Your Android observatory with real-time sky view, AR, telescope control, and the only astronomy app that computes your local horizon from topographic data.
Recommended for new users. Start with the freemium app and unlock premium later with a subscription or one-time purchase.
Prefer paying once up front? Get Mobile Observatory Pro on Google Play. The same lifetime premium access is also available later inside Mobile Observatory.
Everything you need for astronomy, in your pocket
Point your phone and identify stars, planets, and constellations live
Explore planets, moons, and comets in an interactive orrery
ISS passes, Starlink trains, and 10,000+ satellites in real-time
2,500+ nebulae, galaxies, and star clusters with photos and details
50+ event types including eclipses, conjunctions, occultations, transits, and more
Aurora alerts, solar flares, ISS passes, and event reminders
Aurora forecast, Kp-index, solar flares, and NASA SDO images
Phases, eclipses, lunar features, sunspot data, and rise/set times
Real terrain profiles from NASA data for precise rise/set times
Auto-generated session plans based on your equipment and location
Connect your GoTo telescope and slew to any object with a single tap
Hipparcos, SAO, and extended catalogs with detailed star data
See Mobile Observatory in action
From first launch to expert observer
Point your phone at the sky and see stars, planets, and the Sun's path over your real 3D terrain.
Browse upcoming conjunctions, eclipses, ISS passes, and thousands of celestial objects with detailed data.
Generate optimized observing plans, control your telescope, and log your observations like a pro.
Scroll through real app screens — tap to enlarge






There is a symbiotic relationship here. NFPA standards require that equipment be "listed" for the purpose, and UL creates the testing standards (UL Standards, such as UL 268 for smoke detectors) that manufacturers must pass to gain that listing.
In the modern built environment, few systems are as critical to life safety as the fire alarm network. It is the silent sentinel that never sleeps, monitoring the air for smoke, detecting the heat of a burgeoning flame, and providing the crucial seconds needed for evacuation. However, the reliability of these systems is not a matter of chance. It is the result of rigorous engineering governed by a complex framework of regulations.
Understanding is essential for architects, engineers, building owners, and facility managers. These standards are not merely suggestions; they are the codified collective wisdom of the fire protection industry, derived from decades of tragic lessons and technological advancement. This article explores the intricate web of codes, the organizations that create them, and the critical components they govern. The Triad of Authority: NFPA, UL, and ADA To understand fire alarm standards, one must first identify the key players. In the United States, three distinct entities exert the most influence over how fire alarm systems are designed and installed.
While NFPA dictates how a system is installed, UL dictates what equipment is allowed. UL is a testing and certification organization. If a smoke detector or a fire alarm control panel is installed in a commercial setting, it must typically be UL-listed. This means it has been rigorously tested to ensure it performs as advertised under specific stress conditions.
The NFPA is the premier authority on fire safety. While local jurisdictions adopt building codes (like the International Building Code or IBC), these codes almost universally reference NFPA standards for the specifics of fire protection. The most critical document in this realm is NFPA 72: The National Fire Alarm and Signaling Code .
NFPA 72 does not merely suggest how to install a detector; it dictates the entire lifecycle of the system—from the spacing of devices on a ceiling to the maintenance requirements years after installation. It is the "Bible" of the industry, currently updated every three years to reflect new technologies and methodologies.
Tools for astronomers, astrophotographers, and anyone who looks up
Explore the solar system in an interactive 3D view
Track the ISS, Starlink, and thousands more fire alarm system standards
Point your camera and explore the sky
Real-time aurora and solar activity dashboard There is a symbiotic relationship here
Personalized recommendations for your location
Massive astronomical database at your fingertips It is the silent sentinel that never sleeps,
Plan your observing sessions in advance
Detailed Sun and Moon information
Fresh 5-star feedback from astronomers around the world
"The update to version 4 brings several interesting graphical and functional improvements. It's incredibly realistic; the horizon profile at your observation location allows for more precise calculations of star rises and sets. The 3D view has been significantly improved, with updated graphics for the well-rendered planets, and every astronomical event is faithfully reproduced. A full 5 stars for this beautiful app, an indispensable tool for both amateur and professional astronomers."
"If you're wondering which special objects are in the constellation you're looking at right now, and when they can best be observed, then this app is exactly right for you. I've tried just about every astronomy app out there. My conclusion: by far the most valuable app for amateur astronomers who want to explore the night sky themselves with their own telescope."
"This app is simply fantastic and keeps getting better. It offers a huge variety of features, making it the most professional app in the Play Store."
"Version 4 is amazing: intelligently programmed, very well organized. Thank you for this excellent work!"
New users should begin with the freemium app, then unlock premium inside the app when they are ready. If you prefer buying up front, Mobile Observatory Pro remains available as the classic paid edition.
Recommended for all new users
Classic paid edition for users who prefer a separate upfront purchase
The story behind Mobile Observatory
Creator of Mobile Observatory
Wolfgang Zima spent years as a professional astronomer before finding his way into software development. After completing his PhD in Astronomy at the University of Vienna, he worked as a postdoctoral researcher at the Institute for Astronomy at KU Leuven in Belgium for five years. It was there that he discovered a passion for scientific software — writing tools for analyzing spectra of pulsating stars and building a CCD image simulator for ESA's PLATO mission, a space telescope searching for Earth-like exoplanets.
Mobile Observatory started almost by accident: when his Nokia phone broke on a mountain biking trip in late 2010, Wolfgang got his first Android phone and was surprised that no good astronomy apps existed. So he built one. First released in January 2011, Mobile Observatory has since grown into one of the most comprehensive astronomy apps for Android and has been continuously improved for well over a decade.
Wolfgang lives in Freiburg, Germany, where he works as a Senior Mobile Developer at sevdesk. He continues to develop Mobile Observatory with the same enthusiasm as on day one — now with the help of modern AI tools that let him bring new features to life faster than ever.
There is a symbiotic relationship here. NFPA standards require that equipment be "listed" for the purpose, and UL creates the testing standards (UL Standards, such as UL 268 for smoke detectors) that manufacturers must pass to gain that listing.
In the modern built environment, few systems are as critical to life safety as the fire alarm network. It is the silent sentinel that never sleeps, monitoring the air for smoke, detecting the heat of a burgeoning flame, and providing the crucial seconds needed for evacuation. However, the reliability of these systems is not a matter of chance. It is the result of rigorous engineering governed by a complex framework of regulations.
Understanding is essential for architects, engineers, building owners, and facility managers. These standards are not merely suggestions; they are the codified collective wisdom of the fire protection industry, derived from decades of tragic lessons and technological advancement. This article explores the intricate web of codes, the organizations that create them, and the critical components they govern. The Triad of Authority: NFPA, UL, and ADA To understand fire alarm standards, one must first identify the key players. In the United States, three distinct entities exert the most influence over how fire alarm systems are designed and installed.
While NFPA dictates how a system is installed, UL dictates what equipment is allowed. UL is a testing and certification organization. If a smoke detector or a fire alarm control panel is installed in a commercial setting, it must typically be UL-listed. This means it has been rigorously tested to ensure it performs as advertised under specific stress conditions.
The NFPA is the premier authority on fire safety. While local jurisdictions adopt building codes (like the International Building Code or IBC), these codes almost universally reference NFPA standards for the specifics of fire protection. The most critical document in this realm is NFPA 72: The National Fire Alarm and Signaling Code .
NFPA 72 does not merely suggest how to install a detector; it dictates the entire lifecycle of the system—from the spacing of devices on a ceiling to the maintenance requirements years after installation. It is the "Bible" of the industry, currently updated every three years to reflect new technologies and methodologies.