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 

Friday, April 17, 2009

Recovery of comet P/2003 H4 (LINEAR) = P/2009 F7 (LINEAR)

IAU Circular No. 9038, issued on 2009 Apr 15, announces the recovery P/2003 H4 (LINEAR) = P/2009 F7 (LINEAR) by the LINEAR team and the undersigneds; it was last observed in August 2003.

The Lincoln Near Earth Asteroid Research facility: 

picked-up P/2003 H4 on 2009, March 31 during a single-night observing session. We indipendently found the return of this object on 2009 April 15.60 through one remotely controlled telescope of the "Skylive" network, located at Grove Creek (near Trunkey, Australia). 

In our images (stacking of 30 unfiltered images, 60-seconds each, with a 0.35-m f/7 reflector + CCD), the comet showed a diffuse coma about 15-arcsec in diameter, with a central condensation, having m2 about 19.6.

The recovered comet was about 8 arcmin East, South-East to the ephemerids positions, located in Hydra.

Here you can found our recovery image of April 15, 2009:

Afterwards we performed some further follow-up from different observing sites and instruments, that confirmed the aspect of this object. 

Like the Iowa Robotic Observatory (MPC# 857) 20x60 stack of images, obtained on 16 April 2009:

or the GRAS stacking, obtained on the same night under good seeign conditions (details on image):

According to the orbital elements published so far by the Minor Planet Center website (, perihelion will occur on June 2009, with the comet at 1.7 AU from the Sun. This Jupiter-family comet moves along an elliptic orbit in 6.1 years, having a semi-major axis of 3.3 AU, eccentricity of 0.49 and an inclination of 18 deg.

We would like to thank the Grove Creek-Skylive staff for their kind support during this recovery.

by Giovanni Sostero, Enrico Prosperi, Ernesto Guido & Paul Camilleri 

Tuesday, April 7, 2009

New Comet 2009 F6

IAUC Circular No. 9034, issued on 2009, April 6, announces the discovery by R. D. Matson of a new comet from analysis of ultraviolet SWAN-SOHO images obtained on 2009, Mar. 29, 31, Apr. 1, 3, and 4.

We undertaken a first try to locate this object from the private observatory of one of us on (about) Apr. 6.1; however we were unsuccessfull, due to some hardware problems with the telescope.

Afterwards we were able to confirm the existence of this comet remotely, through the GRAS network, using a scope located in Mayhill (NM): on 2009, April 6.5, co-adding of 10 unfiltered exposures, 60 seconds each, obtained by means of a 0.25-m, f/3.4 reflector + CCD, shown a diffuse coma about 2.5 arcmin in diameter, with a sharp central condensation about 20 arcsec in diameter. The magnitude of the central condensation was measured to be at about 14 (unfiltered CCD), while the total magnitude m1 has ben established to be about 11 (unfiltered CCD).

Stacking a total of 20 minutes exposure time, through equalization of the histogram, we can trace a coma diameter of nearly 5 arcmin; image enhancing techniques (azimuthal median subtraction and 1/r theoretical coma subtraction) show the presence of a short extension toward North-East, emanating from the central condensation (hint of a tail, or elongation of the coma?).

Our image is available here:

At the time of this writing, no orbital elements of this comet has been published by the Minor Planet Center. A preliminary calculation, performed by the undersigneds running through FindOrb the observation currently available at the the NEO-CP webpage, gives the following (approximate) orbital solution:

q= 1,3 AU, e= 1, Incl.= 85.5 deg, Peri.= 129.5 deg, Node= 279 deg.

UPDATE (07 April 2009, 14:00 UT)

IAUC Circular 9035 has been released and the new comet is now officially designated C/2009 F6 (YI-SWAN).

According to this IAUC, Dae-am Yi (Yeongwol-kun, Gangwon-do, Korea) has contacted H. Yamaoka, on March 28, informing him about his discovery of a possible comet through a Canon 5D camera + 90-mm telephoto lens. The available astrometry indicate that this is the same object of comet 2009 F6. So, the double denomination.

An Mpec with a preliminary parabolic orbital elements and an ephemeris has been issued too:

UPDATE (07 April 2009, 21:00 UT)

Our image of comet C/2009 F6 (YI-SWAN) rendez-vous with open cluster NGC 7789:

by Ernesto Guido, Giovanni Sostero & Paul Camilleri