if it clears...

I sent a note about the comet to RASC Toronto Centre Yahoo!Group...

I've been receiving clear weather alerts today...  It might clear up around sunset.  If we get decent skies from 7:00 PM to 9:00 PM tonight (Tuesday), there *might* be a chance to see comet C/2011 L4 Pan-STARRS.

Now, let's consider the numbers...

My SkyTools Pro 3 says C/2011 L4 is currently magnitude 1.10. It is starting to dim, now that it has passed the proximal point near the Sun.

It is also retreating from us, the Earth, slowly.  The size of the coma has reduced slightly to 2.9 minutes of arc.

The tail should be pointing slightly up and to the left, to your eye, in normal orientation, or binoculars.  Remember your telescope view might be rotated or flipped, depending on the total number of reflections.

SkyTools predicts, for a central Toronto location, the comet would be visible in a short window of time: between 7:31 to 8:26 PM.  Note: in an 8" telescope!  A slightly shorter window for a 3" to 6" telescope; chop 5 minutes off each end.

I simulated the view with 15x70 binoculars (like the popular Celestrons).  The window is very short. About 15 minutes long starting from 8:01 PM.  When I run a simulation for my 7x50 binoculars, nothing appears! I think you need "big" binoculars or a telescope tonight...

At 8:00 PM, the comet will be at azimuth 267 degrees.  A touch, or two fists, south from due west.  Remember to set your compass for your local magnetic declination.  For the GTA, that's around 10 degrees west.

The comet's elevation or altitude in the sky at this time will be 6.5 degrees. Or three fingers above the horizon.  That puts it at 8.3 airmasses!  In other words, to see it, you'll need to punch through over 8 atmospheres.  Of very clear air.  That causes the magnitude to effectively drop to 4.1.

It is a tricky balance between sky darkness, elevation above the horizon, and aperture.  So, if you're going to try, be ready before the observing window opens and scan for the whole time.

If imaging, shoot many frames at different exposures.

The Moon will be about 4 degrees from the comet.  Almost exactly to the right, horizontally.  The Moon is very young, at 1.2 days. Or around 29 hours.  So, any extremely thin crescent.  Making the Moon itself a challenge to spot.  That said, my career record for a young Moon is 27 hours -- from city limits.

Try to spot the Moon first, then look slightly left of the Moon, for a faint elongated smudge.  Many binoculars show a 5 to 7 degree field.  So if you put the Moon in the right half of the field, the comet would be in the left half.

I wished everyone good luck!