Star trails over Linda Rock, Blue Mountains, N.S.W.

Last night during Earth Hour, Ted Dobosz, a good friend, took this lovely image of star trails circling the south celestial pole. In an email to his various astronomical-minded friends, Ted remarked that he took images of the Sydney sky glow during and after Earth Hour (local time: 8:30-9:30 pm) and found that there was no noticeable reduction in Sydney's light pollution. In asking for Ted's permission to use this image to liven up my blog, he supplied some additional information: "Hi Pete, ... It was taken from the rock looking south. It was taken with a Canon 40D at 400ASA for 30 mins at F4.5. The lens was a Tamron 17-55mm and it was taken at 17mm. ... Conditions last night ordinary with a brown haze and 30% reduction on brightness of all objects. ... Ted."

The rock is Linda Rock in the Blue Mountains to the west of Sydney, Australia; Sydney is about 100 kms (62 miles) distant. In the image the star trails have obvious colour, and the two pieces of 'fog' at two and five o'clock are the Large and Small Magellanic Clouds, satellite galaxies of the Milky Way.

If you enlarge the image the star colours show more clearly, as does the pale blue of the LMC; the colours are real and indicate the temperature of the star making the trail (red through orange 3-5,000 deg C.; white: 8-11,000; blue: 16-50,000). For the LMC the pale blue indicates that the majority of its stars are young and have temperatures above 16,000 degrees centigrade. As a comparison our sun is yellow indicating that the disk we see has a temperature of 5,900 degrees centigrade. The yellow glow at the bottom left (south-east) is from the Sydney metropolitan area, the fainter glow at bottom (south) originates in the suburbs making up the Campbelltown area.

Unlike the north celestial pole there is no bright pole star. To see an untrailed image at similar scale look at this August 2006 image from Astronomy Picture of the Day.

Image (used with permission): © Ted Doboz, 2009.

Comet Lulin (C/2007/N3)

This post is for my astronomical friends, although I sent out an email, I'll post here so you can all see it. After some preparation and a short search with 7 x 50 binoculars, I found Comet Lulin, more formally C/2007/N3, early today at 1:00 AM, AEST (14:00 UT, 21 February). My email sent out just before 2:00 AM to some observing mates, bragging as I say of my sighting:

"Hi all,

I've just seen it, although Comet Lulin is not awe inspiring. Work required me to spend the weekend in Bathurst and tonight I gave it a go: it has been clear except for a few fast moving clouds around 11:50 pm. So using Dave's directions and Astronomy '09 I looked for it and found after a few minutes (at 1 am DST) from my balcony - in the eastern sky. It looks like a small and lumpy globular star cluster; it could be slightly oval; hard for me to say if it has a tail, maybe a darker site other than the mega-polis of Bathurst would help in seeing any tail. Size, possibly 10 to 15 arc min. (very uncertain about that); mag: around 6 to 6.5. I spent 30 minutes examining it in 7 x 50's and found that I could not extract any more detail other than what my brain can manufacture. Sky although clear was not very stable with lots of twinkle, air was nice and cool.

Now I'll stop bragging and go to bed, actually Guys, I was determined to start my observing year off after a month of bad weather and this didn't seem too hard if the clouds stayed away. Cheers, Peter"

Unfortunately, no drawing and no photo to share. A drawing through the binoculars wouldn't show much - a small, round, fuzzy blob in a star field, so I didn't sketch it. "Lumpy" in my email is a metaphor for irregularly bright. For a nice suite of images and some more observational history go to Garry Kronk's Cometography site; this is his Comet Lulin page. Astronomy Picture of the Day has an image as well. Anyway, the observing drought is hopefully broken.