Friday, May 22, 2009

Recovery of 107P/Wilson-Harrington = (4015) Wilson-Harrington

MPECs 2009-K24 & 2009-K27, issued on 2009 May 21 & 22, reports our recovery of comet 107P/Wilson-Harrington, obtained over three consecutive nights: on 2009, May 19 and 20 from Mayhill (NM) through a 0.25-m, f/3.4 reflector + CCD (details on image):

and on 2009, May 21, by means of the 0.61-m f/10 reflector + CCD of the Sierra Stars Observatory, Markleeville (CA).

This object has an interesting story, since its cometary nature (a tail without coma) has been reported only once, at the time of its discovery, so its activity appears to be rather irregular:

Also in our current stackings, the object appears perfectly stellar, with no trace of any coma or tail. Comet107P/Wilson-Harrington was last observed on 2007, March 13 by the Mt. Lemmon Survey.

Ernesto Guido, Giovanni Sostero, Paul Camilleri & Enrico Prosperi

Monday, May 18, 2009

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:

Giovanni Sostero, Paul Camilleri, Enrico Prosperi & Ernesto Guido

Friday, May 15, 2009

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:

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

Wednesday, May 13, 2009

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:


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

by Ernesto Guido and Giovanni Sostero