Sunday, September 03, 2017
Seeing Asteroid 3122 Florence tonight (3 September 2017)
Although NEO Florence (and its newly discovered Moons) has made its record breaking approach to Earth and is now heading away and fading, it is still an interesting telescopic object although dim (magnitude 9) that can be seen to visibly move over a reasonably short observation period.
Over the past few nights the asteroid has not had any good guide stars, making it hard for amateurs without GOTO scopes or modest equipment. Tonight the asteroid will be below the distinctive small constellation od Deplhinus, making for relatively easy star hopping.
After tonight as it passes through Cygnus it will be getting too low in the sky for Southern hemisphere obsevers.
At 22:00 3122 Florence is 4 degrees below 3.8 alpha Delphinus (α on the chart) and 54' above 4.8 magnitude 29 Vulpernica (29 on the chart). As the night progresses the asteroid come nearer to 29 Vul, grazing it shortly after midnight.
The distinctive treadrop shape of the constellation of Delphinus and alpha Del will be reasonably easy to see in the Moonlight. Aim your scope at alpha Del and scan toward the horizon with a widefield eyepiece. The next brightest star is 29 Vul. With 29 Del at the edge of your field Florence should be just above it (or below it, in inverted telescope view), watching over 15-30 minutes you should see the asteroid move substantially against the background stars.