Update about comet 19P/Borrelly

Further follow up performed by the undersigneds with the same instrumental set-up of our previous report (but with 600-sec total integration time) on 2009, May 17.21, shows that the secondary condensation (or knot) that has been reported on comet 19P/Borrelly (see our previous post) has significantly weakened, with an aspect extremely diffuse and elongated compared to our previous observation of May 15.21.

On May 17.21 the optocenter (difficult determination) of this feature had a displacement of about 4 arcsec in PA 301 with respect to the central condensation of 19P/Borrelly.

Our image is available here:

http://tinyurl.com/qnvpvw


Giovanni Sostero, Paul Camilleri, Enrico Prosperi & Ernesto Guido

Secondary condensation on 19P/Borrelly

Prompted by an alert note of Bernhard Haeusler, posted in the newsgroup [Comets-ml] on May 11, 2009 about a possible secondary "condensation" in 19P/Borrelly, we performed some follow-up about this comet.

Images obtained by the undersigneds on 2009, May 15.21 with the 0-61-m Cassegrain + CCD of the Sierra Stars Observatory (Maarkleville, CA) confirms the presence of a tailward, diffuse, secondary condensation or "knot", placed about 4.7 arcsec in PA 301 from the primary central condensation. This feature is nearly 1.5 magnitude fainter compared to the central condensation itself. Image processing techniques (azimuthal median subtraction of the inner coma) enhances the visibility of this detail.

Our image is available here:

http://tinyurl.com/qendnd

Comparing the offset data posted in the same blogspot by B. Hausler (May 7: 13 arcsec in PA 310) and F. Kugel (May 10: 8 arcsec PA 305), this feature apparently approaches the central condensation; however some foreshortening effect might be under course, also considering the fact that, on about 2009 June 5th, Earth will cross the orbital plane of this comet.

Paul Camilleri, Enrico Prosperi, Giovanni Sostero & Ernesto Guido

Possible Nova in Centaurus 2009

Following an alert note posted today by Grzegorz Pojmanski in the vsnet-alert newsgroup about a possible nova in Cen, on 2009 May. 13.57 we performed some follow-up of this object remotely through a 0.25-m, f/6 Ritchey-Chretien + CCD, from the RAS Observatory (Moorook, Australia).

We can confirm the presence of an optical counterpart with unfiltered CCD magnitude about 8.6 (UCAC-2 Catalogue refernce stars) at coordinates:

R.A. = 13h31m15.77s, Decl. = -63o57'38".6 (equinox 2000.0; UCAC-2 catalogue reference stars).

Comparison with an Anglo-Australian Observatory Schmidt red plate (limiting magnitude about 20), obtained on 1997, Feb. 05, show that this position is nearly coincident with a field star, whose position end figures are 15s.68, 38".6, and magnitude about 15 (however, the extreme stellar crowding due to nearby field stars, makes this measurement rather difficult).

Our image of this transient is available at the following URL:

http://tinyurl.com/qlbesc

UPDATE

This nova has been designated V1213 Cen. For more info see also this paper on NATURE.

by Ernesto Guido and Giovanni Sostero

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):

http://tinyurl.com/c4wn6x

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:

http://tinyurl.com/c7b2uf

According to the orbital elements published so far by the Minor Planet Center website (http://tinyurl.com/cqnamw), 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 

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: 

http://tinyurl.com/d5w83g

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:

http://tinyurl.com/dn568m 

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:

http://tinyurl.com/c8nm39

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

http://tinyurl.com/dlol8m

According to the orbital elements published so far by the Minor Planet Center website (http://tinyurl.com/c8k56q), 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 

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:

http://tinyurl.com/co95my

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:

http://www.cfa.harvard.edu/mpec/K09/K09G21.html


UPDATE (07 April 2009, 21:00 UT)

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

http://tinyurl.com/d7h7aj

by Ernesto Guido, Giovanni Sostero & Paul Camilleri

Recovery of P/2001 MD7 (LINEAR) = P/2009 F3 (LINEAR)

IAU Circular No. 9031, issued on 2009 Mar 20, announces the recovery of comet P/2001 MD_7 = COMET P/2009 F3 (LINEAR) by the undersigneds; it was last observed in April 2002.

We picked up this object on 2009 Mar 17, 18 and 20 through a couple of remotely controlled telescopes, located in New Mexico and Australia. The comet appeared as a pale glow, magnitude about 18, nearly 15 arcsec in diameter.

The recovered comet was very close to the ephemerids positions, however its detection has been a little problematic, because it was rather low in the morning sky just before twilight, located in a rich star field in Sgr. We took several nights of observations to locate it, fighting with clouds and moonlight interference.

Here you can see our image of March 22, 2009:

http://tinyurl.com/czgnts

According the orbital elements published by the Minor Planet Center, perihelion will occur in September 2009, with the comet at 1.25 AU from the Sun; at that time P/2009 F3 (LINEAR) will reach about magnitude 12. This object moves along an elliptic orbit in 7.9 years, having a semi-major axis of 3.97 AU, eccentricity of 0.68 and an inclination nearly 13.5 deg.

We thanks the Mayhill-GRAS and Grove Creek-Skylive staff for the kind support they provided us for this tricky recovery.

by Ernesto Guido, Giovanni Sostero & Paul Camilleri