Monday, April 20, 2009

Recovery of comet P/2002 LZ11 (LINEAR) = P/2009 H1 (LINEAR)

IAU Circular No. 9039, issued on 2009 Apr 19, announces our recovery of P/2002 LZ_11 (LINEAR), now designated P/2009 H1 (LINEAR); it was last observed in January 2004 (MPC code #372, Geisei).

After several frustating and unsuccessful tryings due to moonlight interference and stellar crowding (the searched comet was in Sgr) we initially picked-up P/2002 LZ11 on 2009, Apr. 17.45 through a remotely controlled telescope of the GRAS network (details on image):

In our stacking the comet was located about 4 arcmin to the East-Northeast of the ephemerids position: co-adding of 25 unfiltered exposures, 120 seconds each, through a 0.25-m, f/3.4 reflector + CCD, revealed the presence of an extremely compact coma, about 12-arcsec in diameter, and a short tail nearly 25-arcsec long toward West.

We tried further follow-up on April 18 from the same site and from the Skylive-Grove Creek Obs. (MPC #E16), however our efforts were hampered due to the star crowding and to the unsuitable observing conditions (a magn. 19 comet seen through amateurs instrumentation, needs a pretty good sky).

Hopefully we were more lucky using the 0.37-m, f/14 reflector + CCD of the Iowa Robotic Observatory near Sonoita, AZ ((MPC# 857) over the same night: co-adding of 20 unfiltered exposures, 120 seconds each, showed the presence of a tiny coma about 8-arcsec in diameter, with a faint extension toward West (two bright field stars were interfering with the detection of the small tail we had recorded well the day before). Our image is available here:

According to the orbital elements published so far by the Minor Planet Center website (, perihelion will occur on March 2010, with the comet at 2.4 AU from the Sun. This Jupiter-family comet moves along an elliptic orbit in about 7 years, having a semi-major axis of 3.7 AU, eccentricity of 0.35 and an inclination of 11.5 deg.

Ernesto Guido, Giovanni Sostero, Paul Camilleri and Enrico Prosperi 

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