15 Sep '07 Major News

Contents on 15 September '07

Minor-Object News -- five items
Minor-Object Science -- one paper
IAU Minor Planet Center
- NEOCP Activity -- 21 listings: 12 new, 9 updated
- New MPECs -- ten MPECs
- Observers -- 23 observing facilities
Impact Risk Monitoring -- six objects reported
Chronology

Resources:

The latest news: framed access (best), RSS news feed (flags updates), or redirection - Note: A/CC has a main Web site and a backup site.

Navigation tips: Use the << and >> arrows on the menus for each regular section (Observers, Risks, etc.) to move to the previous and next day's news for that section. Use the Index menu item to access specific days this year through a calendar interface. And use the all-up news archive to access news from any time since A/CC began in early 2002. To keep track of what's new each day, watch the Chronology section.

Minor-Object News on 15 September '07

"Fasten Your Seat Belts," Science@NASA 14 Sept. - Quote: "The Discovery program [NEAR, Deep Impact, Stardust, etc.] has been a spectacular success, more than anyone bargained for... Now we're looking to expand it. In the coming year, we're going to start planning dramatic improvements in the kind of missions we can undertake" {permalink}
"September 13th Dawn Journal," NASA Dawn mission 13 Sept. - Quote: "The entire launch sequence is timed so that Dawn will depart Earth at a carefully chosen point in the solar system. For each possible launch day, extensive analysis has established the mathematically optimal plan for reaching Vesta and Ceres." {permalink}
Lowell blog: In the first week of September Lowell Observatory began a blog as a "Web-2 news source ... for friends and donors." There were two entries yesterday. One was a report about a meeting of the New Horizons mission science team at which results were presented from Marc Buie "about the complex orbits of Pluto's three moons from Hubble Space Telescope Observations" and from Henry Roe "from his Keck telescope studies of methane gas in Pluto's atmosphere." In the other entry, Jeffrey Hall addresses a column in the Wall Street Journal that discussed "recent work suggesting that many, if not most, papers that appear in the peer-reviewed scientific literature are wrong." He comments that "I'm an astronomer; I'm used to looking at crappy data," but that's just part of the scientific process. {permalink}
"Two flying objects populate skies Thursday," Santa Fe New Mexican 15 Sept. - Quote: "Susan Burgess of Santa Fe reported seeing a light brighter than the full moon for about eight seconds around 3:20 a.m." {permalink}
"Fragmenting comet reveals inner self," Johns Hopkins News-Letter 13 Sept. - Quote: "The researchers had expected to see substantial differences between the chemical makeup of the two fragments ... however, the two fragments were nearly identical, indicating that comet [73P/Schwassman-Wachmann 3] was relatively homogeneous internally." - Note: See also links to a detailed identification of this object's many pieces. {permalink}

Minor-Object Science on 15 September '07

"An asteroid breakup 160 Myr ago as the probable source of the K/T impactor" by Bottke, William F. with David Vokrouhlicky & David Nesvorny, PDF from William F. Bottke 10 Sept. - Quote: "The terrestrial and lunar cratering rate is often assumed to have been nearly constant over the past 3 Gyr. Different lines of evidence, however, suggest that the impact flux from kilometre-sized bodies increased by at least a factor of two over the long-term average during the past ~100Myr. Here we argue that this apparent surge was triggered by the catastrophic disruption of the parent body of the asteroid Baptistina, which we infer was a ~170-km-diameter body (carbonaceous-chondrite-like) that broke up 160 +30/-20 Myr ago in the inner main asteroid belt. Fragments produced by the collision were slowly delivered by dynamical processes to orbits where they could strike the terrestrial planets. We find that this asteroid shower is the most likely source (>90 per cent probability) of the Chicxulub impactor that produced the Cretaceous/Tertiary (K/T) mass extinction event 65 Myr ago." - Note: This 1.23Mb PDF has a companion 4.0Mb PDF with "Supplementary Discussion," including identifying the Baptistina family with its taxonomy and colors, and determining its age and initial makeup and subsequent impacts on the inner planets. A section also deals with the Earth impact rate from nearly-isotropic comets -- the ones that can come at Earth from any direction. {permalink}

NEOCP Activity on 15 September '07

The MPC's NEO Confirmation Page has 21 listings: 12 new, 9 updated

When last checked at 2334 UTC today, the Minor Planet Center's NEO discovery Confirmation Page (NEOCP) had twelve new and nine updated listings. Of these, fourteen were "one nighters." So far Major News has counted a total of 33 objects listed on the NEOCP at some point today.

To learn how observers use the NEOCP, see the Practical guide on how to observe NEOCP object by Birtwhistle et al. at Suno Observatory.

New MPECs on 15 September '07

Minor Planet Electronic Circulars

As of last check at 2334 UTC, there have been ten MPECs issued today from the International Astronomical Union's Minor Planet Center in Cambridge, Massachusetts.

MPEC 2007-R83 time-stamped "06:07 UT" - Daily Orbit Update - see below
MPEC 2007-R84 time-stamped "14:16 UT" - 2007 RU19 - see below
MPEC 2007-R85 time-stamped "14:18 UT" - 2007 RV19 - see below
MPEC 2007-R86 time-stamped "14:21 UT" - 2007 RW19 - see below
MPEC 2007-R87 time-stamped "14:24 UT" - 2007 RX19 - see below
MPEC 2007-R88 time-stamped "14:27 UT" - 2007 RY19 - see below
MPEC 2007-R89 time-stamped "14:30 UT" - 2007 RZ19 - see below
MPEC 2007-R90 time-stamped "14:33 UT" - 2007 RA20 - see below
MPEC 2007-R91 time-stamped "16:14 UT" - 2007 RC20 - see below
MPEC 2007-R92 time-stamped "16:17 UT" - 2007 RD20

MPEC 2007-R92 - "16:17 UT" - 2007 RD20

K07R20D 2007 RD20 (H=21.0 ~214m) was discovered at 1658 UT 14 Sept. by the Siding Spring Survey (SSS), which observed it at Sept. 14.71-80p7 and 15.64p5.

MPEC 2007-R91 - "16:14 UT" - 2007 RC20

K07R20C 2007 RC20 (small asteroid, Earth MOID=4.4 LD, H=26.6 ~16m) was discovered at 0856 UT 14 Sept. by the Catalina Sky Survey (CSS), which observed it at Sept. 14.37-39p4. The discovery was confirmed by the Mt. Lemmon Survey (MLS) (Sept. 15.23p4).

MPEC 2007-R90 - "14:33 UT" - 2007 RA20

K07R20A 2007 RA20 (risk-listed, H=19.7 ~389m) was discovered at 1431 UT 14 Sept. by SSS, which observed it at Sept. 14.60-66p4 and 14.76-77p4. The discovery was confirmed by CEAMIG-REA (Sept. 15.28-29p3).

MPEC 2007-R89 - "14:30 UT" - 2007 RZ19

K07R19Z 2007 RZ19 (small asteroid, H=22.4 ~112m) was discovered at 0902 UT 14 Sept. by MLS, which observed it at Sept. 14.38-39p4, 14.49p3, and 15.31-33p4. The discovery was confirmed by the Spacewatch 1.8m telescope (Sept. 15.45-46p3).

MPEC 2007-R88 - "14:27 UT" - 2007 RY19

K07R19Y 2007 RY19 (risk-listed, Earth MOID=0.8 LD, H=21.9 ~141m) was discovered at 0828 UT 14 Sept. by LINEAR, which observed it at Sept. 14.35-40p5. The discovery was confirmed by Great Shefford Obs. (Sept. 15.14p3) and Jim Young via Table Mtn. Obs. (Sept. 15.45-46p4).

MPEC 2007-R87 - "14:24 UT" - 2007 RX19

K07R19X 2007 RX19 (risk-listed, i=38.2°, H=18.5 ~676m) was discovered at 0635 UT 14 Sept. by CSS, which observed it at Sept. 14.27-34p6. The discovery was confirmed by Great Shefford Obs. (Sept. 14.92-93p3) and CEAMIG-REA (Sept. 15.14-15p3).

MPEC 2007-R86 - "14:21 UT" - 2007 RW19

K07R19W 2007 RW19 (small asteroid, Earth MOID=9.6 LD, H=25.3 ~29m) was discovered at 0540 UT 14 Sept. by MLS, which observed it at Sept. 14.24-25p3, 14.34-35p4, and 14.40p4. The discovery was confirmed by LINEAR (Sept. 14.24-27p4), Great Shefford Obs. (Sept. 14.90p3), Grasslands Obs. (Sept. 15.17p3), and CEAMIG-REA (Sept. 15.21p2).

MPEC 2007-R85 - "14:18 UT" - 2007 RV19

K07R19V 2007 RV19 (Q=5.322 AU, H=18.8 ~589m) was discovered at 0258 UT 14 Sept. by LINEAR, which observed it at Sept. 14.12-17p5. The discovery was confirmed by Great Shefford Obs. (Sept. 14.97p3), McDonald Obs. (Sept. 15.08-09p3), CEAMIG-REA (Sept. 15.11-12p3), Grasslands Obs. (Sept. 15.14-15p3), MLS (Sept. 15.15-19p6), and Greiner Research Obs. (Sept. 15.16p4).

MPEC 2007-R84 - "14:16 UT" - 2007 RU19

K07R19U 2007 RU19 (small asteroid, Earth MOID=6.8 LD, H=26.6 ~16m) was discovered at 0920 UT 13 Sept. by MLS, which observed it at Sept. 13.39-41p4, 14.35p4, and 15.30p3. The discovery was confirmed by Spacewatch 1.8m (Sept. 15.43-44p3).

<< DOU on 15 Sept. '07 >> MPEC 2007-R83 - "06:07 UT" - Daily Orbit Update

Observations of risk-listed objects
K07R09V 2007 RV9 (arc=4 days, H=20.0 ~339m) from Astronomical Research Obs. (ARO) (Sept. 12.17-18p3), McDonald Obs. (Sept. 14.17-18p3), and Spacewatch 1.8m (Sept. 14.24-26p3)
K07R09U 2007 RU9 (arc=4 days, H=20.8 ~234m) from Stia Obs. (Sept. 13.89-90p3) and Spacewatch 1.8m (Sept. 14.28-29p3)
K07R09T 2007 RT9 (arc=4 days, H=19.2 ~490m) from ARO (Sept. 12.23-24p2 at V=22.1) and Spacewatch 1.8m (Sept. 14.26-28p3 at V=22.7)
Observations of recently (no longer) risk-listed objects
K07R12T 2007 RT12 (small asteroid, arc=2 days, H=23.9 ~56m) from Spacewatch 1.8m (Sept. 14.35-36p3 at V=22.1)
K07R09R 2007 RR9 (Q=4.690 AU, arc=4 days, H=20.3 ~295m) from LINEAR (Sept. 14.18-23p5)
K07R02F 2007 RF2 (arc=9 days, H=20.6 ~257m) from Lumezzane Obs. (Sept. 13.01-02p4) and CSS (Sept. 14.35-37p4)
K07R01J 2007 RJ1 (small asteroid, arc=12 days, H=25.2 ~31m) from Verona Obs. (Sept. 14.85p4)
K07R01E 2007 RE1 (almost small, Q=4.279 AU, arc=12 days, H=22.0 ~135m) from Spacewatch 1.8m (Sept. 14.18-21p5)
Observations of small asteroids (H>22.0)
K07R17S 2007 RS17 (arc=1 day, H=23.0 ~85m) from ARO (Sept. 14.25p3)
K07R17R 2007 RR17 (arc=1 day, H=23.7 ~62m) from LINEAR (Sept. 14.29-34p5)
K07R15P 2007 RP15 (arc=2 days, H=23.0 ~85m) from LINEAR (Sept. 14.24-29p10) and Verona Obs. (Sept. 14.86-87p4)
K07R09S 2007 RS9 (arc=2 days, H=24.7 ~39m) from ARO (Sept. 12.19-20p3)
K07R08Y 2007 RY8 (arc=3 days, H=25.3 ~29m) from ARO (Sept. 12.27-28p3)
Observations of other objects
K07R17V 2007 RV17 (arc=2 days, H=19.0 ~537m) from Junk Bond Obs. (Sept. 14.36-41p3)
K07R17U 2007 RU17 (arc=1 day, H=18.3 ~741m) from Junk Bond Obs. (Sept. 14.35-41p4)
K07R12U 2007 RU12 (arc=2 days, H=19.7 ~389m) from McDonald Obs. (Sept. 14.43-45p3) and CSS (Sept. 14.48-49p4)
K07R10U 2007 RU10 (arc=3 days, H=19.0 ~537m) from Young/Table Mtn. (Sept. 14.16-19p5)
K07R09Q 2007 RQ9 (q=2.313 AU, arc=4 days, H=15.6 ~2.57 km) from Desert Moon Obs. (Sept. 14.12-15p2)
K07R05F 2007 RF5 (arc=9 days, H=18.5 ~676m) from Desert Moon Obs. (Sept. 14.34-35p3) and McDonald Obs. (Sept. 14.48-49p3)
K07R01T 2007 RT1 (arc=10 days, H=20.6 ~257m) from McDonald Obs. (Sept. 14.21-22p3)
K07R01D 2007 RD1 (arc=12 days, H=21.6 ~162m) from CSS (Sept. 14.17-18p4)
K07Q02K 2007 QK2 (arc=24 days, H=20.6 ~257m) from LINEAR (Sept. 14.18-23p5)
K07P11U 2007 PU11 (Q=4.384 AU, arc=3 opp, H=16.3 ~1.86 km) from Gravenwezel (Sept. 13.00-01p4)
K07P08E 2007 PE8 (arc=122 days, H=19.4 ~446m) from Dresden Obs. (Sept. 13.88-90p4) and Gravenwezel (Sept. 13.95-97p4)
K07P06F 2007 PF6 (arc=38 days, H=20.7 ~245m) from Spacewatch 1.8m (Sept. 15.13-14p3)
K07P00Q 2007 PQ (arc=41 days, H=20.6 ~257m) from McDonald Obs. (Sept. 14.14p3)
K07N00Q 2007 NQ (arc=64 days, H=19.4 ~446m) from ARO (Sept. 12.08-09p2)
K07M24B 2007 MB24 (i=47.7°, arc=80 days, H=18.2 ~776m) from ARO (Sept. 12.06-07p2)
K07L32R 2007 LR32 (arc=111 days, H=17.2 ~1.23 km) from Dresden Obs. (Sept. 13.86-87p5) and Gravenwezel (Sept. 13.87-94p10)
K07K00D 2007 KD (arc=126 days, H=20.6 ~257m) from Mt. John Obs. (Sept. 14.47-48p3)
K07J20Z 2007 JZ20 (i=40.5°, arc=126 days, H=18.4 ~708m) from Desert Moon Obs. (Sept. 14.44-46p3)
K07H15E 2007 HE15 (arc=145 days, H=19.6 ~407m) from CSS (Sept. 14.17-18p4)
K07D41L 2007 DL41 (arc=2 opp, H=20.6 ~257m) from Spacewatch 1.8m (Sept. 14.47-48p3)
K07D41A 2007 DA41 (arc=3 opp, H=17.6 ~1.02 km) from Lumezzane Obs. (Sept. 12.94-95p3)
K06R36O 2006 RO36 (arc=2 opp, H=18.0 ~851m) from Stia Obs. (Sept. 13.78-79p5)
K05W56J 2005 WJ56 (arc=3 opp, H=17.9 ~891m) from Stia Obs. (Sept. 13.91-93p5)
K05O01U 2005 OU1 (arc=3 opp, H=20.1 ~323m) from Stia Obs. (Sept. 13.84-85p6)
K03U12R 2003 UR12 (i=60.5°, arc=3 opp, H=17.9 ~891m) from Desert Moon Obs. (Sept. 14.37-42p3)
K03SM2W 2003 SW222 (arc=3 opp, H=17.2 ~1.23 km) from Stia Obs. (Sept. 13.87-88p3)
K02S00V 2002 SV (arc=2 opp, H=19.9 ~355m) from CSS (Sept. 14.25-27p4) and Greiner Research Obs. (Sept. 15.15p10)
K02RC9T 2002 RT129 (arc=2 opp, H=19.5 ~426m) from MLS (Sept. 14.25-26p4) and LINEAR (Sept. 14.32-34p3)
K02RC9N 2002 RN129 (arc=4 opp, H=18.9 ~562m) from LONEOS (Sept. 14.21-28p4)
K02RB8C 2002 RC118 (Q=4.624 AU, arc=2 opp, H=16.8 ~1.48 km) from Lumezzane Obs. (Sept. 13.03-04p4)
K02O20D 2002 OD20 (arc=4 opp, H=18.8 ~589m) from McDonald Obs. (Sept. 14.31-33p3)
J99J03U 1999 JU3 (arc=4 opp, H=19.2 ~490m) from LONEOS (Sept. 14.12-16p3)
J98S15D 1998 SD15 (arc=4 opp, H=19.1 ~513m) from Lumezzane Obs. (Sept. 12.86p4)
J95S00A 1995 SA (Q=4.026 AU, arc=5 opp, H=17.4 ~1.12 km) from ARO (Sept. 12.30-33p3 at V=22.9-23.0)
F3271 153271 2001 CL42 from LINEAR (Sept. 14.36-41p5)
E4900 144900 2004 VG64 from LINEAR (Sept. 14.43-47p4)
D8883 138883 2000 YL29 from LINEAR (Sept. 14.11-16p5)
D6849 136849 1998 CS1 from CSS (Sept. 14.27-28p4)
A0756 100756 1998 FM5 from LONEOS (Sept. 14.39-47p4)
89355 89355 2001 VS78 from SSS (Sept. 14.49-50p2)
86324 86324 1999 WA2 from Lumezzane Obs. (Sept. 12.86-87p4)
68063 68063 2000 YJ66 from LINEAR (Sept. 14.42-47p5)
54686 54686 2001 DU8 from SSS (Sept. 14.69-74p4)
21277 21277 1996 TO5 from Atlante Obs. (Sept. 13.90-91p3)
16636 16636 1993 QP from Verona Obs. (Sept. 8.85-86p4) and LONEOS (Sept. 14.13-20p4)
15745 15745 1991 PM5 from McDonald Obs. (Sept. 14.45-47p2)
14402 14402 1991 DB from the Spacewatch 0.9m telescope (Sept. 14.30-33p3)
05143 5143 Heracles (1991 VL) from LINEAR (Sept. 14.18-23p5)
04954 4954 Eric (1990 SQ) from CSS (Sept. 14.25-27p4)
04183 4183 Cuno (1959 LM) from LINEAR (Sept. 14.18-23p5)
03200 3200 Phaethon (1983 TB) from Atlante Obs. (Sept. 14.16p1 & 14.22p1)
01865 1865 Cerberus (1971 UA) from LINEAR (Sept. 14.41-46p5)

Observers on 15 September '07

A total of 23 observing facilities appear in today's MPECs.

Code	Observer / observatory
`H55`	Astronomical Research Obs. in Illinois, 8 in MPEC 2007-R83 -- 2007 RY8, 2007 RV9, 2007 RT9, 2007 RS9, 2007 RS17, 2007 NQ, 2007 MB24, 1995 SA
`J51`	Atlante Obs. in the Canary Islands, 2 in MPEC 2007-R83 -- 21277, 3200
`I77`	CEAMIG-REA in Brazil, 4 in MPECs 2007-R85, 2007-R86, 2007-R87 & 2007-R90 -- 2007 RX19, 2007 RW19, 2007 RV19, 2007 RA20
`703`	Catalina Sky Survey in Arizona, 9 in MPECs 2007-R83, 2007-R87 & 2007-R91 -- 2007 RX19, 2007 RU12, 2007 RF2, 2007 RD1, 2007 RC20, 2007 HE15, 2002 SV, 136849, 4954
`448`	Desert Moon Obs. in New Mexico, 4 in MPEC 2007-R83 -- 2007 RQ9, 2007 RF5, 2007 JZ20, 2003 UR12
`639`	Dresden Obs. in Germany, 2 in MPEC 2007-R83 -- 2007 PE8, 2007 LR32
`651`	Grasslands Obs. in Arizona, 2 in MPECs 2007-R85 & 2007-R86 -- 2007 RW19, 2007 RV19
`145`	Gravenwezel, 3 in MPEC 2007-R83 -- 2007 PU11, 2007 PE8, 2007 LR32
`J95`	Great Shefford Obs. in England, 4 in MPECs 2007-R85, 2007-R86, 2007-R87 & 2007-R88 -- 2007 RY19, 2007 RX19, 2007 RW19, 2007 RV19
`H51`	Greiner Research Obs. in Wisconsin, 2 in MPECs 2007-R83 & 2007-R85 -- 2007 RV19, 2002 SV
`701`	Junk Bond Obs. in Arizona, 2 in MPEC 2007-R83 -- 2007 RV17, 2007 RU17
`704`	LINEAR in New Mexico, 15 in MPECs 2007-R83, 2007-R85, 2007-R86 & 2007-R88 -- 2007 RY19, 2007 RW19, 2007 RV19, 2007 RR9, 2007 RR17, 2007 RP15, 2007 QK2, 2002 RT129, 68063, 153271, 144900, 138883, 5143, 4183, 1865
`699`	LONEOS in Arizona, 4 in MPEC 2007-R83 -- 2002 RN129, 1999 JU3, 16636, 100756
`130`	Lumezzane Obs. in Italy, 5 in MPEC 2007-R83 -- 2007 RF2, 2007 DA41, 2002 RC118, 1998 SD15, 86324
`711`	McDonald Obs. in Texas, 8 in MPECs 2007-R83 & 2007-R85 -- 2007 RV9, 2007 RV19, 2007 RU12, 2007 RT1, 2007 RF5, 2007 PQ, 2002 OD20, 15745
`474`	Mt. John Obs. in New Zealand, 1 in MPEC 2007-R83 -- 2007 KD
`G96`	Mt. Lemmon Survey in Arizona, 6 in MPECs 2007-R83, 2007-R84, 2007-R85, 2007-R86, 2007-R89 & 2007-R91 -- 2007 RZ19, 2007 RW19, 2007 RV19, 2007 RU19, 2007 RC20, 2002 RT129
`E12`	Siding Spring Survey in New South Wales, 4 in MPECs 2007-R83, 2007-R90 & 2007-R92 -- 2007 RD20, 2007 RA20, 89355, 54686
`691`	Spacewatch 0.9m telescope in Arizona, 1 in MPEC 2007-R83 -- 14402
`291`	Spacewatch 1.8m telescope in Arizona, 9 in MPECs 2007-R83, 2007-R84 & 2007-R89 -- 2007 RZ19, 2007 RV9, 2007 RU9, 2007 RU19, 2007 RT9, 2007 RT12, 2007 RE1, 2007 PF6, 2007 DL41
`A78`	Stia Obs. in Italy, 5 in MPEC 2007-R83 -- 2007 RU9, 2006 RO36, 2005 WJ56, 2005 OU1, 2003 SW222
`6735`	Jim Young via Table Mtn. Obs. in southern California, 2 in MPECs 2007-R83 & 2007-R88 -- 2007 RY19, 2007 RU10
`A48`	Verona Obs. in Italy, 3 in MPEC 2007-R83 -- 2007 RP15, 2007 RJ1, 16636

Impact Risk Monitoring on 15 September '07

**Summary Risk Table for Risk Assessments Updated Today** (last checks: NEODyS and JPL at 2334 UTC)
See the CRT page for a list of all objects rated recently as risks.
Note that the time horizon for JPL is 100 years from today and for NEODyS is now usually the year 2090.
For the latest official risk assessments, and for explanations of the terminology, see the JPL NEO Program Sentry and NEODyS CLOMON (backup) risk pages.
0000NNN000 Object	Risk Monitor	When Noted UTC	0000T0000 Year Range	VI #	000NN00 Prob Cum	T0000 PS Cum	T0000 PS Max	T S	Notes for Today's Latest Risk Assessments

2007 RY19	JPL	1930	2014-2092	752	1.7e-05	-3.03	-3.87	0	JPL: "Analysis based on 12 observations spanning 1.1075 days (2007-Sep-14.35284 to 2007-Sep-15.46036)." Diameter approximately 0.142 km. from mean, weighted H=21.9.

2007 RX19	JPL	2016	2021-2107	53	5.4e-08	-3.81	-4.54	0	JPL: "Analysis based on 12 observations spanning .87310 days (2007-Sep-14.27499 to 2007-Sep-15.14809)." Diameter approximately 0.622 km. from mean, weighted H=18.7.

2007 RV9	NEODyS	1455	2024-2077	13	4.12e-08	-4.53	-4.79	0	NEODyS: "Based on 31 optical observations (of which 1 are rejected as outliers) from 2007/09/10.289 to 2007/09/14.257."
2007 RV9	JPL	1454	2011-2107	8	7.8e-09	-5.23	-5.56	0	JPL: "Analysis based on 31 observations spanning 3.9683 days (2007-Sep-10.28811 to 2007-Sep-14.25639)." Diameter approximately 0.358 km. from mean, weighted H=19.9.

2007 RU9	NEODyS	1455	2013-2076	20	4.41e-06	-2.58	-3.01	0	NEODyS: "Based on 44 optical observations (of which 2 are rejected as outliers) from 2007/09/10.287 to 2007/09/14.293."
2007 RU9	JPL	1454	2013-2071	16	4.4e-06	-2.57	-3.00	0	JPL: "Analysis based on 42 observations spanning 4.0065 days (2007-Sep-10.28596 to 2007-Sep-14.29242)." Diameter approximately 0.234 km. from mean, weighted H=20.8.

2007 RT9	NEODyS	1455	2026-2088	25	7.59e-08	-4.60	-5.17	0	NEODyS: "Based on 27 optical observations (of which 0 are rejected as outliers) from 2007/09/10.285 to 2007/09/14.279."
2007 RT9	JPL	1454	2028-2107	33	7.9e-08	-4.61	-5.20	0	JPL: "Analysis based on 27 observations spanning 3.9942 days (2007-Sep-10.28434 to 2007-Sep-14.27856)." Diameter approximately 0.357 km. from mean, weighted H=19.9.

2007 RA20	JPL	1804	2016-2107	64	4.6e-08	-4.60	-5.15	0	JPL: "Analysis based on 11 observations spanning .68203 days (2007-Sep-14.60499 to 2007-Sep-15.28702)." Diameter approximately 0.362 km. from mean, weighted H=19.9.

Legend: VI# = VI count, Prob Cum = cumulative probability, PS Cum/Max = cumulative/maximum Palermo Scale, TS = Torino Scale

An impact solution, also known as a "virtual impactor" (VI), is not a prediction but rather a possibility derived from an orbit calculation that cannot be eliminated yet based on the existing data. Elimination can come quickly with just a little further observation or may take weeks or months, sometimes years. Once superceded or eliminated, a former impact solution has zero relevance to an object's risk. See Jon Giorgini's "Understanding Risk Pages" for more about this.

Chronology on 15 September '07

Times are UTC for when the items were noted or added by Major News.

2135	Added A/CC news report, "Lowell blog" Added link to news story, "September 13th Dawn Journal" - see above Added link to news story, "Fragmenting comet reveals inner self" - see above Added link to news story, "Fasten Your Seat Belts" - see above Added link to news story, "Two flying objects populate skies Thursday" - see above
2016	Noted that JPL has posted 2007 RX19 as an impact risk - see above
1930	Noted that JPL has posted 2007 RY19 as an impact risk - see above
1804	Noted that JPL has posted 2007 RA20 as an impact risk - see above
1801	Added MOS paper, "An asteroid breakup 160 Myr ago as the probable source of the K/T impactor" - see above
1736	Grabbed MPEC 2007-R91 - 2007 RC20 - see above Grabbed MPEC 2007-R92 - 2007 RD20 - see above
1455	Noted that NEODyS has updated its 2007 RT9 risk assessment - see above Noted that NEODyS has updated its 2007 RU9 risk assessment - see above Noted that NEODyS has updated its 2007 RV9 risk assessment - see above Grabbed MPEC 2007-R83 - Daily Orbit Update - see above Grabbed MPEC 2007-R88 - 2007 RY19 - see above Grabbed MPEC 2007-R89 - 2007 RZ19 - see above Grabbed MPEC 2007-R90 - 2007 RA20 - see above
1454	Noted that JPL has updated its 2007 RT9 risk assessment - see above Noted that JPL has updated its 2007 RU9 risk assessment - see above Noted that JPL has updated its 2007 RV9 risk assessment - see above Grabbed MPEC 2007-R84 - 2007 RU19 - see above Grabbed MPEC 2007-R85 - 2007 RV19 - see above Grabbed MPEC 2007-R86 - 2007 RW19 - see above Grabbed MPEC 2007-R87 - 2007 RX19 - see above

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