Cassiopeia Observatory

Spectroscope Slit Test;
Imaging: Pleiades Spectroscopy, Moon
Posted: 17 October 2011

During the daytime on Sunday, 16 October, I did a slit modification for the spectroscope camera adapter I had made in September. I used single-sided razor blades:

The above image does not show the Fraunhofer lines as clearly as my previous attempt:

I tried to get the blades very close together while still leaving a gap. But the gap must still not be narrow enough. I was surprised that I lost the blue end of the spectrum as well. I have more work to do on this camera adapter spectroscope.

The observatory was opened at 2030 MST, 72°F. The sky was clear and the Milky Way was lovely overhead. I first viewed M57 (the Ring Nebula), M13 (globular cluster), and M92 (globular cluster) at 77X. These are always nice objects to look at. They will soon be gone from the sky as winter approaches. I then looked up the Right Ascension and Declination coordinates of Comet C/2009 P1 (Garradd) for this night using Sky Safari 3 Pro on the iPhone, and at 2052 MST, I observed the comet at 77X. The head and tail were easily visible. By this time, the eastern sky was beginning to brighten from the rising waning moon. At 2100 MST, viewed Jupiter at 77X and 133X; four moons and the Great Red Spot (near the central meridian) were visible. I tried 206X on Jupiter but seeing was not currently good enough.

At 2115 MST, slewed to M45, the Pleiades, and began setting up for D7000 DSLR spectroscopy imaging using the Star Analyser. These are various exposures from 1/30sec down to 1/2sec, ISO 2000, depending on the magnitude of the star.

Pleiades - Alcyone - Spectral Type B7

Pleiades - Atlas - Spectral Type B8

Pleiades - Merope - Spectral Type B6

Pleiades - Electra - Spectral Type B6

Pleiades - Maia - Spectral Type B7

Pleiades - Taygeta - Spectral Type B6

Pleiades - Celano - Spectral Type B7

I am not convinced that all the Fraunhofer lines in these processed images are real. Some may be artifacts from processing the faint spectra.

I ended imaging at 2151 MST and returned to observing Jupiter, now higher in the sky and with much better seeing. There were good views of the clouds bands at 206X and 364X. Adding the moon filter really improved the views, especially at 206X. Details in the atmosphere of Jupiter were clearly visible. By 2213 MST, seeing was excellent and offered tremendous views of Jupiter at 206X with the moon filter.

At 2221 MST, viewed the still low waning moon at 206X; some good views along the terminator. The view was sharper at 133X, as expected. I began setting up for D7000 lunar imaging. Switched to the visual back on the 8" LX200-ACF. This is a 1/320sec, ISO 250, exposure:

At 2252 MST, I ended imaging and resumed visual observing of the moon. Seeing was better now and there were some really great views along the terminator and limb at 364X. I tried pushing the magnification to 1091X (5.5mm eyepiece + 3X TeleXtender), but that was too much for current seeing conditions. However, 619X (9.7mm eyepiece + 3X TeleXtender) yielded some very impressive views of the terminator, especially in the south polar region.

At 2302 MST, returned to Jupiter. Tried using 619X on Jupiter but that was too much magnification. However, disks of all four Galilean Moons were clearly visible at this high magnification. Ganymede was very good.