Vern’s Weblog

Some astronomical objects to view up in the sky during the week of April 13 to 19, 2008.

INTERNATIONAL SPACE STATION

No bright passes this week.

SUN

Our closest star, the Sun, is currently at solar minimum As of today,
Sunday, there are no active regions visible on the solar disk.

For those of us at 40 degrees north latitude the sun rose Sunday morning
April 13th at 6:27 am and set at 7:38 pm MDT.
Next Saturday the sun will rise at 6:18 am MDT and set at 7:44 pm MDT

PLANETS

If we look toward the southwest about an hour after sunset, we can
see the planet Mars about half way between the horizon and the zenith in in
the southwest. It is currently in the constellation Gemini. It is now 1.5 AU
or 139 million miles from earth. It appears quite small in a telescope,
about 6.2 arc sec across in the eyepiece and is magnitude 1.1 in brightness.
The disk is 90% illuminated.

To the south the planet Saturn is visible high up in the constellation Leo.
Saturn is 812 million miles (8.7331 au) from Earth. It is 19 arc sec across
and 0.9 magnitude in brightness It is always great to view in a telescope.
On Saturday Saturns largest Titan (magnitude 8.3) will appear in appear in
the eyepiece about 1.5 arc minutes to the east of saturn. Saturns moon Rhea
(magntiude 9.6) is about 1 arc minute to the east. The 10th magnitude moons
Tethys (above) and Dione (below) are about 0.5 arc minute to the east as
well.

Early morning in the twilight before sunrise is currently the best time to
view and image the planet Jupiter this week. At that time it will be to the
south in the constellation Sagittarius. It is magnitude -2.1 in brightness
and 37 arc sec across. It is now about 4.8 au or 462 million miles away. It
will be getting closer, brighter and larger over the next few months. It is
at opposition and closest to the earth on July 8.

Jupiter’s Great Red Spot crosses the center of the disk at the following times this week. It is visible for about an hour before and after the central meridian crossing,
Tue April 15 at 06:47 am (MDT)
Wed April 16 at 02:38 am
Fri April 18 at 04:17 am
Sun April 20 at 05:55 am

MOON

This week is a good time to view the Earth’s moon. Aim your telescope or binoculars along the terminator. The terminator is the line on the moon’s disk between light and dark. The sun is rising at that location and casting long shadows which emphasize hills, craters, domes, and other geologic
features.
Mon. April 14 : Lunation 9 (that is 9 days after new): Take a look a the spectacular crater Copernicus with binoculars or telescope of any size. Copernicus is one of the most prominent craters on the moon. It is a relatively young crater have been formed only about a billion years ago by a massive impact. The central portion of the crater is about 58 miles (93 km) across. There are 3 terraces visible along inner wall of the crater. The 3 central peaks are about 3900 feet high. Lunar1 targets: Mare Frigoris, Mare Imbrium, Copernicus, Bullialdus. Longomontanus

Tues April 15: Lunation 10. Perhaps one of the most beautiful features on the Moon, Sinus Iridum also called “the Bay of Rainbows” may be viewed. Sinus Iridum is a 162 mile (260 km) wide impact crater in which one side subsided and then filled with lava. To its north are the Jura mountains. The
Promotorium Laplace on the west and Promotorium Heraclides on the east are local high spots rising about 7900 feet (2.4km) above the bay..

Wed April 16 Lunation 11: (Lunar1 targets) Aristarchus, Kepler, Oceanus Procellarum, Gassendi.

Thurs April 17 Lunation 12: (Lunar1 targets) Sinus Roris, Vallis Schroter, Billy, Schickard, Reiner Gamma

Fri April 18 Lunation 13: Look for Rays and bright albedo features

COMETS (brightner than magnitude 12)

17P Holmes is in constellation Auriga, the coma is 70 arc min and is magnitude 5.6
C/2007 W1 Boattini is in the constellation Crater. It is magnitude 8.8 and coma is 8.2 arc min across
C/2008 C1 Chen-Gao is in the constellation Orion. It is magnitude 10.2 and coma is 8.2 arc min across
C/2006 Q1 McNaught mag 11.1 and coma is 1 arc min across
46P Wirtanen is in the constellation Gemini. It is mag 11.5 in brightness and the coma is 3.9 arc min across

ASTEROIDS (brighter than magnitude 10)

All are in the constellation Virgo.
5 Astraea magnitude 9.8 It was discovered in 1845 by amateur astronomer Karl Hencke. The discovery of 5 Astrae led to the demotion of 4 other asteroids which considered to be planets at that time.
7 Iris magnitude 9.6
41 Daphne magnitude 9.4

The following is a summary of some astronomical objects that may be observed during the week of April 6 to April 12, 2008.

INTERNATIONAL SPACE STATION

Mon Apr 7 ISS appears at 9:12 pm Wed Apr 9 ISS apopears at 8:21 pm Thur Apr 10 ISS appears at 8:42 pm Fri Apr 11 ISS appears at 9:03 pm Sat Apr 12 ISS appears at 7:50 pm For times specific to your location see http://www.heavens-above.com

SUN

No active regions are currently visible on the solar disk. Sunday Apr 6 sunrise was 6:38 am and sunset was 7:31 pm MDT Sat Apr 12 sunrise is 6:29 am and sunset is at 7:37 pm MDT

MOON

The following is a list of Astroleague Lunar 1 Club objects that may be viewed on days indicated: Tue Apr 8 Lunation 3: Endymion, Cleomedes, Mare Crisium, Picard, Vendelinus, Petavius, Petavius Wall, Furnerius Wed Apr 9 Lunation 4: Atlas, Macrobius, Proclus, Palus Somni, Messier, Messier A, Fabricius Thur Apr 10 lunation 5: Lacus Mortis, Posidonius, Mare Tranquillitatis, Theophilus, Mare Nectaris, Fracastorius, Piccolomini Fri Apr 11 lunation 6: Aristoteles, Eudoxus, Mitchel, Mare Serenitatis, Plinius, Cyrillus, Catharina, Gemma Frisius, Maurolycus Sat Apr 12 lunation 7: First quarter moon is at 12:32 pm MDT. Cassini, Cassini A, Aristillus, Mons Piton, Montes Alpes, Vallis Alpes, Autolycus, Palus Putredinis, Mons Hadley, Manilius, Mare Vaporum, Hipparchus, Albategnius

PLANETS

Mars is in constellation Gemini. It magnitude +1 in brightness and the disk is 6.5 arc sec across. Just after 1 am MDT Saturday morning, the moon passes about 12 arc minutes north of Mars. Saturn is in constellation Leo. It +0.85 magnitude in brightness and 19.3 arc sec across Jupiter is in constellation Sagittarius. It is magnitude -2.1 in brightness and the disk is 39 arc sec across Jupiters Great Red Spot (GRS) crosses the center at the following times this week: Tue Apr 8 at 06:00 am Wed Apr 9 at 01:52 am Fri Apr 11 at 03:30 am The GRS is visible in a telescope for about an hour before and after the central meridian crossing.

ASTEROIDS

The following asteroids are magnitude 10 or brighter: 5 Astraea is in constellation Virgo and 9.6 magnitude in brightness 7 Iris is in constellation Virgo and 9.4 magnitude in brightness 41 Daphne is in constellation Virgo and 9.3 magnitude in brightness

COMETS

The following comets are magnitude 12 or brighter: 17P Holmes in constellation Auriga it is magnitude 5.7 in brightness and the coma is 70 arc min across 46P Wirtanen is in constellation Gemini it is magnitude 11.5 in birghtness and coma is 3.9 arc-min across C/2006 Q1 McNaught is in constellation Antlia. It is magnitude 11.1 in brightness and the coma is 1 arc min across C/2007 W1 Boattini is in constellation Crater. It is magnitude 8.8 in brightness and the coma is 8.2 arc min across C/2008 C1 Chen-Gao is in constellation Taurus. It is magnitude 10.2 in brightness and the coma is 3.2 arc min across. See http://cometchasing.skyhound.com for charts and more information

DARK SKY OBJECTS

The moon interferes with our deep sky views by the weekend.

The following are a few of the many astronomical objects that may be viewed during the
week of March 30 to April 5, 2008.

International Space Station

The ESA Automated Transfer Vehicle will be maneuvering
close to the ISS this week. Unfortunately, the passes over
the continental United States are far north this week.

Sun

Three regions are currently visible on the solar disk. Region 10989 is located
near the center of the disk. Further west (right) is 10988, and then 10987.
Here is a look at the sun in h-alpha. An h-alpha telescope reveals features on
the sun’s disk not visible in white light. In the image are some ephemeral regions where magnetic
flux tubes emerge on the surface. These appear as bright plage regions. Also visible is a filament
to the southeast of region 10988. Flaments are relatively cool, dense gas that is suspended in magnetic
loops above the surface of the sun. When we look down on them they appear as dark lines as the material
is cooler than the hot photosphere below. When we see them in profile against a dark
sky they are called prominences. This one appeared on the southwest limb on saturday.

On March 30 sunrise was at 6:49 am and sunset was at 7:24 pm MDT On Saturday, April
5th, sunrise is 6:39 am and sunset is 7:30 pm MDT

Moon

New moon is on Apr 5 at 9:55 pm MDT

Planets

Mars is in constellation Gemini. It is +0.9 magnitude in brightness and 6.8
arc sec across.

Saturn is in constellation Leo. It is +0.8 magnitude in brightness
and 20.5 arc sec across.

Jupiter is in constellation Sagittarius. It is -2 magnitude
in brightness 37.9 arc sec across. It will be at opposition on July 9th. Jupiter’s
great red spot crosses the center on Tues April 1st at 5:14 am. The GRS is visible
for about an hour before and after the central meridian crossing.

Asteroids

There are 3 asteroids brighter than magnitude 10, all are currently in the
constellation Virgo.
5 Astraea magnitude 9.4
7 Iris magnitude 9.4
41 Daphne magnitude 9.3

Dark Sky

Dark sky weekend is coming up. Those of us at 40 degress north latitude
will get 8 hrs and 6 minutes of astronomical darkness.

By 10 pm the constellation Coma Berenices is in good position.
Locate the 5th magnitude star 6 Coma Berenices which is just 6
degrees east of star Denebola in Leo’s tail. Just west of this star
is galaxy M98. Messier 98 is a blue-shift galaxy approaching us at
544 thousand miles per hour. It is about 70 million years away
though so the collision is not imminent. Form a south east pointing
triangle with star 6 and the 6th magnitude star to the northwest to
locate M99. Messier 99 is a large red shift galaxy moving away from
us at a speed of 5.3 million miles per hour.

Back to 6 Coma Berenices, follow a string of 6th magnitude stars to
the northeast, between the 3rd and 4th one is M100. Messier 100 is a
fine, face-on galaxy with a small, bright core surrounded by a 6 arc
min wide bright halo.

Locate Alpha Coma Berenices and star hop 5th magnitude stars 36, 27,
24, and 11 Coma Berenices. About half-way between 24 and 11 lies
M85.

Those who can stay awake all night have a second chance to locate
all 110 Messier objects this weekend.

Comets

17P Holmes is in constellation Perseus; it is magnitude 5.7 in brightness and 70′ across
46P Wirtanen is in constellation Auriga; it is magnitude 10.2 in brightness and 5.1′ across
C/2008 C1 Chen-Gao is in constellation Auriga; it is
magnitude 10.2 in brightness and 2.5′ across

C/2007 W1 Boattini is in constellation Corvus; it is magnitude 10.9 in brightness and 1.9′ across

Nice loop prominence was visible on the sun’s southwest limb.

Image taken with Solarscope Ltd. 50mm h-alpha telescope, Televue 2.5X Powermate, DMK 21AF04.AS camera 1/82 sec, 60 fps. Sky was clear, 5 mph wind, temperature 68 °F, turbulence about 6/10, transparency very good, location Louisville, CO.

Image of active regions 10989 (lower left) and 10988 (top center) in h-alpha about 3:20 pm MDT.

Image taken with Solarscope Ltd. 50mm h-alpha telescope, Televue 2.5X Powermate, DMK 21AF04.AS camera 1/500 sec, 60 fps. Sky was clear, 5 mph wind, temperature 68 °F, turbulence about 6/10, transparency very good, location Louisville, CO.