-park when all targets are done or weather becomes unsafe.
Polar Alignment Wizard
Automated three-point polar alignment. The wizard captures and solves three frames while rotating the mount, then computes the precise altitude and azimuth error.
Workflow
Start wizard, capture first frame (auto-solve), rotate mount 90 degrees, capture second frame, rotate again, capture third frame. Error computed automatically with directional correction arrows.
Iterative Refinement
After making physical adjustments to your mount, re-measure to verify improvement. History of measurements shown for tracking progress toward perfect alignment.
Live Stacking
Real-time sub-pixel aligned stacking with sigma-clip rejection. Watch your deep-sky target emerge as frames accumulate during the imaging session.
Alignment
Sub-pixel registration using star matching. Each new frame is aligned to the reference frame before stacking.
Rejection
Sigma-clip rejection removes outliers (satellites, cosmic rays, hot pixels) for cleaner results.
FITS Viewer
Full-featured FITS viewer with zoom, pan, auto-stretch, and WCS coordinate overlay. Interactive per-channel RGB histogram with log scale and stretch presets.
Stretch Modes
Auto-stretch, linear, logarithmic, and histogram equalization. Adjust black point and white point with sliders or presets.
WCS Overlay
When a frame has been plate-solved, overlay catalog labels and coordinate grid directly on the image. Identify objects and verify framing.
Image Annotation
Automatically annotate solved frames with catalog objects within the field of view. Labels, markers, and coordinates rendered on the image.
Weather & Safety Monitor
Real-time weather station integration monitoring temperature, humidity, wind speed, cloud cover, and rain. Automatic park and dome closure when conditions become unsafe.
Safety Actions
When safe_to_observe becomes false: abort current exposure, stop guiding, park mount, close dome shutter. All automated.
Dome & Rotator
Full dome control with shutter open/close, azimuth tracking (follows mount position), and park. Rotator control with absolute and relative positioning.
Dome
Open/close shutter, GoTo azimuth, park. Azimuth tracking follows mount to keep the slit aligned with the telescope.
Rotator
Rotate to absolute angle, rotate relative, sync to angle, and abort. Used for camera angle alignment and framing optimization.
Every panel in the UI has a ? button with inline help explaining the feature. Press F1 anywhere for context-sensitive help.
