News - April 2006

2006 April 29

Additional 19 designated fragments with calculated orbits have been announced. Components AU - BM are in the range of 17^m to 21^m. The number of designated fragments is now at 59. (MPEC 2006-H61)

2006 April 28

First unconfirmed reports of naked-eye sightings of component C of comet 73P/Schwassmann-Wachmann have been received. It has to be stressed that the visibility and estimated brightness of a comet so close to earth and with such a large and faint coma is strongly dependent on sky background and instrumentation. Differences up to several magnitudes in brightness estimations are easily possible. Every observer is strongly encouraged to use the smallest possible instrument or the naked eye for serious brightness estimations as well as the darkest observing location. As paradox as it might sound: A comet visible to the naked eye might be seen drastically smaller or even not at all with a large telescope. (Comets Mailing List)

2006 April 27

Most impressive images of components B and G of comet 73P/Schwassmann-Wachmann obtained with the Hubble Space Telescope have been published. Both show numerous small pieces of the comet, illustrating the continuing fragmentation process. (Press release)
Observations of component G by C. Hergenrother with the Vatican's 1.8-m VATT telescope on Mount Graham on Apr. 27, show 15 or more pieces; similar to the VLT observations of component B. (73P website by C. Hergenrother)

2006 April 26

Four new designated fragments for comet 73P/Schwassmann-Wachmann: AQ (14^m), AR (20^m), AS (17^m), and AT (17^m). (MPEC 2006-H37, MPEC 2006-H48)

2006 April 25

An example what a really large telescope sees when looking at the fragmenting comet 73P/Schwassmann-Wachmann has been presented by the Very Large Telescope. In a press release one sees that the number of fragment is in reality much, much larger than previously thought. Especially the close-up of component B dramatically shows the decay of this comet.
Further to the news item of March 24, 2006, the main-belt object found to show cometary behaviour has received an official cometary designation. P/1999 RE₇₀ = (118401) was found originally by LINEAR in 1999, and the 166^th comet for this survey. (IAUC 8704, subscription required)

2006 April 21

Further three fragments of comet 73P/Schwassmann-Wachmann have been designated (AN, AM, and AP), bringing the total number of designated fragments to 36. AP is the brightest one with about 15^m. Meanwhile component B shows now a nice double condensation as imaged by several observers (e.g. Gonano, Hergenrother, Ligustri, Masi, Sherrod). (MPEC 2006-H26, Comets Mailing List)

2006 April 19

New Discovery!: An apparently asteroidal object, discovered on April 7, 2006, in the course of the Spacewatch Survey has already been found to be cometary in confirmation observations by J. Ticha and M. Tichy (Klet). Since no other confirmations of the cometary nature were reported the object was announced as minor planet 2006 GZ₂. The day after the announcement J. Montani reported that re-inspection of the Spacewatch images as well as Spacewatch follow-up images showed a small coma. The 20^m comet C/2006 GZ₂ (Spacewatch) will pass perihelion Aug. 22, 2006, at about 3.3 AU. This is the 34^th comet for the Spacewatch Survey. (IAUC 8703, subscription required, MPEC 2006-G38, MPEC 2006-H10)

2006 April 18

Further orbits for the now 33 designated fragments of comet 73P/Schwassmann-Wachmann were published in MPECs 2006-G24, -G28 and -H03. The suspected disintegration of component B was most likely the separation of a smaller part of the nucleus. Please see again the page by Carl Hergenrother (news of April 12, 2006). (MPEC 2006-G24, MPEC 2006-G28, MPEC 2006-H03)

2006 April 12

The fragmentation of the complex of 73P/Schwassmann-Wachmann continues. Most remarkable is a probable disruption of the nucleus of component B, as can be seen for instance in images by Carl Hergenrother with the SAO 1.2-meter telescope at Mount Hopkins. (Comets Mailing List)
More astrometry confirmed the suspicion of the cometary nature of comet 2006 G1. P/2006 G1 (McNaught) will pass perihelion on Aug. 20, 2006, at about 2.6 AU. The period is about 10.6 years. (MPEC 2006-G43)

2006 April 07

New Discovery!: R. H. McNaught reports his discovery of a new comet on Apr. 05, 2006, in the course of the Siding Spring Survey. The first and preliminary parabolic orbit for the 18^m comet C/2006 G1 (McNaught) shows perihelion on Oct. 10, 2006, at about 1.6 AU. It is likely that this comet is of short period. This is the 17^th comet for the Siding Spring Survey and the 25^th for McNaught. (IAUC 8699, subscription required, MPEC 2006-G27)
Fragment G of comet 73P/Schwassmann-Wachmann has obviously also experienced an outburst and has been observed visually at 13^m. Components B and C are now almost equally bright, with B more easily visible due to its almost starlike morphology. Orbital elements for all components up to X can be found in MPEC 2006-G24. (Comets Mailing List, MPEC 2006-G24)

2006 April 05

The number of fragments for comet 73P/Schwassmann-Wachmann continues to rise fast. Eric Christensen reports that observations at Mt. Lemmon have revealed about 40 fragments. Peter Birtwhistle (Great Shefford) was able to confirm most of these newly found objects which are in the brightness range of 18^m - 22^m. Unclear until now is how the designation scheme will be extended since one can expect a further increase as the 73P complex nears earth. Until now components C, B, and G, are expected to reach brightness in the range of small to medium amateur telescopes. However, due to the dynamic behaviour of the complex (further fragmentation) and the nightly change of brightness and morphology, this can not be guaranteed. (E. Christensen in Comets Mailing List, P. Birtwhistle in Comets Mailing List, S. Yoshida, 73P-B, -C, and -G lightcurves)

2006 April 03

Further five fragments for 73P/Schwassmann-Wachmann, between 19^m and 20^m have been detected by the Mt. Lemmon Survey. They are denoted u, v, w, x, and y. Peter Birtwhistle reports that most of the already known faint fragments show quick brightness fluctuations and changes in morphology. G. Sostero reports (with the help of confirming reports by Stephane Garro, Francois Kugel and Esteban Reina Lorenz) that component G appears double. J. Bortle reports that component B has undergone an outburst and is now at 10.8^m. UPDATE: Numerous independent reports - both visually and via CCD - have been received by several observers, among them Michael Jäger, Kamil Hornoch, Maciek Jarmoc, Maciej Reszelski, and Juan José Gonzáles. (MPEC 2006-G10, Comets Mailing List)