Bright Comet : C/2011 L4 (Panstarrs) Mar. 2013!

[Gary]

Nice research Gavin. Worth giving a try. A good warm up exercise for ISON.

[Airconvent]

What do you think?

I think I am keeping my fingers crossed for this and also for the "great comet of the century" in Nov too. I figured 2 chances are better than 1!

[starfinder]

Hi Gary, thanks.
Hi Rich, yup, let's keep our fingers crossed. We must make an effort for these two comets this year!


I've just added info into my post above on the comparative distances during the closest to Earth for Comet West and Comet Panstarrs.

What I found interesting about Comet West was how faint it was at around only 40 days before its perihelion, or closest approach to the Sun. It was then at mag 8 in mid-Jan 1976 (41 days before the perihelion on 25 Feb 1976). Also interestingly, at that time (taking the date 15 Jan 1976) its Earth distance was 1.93AU and its Sun distance was 1.15AU. Panstarrs is now (24 Jan 2013) at around a similar apparent brightness of mag 7.5, and 45 days before perihelion on 10 March 2013, with an Earth distance now of 1.85AU and a Sun distance of 1.17AU. These are strikingly similar numbers.
Source: http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=1 ... ;cad=0#orb
http://ssd.jpl.nasa.gov/sbdb.cgi?ID=dK1 ... 0#phys_par

So, the main differences between Comet West and Comet Panstarrs seems to be the latter's somewhat further distance to the Sun during perihelion and greater distance to the Earth during closest approach.

Nevertheless, I think Comet West shows that Comet Panstarrs could still be on track for a great showing.

But I'm certainly no expert on comets. Does anyone know of other similarities or differences between Comet West and Comet Panstarrs?

[starfinder]

I decided to pose the question on a specialist forum, and received responses from some of the world's top comet experts.

You may read their very instructive and helpful replies in the following thread, eg:
http://tech.groups.yahoo.com/group/come ... sage/20527
http://tech.groups.yahoo.com/group/come ... sage/20530
http://tech.groups.yahoo.com/group/come ... sage/20529
http://tech.groups.yahoo.com/group/come ... sage/20526

It seems that Comet West was actually a dynamically 'old' comet, rather than a 'new' one as Comet Panstarrs is. That's a key difference between the two, unfortunately.

[Mariner]

Nevertheless, one can remain optimistic.

[starfinder]

Exactly a month to go before Comet Panstarrs' perihelion!

It's now reported at mag 5.7 and puffing out a tail half a degree long:
http://tech.groups.yahoo.com/group/Come ... ssage/5012

Let's hope the comet's tail gets longer and s-n-a-k-e-s through the sky this new lunar month.

Check out here for the latest images of the comet:
http://rogergroom.com/astro-photography ... annstarrs/

Looks quite dusty! Dust all over a comet is good; no need to spring clean this one.

[starfinder]

Jia Hao has drawn my attention to this image of Comet C/2011 L4 (PANSTARRS) taken today (13 Feb 2013) from New Zealand by a Japanese astrophotographer:
http://spaceweather.com/gallery/indiv_u ... bktpf4to35

The photographer says: "The tail has been longer last five days."

Looks like this cat is now seriously wagging its tail! Actually, that should read "tails" bec this comet has developed both a dust tail and an ion/gas tail.

[starfinder]

I drew up this graph and chart showing the altitude of Comet C/2011 L4 (PANSTARRS) above the local horizon on Sun 10 March 2013, which is the date of the comet's perihelion passage, after sunset when the Sun is at 10 degrees below the local horizon. This is for locations in mid-north to mid-south latitudes, and plotted against a map (public domain) of eastern Asia down to Australia.

It shows that the tropics (including Singapore) are in the best position, though at 4.7 degrees above the horizon, it is still very low. From Singapore, the comet would be in the low West-South-West (bearing 266 degrees approx) just after sunset that day. Of course, local cloud cover is usually quite heavy (i.e. poor for visibility) in the tropics, especially at low horizon levels. The graph also shows that anywhere from the latitude of Bali up to Phuket would be roughly the same.

The data was manually obtained from SkySafafi (for Android) for each location. (I wonder what else this graph shows about the comet's position relative to the Earth and Sun. Hmmm... the comet would be at celestial declination 4 degrees south.)

http://i.picoodle.com/d86ji0gh

[rcj]

Panstarrs and Lemmon in a single fov: http://vimeo.com/59571509

[starfinder]

Below is a screenshot from the Sky Safari (for Android) which shows the location of comet C/2011 L4 (Panstarrs) from Singapore on the date of perihelion (closest approach to the Sun), i.e. Sunday 10 March 2013, at the time when the Sun is 10 degrees below the horizon after sunset (i.e. 7:56pm). The comet would then be very low (only 4.7 degrees) above the horizon near the Sun, at bearing 265 degrees, i.e. 5 degrees to the 'left' of the due West. As the comet would be setting then, there would just be a few minutes to view the comet.

The comet would be in a similar (though slightly lower) position for about 5 days before and after 10 March.

Given that it's usually cloudy here, particularly near the horizon, the chances of having a clear view to the comet are not high.

Btw, since apart from a small handful of people, there seems to be little interest in this forum or amongst Singapore astronomers in comets, I don't think I would be posting much more info.