P/1998 U3 (Jäger)

P/1998 U3 (Jäger)

CopyrightŠ1998 by Akimasa Nakamura (Kuma Kogen Astronomical Observatory, Japan)

This CCD image was taken on 1998 November 10, using a 0.60-m f/6 Ritchey-Chretien telescope.

Discovery

Michael Jäger (Austria) discovered this comet on photographs taken with a 0.25-m Schmidt camera on 1998 October 23.93. He estimated the brightness as magnitude 12.5. The comet was quickly confirmed the next evening by observers in Europe. The comet was typically described as a condensed object 1 to 2 arcmin across, with a tail extending westward.

Historical Highlights

The first published orbit came from Daniel W. E. Green of the Central Bureau for Astronomical Telegrams on October 27. His parabolic solution indicated a perihelion date of 1998 December 9, but he added that the comet was likely moving in a short-period orbit. This was confirmed on November 14, when Green announced the orbit had a period of about 15.4 years and that the comet would pass perihelion on 1999 March 7.
Most observers were estimating the comet as brighter than magnitude 11 as November began. Coma diameter estimates then ranged from 0.9 to 2.3 arcmin. There was not much of a correlation between brightness, coma diameter, and telescope used for the observation, so the variations seemed dependent on the observer or observing conditions. The brightness and coma diameter did not seem to change much as November came to an end.
The orbit was better determined as January began, with Kenji Muraoka determining the perihelion date as 1999 March 10.10 and the orbital period as 14.94 years.
The comet appeared to reach its maximum brightness during early February when estimates were typically between 10.1 and 10.5. The coma was then between 2 and 3 arcmin. By early March observers were estimating the brightness as near magnitude 11.5, while the coma diameter was estimated as about 1.5 to 2.0 arcmin. The comet faded very slowly and by mid-May most observers were estimating the magnitude as 12 and the coma diameter as 1.5 arcmin.

Orbit and Ephemeris courtesy of the Central Bureau for Astronomical Telegrams

Additional Images

1998 December 13--0.13-m telescope

Yuichi Chimura image of P/1998 U3 exposed on 1998 December 13

This image was taken by Yuichi Chimura (Japan) on 1998 December 13. He was using a Takahashi MT-130 (0.13-m, f/6.1) and an SBIG ST-7 CCD camera.

M. Jäger image of P/1998 U3 exposed on 1998 December 26

This image was taken by Michael Jäger on 1998 December 26.10. He used a 0.18-m f/6.0 refractor. Exposure time was 52 minutes and the photographic emulsion was hypered TP6415. The image was cropped by the webmaster to save space. (Thanks to Gerald Rhemann for permission to use this image. Images by Rhemann, Jäger, and others are located on Rhemann's web site.)

1999 January 14--0.20-m Celestron

Stefano Sposetti image of P/1998 U3 exposed on 1999 January 14

This image was taken on 1999 January 14, using a 0.20-m f/7.1 Celestron and a Hi-SIS22 CCD camera. The image is composed of 60 30-second exposures..

1999 February 28--0.20-m telescope

Masayuki Suzuki image of P/1998 U3 exposed on 1999 February 28

This image was taken on 1999 February 28, using a 0.20-m f/9 telescope and a CCD camera. The image is a 120-second exposure. The image measures 16 by 12 arcmin.

M. Jäger image of P/1998 U3 exposed on 1999 March 18

This image was taken by Michael Jäger on 1999 March 18.83. He used a 0.25-m Schmidt camera. Exposure time was 9 minutes and the photographic emulsion was hypered TP6415. The image was cropped by the webmaster to save space. (Thanks to Gerald Rhemann for permission to use this image. Images by Rhemann, Jäger, and others are located on Rhemann's web site.)

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