comet ISON C/2012 S1

see also:

• comets
• wikipedia comet ISON
• ephemerides for comet ISON
• cometography.com - comet ISON

Nov 21st: taken by Gerald Rhemann in Namibia/SW Africa using an Astrograph 12“ f/3.8 telescope and FLI ML 8300 camera, exposure time: LRGB 3/2/2/2 min

Nov 15th by Damian Peach. 106mm F5.0 with STL-11k. LRGB. L: 5x2mins. RGB: 1x2mins. Field is 2.5deg wide.

comet image taken Nov 3rd, 9th, 12th and 14th by juanjgon after it had developed multiple ion filaments - see blog

• expected to be naked eye visible in mid-late November 2013 when it enters Leo constellation, and then in December 2013 as it enters the evening twilight sky
• 1st October 2013, passes within 6.7 million miles (10.8 million km) from Mars
• Nov 4th 2013, expected to brighten to magnitude 7.0, and be 50deg from the sun, visible before sunrise on the east horizon in southern Australia, and have a declination of + 5deg so visible from both hemispheres
• Nov 20th, 2013, may brighten to magnitude 4.0, be 28deg from the sun. For those in southern Australia it will rise to be low on the ESE horizon just before sunrise
• after Nov 20th, although it rapidly brightens, it also approaches the sun making it difficult to see and photograph
• 24th Nov may be the last morning of good viewing before perihelion
• 26th Nov, 3rd quarter moon
• from 26th Nov to 2nd Dec it is within 10 deg of the sun, and although at its brightest, observation and photography may be challenging
• Nov 28th, 2013, perihelion, grazing the sun coming as close as 730,000 miles (1.2 million km) of the sun's visible surface (ie. closer than 3 solar radii) - hence a “sungrazing” comet, and ~10% of its diameter will be eroded away
• after perihelion it tracks a line roughly from the sun to the north celestial pole, this means the comet itself will NO LONGER be visible to southern hemisphere viewers at night as that line is always below the horizon at before sunrise or after sunset. Their only option is daylight viewing if it is bright enough. Viewers at latitudes north of 35deg N will be best placed to view it after perihelion.
• 3rd Dec, New Moon
• from 3rd Dec-5th Dec, it is visible after sunset hopefully at magnitudes around 2.0-3.0, but within 15deg of the sun and in association with a crescent moon.
• from 6th Dec to 15th Dec 2013 it is more than 20deg from the sun and it's brightness is expected to fall to magnitude 4.5, but it again should be a good time for photography, particularly as the tail is expected to be long, although it is rapidly travelling north.
  • from the 9th Dec onwards it will be visible just after sunset from latitudes as far south as ~20deg N such as Hawaii, although it will be close to the horizon at such latitudes at sunset.
  • the moon will be at 1st quarter on 10th Dec 2013 and from then on, its light will interfere with photography of the tail.
• passes Earth on Dec. 26 2013, approaching within 39.9 million miles (64.2 million km) or about 167 times farther than the moon
• passes within 2 deg of Polaris on Jan 8th 2014

Dawn in Adelaide 24th November 2013 (screenshot from C2A software):

visual magnitude light curve produced by Terry Lovejoy

A very cool animation of it's course posted at SolarSystemScope.com

• John Drummond, NZ. October 15, 2013, comet only one degree north of Mars
  • 13cm f3.3 Takahashi Epsilon reflector and Canon 550D DSLR to catch the pair. Regulus (Leo) is also there. He combined 10 x 1 minute @ 1600iso exposures.