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Welcome! to CACAO!

After a long hiatus, the Amateur Observers' Program is ramping up to support the Comet Wirtanen Observing Campaign. We've learned alot from supporting:

Comet Wirtanen is back!

46P/Wirtanen was recovered on May 8, 2018 in images obtained by Nick Moskovitz (Lowell Observatory), in collaboration with Tony Farnham and Matthew Knight (University of Maryland). Six images of the comet were obtained at the Discovery Channel Telescope operated by Lowell Observatory. They were obtained during astronomical twilight at 4.5-5.1 airmass. (The coadded recovery image is attached.)
At the time of the recovery, Wirtanen was at a heliocentric distance of 2.61 AU, geocentric distance of 2.80 AU, and had an r' magnitude of 20.3. There is no obvious coma visible in the images, but the comet's brightness suggests that it is already exhibiting activity.
The updated orbit solution confirms that Wirtanen will make its close approach to the Earth at a distance of 0.078 AU on December 16, 2018, but with only limited 2018 observations, the exact time of close approach has an uncertainty of several hours. Additional astrometry is requested to refine the orbit and constrain the effects of non-gravitational forces.
For more information about the comet, visit the campaign website at
Tony Farnham
for the Wirtanen Campaign

Image/File Submissions

We are now accepting observations (images, sketches, lightcurves,...) of

  • currently visible comets
  • asteroid Ceres
  • asteroid Vesta

  • any of our past targets
  • UMD asteroids

Please visit the LogBook to find out how to submit your observations.

Don't worry, you won't need to know much about astronomy, comets or asteroids. That's what this site is about!

So, let's get started...


Updated: 01-Jun-2018