Entry for June 06, 2007 – Observational Notes

Location: Tomball, TX
Cloud cover: 5%-10% – Stratus – up to 80% later
Transparency: avg.
Seeing: avg (3/5)
Darkness: city sky glow, no moon
Limiting Magnitude: 4 (unaided), 9-10 (scope)
Wind: mild
Humidity: 65%-70%
Temperature: mid-70’s
Start Time: 9:30 pm CDT
End Time: 11:00 pm CDT

Instrument: Bushnell 3″ Newtonian

Venus: bright half disc resembling 1st quarter moon.

Saturn: crisp outline and ring separation; Titan trailing ~3 ring diameters behind planet.

Graffias (beta1 Sco): split double beta2 Sco with 7.9mm eyepiece. Both stars nice blue.

Jupiter: clear disc, no cloud bands visible. Moons Europa, Io, Ganymede, and Callisto trailing eastward, followed by HD 152516 (HIP 82734) at ~2X separation of Jupiter-Callisto.

Increasing cloud cover made further observing difficult.

Entry for June 05, 2007 – Observational Notes

Cloud cover: 5%-10% – Cirrus
Transparency: below avg.
Seeing: below avg (4/5)
Darkness: city sky glow, no moon
Limiting Magnitude: 4 (unaided), 8 (bino)
Wind: none
Humidity: 85%-90%
Temperature: mid-70’s

Instrument: Bushnell 12×50

Compared to last night, tonight was a a little “hazy-er”. Not sure if this is due to worse transparency or higher humidity. Last night’s transparency might have been better than I rated it.

Jupiter was a bright disc surrounded by atmospheric glow that encompassed its moons. Callisto, Ganymede, Io, and Europa were all visible.

Antares appeared much as last night, yellow-orange with a lot of atmospheric sparkling that included green.

Vesta formed ~120° angle with HIP 80793 and phi Oph.

Spica was bright and blue; Arcturus yellow-white.

I could just make out the bright oval of Saturn, but no ring separation and no moons.

Venus large and very bright orange-white. Could not discern phase, perhaps due to brightness and/or haze.

Entry for June 05, 2007 – Observational Notes

Cloud cover: 10%-20% – Cirrus
Transparency: below avg.
Seeing: avg (3/5)
Darkness: city sky glow, no moon
Limiting Magnitude: 4 (unaided), 8 (bino)
Wind: none
Humidity: 75%-80%
Temperature: mid-70’s

Instrument: Bushnell 12×50

Jupiter: bright disc, no cloud bands. Right bino tube seems to have slight astigmatism; right eye has no astigmatism in left tube.

Ganymede: distinct dot ~2d right of Jupiter’s disc. According to S&T’s online utility for identifying Jupiter’s moons, the dot must be Ganymede.

Antares: yellowish-orange color that sparkles under magnification. Very nice.

M4 not visible, presumably due to sky glow and low-ap binos.

The “Antares pentagon” fills 80%-90% of bino’s FOV.

Vesta: approx. same mag. as nearby HIP80793, distinctly dimmer than phi-chi-psi ophiuchus.

Celestia data for Vesta was incorrect. To display Vesta’s correct position, Celestia’s database must be updated. In the file Celestia/data/asteroids.scc, in the section for Vesta, the orbital parameters should be:

EllipticalOrbit
{

Epoch 2453700.5 # November 26, 2005
Period 3.62885
SemiMajorAxis 2.36145
Eccentricity 0.08902
Inclination 7.133
AscendingNode 103.926
ArgOfPericenter 150.297
MeanAnomaly 205.652

}

These values were copied from wikipedia’s entry on Vesta. Some values lacked precision of metric values, so where more precision was desired the values were computed by dividing Vesta metric data by Earth metric data.

Used house fan to repel mosquitos. Need two fans as mosquitos bit leeward side (get it?) inside shirt.

Vesta! – June 04, 2007

The asteroid Vesta currently appears quite bright (for an asteroid) in the night sky. It’s bright enough to be seen with a pair of binoculars, or if you’re in a dark location you may be able to see it unaided.

The chart above shows tonight’s relative position of Vesta using Jupiter and Antares as guides. You’ll have to click the chart to see a larger, clearer view of Vesta. The good news for me is that it appears to be a few degrees north of Jupiter, so it should be mostly above the treetops behind my house.

Star-Hopping

Star-hopping is a method of finding dim objects (like an asteroid) by starting with bright objects and “hopping” with your binoculars from star to star until you find the target object. I’ve been suffering cloudy nights recently, so I haven’t actually tried to find Vesta yet, but from the chart it looks pretty easy to do.

Antares is the brightest unaided-view star near Vesta, so we’ll start there. Get a star chart that shows the location of Antares in the night sky. Sky and Telescope has a nice article on their site that includes a chart of Scorpius and Jupiter and more interesting details about Vesta. Antares rises in the southeast and moves higher and westward into the night. It’s the brightest star in the constellation Scorpius, although nearby Jupiter is even brighter. Once you have found Jupiter and Antares, you’re well on your way to Vesta.
Now let’s start hopping! Find Antares in your binoculars. Notice that it is a base vertex in a pentagon that can be easily seen in binoculars. North of the pentagon (and “up” in the star chart) there are three mag 4.2-4.5 stars (phi, chi, and psi ophiuchus) in a line pointing a couple degrees left of Vesta. Finally there’s a mag 5.6 star just left of Vesta, which is currently about 5.5 itself. Just remember the numbers five-three-two and you have the star-hops memorized!

Vesta is moving quickly to the west (to the right in the chart), so if you observe it several nights in a row you should notice the relative change in position.

I hope to get a chance to observe Vesta sometime this week.