Various series of astrometric and photometric reductions on comet 29P Schwassmann - Wachmann 1 (29P/SW 1) are presented at heliocentric distances of 5.1 (UA) . Even though the great distance to the Sun this comet presents an unexpected and irregular activity. Itís brightness has changed up to 4 magnitud orders during the detected outburts in 2002. Thereís no commonly accepted theory explaining this behaviour as yet. In this work it is tried to show the cometary behaviour as observed by amateur astronomers using a novelty photometric estimation method.
IntroductionNowadays we know comets are ice and rock particles, that from time to time enter the solar system from some external region (probably the Oortís cloud). These bodies sometimes perform their travel periodicaly trapped by the Sun. When comets reach the Sunís neighborhood, the heat makes itís components to evaporate. The gas nucleus and the dust form long tails that can be seen from Earth. These tails may extend as far as tenths of millions of kilometers.
Thereís a comet group trapped in eliptical orbits, most of them with low inclination to the ecliptic plane and moving in the direct sense. This comet group, named the Jupiterís family, lies orbiting in between Jupiter and the Sun and they all have periods under 20 years.
The discovery of comet 29P/Schwassmann-Wachmann 1.-
The brightness determination has been one of the most important goals of the comet observers. The defy of doing reliable estimations has been enormous given that we are measuring non punctual sources moving over the background stars. Most of the magnitud estimations have been accomplished by photographic or visual methods. Nevertheless, in last years different methods for magnitud estimation are being used.
· James Scotti comaís substraction method (Spacewatch).m2
· Estimations by other professional astronomers using CCD attached to big telescopes (m2). David Jewitt ,Licandro and others.
· Amateur estimations with CCD cameras. Various methods.
· Amateur visual observations with little telescopes and binoculars (m1)
The (m1) magnitud.
Nuclear magnitud (m2).
Magnitud estimation with the 10x10 method.
V02 Rafael Benavides Palencia. SC 23cm f/10Telescope
V03 Carlos Labordena Barceló. SC 20-cm f/10Telescope
V04 Carlos Segarra García. Newton 25cm f/5Telescope
V09 Maciej Reszelski
You can find theobserverís technical data at:
Photometry with the USNO catalog (in R band)
· 57% of the stars have error lower than .2 tenths
· 43% of the star have errors bigger that 0.2 tenths
The data gathered at the mail list "Cometas_Obs" are the following:
12 visual observations
30 CCD images
The light curve has been represented as corrected magnitud for the distance to the Earth against the time. UIT the observational data it can be seen the different outbursts the comet has undergo during the year.
The posible cyclic changes that can show a rotation period are masked,
but we can see instead the bchanges in more than one magnitud that are
probably related to outburts of CO2 ice deposits (carbon dioxide) and CH4
(methane) than the Sun heats gradually.
Curva realizada por Julio Castellano
The cometís coma is a matter halo sorrounding the cometís actual nucleus. The coma and the tail is all we really see from Earth. The comaís shape and size may vary for the smae comet during aparition. The shape depends on the distance to the Sun and the relative quantities of dust and gas production. For comets producing little dust, the coma is generally spheric. Comets producing great amounts of dust, use to have tails with parabolic shapes. This is due to different dust grain sizes. The bigger grains are ejected along the cometís orbit whereas the tiny dust particles are ejected against the Sun by the pressure of radiation of light. When thereís a distribution of dust particles sizes a tipical tail with beautiful shape develops.Comaís diameter
In general the comaís diameter is given as arc minutes (´) when
the coma grows it can be expressed as degrees. When the coma is elongated,
the measure stands for the shortest dimension. In the acompaning table
we show the 29P comaís actual diameter, against the distance to the Earth,
based on the angular diameter as obtained from the CCD images. The images
used for the coma size estimation have always been obtained with the same
integration time (exposure) and the same values of the background have
been used to calculate the relative size. We can see a relation between
the cometís brightness and the comaís diameter. In continued followup we
always found coma sorrounding the nucleus changing in size from day to
Conclusion.-· 278 CCD observations have been gathered, 12visuale and more than 30 CCD pictures of a great quality.
· The light curve is non typical for a standard comet and this probably speaks of a nucleus with gas deposits that provide the cometís extra unexpected brightness.
· Thereís a correlation between the brightness
and the coma size.
It is important to note there are not many comets with such a big activity at a large heliocentric distances 6AU. In effect, another object from the external solar system is the asteroid Quiron, with orbit between Saturn and Uranus, a coma was detected around his nucleus in the year 1989.
Iím gratefull to Julio Castellano for his cooperation with bthe graphics.
The observations with astrometry, photometry and images can be obtained