Velocity, gravity & ground clocks as they relate to GPS satellites
  • Intro & New Members – Lauri Roche
  • Sid’s Books – Lauri Roche
    • Early 1900s to volumes of modern publishing as well
    • Our Librarian Alex Schmid has first dibs
    • Sky Atlas 2000 laminated
    • Burnham Handbook
    • Norton Star Atlas
    • Books will be given away over the next few weeks
  • Remembering Mark Tovey – Peter Jedicke
    • Wrote a book of astronomy poetry
    • Curator of the Hume Cronyn Memorial Observatory at Western University
    • Mark Tovey – Obituary
  • Coordinated Universal Time and UTC, GMT and all that – Jeff Pivnick
    • Local Time originally used by each community and country
    • Train travel needed a time standard and time zones
    • 1972 – GMT replaced by UTC by the International Telecommunications Union (ITU)
    • Greenwich Mean Time based on the Prime Meridian and calculating position using accurate time
    • Definition of the Second based on the mean solar day, but the Earth’s rotation is not consistent, so corrections were needed.
    • Universal Time – several definitions were used before UT1 was finally adopted over GMT
    • Atomic clocks in 1956 were more accurate, so in 1967 a new definition of a Second was implemented
    • Leap seconds is used to sync solar time with the atomic clock standard
    • “Zulu Time” is synonymous with UTC
    • CBC Time Signal – maintained by NRC (within 100 nanoseconds. Stopped Oct 9, 2023 due to transmission inaccuracies creeping in.
    • Erratum: Jeff Pivnick notes that during his presentation about Co-Ordinated Universal Time (UTC), slide #10 and the accompanying verbal transcript erroneously noted that Ultrasound radiation (energy) of a specific frequency was used in the atomic (cesium) clock to define one (atomic) second. The reference should have been to Microwave radiation (energy).
  • Coordinated Lunar Time (LTC) – Randy Enkin
    • What time is it on the Moon?
    • Space missions going to the Moon which need LTC for accurate navigation
    • Hafele-Keating experiment – two flights around Earth in different directions with atomic clocks aboard confirmed relativity by measuring time lag and lead to time on the ground.
    • GPS clocks have to run at a different speed to ground-based  clocks due to gravity and velocity.
    • Clock rates on the Moon examined by NIST in 2024
    • Twin paradox – Earth-bound twin ages at a different rate than the other twin who travels through space.
    • LTC is not a time zone, it’s a time scale.
  • Lunar Halo photo – Randy Enkin
    • Hexagonal ice crystals in Cirrus clouds
  • Artemis II Mission to the Moon – Chris Gainor
    • Send your name around the Moon – pin code and boarding pass
    • Launch preparations – crew in quarantine and rocket on the launch pad
    • Launch windows – 5 days in February and March, 6 days in April
    • Earliest possible launch is Feb 6th
    • Launch sequence and flight track – 10 days long
    • 4-5,000 miles above Moon’s surface
    • Heat shield
      • Apollo verses the Artemis heat shields
      • Artemis I heat shield had problems
      • Re-entry track for Artemis II will be more gentle than the first mission to reduce exposure to heat
    • Observing the Artemis II mission as it flies to the Moon could be photographed from Earth (with some difficulty).
  • Jeremy Hansen’s mission patch – Natasha van Bentum
  • Aurora and hunt for Comet 24p/Schaumasse – Jan 20th early morning – David Lee
  • VCO Jan 23 Observing Report – David Lee and Reg Dunkley
    • Saturn & moons, Jupiter & moons, M42 trapezium, the Moon
    • Need new Members-In-Charge to host observing sessions
    • Bring your camera to attach to the back of the Takahashi to take some lovely photos of the celestial objects
    • Dobsonian is great for visual observing
  • Events

Video recording of meeting

Astronomy Cafe – Jan 26, 2026
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