Cassiopeia Observatory

D7000 Imaging: Crescent Moon, More Star Spectrum Tests

Posted: 23 June 2012

Opened the observatory Friday, 22 June 2012, at 1916 MST, 100°F. The sky was mostly clear, with some clouds low in the south, some haze, and a breeze. At 1924 MST, viewed Mercury, 77X and 206X. Then went to Saturn, 77X. No moons were visible before sunset. At 1928 MST, took a quick look at the crescent moon, 77X.

At 1935 MST, switched to using a visual back and mounted the D7000 DSLR at prime focus of the 8" LX200-ACF. I then began photographing the moon. (At 1950 MST, I saw the same large quail family walk by that I had seen on the previous night. There were definitely 12 chicks.) At 1955 MST, I captured this image of the moon, 1/250sec, ISO 800:

I then removed the camera and visual back, switched back to using the star diagonal, and did some lunar observing, 77X, 133X, and 206X. Seeing was not ideal but there were some nice views at times.

At 2005 MST, I returned to Saturn, 77X. Three moons were visible: Titan, Rhea, and Dione. Using 133X and 206X, I tried for Tethys and Enceladus but they were too close to the planet to be visible, given the poor seeing.

At 2012 MST, I began preparations for doing more star spectrum tests using the Star Analyzer. Unlike the previous night when I used a high ISO setting of 1000 and short exposures of 1/20sec and 1/30sec, this night I used ISO 200 and longer exposures. I did a focus test using the Bahtinov Mask on the star Spica with the Star Analyzer installed on the prime focus camera adapter. I then did a series of exposures (without the mask) from 1 second to 1/10sec. This is a cropped image at 1/2sec of Spica (Spectral Type B1):

This is the processed image with some real spectra lines visible:

I repeated the imaging on Vega (Spectral Type A0). This is a 1/4sec, ISO 200, exposure, cropped:

And the processed image, showing spectral lines:

It does appear that using longer exposures at a low ISO setting improves the image quality, reducing the affects of digital noise.

Closed the observatory at 2052 MST, 84°F. One Kissing Bug terminated.

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