Observing and Photographing Satellites

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Observing and Photographing Satellites

• Elizabeth Warner
• UM Observatory
• 5 July 2006

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Satellites

• Man-made objects orbiting Earth
• Spy, weather, communication, science and lots of
  junk (rockets)
• Easiest to see shortly after sunset or before
  sunrise, although summer is best why?

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Observatory homepage, left menu, select satellites
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Select College Park, (I live in Alexandria) You
can also register at heavens-above.com and
bookmark your own observing locations
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Lots of options here You can see a list of when
just the ISS or HST (and when its up, they also
list the shuttle) are visible, a list of
satellites visible on a particular evening,
Iridium flares.
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What do these numbers mean?
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Coordinates?

• On Earth, we can use latitude and longitude to
  find points on the ground. There is a similar set
  of coordinates for the night sky. However, while
  very useful for finding fixed objects (stars,
  nebulae, etc), RA and dec are not useful for
  satellites.
• Horizon System
• Azimuth -- direction along horizon where
  North0, East90
• Altitude how high off the horizon (horizon0 ,
  zenith90 )
• Satellites are visible for local places. For
  example, while it may be sunset for us, it is
  still late afternoon in CA. Same thing for
  satellites, we may see one in our skies, but
  other parts of the world will see them at
  different times.

Altitude (alt) height of target above
horizon Azimuth (az) direction along horizon
(N0, E90)
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Horizon System

• Coordinate system
• Is very local

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Arc across sky

• Points of light that move across the sky.
• Can describe the arc with three points
• Start, Max Altitude, Set

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Numbers describe an arc
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Iridium Flares
Iridium flares are usually only visible along one
portion of their arc, hence just one set of
alt-az coordinates. They resemble meteors (aka
shooting stars) but are a bit slower
moving. NOTE Magnitudes (brightness)
Max
Start
End
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Observing Satellites

• Look up satellite info for evening (copy or print
  page)
• Heavens-above.com is a good website, can also use
  planetarium software like Starry Night
• Have accurate watch
• Go outside and orient yourself (where is north,
  etc)
• Figure out roughly where arc or segment is in the
  sky
• Make sure trees are not in way and move if
  necessary
• Start looking about 1 minute before and scan
  section of sky
• Moving objects that blink regularly or have red
  lights are airplanes!
• Be sure to wave if its the shuttle or ISS!

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Photographing Satellites

• Any camera with a bulb setting or that allows
  up to 30 second exposure
• Shutter-release cable (optional but very useful)
• Tripod (beanbag, rock, anything to hold camera
  steady during exposure)
• (I would) use a 50mm or wider angle lens for most
  satellites, Iridium Flares you can zoom in some
• Make sure you have the aperture open (low f-stop
  number)!

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Photographing Satellites

• Setup as for observing, but knowing directions
  and estimating altitude is more critical since
  camera sees less of the sky than your eyes
• Exposure with bulb setting, you can make the
  exposure as long as you like, however, its best
  to frame the field of view first then start an
  exposure right before the satellite enters the
  field and end the exposure as it exits the field
  if you have a set timer, then youll need to be
  more judicious with your exposure length and
  start time
• Generally aim for max alt portion of arc or
  portion that satellite is brightest
• Get creative with foreground

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Photographing Satellites
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Photographing Satellites
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Photographing Satellites

• closeups of the ISS or shuttle
• Webcam looking through telescope
• Very hard to track satellite so best to let it
  pass though field of view although there are some
  telescope mounts that can follow
• Background sun or moon for contrast, but not
  absolutely required
• Gettting a webcam movie, you can then select the
  best frames and stack them or make an animation

www.hobbyspace.com/SatWatching/
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No telescope needed!

• Satellites can be seen from most anywhere.
  However, the darker/clearer it is, the easier it
  is to see dimmer ones.
• Once you start looking, you will sometimes see
  some that are not on the list spy satellites!
• If you change observing locations, you should
  update your location in Heavens-Above.

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What about Geosynchronous Satellites?

• 1 revolution (orbit) of satellite 1 rotation of
  Earth
• Means satellite appears stationary over one
  location
• 25,000 miles out, over equator but at different
  longitudes
• Weather, communications for a region
• Much harder to see because they are very dim
  (very far away!)
• satobs.org/geosats.html

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Photographing Geosynchronous Satellites

• Camera on tripod, shutter release cable
• Dark location (no light pollution)
• Aim towards celestial equator (slightly below)
• Take long exposure
• Stars will trail, but satellites will show up as
  dots

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Clear Skies!

• How many satellites can you observe?
• www.heavens-above.com/
• www.heavens-above.com/iridiumhelp.asp
• www.satobs.org/
• www.satobs.org/satintro.html
• www.gma.org/surfing/satellites/
• www.thetech.org/exhibits/online/satellite/home.htm
  l
• collections.ic.gc.ca/satellites/english/index.html
  
• web.austin.utexas.edu/edcannon/satellite.htm
• members.ozemail.com.au/lbrash/satellites/
• members.aol.com/jwholtz/sat/background.htm