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.
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
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
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.
All images from video with North up and West right