12 February 2005 - Saturday
Risk monitoring: NEODyS today posted 2005 CF41 with impact solutions. See news yesterday below for more about this half-kilometer object.
Today's Daily Orbit Update (DOU) MPEC reports observation of 2005 CW25 from yesterday morning from Powell and Farpoint observatories, both in Kansas. And today NEODyS and JPL removed their impact solutions for this object, which is estimated to be on the order of 0.66 km. (0.41 mile) wide.
Powell and Farpoint also observed 2005 CC37 yesterday morning, along with UKAPP in Northern Ireland remotely working the Faulkes Telescope North in Hawaii. Today the risk assessments for this small object appeared to be converging as JPL slightly lowered, and NEODyS slightly raised, overall risk ratings.
And the DOU has observation of 2004 MN4 from early yesterday from Farpoint Observatory and Pla D'Arguines Observatory in Spain, as well as from January 13th from Smolyan Observatory in Bulgaria. Today NEODyS very slightly raised its risk assessment.
2004 MN4 update: Lance Benner at JPL writes to correct yesterday's 2004 MN4 update below, which originally indicated that JPL's current diameter estimate was derived from radar observation: "Given sufficient signal-to-noise ratios, we can directly measure the dimensions of near-Earth asteroids with radar imaging, but that wasn't possible with 2004 MN4 because the echoes weren't strong enough." The diameter, he says, is "based on unpublished results obtained by Richard Binzel et al. (MIT) as part of the SMASS project. They obtained spectroscopy suggesting that MN4 is a Q-type asteroid. Their previous results indicated that many of Q-type objects have albedos of ~0.35, which, given MN4's absolute magnitude, yields a diameter of about 320 meters."
The Small Main-Belt Asteroid Spectroscopic Survey (SMASS) site tells about an NEO Spectral Reconaissance joint campaign since last year with NASA's 3m Infrared Telescope Facility (IRTF) on Mauna Kea in Hawaii. And the data from a 2004 MN4 observing run with the IRTF on January 8th has been posted with the caveat that, while fully reduced, it has not yet undergone peer review for publication.
"Q" is an asteroid surface reflection spectral type closely associated with the more common S-type "stony" asteroids. In the book Asteroids III, published in 2003, Richard P. Binzel et al. state that approximately "20% of all observed NEOs have spectral properties placing them in the taxonomic class Q. [Q class asteroids have spectra most similar to laboratory spectra of ordinary-chondrite meteorites (McFadden et al., 1984; Bus et al., 2002).]"
11 February 2005 - Friday
Recoveries: The recovery of two potentially hazardous asteroids was announced yesterday (MPECs 2005-C46 and 2005-C47), both accomplished by Andrea Boattini's team using the ESO/MPI 2.2m telescope at La Silla in Chile. 2003 MK4 [alt. link] hadn't been seen since 4 August 2003, and 1989 DA since 27 May 1989, until both were picked up early Wednesday. 1989 DA was a serendipitous discovery of the Palomar Sky Survey II with Mt. Palomar's Oschin 1.2m telescope on 27 February 1989, and is estimated from its absolute magnitude (brightness) to be a bit over a half-kilometer wide. 2003 MK4, which was discovered by LINEAR in New Mexico on 28 June 2003, was listed with impact solutions from the next day until August 5th that year, and is estimated at roughly 225 meters/yards wide.
MPEC 2005-C52 today reports that Vasilij Rumyantsev and Vadim Biryukov caught 2001 FF90 on 4-6 February with the 2.6m telescope at the Crimean Astrophysical Observatory (CrAO, mirror site) at Nauchny in the Ukraine. This object was discovered with NEAT's telescope in Hawaii on 26 March 2001 and hadn't been observed since November 18th of that year. Estimated at roughly 1.55 km. (0.96 mile) wide, it crosses the orbit of Mars and comes close to Earth, but not close enough to be considered hazardous.
Risk monitoring: NEODyS yesterday posted 2005 CW25, which JPL has had listed since the discovery announcement on February 7th. Observations were most recently reported from Monday morning, but the MPC Last Observation page is showing that Farpoint Observatory in Kansas caught it this morning.
Yesterday's Daily Orbit Update (DOU) MPEC reported observation of 2005 BX26 from Andrea Boattini's team at La Silla in Chile Wednesday morning, and yesterday both NEODyS and JPL removed their impact solutions for this half-kilometer object. It has been reported observed only by Boattini's team so far, and was first posted as a risk on January 29th. (The team has another NEO discovery, small object 2004 CG41, announced this morning in MPEC 2005-C51, and see immediately above about recovery work.)
Today JPL posted 2005 CF41 with three impact solutions. This half-kilometer object is the fourth NEO discovery credited to the Mt. Lemmon Survey, a part of the Catalina Sky Survey (CSS). The discovery Wednesday morning was announced today in MPEC 2005-C50. Discovery confirmation was provided by Powell Observatory in Kansas early yesterday and today.
Yesterday and today's DOUs report observation of 2004 MN4 from the nights of the 8th from Postel Observatory in Italy and the 9th from Eschenberg Observatory in Switzerland and Sormano Observatory in Italy, plus a single position from Hereford Arizona Observatory on January 16th (see immediately below for more about Hereford). The net change in the NEODyS 2004 MN4 risk assessment is very slightly downward.
The two DOUs also reported observation of 2005 CC37 from Eschenberg Observatory the night of the 9th, yesterday morning from Powell and Farpoint observatories, and last night with the Faulkes Telescope North in Hawaii (code "3"). The net changes are slight and mixed in the rather different but overall low-rated risk assessments at NEODyS and JPL.
And today's DOU has observation of 2005 CM7 from Powell Observatory early yesterday. Only NEODyS has this small object listed as a risk, and today slightly lowered its overall very-low risk ratings.
It is no longer on the risk lists (see news February 5th), but it's good to note that the kilometer-size 2005 AH14 was caught yesterday with the Faulkes Telescope North (code "3"). This added 6.166 days to what had been a 27.966-day observing arc.
2004 MN4 update: Although Minor Planet Center observatory code G95 has appeared in MPECs since last October, the observation of 2004 MN4 reported in today's Daily Orbit Update MPEC was the first that Hereford Arizona Observatory has come to A/CC's attention. The observer, retired JPL astronomer Bruce Gary, was mentioned in January 11th news as being part of a 2004 MN4 photometric study. The lightcurve page mentioned then has since been updated, and it is interesting to note again that photometry indicates a somewhat brighter absolute magnitude for 2004 MN4 (H=19.0 is Gary's latest calculation) than derived from astrometry (H=19.3 at JPL in January, 19.2 now). By standard formula, those magnitudes convert to be on the order of 465 to 535 meters/yards wide. The infrared-derived diameter is 320 meters, which theoretically would correspond with about H=20.1 for the average near-Earth asteroid (larger numbers yield smaller sizes). [Originally A/CC reported the 320m-diameter as being radar derived, but see above for the correction and a lot more info.–Ed.]
Bruce Gary tells about his operation and receiving an MPC code on a page about observing exoplanet transits, and has a hardware page. His astrophoto page includes a link to comet images and, at bottom, several very interesting tutorial links regarding CCD use and photometry.
Thanks to Marco Langbroek for pointing out that Astronomy.com posted an article yesterday by NASA astronomer Bill Cooke, "Will Earth break up 2004 MN4?"
According to Dan Durda, another SWRI astronomer, 2004 MN4 is likely to be a "rubble-pile" asteroid, consisting of material only loosely held together by gravity. Because the asteroid will pass us at just 2.5 times Earth's diameter [in April 2029], tidal forces could tear it apart. The result would be a trail of rocks drifting slowly apart with the passage of time. One or more of these might hit Earth in the more distant future, creating a spectacular fireball as it burns up in the atmosphere.
9 February 2005 - Wednesday
Amateur, NEO & meteor news: The first two amateur-discovered NEOs of 2005 were found on the night of February 6th and early on the 8th at Crni Vrh Observatory in Slovenia. The first, 2005 CC37 announced in MPEC 2005-C30 dated "Feb. 7, 21:54 UT," was discovered by Stanislav Maticic and was soon posted by the risk monitors with impact solutions (see more about that below, including the confirmation circumstances). 2005 CR37 was credited to Herman Mikuz and was announced less than 24 hours after the first in MPEC 2005-C32, time-stamped "Feb. 8, 18:40 UT." Its discovery was confirmed by Jeffrey Sue in Hawaii and Robert Hutsebaut in Belgium independently using Rent-A-Scope at New Mexico Skies, and by Modra Observatory in Slovakia. See Crni Vrh's home and news pages for more about the discoveries, and about the drift scan technique used and the software that made the detections.
Lance Benner told the Minor Planet Mailing list (MPML) today that time is being sought to observe 2005 CR37 by radar. This was an aside to an urgent request for optical observations of 2004 RF84 to help prepare for observing it by radar. "Currently RF84 is a ~19th magnitude object only about 60 degrees from the Sun, although its solar elongation is gradually increasing and its apparent magnitude is getting brighter." This kilometer-size PHA was listed with impact solutions from 11 to 14 September last year.
One of the biggest amateur discoveries of the last decade was that of comet C/1995 O1 (Hale-Bopp), and Alan Hale has announced that there will be a tenth anniversary celebration in Alamogordo, New Mexico on July 23rd. The German Comet Section is reporting from an IAU Circular that C/1995 O1 was observed on January 8th with the Magellan Observatory 6.5m Clay telescope in Chile and was found to be sporting a tail of at least 8.5" length when 21 AU from the Sun.
Noticed today at the Crni Vrh Web site is recent fireball activity recorded by the observatory's all-sky camera, including a bright one caught on the night of February 6th (JPEG).
Risk monitoring: JPL posted 2005 CC37 yesterday UT, but still Monday local, and NEODyS posted it later in the day with impact solutions. This object was announced late Monday UT in MPEC 2005-C30 as discovered by Stanislav Maticic (and Herman Mikuz provided follow-up) Sunday night at Crni Vrh Observatory in Slovenia. Confirmation came from Great Shefford Observatory in England on both sides of midnight, and confirmation came very early Monday UT from McCarthy Observatory in Connecticut and Modra Observatory in Slovakia, later that morning from McDonald Observatory in Texas, and Monday night from Wildberg Observatory in Germany. By A/CC's tally, this is the first amateur-discovered NEO of 2005, and the second was close behind, also from Crni Vrh — see immediately above. Today's Daily Orbit Update (DOU) MPEC reports positions from Great Shefford last night, and today NEODyS lowered, and JPL very slightly lowered, 2005 CC37's overall risk ratings. JPL puts this object's diameter estimate at roughly 100 meters/yards.
Yesterday and today's DOU MPECs carry observations of 2004 MN4 from McCarthy Observatory spanning midnight of 4-5 February, and from Dresden Observatory in Germany Sunday night, McDonald Observatory the next morning, Monday night from Rezman Observatory in Slovenia, Wildberg Observatory, and Ondrejov Observatory in the Czech Republic, and last night from Great Shefford Observatory. Today's DOU also has five corrected positions from the Spacewatch 0.9m telescope prediscovery of last March 15th. This data, which includes a new earliest sixth position, has been in use by the risk monitors since their first post-radar 2004 MN4 risk assessments on February 2nd. NEODyS updated its 2004 MN4 risk assessment yesterday and today, for a net very slight increase in overall risk ratings. Because daily changes from new optical observations will be so slight, JPL, which last updated its 2004 MN4 risk assessment on February 4th, has decided to update only "every week or two, as appropriate." See much more about 2004 MN4 immediately below.
Yesterday's DOU also has observation of 2005 CM7 late Monday from KLENOT in the Czech Republic. Only NEODyS has this small object listed with impact solutions, and yesterday it raised its risk ratings, which are still very low.
And yesterday and today's DOUs report observations of 2005 CW25 from Mt. John Observatory in New Zealand on Monday, from Robert Hutsebaut in Belgium using Rent-A-Scope at New Mexico Skies last night, and early today from Wildberg Observatory. Only JPL has this object listed, and the net change in its risk ratings has been slightly downward.
Update: This evening in Pasadena, after midnight UTC, JPL has updated its 2004 MN4 risk assessment, very slightly lowering its overall risk ratings.
2004 MN4 update: As noted in the risk monitoring report immediately above, today's Daily Orbit Update MPEC carries a restatement of five positions from the Spacewatch 0.9m telescope's 15 March 2004 prediscovery of 2004 MN4 (see MPEC 2004-Y71 of December 27th). These five are coded "C" for "correction to earlier position," and there is also a new earliest sixth position reported. A/CC has learned that the five positions had to be recalculated after it became "quite evident" that the data was "incompatible" when the orbit solution was significantly improved by late-January radar observations. The improved data from the Spacewatch observations was used by the risk monitors in their first post-radar risk assessments of February 2nd, and has been on the NEODyS 2004 MN4 observation tally since then.
A/CC has done some straightening up of its own. In the CRT page 2004 MN4 risk assessment listings, several December-January JPL and NEODyS assessments have been removed that, although posted, were incorrect in briefly putting 2004 MN4 at Torino Scale 0 ("no likely consequences"). This object has never actually been officially listed below TS-1, which is a routine alert that an object "merits" the "special monitoring" that 2004 MN4 has certainly been getting. Also changed is JPL's first post-radar 2004 MN4 risk assessment, which on February 2nd appeared to put its cumulative risk rating higher than at NEODyS, when in fact it was about the same. JPL corrected this at the time of posting its next-day's assessment, and A/CC has now matched that. (Please note the CRT page advisory that, for each object, ONLY ONE assessment from each monitor matters — the one most recent, and that only until the next next appears or all impact solutions are removed. Earlier assessments are interesting only for studying the progression of risk analysis and have NO relevance to the actual risk of an object.)
While discussing the CRT listing changes with Steve Chesley at the JPL NEO Program Office (NEOPO), A/CC took the opportunity to ask the question on many minds: "Why did it take from January 31st publication of the 2004 MN4 radar observations until February 2nd for risk assessments to be published incorporating that data." He responded that "this was already very technical work and 2004 MN4 is by far the most challenging Sentry case ever encountered." The risk monitors "have never used our impact monitoring techniques on such a well determined orbit before. Several technical issues surfaced that are very specific to MN4, and these had to be dealt with." Also, "The 2029 encounter introduces an extraordinary amount of uncertainty into the post-2029 trajectory. Unlike 29075 1950 DA [alt. link], which has a stable orbit, 2004 MN4 has a very chaotic orbit, and even that chaos is hidden behind the 2029 curtain. It will likely take another optical apparition to significantly improve the situation." (29075 1950 DA is an interesting comparison, for having an impact solution in March of the year 2880.)
Because 2004 MN4's observation arc goes back to last March, and because of the weight of the Arecibo radar observations of 27-30 January in calculating 2004 MN4's orbit and its risk assessment, he says daily changes from new optical observations will be "minuscule," and so JPL plans to only update its risk assessment "every week or two, as appropriate." It had last updated on February 4th until a new risk assessment was issued this evening local time, after midnight UTC (see above).
2004 MN4 is predicted to be in view until mid-May this year, and optical observations over that length of time will have an "appreciable effect" on its orbit solution. NEODyS is showing that the next close 2004 MN4 approaches will be in January 2013 and March 2021. Steve Chesley notes that it will also be "easily observable with meter-class instruments in mid-2006, and, with somewhat more difficulty, a few more times before 2013."