COMET SHOEMAKER-LEVY 9 COLLIDES WITH JUPITER

By: Jeff Beish, A.L.P.O. Observer

INTRODUCTION

This brief report is an account of the first visual observations of fragment 'A' (21) impact site of the Comet Shoemaker-Levy 9 (1993e) after it collided with Jupiter on 16 July 1994. These observations were made at The Beish Observatory located 20 miles south of Miami, Florida. Observations began at 1930 UT (3:30 p.m. EDT), 16 July 1994 and ended at 0400 UT (12 a.m. EDT), 17 July 1994. Observers used the observatory's excellent 16-inch (41cm) f/6.9 Newtonian telescope with optics by Dan Joyce of Chicago, Illinois.

Ambient conditions during observations were: temperature 98°F, humidity 53%, barometric pressure 1010mB. The sky was mostly clear and deep blue with about 20% "fair weather" cumulus clouds and 20% cirrus and cirrocumulus clouds with winds of 5 to 10 MPH from the east. Conditions remained the same until 8 p.m. when it cooled to 91°F and the wind decreased to the usual 3 to 5 MPH.

The author acquired Jupiter visually in the telescope at 3:30 p.m., 16 July 1994 (July 16.813 UT). Jupiter was very close to the Moon at the time, so it was not too hard to locate. The telescope was in focus from observations the night before. Since this was daylight the chances of possibly seeing the impacts of comet Shoemaker-Levy-9 were slim to none, but the work continued even with less than desirable conditions. High afternoon air temperatures rendered "astronomical seeing" poor and a light haze and cloudiness reduced transparency. All that could been identified on the boiling image of Jupiter was the North Equatorial Belt (NEB) and South Equatorial Belt (SEB). Also noted was a faint dark patch in the south limb on the planet's morning limb.

THE FIRST REPORT OF IMPACT SITE

One hour later after acquiring Jupiter in the telescope, at 2130 UT (July 16.896 UT) seeing had increased to 5 or 6 (A.L.P.O. scale 0-10[perfect]) and transparency to 5 (A.L.P.O. scale 0-6 [6th magnitude] ). At 2130 UT a dull blurry dark area was seen about 10 or 20 degrees away from Jupiter's morning limb in the general latitude of the South Tropical Zone (STZ). The area was barely visible and was only slightly darker than the zone or combination of zone and belt. It appeared to be a "limb effect" or a darkening of the morning limb in that general region. A brief note and rough drawing was made (See Figure 1).

Figure 1. Southern half of Jupiter as drawn by Jeff Beish on 16 July 1994 at 2130 UT using 16-inch f/6.9 Newtonian telescope. Chart shows dark, diffuse feature in South Tropical Zone of Jupiter that turned out to be the first visual observation of the impact site of comet Shoemaker-Levy 9 (1993e) on Jupiter. "Astronomical seeing" poor due to daylight observation and light cirrus clouds.

After returning to the telescope 15 minutes later the appearance was the same as before and this observer was not concerned. After all, we had predicted a bright cloud or white area after the comet fragment hit the upper atmosphere of Jupiter. Science wins, guessing loses.

At 2255 UT (July 16.955 UT) the German equatorial mounted telescope was turned through the meridian and again Jupiter was re-acquired visually. A quick glance at Jupiter revealed the same appearance and the dark area was noted to have become darker; however, fine details of the feature could not be seen clearly. As stated before, observers were expecting a bright area where the comet 'A' fragment was to impact. The primary end of the telescope hit the patio floor with 14:00 on the Right Ascension circles and observations were resumed in a few minutes (Jupiter was at R.A. 14:12, Declination -12°).

At 2312 UT I re-acquired Jupiter visually and began to set the clock driver corrector and general set up for observing. I glanced at Jupiter but didn't notice anything in particular, except for the dark patch in the STZ. Satisfied that the telescope was tracking okay and operating satisfactorily I went into the house to cool off and drink water. Returning to the telescope at 2030 UT the seeing had increased to 8, transparency to 6+, and I began to observe Jupiter at 382x.

I noticed something strange near the central meridian (CM). At 2335 UT (16.983) I saw what I believed to be the impact site of fragment 'A" of the comet. It appeared as a dark round spot with a small clockwise tail about as long as the diameter of the spot winding south east (planetographic) and was surrounded by a defuse ring or semi-circle of dark material. Without revealing what I had seen I then called out for someone in the house to come and observe Jupiter.

My daughter, Natalie K. Beish, was first to arrive and observed for a few minutes. She then remarked that a strange dark spot was on the surface near the center-left and near the south of the planet. She asked where the spot was located on Jupiter and I answered the STZ. She acknowledged and verified the observation at that time. Natalie is an experienced observer and recognized the unusual feature on Jupiter right away. While my daughter observed I began to record my impressions and made a drawing of the south half of Jupiter (See Figure 2).

My daughter then went into the house and called Carlos E. Hernandez, A.L.P.O. Mars Recorder, to come observe. Carlos arrived and observed. He remarked that this must be the impact effects that he had never seen anything like that on Jupiter ever. My wife, June Beish, also an experienced Jupiter observer, then observed and remarked in a similar manner.

At 2340 UT I then called Don Parker, A.L.P.O. Mars Recorder, Carol Gables, FL and Phil Budine, A.L.P.O. Jupiter Recorder, in Walton, New York and reported that we had observed dark feature of first comet fragment impact. I later called both observers again and they verified the feature. Parker made a CCD image of Jupiter at 0006 UT, 17 July 1994 using 16-inch (41cm) f/6 Newtonian and LYNXX PC CCD camera (See Figure 3).

At 2359 UT I notified Brian Marsden of the Central Bureau for Astronomical Telegrams that I had observed an unusual phenomena on Jupiter and believed it to be the fragment 'A" impact of comet Shoemaker-Levy-9.

Figure 2. (Top) Southern half of Jupiter as drawn by Jeff Beish on 16 July 1994 at 2235 UT and (Bottom) full disk drawing by Carlos Hernandez a few minutes later using 16-inch f/6.9 Newtonian telescope. Chart shows dark, well defined feature in South Tropical Zone of Jupiter the first reported visual observation of the impact site of comet Shoemaker-Levy 9 (1993e) on Jupiter.

OBSERVATIONS CONTINUED

Observations of the comet collisions continued into the next morning at the same location with Carlos Hernandez, Natalie and June Beish. Fragment "B" impact site was observed at 0335 UT, 17 July 1994 and a there appeared to be a "bow shock wave" effect to the surrounding areas. This impact even effected STB. We observed until Jupiter was nearly set in the western sky.

Figure 3. First CCD image of dark, well defined feature in South Tropical Zone of impact site of comet Shoemaker-Levy 9 (1993e) on Jupiter. CCD image take on 17 July 1994 at 0006 UT with LYNXX PC CCD camera and 16-inch f/6 Newtonian telescope by Don Parker of Coral Gables, Florida.

On 18 July 1994 at 6:12 PM (1812UT) we found a dark defuse spot on CM at 6:16 p.m. (1815UT) we considered to be fragment 'H'. SEB had faded, about 25% as dark as NEB. Observers Carlos Hernandez, Patty and Tippy D'Auria.

We continued to observe and record all of the collisions of comet 1993e and Jupiter for the next several weeks along with an occasional experienced observers: Steve O'Meara (Sky and Telescope Magazine), Dan Joyce (Chicago mirror maker), Jim Carroll (Chicago mirror maker) and others, who dropped in from time to time.

Complete reports and references can be found in The Strolling Astronomer (the A.L.P.O. Journal) and Through the Telescope (A.L.P.O. newsletter).

DISCUSSION

After first seeing a dark fuzzy feature on morning limb of Jupiter's southern hemisphere in the STZ this author passed it off to a "seeing effect" often seen on the planets while observing in daylight. The atmosphere is very turbulent during the day time and often distortions or discoloration on the planets can be seen that is cause by the atmospheric turbulence. We were in luck that day because the previous weeks the "astronomical seeing" was very bad due to a dusty haze over South Florida from a dust storm in the African desert.

At first, I did not recognize the dark feature as anything unusual, but began to suspect something after a couple of hours of observing Jupiter a few minutes each quarter hour. When it finally dawned on me that this was a unusual feature I was sure that it was the remains of the fragment 'A' (21) of the comet collision, but was dark instead of the expected bright cloud area.

I immediately called two of the ALPO observers who were setting up to observe the events and then to report the observation to Brian Marsden at the Smithsonian Astrophysical Bureau for Astronomical Telegrams (IAUC). He reported to me that I was the first to call and notify him of an observation of an impact site. He then called the Teide Observatory and Nortic Optical Telescope sites (Canary Islands) to confirm the observations. Their reports can be read telegrams Iauc 6022 and Iauc 6023 on 16 July 1994.

This astronomical event was truly spectacular and something none of us are likely to forget very soon. The fact that humans saw an object of comet size hit another planet in our Solar System is amazing in itself; however, the impact (sic) of this event will make us think -- we on Earth are not 100% safe from such collisions.

This report, and thousands of similar accounts by amateur astronomers all over the world, should put an end to such nonsense as was reported on TV that amateur astronomers would probably be unable to see the effects of the comet impacts on Jupiter. Those who claim that amateur astronomers were so ill equipped and incapable of observing such an event have their heads buried deeply in sand. Even some amateur astronomers discounted the value amateur contributions and should be ashamed of themselves.

References after this paper was published

Beish, J.D. and C.E. Hernandez, "A Collision in the Solar System:
Observations of the First Impacts of Comet Shoemaker-Levy 9 with the Planet
Jupiter,"  Southern Sky Magazine, Number 8, Nov/Dec 1994.

Beish, J.D., and Carlos Hernandez, "A Collision in the Solar System,"
Through the Telescope, No. 2, September 1994.

Beish, J.D., and Carlos Hernandez, "Observations of the Impact of Comet
Shoemaker-Levy 9 With Jupiter," Through the Telescope, No. 3, November 1994. 

Hernandez, C.E., P.W. Budine, D.C. Parker, and J.D. Beish, "A Collision in
the Solar System: The Impact of Comet Shoemaker-Levy 9 with the Planet
Jupiter," J.A.L.P.O., Vol. 39, No. 3,  February 1997.

Naming me first to see Comet Showmaker-Levy 9 fragment 'A' Impact on
Jupiter, International Astronomical Union Telegram: Smithsonian
Astrophysical Observatory; Circular No. 6023, 17 July 1994.

Pujic, Zac, "Amateurs Observe Comet Impacts," Southern Sky Magazine, No. 7,
P. 53, Sep/Oct 1994.

MacRobert, Alan, "Amateur Astronomy's Greatest Week," Sky and Telescope
Magazine, Vol. 88, No. 4, P. 24-26, October 1994.

O'Meara, Steve, "The Great Dark Spots of Jupiter,"Sky and Telescope
Magazine, Vol. 88, No. 5, P. 30-35, November 1994.

Eicher, David J., "Jupiter's Embattered Cloudtops," Drawings of Comet
Impacts on Jupiter by Beish et al, Astronomy, Vol. 22, No. 12, pp., 70-77,
December 1994.

Spencer, John R., and Jacqueline Mitton, The Great Comet Crash,  Cambridge
Press.  Drawings and references to my observations of comet/Jupiter event.

"Celestial Firworks: Comet chunk smashes into Jupiter, creating huge
plume," The Miami Herald, (July 17, 1994)

"Outer Limits: Thousands of South Floridians are turning out to see
celectial show," Sun-Sentinel, (July 20, 1994)

"Comet Pummels Jupiter, revealing Details," The New York Times, (July 18,
1994)

"Amateur astronomer first to see Jupiter's heavenly firworks,"  South Dade
News Leader, (July 22, 1994)

"Comet impact sighting wasn't heavenly for finder," Sun-Sentinel, (July 15,
1995), Associated Press, Press release.