Jim Loudon Observatory
Mercury Transit Observations

Richard E. & Dolores H. Hill JIM LOUDON OBSERVATORY 10130 E. King Manor Tucson, AZ 85730 Longitude:110.77554 deg. W or 110 deg. 46' 31.9" Latitude: 32.18006 deg. N or 32 deg. 10' 48.2" Height above sealevel: 2875 ft. Equipment: C11 with 5" off-axis aperture of Solar Skreen. Data recorded with GBC505e video camera filtered further with wide band H & K-line interference filter. 6" f/10 visual Newtonian Solar Telescope (uncoated mirrors and mild additional filtration). C5 with Tuthill Prominence Filter and 1.5" off-axis aperture. ETX with visual (Solar Skreen) filter. =====================================
Dolores and I observed the transit from our home. I spent about 4 hours ensuring everything was ready, visual instruments, H-alpha and video system. Fortunately there were plenty of good sunspots for the task. An attempt was made to see the planet against any H-alph features but none were seemingly available. Video and visual observations were begun at 2105 UT. The planet was located about a minute after first contact as a clear notch in the limb of the sun. From this point on continual, uninterrupted video was done. As we watched and recorded, at no time did we observe the true ink-drop effect where a dark extension connects the planet with the solar limb. This was recorded too. Instead we saw a thin thread of light form with a slight outward bulge that got wider with time. Both the visual (Dolores) and video observed second contact to be:21:22:20 UT. Once on the solar disk Mercury was seen to be definately darker than the sunspot umbrae. At mid-transit about, 21:40 UT, we observed that the planet was inward from the limb approximately two thirds it's own diameter (9.9"). At that time it passed a small bright polar facula (as seen at the video wavelength around the H & K lines of Calcium). This could only just be seen in visual light through the 6" and not at all in the ETX. Third contact occurred at 21:58:30 as seen by both observers, again without any ink-drop. This leads me to conculde that this effect must be more a function of local atmospherics than anything else. Last contact was mutually observed to be:22:08:40 in seeing of 2-3". Video continued for several minutes afterwards and then a recording of the major sunspot groups.

The equipment used, all in a bunch. From left to right: C5 (in back) with visual (Solar Skreen) filter, 6" f/10 Solar Newtonian (uncoated mirrors and filter), ETX with Solar Skreen filter, C11 with 5" off-axis Solar Skreen filter to record video. All darker parts were covered with cloth to minimize solar heating, a big problem in Arizona were our temperatures were in the high 80's (F) during the transit.

Close up of the C11 and video cart. Note the box over the video monitor to allow use in full sunlight. Everything had to be covered with white cloth.

The new little ETX with a Solar Skreen filter used for visual observation. This telescope did a splendid job of showing Mercury's disk on the sun.

the front end of the C11 with the 5" off-axis aperture Solar Skreen filter.

The C5 with a full aperture Solar Skreen filter. I do not recommend a brass filter holder as it heats up too much!

The 6" f/10 Solar Newtonian consisting of two uncoated mirrors (primary and diagonal) with the addition of #8 filtration on the eyepiece. WITH SUCH PREFILTERING IS THE ONLY TIME AN EYEPIECE FILTER CAN BE SAFE!! The old (washed!) sock on the focusser prevents burns from the eyepiece heating in the ambient sunlight.

Active Region 8765, the largest on the sun the day of the transit. This was a naked eye spot group. Note granulation. This photo was taken by simply using the digital camera to snap a pic. of the monitor.

The Transit

All images from video with North up and West right