2 Sep 2009 – Shutter Shake, Jupiter Eclipsed

Location: at home in Tomball, TX
Cloud cover: less than 5%
Transparency: average (3/5)
Seeing: avg (3/5) or sometimes slightly better
Darkness: no moon, city glow
Wind: almost none
Temperature: 76º-82º
Humidity: 57%-67%
Dew Point: 65º
Time: 10:00 pm – 12:30 am CDT
OTA: 8″ SCT
Guidescope: 70mm refractor

First light with guidescope. Very disappointed to discover PHD Guiding software did not recognize the NexImage and it claimed my scope did not support pulse mode. Fiddled with it longer than I should have. Bottom line: zero success.

Guidescope was very useful for making fine adjustments while D50 was attached to the main scope. Best practice using laptop to view real-time output from NexImage in the guidescope, but eyepiece use works ok, too.

Tried to image Jupiter, photos were awfully blurry. First image seemed to show moon touching jupiter’s limb, no other moons. Tried again with ep. No moons visible, black spot visible at edge. Re-installed D50, tried to re-focus, star image was an irregularly shaped streak even with relatively short exposure times less than 1/10 second. I suspect vibration from the shutter, but it was late and I was tired of trying to debug it.

Finally reverted to visual observation. By this time two distinct black spots were visible. I thought I was seeing a double eclipse, but later cross-ref with SNP and SkyViewCafe indicated one spot was the shadow of Europa and the other Ganymede itself. In the illustration below, the top spot is the shadow of Europa and the bottom spot is Ganymede.

Illustration of Eclipse on Jupiter's clouds

It’s All About Control – 28 August, 2009

Location: at home in Tomball, TX
Cloud cover: less than 5%
Transparency: average (3/5)
Seeing: below avg (4/5)
Darkness: no moon, city glow
Wind: almost none (see below)
Temperature: 70º-72º
Humidity: 95%+
Dew Point: 69º+
Time: 10:45 pm – 12:15 am CDT
OTA: 8″ SC

First light using Starry Night Pro to control the telescope via serial cable. I have an old version of SNP (4.5) and there are a few minor user interface quirks, but generally I was pleased with the operation. Also first light using DIYPhotoBits to control the Nikon D50 via USB. I was very pleased with the results. I’ve actually modded DIYPB to display images after download using IrfanView, making it much easier to center and check focus.

I started with M57, the Ring Nebula. Exposures above 10 seconds exhibited elongation. It didn’t occur to me until later to use DIYPB’s time lapse feature to collect a set of images for stacking, so I only captured two at that speed. M57 is hardly visible at only 10 seconds, even using ISO1600, so there’s not much to see there.

Next I captured photos of Jupiter and the Galilean moons. Due to the bad seeing and the humidity the image quality was quite poor. The two main bands were visible but murky and the entire image seemed slightly out of focus. I rechecked the focus with the Hartman mask and that was not the problem. The composite photo below shows the relative positions of the planet and its four moons. Io and Europa (on the left) passed in conjunction over the next couple of hours, but it was already late and I didn’t want to stay up for it.

Jupiter and its moons (composite image)

Last I photographed M52, an open star cluster in the constellation Cassiopeia. As earlier with M57, I was unable to get an exposure longer than 10 seconds without elongation. It occurred to me then to use DIYPB’s time lapse feature to take several photos (10, actually) in quick succession then try to stack and merge them later. I tried stacking with RegiStax5, but I was not pleased with the results: the stars looked dull and washed out. I stacked the frames by hand and the result was much better.

Composite image detail of M52(click image for 1000x800 resolution)

This image shows far fewer stars than you might see in a typical photo of M52. This view is representative of what you might see in an amateur telescope. You mileage will vary depending on your telescope and sky conditions.

Entry for July 04, 2007

Location: Uniontown, OH
Cloud cover: < 5%
Transparency: avg.
Seeing: avg (3/5)
Darkness: city sky glow, no moon
Wind: < 5mph
Humidity: 85%-90%
Temperature: 65°F-70°F
Start Time: 9:30 pm EDT
End Time: 10:30 pm EDT
Instrument: Meade 50mm telescope; eyepieces: 17.5mm, 12mm, 9mm
Bushnell 12×50 binoculars

Saw Venus and Saturn side by side in binoculars. With telescope Venus crescent and Saturn’s rings clearly visible, but not gap between rings and planet. Could not find Titan at ~8.5

Saw Jupiter and 4 Galilean moons. Jared drew diagram of moons relative to planet, then searched for reference and identified each of the four moons.

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: 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.