The Virtual Impactor Minor Planet 2008 HJ

After its posting on the NEO Confirmation Page with the NEO-Confirmation Page with code BK08329, follow-up was secured by a number of observers, among which our osservatory (M.P.C. Code #473).

M.P.E.C. 2008-H26, issued on 2008 April 25 , 20:51 U.T. , has announced the discovery of 2008 HJ: this is the tempoarary designation of the object, by the M.P.C. observatory code #704 Lincoln Laboratory ETS.

After few days, the asteroid has been catalogued as a "virtual impactor", because it has a very little probability that its orbit could be a threat for our planet; however currently it is flagged with a level "0" in the Torino scale. This situation could change, so these kind of minor planets are kept under strict monitoring by two istitutions , that are collecting the updated astrometric measurements about 2008 HJ : the Neo Object Program and Neo Dys Risk Page.

As suggested by the Minor Planet Center, it is mandatory to perform futher follow-up of this asteroid in next months, in order to improve the knowledge of its orbit with new measures. This is important to reduce the uncertains on orbital parameters and to confirm that 2008 HJ really belongs to the 0 class of Torino scale, that rappresents a very low level of hazard.

The image below of 2008 HJ has been obtained by Remanzacco Observatory team in the same day of its discovery.

At the time of discovery, 2008 HJ had the smallest known rotation period in the Solar System, completing one revolution every 42.7 seconds (see lightcurve below).

Credit: R. Miles

by Ernesto Guido

Comet C/2008 J2 (BESHORE)

IAU Circular nr. 8941, issued on 2008, May 7, announces the discovery by E. Beshore of a new comet named C/2008 J2 (BESHORE).

It was discovered with the 1.5-m reflector of the "Mount Lemmon Sky Survey" on 2008, May 6.44, and it has been described by the discoverer as having a bright condensed coma, diameter of 20 arcsec. Preliminary orbital elements from the Minor Planet Center show that this object moves along a parabolic orbit (i= 16.6 deg, q= 1.1 AU); perihelion is expected to occour on 2008 October 7th. According the current ephemerids, the new comet "Beshore" will reach approximately magnitude 8.5 at perihelion.

Soon after its posting in the M.P.C. NEO_Confirmation Page (around noon, April 6th) with the ID code "8JBD660", we wanted to get a close look at this relatively bright object, picked up just hours earlier. Unfortunately the weather conditions in our traditional observing site (Remanzacco Observatory, MPC code 473) were poor. So we decided to gave it a try from a new observatory (now under completion) that is operated by our astro club:

This new observing site is located about 20 Km East of Remanzacco, in the slopes of a nice mountain, named Mount Matajur. Since the Mount Matajur Observatory is 1340-m high, we hoped to skip at least some part of the haze that was affecting the plains where the Remanzacco observatory is located.

It was a wise decision, since while there, the sky suddently cleared up, so we were finally able to inaugurate our NEO/comets follow-up observing program from the recently "appointed" astrometric site MPC #B68!

When we located this relatively slow moving interloper in Ophiucus through a 0.2-m f/3 reflector + CCD, we initially considered it a star-like object (or at least, this was our very first impression looking at the single raw images that appeared on the PC monitor). However, when we carefully inspected the final stacking of 20 unfiltered exposures (60 seconds each) obtained on 2008, May 6.95, we immediately realized that this was not the case, since we noticed an extremely compact coma of almost uniform brightness about 20 arcsec in diameter, slightly elongated toward south-west:

The total magnitude m1 was measured to be R~14.

Afterwards, we decided to continue the study of this comet candidate (still listed in the NEO-Confirmation Page as object "8JBD660") with the instruments of the "Rent A Scope" network. So, on 2008, May 7.3 we connected with a 0.25-m f/3.4 reflector + CCD located near Mayhill (NM), where we initially collected 10 unfiltered exposures, 60-seconds each, that we stacked. Analyzing the result, we were able to confirme the existence of a coma nearly 25 arcsec in diameter elongated toward PA 240 deg, with a very flat photometric profile:

Filtered photometry performed soon afterwards (on 2008, May 7.37) through the same scope and a Cousins Red filter provided a total m1 magnitude of R~ 13.9, while a preliminary afrho calculation (proxy of the dust abundance within the coma) gave a value of nearly 450 +/- 80 cm; considering its current distance from the Sun, this seems to point toward an active comet.

by Giovanni Sostero & Ernesto Guido

Recovery of Periodic Comet 15P/Finlay

Periodic comet 15P/Finlay has been picked-up by the undersigneds on 2008, April 27.79 by means of a 0.25m, f/6 reflector + CCD (remotely, near Moorook, AU) and confirmed on 2008, April 28.70 through the same instrumentation.

Our recovery image:

 

Our astrometry:

0015P C2008 04 27.79053 22 58 27.09 -12 37 33.0 17.2 N EJ027D90

0015P C2008 04 27.79941 22 58 29.31 -12 37 19.0 17.5 N EJ027D90

0015P C2008 04 28.78638 23 02 33.02 -12 10 37.3 17.4 N EJ027D90

0015P C2008 04 28.79848 23 02 36.10 -12 10 18.9 17.5 N EJ027D90

According to the Minor Planet Center's website "Dates of last observation of comets" it was last observed on: 2002 03 30.42 14.0 T 340

W. H. Finlay (Royal Observatory, Cape of Good Hope, South Africa) discovered this comet with a 7-inch equatorial on 1886 September 26.83.

It's interesting to notice that, due to the proximity to Earth of its orbit (15P/Finlay is a Jupiter-family comet in a low inclination orbit just outside Earth's orbit), comet Finlay has been studied by several authors as a potential candidate for meteoroid delivering. D.A.J. Seargent discussed a potential relation of the famous Murchison meteorite fall with 15P/Finlay.

"Lubor Kresak identified comet 15P/Finlay as a likely source of meteor storms in the period 2004-2064. Neslusan and coworkers searched for photographed orbits in the IAU database, expecting activity around september 24, but no orbit could be linked to this comet. Martin Beech found that in the years 2001 and 2008 some meteoroids can make it toward the Earth's orbit, but Earth is not a the right time at that spot to cause a meteor outburst." (P.Jenniskens, 2006, chap. 19)

In a paper published in 1993, Z. Sekanina investigated about the orbital anomaly of 15P/Finlay (and few other periodic comets) as a result of the temporary activation of new discrete sources in cometary nuclei.

by Ernesto Guido & Giovanni Sostero

References

G. Kronk, http://www.cometography.com/pcomets/015p.html

P. Jenniskens (2006), Meteor Showers and their Parent Comets

L. Kresak (1992), Meteor Storms. Meteoroids and Their Parent Bodies

Comet C/2008 J1 (BOATTINI)

IAU Circular nr. 8940, issued on 2008, May 3, announces the discovery by Andrea Boattini of a new comet (his second) named C/2008 J1 (BOATTINI).

It was picked-up with the 0.68-m schmidt of the "Catalina Sky Survey" on 2008, May 2.46, and it has been described by the discoverer as having a coma diameter of nearly 50 arcsec, and a fan-shaped tail 2 arcmin long toward PA 235 deg. After posting on the Minor Planet Center's 'NEOCP' webpage, a number of observers performed follow-up of this object. The undersigneds observed it through the 0.45-m, f/4.4 reflector + CCD of the Remanzacco Observatory (Italy) on 2008, May 3.0: we noticed a small compact coma, almost 15 arcsec in diameter, having a total magnitude of 14.7 (m2 nearly 15.5); an apparent tail spans almost 35 arcsec toward PA 280 deg. (see image below; click on it for a bigger version).

Preliminary orbital elements from the Minor Planet Center show that this object moves along a parabolic orbit (i= 46 deg, q= 1.5 AU); perihelion has been reached in the middle of March 2008. According the current ephemerids, the new comet "Boattini" will decrease its brightness as it will recede from both, Sun and Earth.

Congratulations to Andrea Boattini!

UPDATE - May 04, 2008

This is the discovery image of C/2008 J1 (Boattini) courtesy of Andrea Boattini (30 seconds exposure by 0.68-m Schmidt + CCD):

by Giovanni Sostero & Ernesto Guido

Apollo asteroid 2008 HW1

M.P.E.C. 2008-H35, issued on 2008 Apr. 28, 18:44 UT, announces the discovery of 2008 HW1, an Apollo asteroid in a very comet-like orbit (Tj nearly 2.4; Jupiter family comets have Tisserand parameter TJ between 2 and 3). It was picked-up by the staff of Lincoln Laboratory ETS through a 1.0-m f/2.15 reflector + CCD, on 2008 April 25.35091. After its posting on the NEO Confirmation Page, further follow-up was secured by a number of observers. 

According the preliminary orbital elements published by the Minor Planet Center, 2008_HW1 moves along a very elongated orbit (e~0.96), that takes a little more than 4 years to be completed; at aphelion it approaches the orbit of Jupiter (Q~ 5 AU), while at perihelion (that will be reached in middle of next June) is passes only 0.1 AU - or nearly 15 Million Km - from the Sun. This is a rock whose diameter is supposed to range from nearly 600-m to 2-Km (depending on its surface reflectivity).

We performed some follow-up on 2008, April 28.0, from the Remanzacco Observatory (MPC #473):

In spite of its very comet-like orbit, in our stackings (total exposure time of 30 minutes) this object appears perfectly stellar, with no hints of any detectable coma or tail within our seeing limit.

by L. Donato, M. Gonano, V. Gonano, E. Guido, V. Santini and G. Sostero

Comet P/2008 G2 (SHOEMAKER)

IAUC nr. 8939, issued on 2008, April 24, announces the recovery of P/1995 J3 = 1994k = 1994 XXVIII (Shoemaker), providing it the new designation P/2008 G2 (SHOEMAKER). It was picked up by T. Spahr, analyzing the astrometry of Apr. 10, reported by the Catalina Sky Survey (observer: R.A. Kowalsky, no comments about any potential cometary appearance) to the Minor Planet Center; linkage to further archive data of Apr.1 was provided by B. G. Marsden. The object was reported as having a magnitude of about 18.6.

We performed some follow-up of this comet on 2008, Apr. 24.9 from the Remanzacco Observatory (details on image; click on it for a bigger version):

From our stacking we have evidence of a tiny coma, nearly 10 arcsec in diameter, possibly elongated toward North-West. The measured total magnitude is about 18.5 (R unfiltered).

Perihelion of P/2008 G2 (Shoemaker) will occur in April 2009. At that time the comet will have m1 nearly 17. The maximum brightness is expected to be just half a magnitude better, in August 2009, when the comet will mostly be a southern object.

by Giovanni Sostero & Ernesto Guido (AFAM-CARA, Italy)

New Comet C/2008 H1 (LINEAR)

CBET No. 1343, issued on April 20th, announces the discovery by the Lincoln Near Earth Asteroid Research team of a 18.th magnitude comet in Ursa Minor officially designated C/2008 H1 (LINEAR).

It was picked-up on 2008, Apr. 18.34722 with a 1.0-m, f/2.15 reflector + CCD located in New Mexico (USA). After its posting on the Minor Planet Center's 'NEOCP' webpage, several observers performing its astrometric follow-up, reported about its cometary nature: in particular, E. Reina (April 19.0, Masquefa Observatory, Spain) commented about a magn. 16.6 coma almost 25 arcsec in diameter, and a 43 arcsec tail toward P.A. 233 deg. J. M. Aymami (April 19.8, Observatorio Carmelita, Spain) mentioned a suspected coma elongated toward P.A. 209 deg, while R. Apitzsch (April 19.8, Wildberg, Germany) noticed a tail toward southwest.

On April 19.5 we performed our own confirmation images, remotely through a 0.25m, f/3.4 reflector + CCD from the Rent A Scope network (Mayhill station, NM). The sky was clear, however the full Moon increased quite a lot the sky backgound noise; moreover, due to some technical problems, we couldn't stack more than 20 single unfiltered exposures, hampering our detections of very faint details. Anyway, also on our image, below the trail of a faint field's star, it's possible to appreciate the presence of this new comet, with the typical diffuse shape of this kind of objects.

With some image processing, from our image it's possible to notice a central condensation, surrounded by a ~30 arcsec diameter very faint coma, elongated toward South-West (details on image):

A photometric analysis perfomed via Roberto Trabatti's Winafrho software (CARA's dedicated data reduction package), provides m2~ 18 (Ru) for the central condensation, and m1 ~16.5 (Ru) for the total coma brightness. The Afrho parameter (proxy of dust abundance within the coma) upper limit for this comet is then estimated to be nearly 90 +/- 30cm; considering that C/2008 H1 currently is at almost 2.8 A.U from the Sun past perihelium, this result seems to point toward a comet of modest activity.

Preliminary orbital elements published by the Minor Planet Center on M.P.E.C. 2008-H09 show that this object moves along a very elongated and tilted orbit (e= 1, i= 76 deg); perihelion occured on 2008, March 11, with q~ 2.8 AU. According to the ephemerids, for the next few months this object will remain mainly a northern hemisphere target, and it will decrease its brightness from V~ 16.8 to nearly V~ 18.

by Ernesto Guido & Giovanni Sostero