Another thread in this forum, "Asteroid 3200 Phaethon: Geminid Parent at Its Closest and Brightest" started by Lindon
http://www.iceinspace.com.au/forum/s...d.php?t=163149
describes the close approach of the Geminid Parent to Earth mid December. The asteroid passage also coincides with the Geminid meteor shower and a waning crescent moon.
The geometry of this passage and the Lunar phase favours observation of meteor impact flashes on the dark Earth-lit part of the lunar crescent during the early morning (pre-dawn) hours of December 13-15 from debris from this body.
Lunar impact flashes, seen through Earth-based telescopes occur at a rate of about one per several hours, but are more frequent during major meteor showers.
Here are possible observation windows in EDT for Canberra.
December.........Moonrise.........% sunlit.......AST TWI.....Obs window
13......................2:44....... ......26%...........03:55.......... ..60 mins
14......................3:16....... ......18%...........03:55.......... ..30 mins
15......................3:49....... ......11%...........03:55.......... ...0 mins
Sydney and Melbourne times will be similar. If you have your location set in your IIS settings, the Moon phase calculator will calculate Moonrise and twilight times for you. The observation window on the 15th is marginal. The moon is unlikely to gain sufficient altitude to enable observations of any but the brightest flashes before twilight sets in. I have allowed 10mins after astro twilight and 20 mins after moonrise for the Moon to reach about 5 degrees altitude in my estimates of the length observation windows.
Impact flashes are red and estimated to be around magnitudes 7-10, some even brighter.
The attached image shows the impact distribution diagram for the 2017 Geminids against the Moon’s night side. Orientated with north towards the top.
Source:
https://britastro.org/node/11854
The source article deals with a project coordinating timed video observations and contains more info if you are interested.
Joe