Vern’s Weblog

Comet C/2007 E2 (Lovejoy) was high up in the constellation Lyra when these images were taken early Sunday morning around 4 am. It was discovered by Australian amateur astronomy Terry Lovejoy on the 15th of March with a Canon 350D digital camera.

It was easy to find visually through the eyepiece. Not nearly as bright as the nearby ring nebula which I had to check out while in the neighborhood. The comet appears to have a bright core in this image — it did not have that appearance in the eyepiece. The hazy area of the outer coma is visible, though quite faint. The comet is far to faint for color to show except in enhanced time exposurers such as this.

This was my first attempt to image a comet in color. I used two separate alignments. One was stacked using median combine aligned on the stars and the other aligned on the comet. This way you end up with an image of only the comet with some faint star streaks in the background. The other image is of the stars with a very faint blur of the comet moving through. Photoshop was then used to align the star field and the comet with one of the originals. I’m not sure I like the technique. It seems to be bordering on total fabrication as the separate stacked comet image is simply positioned on the background star images.

Images taken with Celestron Nexstar11 telescope, F6.3 focal reducer, and Canon Xti camera at cassegrain focus. Exposures were 20 seconds at ISO 1600, unguided. Images aligned and stacked with ImagePlus, and then enhanced, positioned, and color adjusted with Photoshop. A larger version 1280×1024 without the text annotation is available.

This periodic comet was discovered in 1986 by Don Machholz. It has an orbital period of 5.24 years and is possibly the brightest periodic comet known. Unfortunately for us earthbound observers, it is always too close to the sun when it peaks.

Images acquired with Celestron Nexstar11 telescope, F3.3 focal reducer, and StellacamII video camera from Louisville, CO. The sky was mostly clear, transparency very good, temperature 58°F, no wind, and good turbulence (6/10).

A list of some objects to view for the week of April 29 through May 5, 2007. Please note that some of the events and times given are specific to the Colorado front range (40° N and the MDT timezone).

International Space Station
There are no visible passes this week for those of us along the front range in Colorado.

Sun

The sun rises 6:05 to 05:58 am MDT this week. Its sets 7:54 to 8 pm.

Region 10953 rotated into our view on Apr 26th. It is a fairly large region with an area of 500 millionths solar hemisphere or 1,522 million square kilometers. The entire surface area of the planet earth is 510 million square kilometers. See image on my weblog at http://www.raben.com/weblog/2007/04/26/ The region should be near mid disk on Tues. Solar activity is expected to remain low this week although there is a 20% probability of a M-class flare event from region 10953 (according to NOAA/NWS).

The current estimate for solar minimum has been changed to March 2008 which is over a year later than originally expected (see http://spaceweather.noaa.gov/SolarCycle/SC24/index.html ). The next solar spot maximum is projected to be late 2011 or early 2012.

Moon

The moon will be full on May 2 at 04:09 MDT.
On Sun Apr 30 checkout craters Pythagoris, Shickard, and Wargentin.
On Mon May 1 the battered partial mare-filled Grimaldi is at its best.
On Tues May 2 the moon is full so look for the bright rays extending from Tycho and Copernicus. Also consipicuous is bright white crater Aristarchus in the northwest.
On Wed May 3 the terminator is near Mare Crisium and craters Cleomedes and Petavius
On Thur May 4 the craters Atlas and Taruntius should be a great view.

Planets

Venus is in the constellation Taurus and shines at a brilliant magnitude -4.1 in the western sky after sunset.

Saturn is getting dimmer, now +0.4 in magnitude but is still providing great views for early evening viewing.

Jupiter is in constellation Ophiucus and is now at magitude -2.5. 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 29 at 04:56 am
April 30 at 00:47 am
May 2 at 02:25 am
May 4 at 04:03 am
May 4 at 11:54 pm
The GRS is visible about an hour before and after the central meridian crossing.

Pluto is constellation Sagitarius at magnitude 14.

Mars is in constellation Aquarius is magnitude 1.0 in brightness. The next Mars opposition is on Christmas eve, Dec 24.

Uranus at magnitude 6 and Neptune at magnitude 9 are both in constellation Aquarius.

Mercury is not visible this week.

Comets

Comet C/2007 E2 (Lovejoy) is high up in the morning sky and moves from constellation Lyra to Hercules this week. It should now be at its brightest at magnitude 7.9 and with a 8.1 arc-min wide coma. T

Also visible in the morning around 4 am is periodic comet 96P Maccholz in constellation Pegasus. It is magnitude 10.8 in brightness and has a 3.5 arc-min wide coma.

Comet C/2007 E1 (Garradd) is visible in the early evening in constellation Cancer. It moves to constellation Gemini at the end of the week. It is magnitude 11.5 and has a 1.2 arc-min wide coma.

See http://www.skyhound.com/sh/comets.html for more details and charts.

Asteroids

There are currently 6 asteroids that are brighter than magnitude 11.
20 Messalia (vmag 10.6) and 516 Amherstia (vmag 10.9) are in constellation Cancer.
11 Parthenope (vmag 10.8) and 23 Thalia (vmag 10.5) are in constellation Leo.
3 Juno (vmag 10) and 28 Belona (vmag 10.9) are in constellation Virgo.
4 Vesta (vmag 6.1) is in southern part of constellation Ophiuchus.

Asteroids positions change quickly so consult your sky chart software.

Double stars

In addition to viewing the moon, the bright moonlit nights this week are a good time to check out some double stars.

In constellation Leo the blue-white Regulus (magnitude 1.36) has a yellowish dwarf magnitude 7.7 companion 176 arc-sec (almost 3 minutes) to the WNW. Also in Leo is 2.6 magnitude yellow star Algeiba which has a 3.8 magnitude orange companion star located 4.4 arc sec to the SE.

In the southern part of Ursa Major is double star Xi Ursa Major (magnitude 4.3) which has a close orbital companion (magnitude 4.8) only 1.6 arc-seconds to the west.

The stars Alcor and Mizar at the bend of the Big Dipper’s handle are a splendid pair through binoculars. The star Mizar (magnitude 2.3) has an orbital companion (magnitude 4) located 14.4 arc seconds to the SSE. This was the first double star found with a telescope by Riccioli in 1662.

The brightest star in constellation Canes Venatici, Cor Caroli (magnitude 2.9), has a 5.5 magnitude secondary companion 19.4 arc-sec to the SSW.

Dark sky Objects

The bright moonlight interfers with evening dark sky views until about Friday when the moon rises quarter til 11pm.

An image 0f the moon at lunation 10.7 days on Friday, April 27.

Images taken around 10 pm MDT Friday, April 27, 2007 from Louisville, CO with Canon Xti camera, Celestron F6.3 focal reducer and Nexstar11 telescope. Transparency was very good with a few high thin clouds. Temperature was 68°F, no wind, and good turbulence (6/10) overall.

Lunar crater Copernicus is one of the most prominent craters on the moon. It is 93 kilometers (57.8 miles) wide. It has distinctive terraced walls and three central peaks which rise over a kilometer above the crater floor.

Across the upper left of the image (north) are the Carpathian mountains which at the southern end of Mare Imbrium. Crater Gay-Lussac appears as a horseshoe shaped crater in the north. Crater Hortensius is to the left of Copernicus. Crater Fouth is part of the double crater shape below Copernicus.

Video images taken 9:35 pm MDT Friday, April 27, 2007 from Louisville, CO with Phillips 840K webcam and Celestron Nexstar11 telescope at Cassegrain focus. Transparency was very good with a few high thin clouds. Temperature was 68°F, no wind, and good turbulence (6/10) overall. Occasionally the turbulence was exceptional (8/10) but only for few moments.