Vern’s Weblog

A new active region AR 10953 rotated into our view on the east limb of the sun yesterday. It has been about a month since there has been any solar activity of significance.

White light image acquired with Celestron Nexstar11 telescope, F6.3 focal reducer, and Canon Xti camera (ASA 400, 1/3200 sec exposure). Images were cropped and then stacked and aligned with Registax4.

Mostly clear, high thin clouds, transparency good, turbulence 6/10, no wind, temperature 67°F.

Grab your red and green stereo glasses and go take a look at the impressive anaglyphs of the Sun taken by the STEREO satellites at the NASA press release site or at the mission website. Images from the STEREO satellites provide our first true stereo view of the sun. In the past it was possible to produce only pseudo stereo images of the sun by taking images at different times or by changing the projection point of view. These images were created by taking images simultaneously from the two satellites in various wavelengths.

A list of some objects to view for the week of April 23 through April 29, 2007. Please note that some of the times given are somewhat specific to the Colorado front range (40° N and the MDT timezone). 

International Space Station

There are a couple impressive flyovers of the ISS this week. On Tues, April 24 it appears in the NW at 8:58:19 pm MDT. It reaches a maximum altitude of 60 degrees at 9:01:02 pm and is brightest at magnitude -0.8. A few seconds later it passes near Alioth, the brightest star in the handle of the Big Dipper. It then disappears in the ESE at 9:02:02 pm.
On Friday April 27 at 10:22:24 pm the ISS appears in the WNW at 8:25:05 pm MDT. It reaches an amaximum altitude of 45 degrees at 8:27:42 at -0.2 magnitude. At that time it will be very, very close to the star Procyron (mag 0.38) in constellation Canis Minor. It disappears in the SSE at 8:27:42 pm. For additional information visit http://www.heavens-above.com

Sun
The sun rises at 6:13 am MDT early in the week and 6:05 am next Sunday. It sets 7:48 pm to 7:54 pm. There are currently no activie regions visible on the sun in white light. There is not a whole lot going on in halpha either. Needless to say, solar activity is expected to remain at very low levels this week. For additional information visit http://spaceweather.noaa.gov
The NASA is scheduled to release the first 3D images of the sun taken with the STEREO space crafts tomorrow.

Moon
The moon is in first quarter on Tues April 24 at 0:35 am MDT. This week is a good time to explore the many fascinating mountains, craters, and other features on the moon.

Tonight the moon will enter the debris trail of comet Thatcher which raises the possibility that flashes from meteor impacts might be observed through a telescope. Look for them in the northern hemisphere on the unlight side of the lunar disk.
Mon Apr 23 is a great time to check out prominent crater Aristotle (Rukl chart 5). It is 55 miles wide and 12,000 feet deep and is complex crater with terraced walls and radial ridges. It is an unusual example of a large crater super-imposed over a smaller one (Mitchell).
Tues Apr 24 locate Hadley Rille on the southeast edge of Mare Imbrium near the Apollo 15 landing site. Also, crater Cassini with its two central peaks should be well lit for viewing.
Wed Apr 25 the terminator is just west of the straight wall or Rupes Recta and it will be a good time to image or view this spectacular feature.
Thur Apr 26 Check out craters Copernicus and Longomontinus as well.
Fri Apr 27 the terminator is near the Bay of Rainbows or Sinus Iridium and the Jura mountains.
Sat Apr 28 view the crater Aristarchus with its sharp rim crests, terraced walls and flat floor. Compare this view again at full moon on May 2nd. Aristarchus has the highest albedo of any feature on the moon.

Planets
Venus is in the constellation Taurus and shines at a brilliant magnitude -4.1 in the western sky after sunset.
Saturn at magnitude +0.3 is between constellations Leo and Cancer is still high in the SSW in the early evening.
Jupiter rises 11:28 pm to 11:03 pm in the constellation Ophiucus. It is very bright at magnitude -2.4. It will be at opposition on June 5th.
The great red spot (GRS) crosses the center of Jupiter at the following times this week:
April 23 at 00:02 am
April 24 at 05:49 am
April 25 at 01:40 am
April 27 at 03:18 am
April 29 at 04:56 am

The GRS is visible about an hour before and after the central meridian crossing
Mars is at magnitude +1 is in constellation Aquarius. It is currently about 5 arc seconds across. It will be difficult to observe much detail through our telescopes until this fall. Mars opposition is on Christmas eve, Dec 24.
Mercury is not visible this week.
Uranus and Nepune are very low in the southeast in the early morning and not in good position.
Pluto is at magnitude +14 in constellation Sagitaurius.

Comets
C2007/E2 (Lovejoy) is in constellation Aquila and moving to Lyra. It is magnitude +8 in brightness and has a 8.2 arc min wide coma. Best time to view is around 03:30 am. There is an image of this on my blog at http://www.raben.com/weblog/2007/04/15
96P Machholz is in constellation Pegusus. It is projected to fade from magnitude 10 to 11 this week and has a 3.5 arc min coma. Best time to view is around 03:30 am.
C/2007 E1 (Garradd) is in constellation Cancer. It is magnitude 10.4 and a 2.5 arc min coma. Best time to view is about 8:30 pm.
For additional information about current comets such as sky charts, etc. visit http://www.skyhound.com/sh/comets.html

Asteroids
Of the estimated 1.5 to 1.9 million asteroids in main belt between Mars and Jupiter, there are currently 4 fairly bright (vmag 10) visible in early evening this week:
7 Iris is in constellation Gemini
11 Parthenope is in constellation Leo
Two of them are visible in constellation Virgo and track nearly parallel paths
3 Juno
28 Bellona

Best way to locate asteroids is to get the coordinates from your star chart program and then take multiple images of the region 10 or more minutes apart — or draw careful sketches of the star field half an hour or more appart.

Double Stars
Algeiba in constellation Leo the Lion is an attractive double star in the curve of the cyle NNE of Regulus. The primary (Algeiba) is a 2.6 magnitude yellow star (spectral class K0). The secondary is 3.8 magnitude orange (spectral class G7) star located 4.4 arc sec to the SE. The secondary is about 150 AU distant from the primary and takes approximately 600 years to complete an orbit.

Izar in constellation Bootes is great target for small scopes 3 inch or larger to show color contrast. The primary (Izar) is a 2.9 magnitude golden yellow star (spectral class K0). The B component is bluish-green (spectral class A0) magnitude 4.9 magnitude star located 2.8 arc seconds to the NNE of Izar.

Dark Sky
The Lyrid meteor is at its peak this Sunday and Monday and will continue through Wednesday. Best time to observe is after moonset, 2 to 3 am MDT. Between 5 and 20 meteors per hour are typically observed during this shower. The Lyrid meteor occurs annually as Earth passes through the debris tail of comet Thatcher. Comet Thatcher has an orbital period of 450 years and last made a close approach to the sun in 1861. See http://www.spaceweather.com/meteors/lyrids/lyrids.html for charts and more info.

Moon interfers with dark sky views this week unless you get up early in the morning. That limits our views to the brightest of the deep sky objects such as galaxies M81 and M82. Globular M3 inshould show up well even in the bright moonlight as well.

There is a possibility for us in Colorado this month to break some thin crescent observing records that Peter mentioned in his blog last January. Inspired by that prospect (or maybe temporary insanity), I got up about 4:30 am this morning, packed up the notebook, binoculars, and camera and headed off to a parking area east of Louisville’s Monarch High School to see if I could spot the waning crescent. I started scanning the horizon at 5:40 with 10×50 binoculars but wasn’t able to see it until 6:03 am, only 20 minutes before sunrise. Only a thin patch was visible, maybe 10 arc minutes long. At first I thought it was just a small jet contrail as contrast between it and the background was better than expected. Also the azimuth was to the south (right) of sunrise point. I had figured earlier it would be to the north (left). A quick check with sky chart software confirmed that the position was correct and I’d been searching mostly in the wrong direction earlier.

I changed my position so that the limb of a distant tree was just below the crescent to see if I could see it without the binoculars. I was able to see a small light point that matched with the binocular position. I switched between binoculars view and no binoculars several times to check. I was only able to spot the faint patch only twice out of 5 or so tries though, so it was at the muddy edge of visibility.

I also shot a number of images of the horizon with a Canon Xti but used too wide an angle. I suspect high magnification is needed to increase contrast between the bright twilight and the scarcely brighter thin crescent. Sky was mostly clear, no wind, temperature was 47° F, transparency excellent, turbulence fair or better.

Unfortunately, weather is turning rainy for a few days here, so the prospects for seeing the new crescent Tuesday evening and breaking the crescent moon bracket interval aren’t looking good.

Update April 17

The skies cleared late in the afternoon, so I packed up the cameras, scopes, and other equipment and set up at a trail head on Davidson Mesa just off nearby McCaslin Blvd. Unfortunately there was a band of clouds over the mountains to the west which was in exactly the wrong place. It was clear to the south, north, and overhead. Maybe next year..

Last evening 14 of us in the Boulder, Longmont, and Fort Collins astronomy clubs met at Crow Valley Campground north of Briggsdale, CO for a very enjoyable night under dark skies. Conditions were very good — one of those evening we all hope for but only rarely experience. Excellent transparency, a cloudless sky, no wind, and even fairly warm temperatures for this time of year. Temperatures were in high 40s and 50s early in the evening so most of us were in light jackets until 9 or 10. Turbulence was only fair, about 5/10 most of the evening. It got a bit frosty around 4 am with temperatures in the low 20s. In Colorado you soon learn to bring your cold weather gear along year round, so it wasn’t a problem for most.

I spent most of the evening checking off spring objects in Ursa Major and Canes Venatici. I held off imaging until just before 4 so I could catch Jupiter’s red spot and comet Lovejoy. I tried for 96P Machholz as well, but it was behind the trees to the east.

I managed to get in some practice shooting the crescent moon at dawn in preparation for tomorrow morning and Tuesday evening this week. The shot above was not the best. I had better composition in some earlier shots which I lost due to an incorrect setting in my focusing software — it deleted all but the last image taken. In early shots the moon was lower and the wind mill wasn’t against the tree in the background. Darn… It makes a fairly nice desktop wall paper though, despite the obvious flaws. Here is a 1280×1024 version.