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Annular Solar Eclipse 1999

Report on the Annular Eclipse 1999 Feb 16

by Fred Espenak (Greenough, AUSTRALIA)

Pat Totten, Bob Shambora and I traveled to Western Australia for the annular solar eclipse of 1999 Feb 16. This eclipse was unusual in that it was very nearly total. I calculate that the actual eclipse magnitude (fraction of Sun's diameter covered by the Moon) was 0.9906.This meant that the thickness of the annular ring from center line was only 9 arc-seconds!I had seen a similar eclipse in 1984 (magnitude 0.9979) and was able to photograph the chromosphere, so I was determined to try it again in 1999.

Our observing site was located at the Hampton Arms Inn, Greenough, Australia (south of Geraldton). That location was about half way between the center line and the northern limit. One of the reasons I picked this location was because it would provide an excellent view of Baily's beads, and yet still offer around 9 seconds of annularity (no beads).It would also provide creature comforts and amenities including toilets, welcome shade and a bar.

We were obviously expected when we arrived at the Hampton Arms Inn early on eclipse day. Innkeeper Brian Turnock met me in the drive with the greeting "You must be that mad American! I hear that you bite anyone who comes near your telescope!"I guess my reputation had proceeded me even way out here in Western Australia!

Brian allowed us to select a quiet location behind the Inn where I wouldn't be disturbed during the eclipse. We quickly set up our equipment and were ready several hours before first contact (about 2:01 PM). In the meantime, the Hampton Arms became a bustle of activity as eclipse chasers from all around the world descended on the place. There was a big Japanese group and a bus load of amateurs from Perth as well dozens of news media. Swiss eclipse chaser Olivier Staiger was there to carry the eclipse live on his High Moon web site and American eclipse expert Prof. Jay M. Pasachoff gave an eclipse lecture before lunch. Helicopters flew overhead all morning videotaping the growing chaos for the evening television news.I was interviewed half a dozen times, but only when I left my observing site.Apparently no one would approach me when I was near my telescope. It's amazing how the word had spread!After annularity, one journalist shouted a follow-up question to me from 10 meters away... as if fearing he would be torn to shreds if he ventured nearer!Yikes! Am I that ferocious???

Espenak at the 1999 Annular Eclipse

The weather conditions for the eclipse couldn't have been better. The sky was a crystal clear blue and not a single cloud was seen all day long. First contact occurred on time as the excitement of the crowd grew. The Sun was covered with a number of large sunspots which made the partial phases much more interesting to watch.By 3 PM (magnitude 0.66) we noticed the light falling along with the temperature.Venus was easily spotted in the darkening sky five minutes before mid-eclipse. I made a quick search for Jupiter but was unsuccessful. I would have searched nearer to annularity, but I was busy with my photographic program. The temperature at 1st contact was 99° F (ground 110° F), but it dropped to 77.2° F (79.5° F ground) at annularity. Then, it climbed back up to nearly 100° F by the time 4th contact arrived.

The nominal predictions for our position (without limb corrections) are:

                Lat.= 28°57.8'S      (position measured from GPS)               Long.=114°45.1'E      (Western Australia +8 hours ahead of UT)               Ecl.Dur.=02h43m52.3         Eclipse Mag.= 0.9906               Umb.Dur.=   00m36.4s        Eclipse Obs.= 0.9813                                        Diameter Ratio = 0.9906                        Universal  Sun    Sun    Sun   --Position Angles--               Contact    Time     Alt  Azimuth   HA     P      V      Q                        h  m  s     °      °      h      °      °      °                  1    06:00:44.4  64.2  305.2   1.43  244.2  111.6  132.6                  2    07:27:50.8  46.7  283.1   2.88  206.6   87.6  119.0                 Max   07:28:08.9  46.6  283.1   2.88  155.0   36.0  119.0                  3    07:28:27.2  46.5  283.0   2.89  103.3  344.3  119.0                  4    08:44:36.7  30.0  272.0   4.16   66.1  309.9  116.3

However, limb corrections indicated that the times of second and third contacts would acutally be:

                        Universal               Contact    Time                           h  m  s                    2    07:28:00.3   (including  +9.5s correction)                  3    07:28:09.3   (including -17.9s correction)               Actual duration of annularity (including limb profile) =   9.0s

Apparently, there were some rather large mountains along the Moon's southeast limb which would terminate the annular phase 18 seconds early.

Annular Eclipse Sequence

I photographed the eclipse with two telescopes. The first was a Vixen 80mm f/8 flourite refractor with a TeleVue Big Barlow. This gave me an effective focal length of about 1700mm. I used a Thousands Oaks Type 3 filter to photograph the event on Kodak Royal Gold 100 (color negative).

Baily's Beads and Annularity

The second telescope was a Vixen 90mm f/8 flourite refractor. I used this instrument to photograph annularity using NO SOLAR FILTER! The five image composite shot around annularity clearly show the chromosphere, a prominence and Baily's beads at both 2nd and 3rd contacts.Film was Kodak Royal Gold 100 (color negative) and the exposure was f/8 at 1/1000 for all frames.

Chromosphere at 2nd Contact

I stole a glance through the camera viewfinder at second contact and could see Baily's beads, but it was too bright to visually confirm the chromosphere and prominence (let alone search for the corona!).

Baily's Beads at 2nd Contact

After the eclipse, we packed up all our equipment and drove north. I had organized an impromptu dinner at a local restaurant in Geraldton for around 100 eclipse chasers from around the world. We had a wonderful time telling stories of the day's events and meeting many people I have only known through letters or email.

All in all, it was a fantastic eclipse and a good rehearsal for 1999 August's total eclipse on the Sun!

Special thanks to the generous invitation of Perth astronomer Jamie Biggs to share his observing site with us.We also thank the wonderful hospitality of Brian & Judy Turnock of the Hampton Arms Inn.

- Fred Espenak, 1999 March 11

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