Cassiopeia Observatory

D7000 DSLR Spectroscopy: Stars, M45

Posted: 10 October 2011

Opened Cassiopeia Observatory Sunday, 9 October, at 2040 MST, 62°F. The moon was a bright waxing gibbous phase, high in the sky. At 2044 MST, viewed Jupiter; 4 moons and the Great Red Spot (actually, a Pale Pink Smudge) were visible in the 26mm and 15mm eyepieces. Jupiter was too low for the 9.7mm eyepiece. Then I slewed to the waxing gibbous moon and did a brief terminator tour using the 9.7mm eyepiece. There were some interesting shadows and highlights. I took this iPhone 4 photo of the moon at 2054 MST. It is afocal, 26mm eyepiece, with the MX-1 afocal adapter.

I then began setting up for another night of D7000 DSLR spectroscopy using the Star Analyser. The bright moon doesn't interfere with bright star imaging. These are processed, 1/20sec, ISO 1600, exposures:

Polaris - Spectral Type F7

Algol - Spectral Type B8

As a test, I grabbed this 1/60sec, ISO 1600, exposure of Jupiter and its spectrum. Since there is no "slit", the spectrum blurs out. But an interesting image anyway.

I then added the focal reducer to the 8" LX200-ACF so that I could image M45, the Pleiades, using the Star Analyser. I did a test exposure to verify framing and then waited for M45 to rise higher in the sky. At 2200 MST, I took this spectrum of M45, 1/4sec, ISO 1600:

Some Fraunhofer lines are visible in the unprocessed image. I plan to image each of the bright stars in the Pleiades on the next session. Beginning at 2245 MST, I imaged two more stars, 1/30sec, ISO 1600:

Capella - Spectral Type G8

Aldebaran - Spectral Type K5

I ended the spectroscopy imaging for the night. I plan to do a single web page containing all the spectra that I capture. The page will be posted on some future Cassiopeia Observatory web site update.

At 2256 MST, I returned to Jupiter, now high in the sky. With the 26mm eyepiece, I noticed a moon's shadow just beginning its transit of the planet's disk. I switched to the 9.7mm eyepiece. From the size of the moon next to the planet and the size of the shadow, I guessed that the moon was Ganymede and that it was Ganymede's shadow in transit. I checked and I was correct.

At 2310 MST, the moon was high and just west of the meridian. Using the 9.7mm eyepiece, I did some more lunar terminator observing. I then switched to the 5.5mm eyepiece for some really great views along the terminator. I also went all around the lunar limb, observing craters and mountains along the limb. It is always neat to see surface features sticking up beyond the lunar limb or as a depression along the limb.