Venus (07 March 2007)

Date: 07 March 2007 U.T.
Time: 1:28 - 1:42 U.T.
Telescope: 30cm Newtonian
Magnification: 200x
Filters: #80A (Blue), Moon&SkyGlow (Multiband)
Seeing: Poor to Fair
NELM: Twilight
Temperature: +46 F (+8 C)




The above sketch shows the basic appearance of Venus on this evening. South is up. Preceding is to the left. The 'X' shaped pattern was caused by 'spider diffraction.' The telescope's diagonal mirror is supported in the center of the tube by four, thin vanes (the spider). Usually spider diffraction isn't noticed; but on bright objects such as Venus enough light is transferred to the diffraction pattern for the eye to notice.

The fat, gibbous phase of the planet was the only obvious feature seen. During the first half of the observation a #80A filter was used. During the second half of the observation a Moon-SkyGlow filter was used along with the #80A filter. The #80A filter transmits 30% of the incident light. The Moon-SkyGlow filter transmits significantly more light and works like an RGB-Intensifier.

The filters gave the planet a weak, bluish tint. The diffraction spikes had a silver-gray color. The background sky was grayish. A break (gap) in the diffraction spikes was apparent approximately 5 or 6 planetary diameters from the planet.

Part of the west wall of my open-air observatory was lowered earlier in the day in order to allow the telescope to 'see' lower in my western sky. In an earlier attempt to observe Venus with the 30cm telescope the wall had gotten in the way.