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.

Photo Frenzy – August 16, 2009

Location: at home in Tomball, TX
Cloud cover: 0%
Transparency: above average (4/5)
Seeing: est. avg (3 or 4 out of 5)
Darkness: no moon, city glow
Wind: almost none (see below)
Temperature: 80º-85º
Humidity: 70%-85%
Dew Point: 72º-75º
Time: 9:00 pm – 1:00 am CDT
OTA: 8″ SC

Began with visual observation of Jupiter. Best view I have ever seen. Two main belts easily seen, two thin faint belts also visible in steadier seeing. All four Galilean moons visible: one left and three right.

Took photos of many targets using the D50. Most images had elongated stars varied in length and direction. In a couple of photos the stars are almost doughnut-shaped with dark centers. A few photos had no elongation, even at long exposures. Magnification shows elongated shapes are often irregularly shaped. My best explanation for the elongation is wind, although I felt no wind all night with only rare light gusts. Shutter is on 5 second timer. Perhaps I will try a longer timer next time.

Photos of M103 and M31 suffered from elongation. Photos of η Cas and Albireo (shown below) came out well. M76 was barely discernible even with a 30 second exposure at ISO 1600. Cat’s Eye Nebula (NGC6543) small, vivid teal, somewhat hazy — maybe from initial dew buildup that I didn’t recognize until much later.

Also took several photos of Jupiter and its moons, none of which were very good because of (as yet undiscovered) dew on the corrector. Several photos of Neptune and Uranus showed good color but no detail.

Albireo (β Cyg - double star). Click image for large (1500x1000) size.