======================================================================== Visual Satellite Observing F A Q Chapter-00 Table Of Contents ======================================================================== Chapter-01 What Is "Visual Satellite Observing"? Chapter-02 How Can I Predict When A Satellite Is Visible? Chapter-03 What Are The Different Types Of Satellites? Chapter-04 What Are The Different Kinds Of Satellite Orbits? Chapter-05 What Are The Mechanics Of A Satellite In Orbit? Chapter-06 What Can I Expect To See When I Look At Satellites? Chapter-07 Satellite Observations: More Than Just Looking Chapter-08 What Are Some Of The Rockets Used To Place Satellites In Orbit? Chapter-09 What Are Some Of The Ground Facilities In Use Today? Chapter-10 What Are Some Of The Satellites That Can Be Seen? Chapter-11 Miscellaneous Questions Chapter-12 Where Can I Learn More? Chapter-13 Glossary ======================================================================== Chapter-01 1.0 What Is "Visual Satellite Observing"? 1.1 How Many Satellites Are In Orbit? 1.1.1 Payloads 1.1.2 Rocket Bodies 1.1.3 Platforms 1.1.4 Debris 1.2 How Many Satellites Can Be Seen? 1.2.1 How Many Can Be Seen With The Naked Eye? 1.2.2 How Many Can Be Seen With Binoculars? 1.2.3 How Many Can Be Seen With A Telescope? 1.3 When Are Satellites Visible? 1.3.1 Factors Affecting Satellite Visibility 1.3.1.1 Orbit Altitude And Inclination 1.3.1.2 Earth's Shadow 1.3.1.3 Ground Track Precession 1.3.1.4 Other Factors 1.3.2 Times Of Satellite Visibility 1.3.2.1 Evening Viewing 1.3.2.2 Morning Viewing 1.3.2.3 Other Times 1.4 What Do Satellites Look Like? 1.4.1 "Normal" Satellites 1.4.2 "Flashing" Satellites 1.4.3 "Flaring" Satellites 1.4.4 What Do The Mir Complex And Space Shuttle Look Like? 1.4.4.1 Mir Complex 1.4.4.2 Space Shuttle 1.5 What Equipment And Knowlege Are Needed To See Satellites? 1.5.1 Equipment 1.5.1.1 Binoculars 1.5.1.2 Telescope 1.5.1.3 Tracking Programs And Internet Resources 1.5.1.3.1 Home Computer Tracking Programs 1.5.1.3.2 Orbital Element Sets For Tracking Programs 1.5.1.3.2.1 TLE And Satellite Data On The Internet 1.5.1.3.2.2 TLE And Satellite Data On Bulletin Board Systems (BBSs) 1.5.1.3.2.3 Brief Introduction To TLEs And Satellite IDs 1.5.1.3.3 Satellite Prediction Services On The Internet 1.5.1.4 Watch And Computer Time Settings 1.5.1.5 Stopwatch 1.5.1.6 Tape Recorder 1.5.1.7 Chair 1.5.2 Knowlege 1.5.2.1 Celestial Coordinates 1.5.2.1.1 Right Ascension (RA) 1.5.2.1.2 Declination (Dec) 1.5.2.2 Local Coordinates 1.5.2.2.1 Azimuth (Az) 1.5.2.2.2 Elevation (Alt) 1.5.2.3 Brightness Of Stars 1.5.2.4 Tracking Considerations 1.6 What Can Be Learned About Satellites By Visual Observation? 1.6.1 Positional Observations 1.6.2 "Visual Appearance" Observations Chapter-02 2.0 How Can I Predict When a Satellite is Visible? 2.1 Prediction Software 2.1.1 Software for DOS PC's 2.1.1.1 QuickSat 2.1.1.2 STS Plus 2.1.1.3 SkyMap 2.1.1.4 Traksat 2.1.1.5 PC-Track 2.1.1.6 SatPro 2.1.2 Software for Windows 2.1.2.1 SatSpy 2.1.2.2 Micro Orbiter 2.1.3 Software for the Apple 2.1.3.1 Orbitrack 2.1.4 Software for Unix machines 2.1.4.1 Sattrack 2.1.4.2 Xsat 2.2 Orbital Element Data 2.2.1 What are "two-line elements" (TLE's)? 2.2.1.2 Where can I get TLE's? 2.2.1.2.1 Internet resources 2.2.1.2.2 Uncompressed TLE files 2.2.1.2.3 Compressed TLE files 2.2.1.2.4 BBS's 2.2.1.2.5 FidoNet 2.2.3 Why are there so many different types of TLE files? 2.2.4 What are "keplerian elements"? 2.2.5 What are "state vectors?" 2.2.5.1 What is VEC2TLE? 2.2.6 How often should TLE's be updated? 2.3 Helpful Utilities for maintaining TLE files 2.4 Troubleshooting -- I Didn't See Anything. Why? 2.4.1 Is your latitude and longitude entered correctly? 2.4.2 Is the offset to Universal Time set correctly? 2.4.3 Were you looking in the right place? 2.4.4 Did the satellite maneuver or decay? 2.4.5 Was the satellite bright enough to be seen? 2.4.5.1 Phase Angle 2.4.5.2 Could the satellite have already gone into the Earth's shadow? 2.4.6 Is your time accurate? 2.4.6.1 Radio time services 2.4.6.2 Telephone time services Chapter-03 3.0 What are the different types of satellites? 3.1 Remote-sensing satellites 3.2 Communications satellites 3.3 Navigational satellites 3.3.1 GPS (Global Positioning System) 3.3.1.1 GPS Signal Characteristics 3.3.1.2 GPS Time Transfer 3.3.1.3 GPS Positioning Services 3.3.1.4 GPS Selective Availability and Anti-Spoofing 3.3.1.5 GPS System Time 3.3.2 GLONASS (URAGAN/Hurricane) 3.3.3 TRANSIT 3.3.4 TSIKADA/NADEZDHA/PARUS 3.4 Research satellites 3.5 Military satellites 3.5.1 What does "ELINT" mean? 3.6 Manned Spacecraft 3.7 Inert Rocket Bodies and Boosters 3.8 Space Debris 3.9 Space Probes 3.10 Amateur Radio Satellites Chapter-04 4.0 What are the different kind of satellite orbits? 4.1 Low Earth Orbit (LEO) 4.1.1 Low-inclination orbits 4.1.2 Polar orbits 4.1.3 Sun-synchronous orbits 4.1.4 What is an n-th resonant orbit? 4.2 Geosynchronous Orbit 4.3 Geostationary Orbit 4.4 Molniya Orbit 4.5 Mid-Earth Orbit (MEO) 4.6 What is a "transfer orbit"? What does GTO mean? 4.7 High-Earth Orbit (HEO) 4.8 Solar orbit 4.9 Beyond Solar orbit Chapter-05 5.0 Astrodynamics, TLE Files and Prediction Models 5.1 The Study of Orbits: Celestial Mechanics and Astrodynamics 5.1.1 The Six Fundamental Orbital Elements 5.1.1.1 Semi-Major Axis 5.1.1.2 Eccentricity 5.1.1.3 Inclination 5.1.1.4 Argument of Perigee 5.1.1.5 Right Ascension of the Ascending Node 5.1.1.6 Time of Perigee Passage 5.1.2 Adjusting The Theoretical Orbit 5.1.2.1 The Earth is Lumpy 5.1.2.2 Ascending Node Precession 5.1.2.3 Perigee Precession 5.1.2.4 It's a Drag 5.1.2.4.1 Neutral Drag 5.1.2.4.2 Charged Drag and Thermal Drag 5.1.2.5 Lunar and Solar Perturbations 5.1.3 Other Definitions 5.1.3.1 Apogee 5.1.3.2 Period 5.2 How do TLE's describe a satellite in orbit? What do all those numbers mean? 5.2.1 Line 0 -- Satellite Name 5.2.2 Line 1 5.2.2.1 Line Number 5.2.2.2 USSPACECOM Catalog Number 5.2.2.3 International Designator 5.2.2.4 Epoch 5.2.2.5 First time derivative of mean motion 5.2.2.6 Second time derivative of mean motion or n-dot-2 5.2.2.7 BSTAR drag term 5.2.2.8 Ephemeris Type 5.2.2.9 Element number and Checksum 5.2.3 Line 2 5.2.3.1 Line Number 5.2.3.2 USSPACECOM Catalog Number 5.2.3.3 Inclination 5.2.3.4 Right Ascension of the Ascending Node 5.2.3.4.1 What is an Ascending Node? 5.2.3.5 Eccentricity 5.2.3.6 Argument of Perigee 5.2.3.7 Mean Anomaly 5.2.3.8 Mean Motion 5.2.3.9 Revolution Number 5.2.3.10 Element number and Checksum 5.3 What are the various prediction models? 5.3.1 SGP4 5.3.2 SGP 5.4 How do satellites decay? 5.4.1 Factors in decay 5.4.2 What decreases with decay -- apogee or perigee? 5.4.3 Can decay be predicted? 5.5 Tracking Facilities and Methods 5.5.1 The Space Surveillance Network (United States) 5.5.1.1 Dedicated Sensors 5.5.1.2 Collateral Sensors 5.5.1.3 Contributing Sensors 5.5.2 Tracking Methods 5.5.2.1 Visible 5.5.2.2 Infrared 5.5.2.3 Radar 5.5.3 The Products 5.5.3.1 Two-Line Element Lists 5.5.3.2 SPACEWARN Bulletin 5.5.3.3 Weekly Decay Message Chapter-06 6.0 What Can I Expect to See When I Look at Satellites? 6.1 Factors Influencing Brightness 6.1.1 Range And Altitude 6.1.2 Size And RCS 6.1.3 Surface Characteristics 6.1.4 Phase Angle And Attitude 6.2 "Flashing" Satellites 6.2.1 Glints And Irregular Flashing 6.2.2 "Regular" Flashing 6.2.2.1 Is The Rotation Period Constant? 6.2.2.2 What Causes The Rotation Period To Increase? 6.2.2.3 What Causes The Rotation Period To Decline? 6.2.2.4 Synodic Effect 6.2.2.4.1 Why And How Satellites Flash 6.2.2.4.2 Origin And Size Of The Synodic Effect 6.3 Molniya And Geosynchronous Satellites 6.4 Shadow Entry and Emergence 6.5 Satellites During Re-entry: What do they look like? 6.6 What Does the Space Shuttle Look Like? 6.6.1 Background Information on the Shuttles 6.6.2 Visibility to the Observer 6.6.2.1 What Can Be Seen on Launch? 6.6.2.2 What Can Be Seen While in Orbit? 6.6.2.2.1 External Tank (ET) Reentry 6.6.2.2.2 Shuttle Reentry 6.7 What Does the Space Station Mir Look Like? 6.7.1 Background Information on the Mir Complex 6.7.2 Visibility to the Observer 6.8 What are the ten brightest satellites? Chapter-07 7.0 Satellite Observations: More Than Just Looking 7.1 Positional Measurements 7.1.1 Required Equipment 7.1.2 Technique 7.1.3 Reporting Positional Measurements 7.2 Flash Period Timings 7.2.1 Required Equipment 7.2.2 Technique 7.2.2.1 Using An Old-Fashioned Stopwatch 7.2.2.2 Using A Multiple-Memory Stopwatch 7.2.2.3 Estimating The Accuracy Of The Measurement 7.2.3 Reporting Flash Period Measurements 7.2.3.1 PPAS Format 7.2.3.2 How And Where To Report PPAS Observations 7.2.3.3 What To Observe: BWGS Observing Program 7.3 Determination Of Rotation Axis (DRA) Project 7.3.1 Why Bother Trying To Determine The Rotation Axis Vector Of A Satellite? 7.3.2 What Data Is Needed For DRA ? 7.3.3 What Are The Caveats For DRA Timings ? 7.3.4 What (Timing) Accuracy Should Be Endeavored? 7.3.5 How Should The DRA Observations Be Reported? 7.3.6 What Satellites Should Be Observed? 7.3.7 How Many Timings Are Needed For The Analysis? 7.3.8 Which Kind Of Passes Should Be Observed ? 7.3.9 Where Should DRA Observations Be Submitted? 7.3.10 How Will The Observations Be Used? Chapter-08 8.0 What are some of the rockets used to place satellites in orbit? 8.1 Russian Rockets 8.1.1 Proton 8.1.1.1 Proton D 8.1.1.2 Proton D-1 8.1.1.3 Proton D-1-e 8.1.1.4 Proton KM 8.1.2 Tsiklon 8.1.3 Zenit 8.1.4 Soyuz 8.1.5 Cosmos 8.1.6 Molniya 8.2 USA Military and NASA Rockets 8.2.1 Delta 8.2.2 Atlas 8.2.3 Titan 8.2.4 Pegasus 8.2.5 Centaur 8.2.6 Inertial Upper Stage (IUS) 8.2.7 Payload Assist Module (PAM) 8.2.8 Integrated Apogee Boost System (IABS) 8.2.9 Taurus 8.2.10 Space Shuttle 8.3 USA Commercial Rockets 8.3.1 LLV-1 8.3.2 Conestoga 8.4 European Space Agency 8.4.1 Ariane 8.4.2 Ariane 5 8.5 Rockets of Other Nations 8.5.1 Long March (China) 8.5.2 Japan 8.5.2.1 M5 8.5.2.2 H2 8.5.2.3 J1 8.5.3 India 8.5.3.1 PSLV 8.5.3.2 GSLV 8.5.4 Israel Chapter-09 9.0 What are some of the ground facilities in use today? 9.1 Russian and Former Soviet Facilities 9.1.1 Baykonur (Tyuratam) 9.1.2 Plesetsk 9.1.3 Kapustin Yar (Volograd) 9.2 USA Launch Facilities 9.2.1 Kennedy Space Center (Cape Canaveral) 9.2.2 Vandenberg Air Force Base 9.2.3 Wallops Island, Virginia 9.3 European Space Agency (ESA): Kourou, French Guyana 9.4 Other Nations 9.4.1 Japan 9.4.1.1 Kagoshima Space Center 9.4.1.2 Tanegashima Space Center 9.4.2 China 9.4.2.1 Jiuquan 9.4.2.2 Xichang 9.4.2.3 Taiyuan 9.4.3 India 9.4.4 Israel Chapter-10 10.0 What Are Some Of The Satellites That Can Be Seen? 10.1 The Ubiquitous Cosmos 10.1.1 Zenit 10.1.2 Cosmos J-flashers 10.1.3 Cosmos G-flashers 10.1.4 Other 10.2 Weatherbirds: NOAA, DMSP, Midas, Meteor 10.3 Spysats: Lacrosse, NOSS and other "USA" birds 10.4 Research Sats: UARS, HST, SeaSat, OAO 10.5 Orbiting Space Museum: Vanguard and Explorer Chapter-11 11.0 Miscellaneous Questions 11.1 Have satellites ever collided in orbit? How likely is it? 11.2 Is "Space Junk" a problem? 11.2.1 Does space debris pose a risk to astronauts? 11.3 Can a decaying or reentering satellite hit the ground? 11.4 Do reentering satellites ever spread radioactive material? 11.5 Can spy satellites actually read automobile license plates? Chapter-12 12.0 Where Can I Learn More? 12.1 Internet Resources 12.1.1 Web Pages 12.2.1.1 Visual Satellite Observer's Home Page 12.2.1.2 Other Web Pages 12.1.2 Mailing Lists 12.2.2.1 SeeSat-L 12.2.2.2 Shuttle Elements list 12.1.3 FTP Sites 12.1.4 Telnet: OIG BBS 12.1.5 USENET 12.2 Bulletin Boards and FidoNet 12.3 Recommended Books Chapter-13 13.0 Glossary of Terms ======================================================================== This FAQ was written by members of the SeeSat-L mailing list, which is devoted to visual satellite observation. Members of this group also maintain a World Wide Web site. The home page can be found at the URL: http://www.satobs.org/ The information on the VSOHP web site is much more dynamic than that found in this FAQ. For example, the VSOHP site contains current satellite visibility and decay predictions, as well as information about current and upcoming Space Shuttle missions and Mir dockings. The VSOHP site also contains many images, equations, and data/program files that could not be included in this FAQ while maintaining its plain text form. This FAQ and the VSOHP web site are maintained asynchronously, but an effort is made to synchronize information contents as much as possible. The material in this Table of Contents was last updated February 1998. ========================================================================