Sunday, May 19, 2013

Night of the Comets!

I've heard that a couple bright comets (visible in binoculars, NOT naked eye!) were putting on a good show, so with the brightening moon already half illuminated and it being Saturday night, time to hit the road!  Since I wanted dark northeastern skies, I chose to go up the Mount Lemmon Highway to Geology Vista.  While it looks out over the Tucson Valley with a pretty view of the lights, there is absolutely nothing to the north, so the sky in that direction is quite nice!  Also, since the bright moon was up till about 1am, there was no hurry to leave home - with Melinda working, I left about 11:30, bringing up a pair of cameras, the 14" Hyperstar, and the Meade 80mm APO triplet.

Setting up in the dark is one of my pet peeves - I
try not to do it, but sometimes, like last night, you don't have a choice.  It takes about an hour  to set up for imaging and get aligned on Polaris and fortunately with my new (to me) AP1200, for short exposures, I don't need to track, at least that was the plan...  Comet PanSTARRS (C/2011 L4) was up first - it is actually only a few degrees from Polaris, so is up all night!  But while readily visible in binoculars, it held its secret until you get a picture of it.  We're about to cross the plane of its orbit next week, and it has been developing a very nice sunward-pointing spike!  I didn't observe it visually thru the 14" (can't with the Hyperstar Lens in place), but even in a telephoto lens, it was impressive.  It looks darn near like a jetliner with its headlight on coming in to land!  The left picture is with the Hyperstar (660mm focal length), and the sunward spike juts out of the frame, so I tried the wider field of the Meade APO (480mm focal length), and it still shot out of the field!  North is approximately up in both frames.

So I switched to an 85mm telephoto lens - a Nikon F/1.8, shooting at F/2.8.  Shown here at left is the result.  The star at upper right is Polaris, the one at lower right is Gamma Cepheii (Errai).  Measuring with a ruler on the screen, the tail is OVER 4 degrees long, and likely to get longer as we cross its orbital plane next week (27th).  Unfortunately, it happens a couple days after full moon, and it may be difficult, if not impossible to observe well.  Also visible is the open star cluster NGC 188 to the left of the comet and lower right from Polaris.

The other bright comet out last night was Comet Lemmon (C/2012 F6).  It was a new comet to me, but has been putting on a good show in the Southern hemisphere the last few months.  It is just now moving north and can be seen rising to the left of the great square of Pegasus just before dawn.  The photo here is thru the Hyperstar again, and is a total of 8 minutes of exposure in a brightening sky.  It shows a nice blue ion tail to the right, as well as a dust tail below.  Both comets are on the other side of the sun from us, well over 1 AU(an astronomical unit is the earth's distance from the sun, about 93 million miles) from the sun and both 1.7 AU from earth.

It was great getting out seeing some bright comets (any time they can be seen in binoculars, they are considered bright!), and keep in practice imaging them.  I definitely need to improve my imaging skills, but fun nonetheless!

1 comment:

Andrew Cooper said...

I have been wanting to photograph these comets.. I even have some new gear to test out in that role. Unfortunately the weather has not been cooperative! Raining this afternoon, still some hope for clearing this evening.