Observe tonight
Weather, Moon, and darkness
Check whether tonight is worth setting up and what the Moon will do to the sky.
Observer's toolkit
Astronomy Tools
Practical calculators and planners for observing, telescope decisions, astrophotography, sky events, and mission tracking. Use the quick path below or go straight into the optical calculators.
Start with your goal
What are you trying to do?
Choose gear
Compare before buying
Use optical measurements and practical tradeoffs before brand or affiliate links enter the decision.
Plan imaging
Frame, sample, power, expose
Work through camera framing, sampling, battery runtime, and fixed-tripod shutter-speed planning.
Track events
Know what happens next
Follow launches, mission events, eclipses, Moon phases, and the major dates worth saving.
My Gear Locker
Use one of your saved setups
Choosing a profile fills matching telescope, eyepiece, and camera fields below. Nothing changes until you select a profile.
Your optical setup
Enter four numbers.
Try a common setup
Magnification
48×
Telescope focal length ÷ eyepiece focal length, adjusted for the Barlow.
Exit pupil
4.2mm
Bright, comfortable low-to-medium power.
True field of view
1.08°
A practical estimate using apparent field ÷ magnification.
Focal ratio
f/5.9
Telescope focal length ÷ aperture.
Dawes resolution limit
0.57″
A theoretical double-star resolving limit. Atmospheric seeing often becomes the real limit first.
Rule-of-thumb magnification range
29× – 406×
Roughly a 7 mm exit pupil at the low end and 2× aperture in millimeters at the high end. Seeing and optics matter.
Astrophotography calculator
Image scale + camera field of view
See how telescope focal length, camera pixel size, sensor dimensions, and reducers or Barlows change sampling and framing before you assemble the imaging train.
Sensor presets
Image scale
1.62″/ pixel
Calculated from effective focal length and pixel size.
Effective focal length
480mm
Includes the selected reducer or Barlow factor.
Estimated camera field of view
2.81° × 1.87°
Width × height. Actual framing can vary slightly with the optical train and usable sensor area.
Sampling context
This is a moderate image scale that can suit many deep-sky setups. Seeing, guiding, focus, optical quality, and target size still determine whether it is a good match.
Moon
18%
Approx. frame width
Andromeda
107%
Approx. 3° span vs. width
Orion Nebula
36%
Approx. 1° span vs. width
Read the numbers correctly
More magnification is not automatically better.
The atmosphere, optical quality, target brightness, collimation, thermal stability, and your own eyes can matter more than the theoretical maximum. A lower-power view that is sharp, bright, and steady is often more useful than a larger but soft image.
01
Magnification
Useful for matching an eyepiece to planets, the Moon, double stars, clusters, and deep-sky objects.
02
Exit pupil
A quick way to understand image brightness. Large exit pupils favor bright wide-field views; very small ones get dim fast.
03
True field
Helps estimate how much sky fits in the eyepiece, especially useful for large clusters, nebulae, and star hopping.
More StarStation tools
Plan the whole night.
Saved setups
My Gear Locker
Save private telescope, eyepiece, camera, sensor, and battery profiles with calculated setup metrics.
Learn
Astronomy Glossary
Plain-English observing, optics, imaging, universe, spaceflight, and space-weather terminology with practical context.
Eclipses
Eclipse Center
Upcoming solar and lunar eclipses, countdowns, NASA maps, and safe-viewing guidance.
Moon
Moon Planner
Plan around lunar phase, illumination, moonrise, moonset, and dark-sky windows.
Meteors
Meteor Shower Center
Peak nights, parent objects, moonlight context, observing guidance, and calendar downloads.
Plan
Observing Session Planner
Save a date, location note, targets, equipment, and session goal, then add the plan to your calendar.
Deep sky
Messier 110 Challenge
Track all 110 classic Messier targets with local progress, milestones, filters, and CSV export.
Moon
Lunar 50 Challenge
Learn 50 maria, craters, mountains, valleys, rilles, scarps, and unusual lunar surface features.
Record
Observer Logbook
Keep a private observing history with search, print, CSV export, and restorable backup.
Night-sky photo
Untracked Star Exposure
Compare NPF and 500-rule shutter-speed estimates for fixed-tripod night-sky photography.
Power
Astro Power Runtime
Estimate battery runtime from mount, camera, dew-heater, computer, and accessory loads.
Imaging
Target Framing Planner
Visualize how popular deep-sky targets fit different camera sensors and focal lengths.
Eyepieces
Eyepiece Planner
Compare magnification, exit pupil, and true field across an entire eyepiece set.
Compare
Telescope Setup Compare
Compare aperture, focal ratio, resolution, magnification, weight, and price side by side.
Plan
Space + Sky Calendar
Launches, mission events, and Moon phases in one chronological view.
Observe
Tonight's Sky
Moon timing and observing context for tonight.
Conditions
Space Weather
Solar activity and geomagnetic conditions from official sources.
Watch
Launch + Missions
Upcoming launches, mission events, countdowns, and official webcasts.
Gear Lab connection
Use the math before you spend the money.
StarStation's long-term Gear Lab model is simple: explain the optical tradeoffs first, then recommend equipment only when it solves a real observing problem.