June 2010
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A morning comet

Use a chart like this to locate where to look for your object

Can you find the constellation Perseus and comet McNaught in Mojo's lovely skyscape?

Mojo's photo of Comet McNaught

Quick comet sketch with notes. See the long ion tail, the bright coma, and the short dust tail in my sketches

Comet C/2009 R1 (McNaught) June 13, 3:45 am from Chuckwalla Bench observing site, Colorado Desert. Lat 33N, Long 114W, Elev 1400 ft

I wish everyone in the world could see just one comet! Right now, there is one visible just as the dawn brightens the night sky. Unfortunately, it’s not easy or convenient to see this one, and in another ten days it will disappear below our horizon. It’s just barely visible to the unaided eye. Timing your viewing window is tricky, too. You have to find a balance between the time the comet rises high enough to see, and the coming of dawn, which robs the night of its darkness and guidepost stars an hour or two later.

Here are some tips to help you have a successful comet viewing experience now or in the future. When you first hear about a visible comet, you can usually find some online sky charts from astronomy magazines such as Sky and Telescope and Astronomy. Many online sources can offer guidelines and observations, too.

Star charts are fine, but you have to go out and navigate the real sky to find unfamiliar constellations. From the city, or close to dawn, this is a real challenge. You may only see a few bright stars in the sky. Try to see the stars making up the constellation Perseus in Mojo’s image. I’ll admit, it isn’t easy, especially when you are rushing against time. Now, compare his image to the star chart. And you’ll soon see the figure of the hero, Perseus, starting to emerge.

I use the familiar “W” shaped constellation Cassiopeia as a signpost to locate Perseus. Then I see Perseus with his two running legs, joined at the bright star Alpha Perseus (Mirfak). Nearby you can see the naked-eye open cluster known as either Melotte 20 or the Alpha Perseii cluster. Next, I make a mental triangle out of Alpha, Delta and Kappa Perseii, the three bright stars closest to the comet shown on the star chart.

Finally, I aim my binoculars at the triangle of stars and hold my breath. Then I see it, and I quietly say “hello” to the swift celestial traveller. I get chills every time I see a comet. And this time is no different. A little green fuzzball is right where the comet should be.

Now I jump into action. I dust the cobwebs out of my brain, as well as I can at 3:45 am in the morning. I’ve just woken up from a short nap. I quickly sketch what I see in the eyepiece of my big telescope, taking care to mark any stars nearby, and note the time. Then I call everyone who is awake over for a look. We all move sluggishly in the near dawn light, like we are walking through sandy molasses. We share views with one another, through binoculars and a variety of telescopes large and small.

Overhead, the Milky Way has disappeared, and the glow of twilight grows brighter. I have yet another predawn observing target, so I quickly make a second sketch with a little more detail. Then I nod goodnight to the beautiful green comet, aim my binoculars just a little to the east and wait. It will be nearly one hour before Mercury will rise over the mountains.

This comet is making its first approach around the sun, in its long hyperbolic orbit from the Oort Cloud. At the time of my observation, the comet was 0.6 AU from the Sun and 1.1 AU from Earth. By the end of June, it will be lost to our view. It reaches perihelion on July 2nd when it is about 0.4 AU from the sun. Then it will fade and be seen no more.

Added postscript: According to this Space.com article, the comet may be visible “after June 22 both in the evening sky for a short while just after sunset very low above the north-northwest horizon and in the morning sky just before sunrise very low above the north-northeast horizon.” I’ll update if/when I learn more.

See more of Mojo’s photos from this observing night.

Read my other observing writeup from this same night.

Join our Old Town Sidewalk Astronomers email list and find out when our next dark sky outing will be. Or join us at our next in-town new telescope users clinic and planet/moon viewing event. Hey, that’s tonight, June 19! Clinic (RSVP required) begins before dark at 7 p.m. Star Party continues until 9:30 p.m. at Library Park in Monrovia, CA.

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