|
Ison Prospects
Hi Colin,
yes you will be a busy boy!
It's not going to be easy with ISON. For us it will be a bright object sitting above the morning twilight throughout November until perihelion. If it has developed any significant tail by then we will know about it.
On the morning of perihelion (Nov 29th) the comet will rise about 7 minutes before the sun. I am not really sure if it will make too much difference in the end given that the sun is so close by, but I would advise observers and photographers to find somewhere with a true south east horizon. no hills, mountains, trees or buildings. Have bino's with you for looking for the comet, but as soon as the green or blue flash from the rising sun appears then put the bino's away.
There is no point in going to the northern hemisphere at perihelion. Given the quality of austral skies observers will have a better chance of seeing ISON in daylight from home, if the weather is kind, and the comet makes the magnitude estimates.
I was lucky enough to see Comet McNaught in daylight on two consecutive days back in '07. This should outdo McNaught in that respect, and ISON may even rival The Great September Comet of 1882 as far the record for the number of days, which satnds at 5, where naked-eye visibility is concerned as well.
Back to the tail. If the tail is already prodigious before perihelion, and there are no guarantees, then it will pose a very similar sight to Lovejoy around Christmas last year, although it will most likely be curving and swishing to the right very rapidly on perihelion day. This affect was recorded well by japenese astronomers at the time of perihelion passage for Comet Ikeya-Seki in 1965.
Looking at prospects for the northern tropics post-perihelion it doesn't look that great. It is all to do with angles. For all of December the comet will be setting with the sun. Even for higher northern latitudes it won't be until just before Christmas that the alignment will improve enough for the comet to get above the evening twilight. Christmas Day should be the pick of it with the moon out of the evening sky. Even then the tail will cut a low trajectory across the northern horizon much like McNaught at the end of January in the morning sky (see my picture attached) but even flatter. The bonus for comet lovers could be a massively long tail of 90 degrees or longer! Now that could be worth travelling that far for?
Cheers
Coops
|