Yesterday it was very hot and humid with 34 degrees Celsius and 90% humidity. Late in the afternoon some really big thunder clouds where forming. Around 19.00 hours UT the Sun was setting behind one of these huge clouds. It was quite a spectacular site as you can see on the image below on the left (click to enlarge). The image was shot with the Nikon Coolpix 775 with automatic settings.

The image on the right shows a sunset on the German island of Ruegen, about two weeks ago. The sun sets just behind Cape Arkona, the north cape of Germany. The image was shot with the Canon MVX25i with a resolution of 640x480 pixels.




Click on images to enlarge

The days are getting very long at the moment, so you only get a few hours of observing time every night. Still there are always some interesting objects to observe, even with the naked eye. If you go outside around midnight you can see three bright stars high in the eastern sky, Deneb in Cygnus (the Swan), Vega in Lyra (the Harp) and Altair in Aquila (the Eagle).

Together these three bright stars form an asterism called the Summer Triangle. They range in brightness is from magnitude 0.03 to magnitude 1.25. Can you tell which one is the brightest and which one is the faintest? Maybe a good way to train your eyes and brains, learning to estimate the different magnitudes of stars.

Magnitude: the brightness of a star or any other celestial object. The higher the magnitude, the fainter the object.

On the map below (click to enlarge) you can see the Summer Triangle as a red triangle. Within the boundaries of this map lie two of my all time favorite binocular objects for 7x50 binoculars, the Cygnus star Cloud and the constellation Delphinus. In July/August I will try to observe these two brilliant objects. If I succeed, I will be back with some observing reports, finder charts etc. in the Deepsky Section (Binocular objects).



Image from SkyTools2 by Capellasoft, slightly processed

During my vacation on the German island Ruegen I was so lucky to see my youngest Moon until now. On the evening of June 8th 2005 just after sunset I saw a thin crescent in the northwestern sky. When I came home I checked the lunation in Virtual Moon Atlas; the Moon was 1.94 days old on the evening of June 8 around 19.30hrs UT. Below the Moon a barely visible Venus was setting.

I shot some footage with my camcorder, which I processed into the two images below. If you look very carefully at the first image, you might see a small bright spot in the clouds near the horizon just above the black band of clouds. This is Venus. The second image was shot an hour after the first image. The small black band you see below the crescent Moon are some thin clouds. Later I tried to observe the Moon with my 7x50 binoculars for some details, but for several reasons I didn't succeed. It was not dark enough, so the contrast was poor and the Moon was already very low in the northwestern sky, so the atmosphere caused a lot of turbulence.

Still, the unobstructed naked-eye view of this thin crescent Moon in a blue sky was a fantastic view on its own. (Click on the thumbnails to enlarge)

Here's a nice image of Pythagoras (Rukl map 2), a large complex crater that is situated near the northwestern limb of the Moon. On the image you can see the central mountains throwing their shadow across the crater floor. This young crater with a diameter of 128 km and a depth of 5000 meters is a typical example of a complex crater with terraced walls, central peaks, and a relatively flat floor full of hills.

A few degenerated large craters surround Pythagoras. In front of Pythagoras, to the left, lies Babbage with on its floor two smaller craters, Babbage A and C. In front of Babbage lies a more or less rectangular degenerated crater South. This crater is very hard to detect on this image. Only the eastern rim is clearly visible. To the east and southeast of Pythagoras lies Anaximander and J. Herschel. These are both more or less degenerated craters as well. Towards the lunar limb you see the walls of two other craters lit by the Sun. These craters are Desargues and Pascal.

To find the Pythagoras area, start from Sinus Iridum (Rukl map 10) and move in north-northwestern direction across Mare Frigoris.

This image was shot on 22 April 2005 with the TAL 200K, a 20mm Vixen Lanthanum eyepiece, the Coolpix 4500 with 4 x optical zoom and two filters, the Baader Contrast Booster and the Baader IR/UV cut filter. Settings where shutter 1/30s, f 5.1, ISO 100. This image is the result of 10 stacked images (Keiths Image Stacker), processed changing the levels and applying unsharp masking.

Click on the thumbnails to enlarge.

Yesterday around 16.00hrs I noticed a wonderful sundog, which was very easy to see. On the first image the Sun is just behind the tree to the left. The sundog is the bright spot in the clouds about 10 degrees to the right of the Sun. The second image is a close-up of the sundog.

The images where shot with the camera (Nikon Coolpix 775) set to "auto". I did some level adjusting with image processing software to bring out the sundog a little more. Click on the thumbnail images to enlarge.

Welcome to my new blog, Clear Skies On Demand (.... a backyard-astronomer's dream). After using my Astro Weblog for two years I decided it was time for a little change. I had the weblog completely re-designed by Moxie design studios. You can access Clear Skies In Demand through my website http://www.backyard-astro.com or directly using this link: http://www.backyard-astro.com/blog/

If you enter Clear Skies On Demand, it always will open in a new window. You can return to my website by clicking on backyard-astro.com in the banner at the top.

Due to security problems I had to remove the comments in the old Astro Weblog (spammers). Now you can register as a member (top right). Then you will be able to post comments on all entries. You can also browse through the archives by month, by date and by category.

I hope you will enjoy the new design (and of course the present and future content). Feel free to leave your comments.

Clear Skies to all of you!

Math

On May 11 2005 I observed Petavius and Rimae Petavius with the 8 inch TAL Klevtzov-Cassegrain. Petavius is a large, complex floor fractured crater near the eastern limb of the Moon. For a detailed observing report and a digital image of the Petavius area follow this link.

The next day, on May 12 2005 I joined Leo, a fellow observer who lives just down the road, to observe the Moon through his new telescope, the TAL 250K, a 10-inch Klevtzov Cassegrain mounted on a Lichtenknecker mount. The seeing wasn’t too good, but we still had a lot of fun observing the Moon, especially Petavius and the western Mare Crisium area with two ghost craters and some old capes. For a more detailed report and some digital images of the Moon and the new telescope follow this link.

Last night the clouds parted for only two hours, so I quickly got out my telescope and hopped along a few deepsky objects. M3, M5 and M13 looked great but for me the most impressive object last night was Arcturus, the fourth-brightest star in the sky, and the brightest star north of the celestial equator.

Arcturus is a a really beautiful, magnitude -0.3 star, with a lovely golden-yellow colour.  Its spectral type is K1 and its surface temperature is 4.300 degrees Kelvin. This giant is about 37 light years away from us and has a diameter 25 times the diameter of the Sun. If it would replace our Sun, Arcturus would appear 12 degrees across in the sky (which Coronado would you need to capture the whole disk into the field of view?). 

Arcturus can be found at the tip of the big kite shaped constellation of Bootes.

Image from SkyTools 2 by CapellaSoft

Arcturus, or the “Guardian of the Bear”, follows the Great Bear (Ursa Major) across the night sky. The name Arcturus comes from the Greek “arktos”, meaning bear and our word “arctic” that references the Bear’s northerly position. (Kaler, The Hundred greatest Stars p.21) While observing Arcturus I realized that a single bright and colourful star against a black background can be as beautiful and spectacular as any other deepsky treasure. Be sure to pay Arcturus a visit the next time you’re observing! Take your time for a closer look.