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Dec.
2004
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31 December 2004 - Friday
Comet news: Only a handful of more than 890 SOHO-discovered comets have gone on to be observed from ground-based telescopes. And now C/2004 V13 (SWAN) is one of them, reported in MPEC 2004-Y78 today as picked up December 26th and yesterday by Ken-ichi Kadota at Ageo Observatory in Japan. Previously it had been observed only via SOHO's SWAN and LASCO C3 cameras. See a news thread below about this object's discovery.
Space.com has an article today, "Doorstep Astronomy: New Comet Looking Bright" about comet C/2004 Q2 (Machholz), which "put 2004 into the books as a record year for naked-eye comets." See also a Danbury, Connecticut News-Times article from December 29th, "Combing night skies for comets pays off for amateur astronomer."
Risk monitoring: Today's Daily Orbit Update MPEC carries observations reported from Europe, the U.S., and Australia of four objects with impact solutions, all observed early this morning and three yesterday. Today NEODyS eliminated its last impact solutions for 2004 XM29, and JPL is down to one very low-rated solution. The two risk monitors' assessments for 2004 MN4 have changed little, but are up from yesterday. Their overall risk ratings for 2004 VD17 are up slightly, and JPL raised its 2004 XP14 assessment slightly.
Genny Sansaturio tells A/CC that "The computer 'newton' hosting NEODyS at Pisa has failed again and there is no hope for any action to be taken before Jan 3." She notes that users "can get all the services from NEODyS at Valladolid, which will continue to be timely updated." A/CC's CRT page normally has all NEODyS links doubled up to include the alternate site in Spain, and under the current circumstance has shifted those links to be primary. The main Web site in Pisa, Italy is occasionally off-line, sometimes due to external problems, and had an outage in August from the 16th to the 23rd or 24th (see news).
Dec.
2004
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30 December 2004 - Thursday
Meteor news: Many news sites are carrying a short Associated Press wire story, such as KRQE-TV Albuquerque, New Mexico today, about University of New Mexico researchers identifying meteorite NWA 773 as "the youngest dated lunar rock." See also a UNM December 15th news release and December 18th news links.
Some news sites, such as News24 in South Africa today, are carrying a brief AFP wire story with information attributed to the Iranian Islamic Republic News Agency, saying that a "meteorite" described as "sparkling crystalline" and "weighing at least 16kg" has "hit a home in Saravan in Sistan-Baluchestan province." A date isn't given.
SpaceWeather.com tells that the Quadrantid meteor shower peaks Monday, January 3rd, at 4:20 am PST (12:20 UTC). "Observers in western parts of North America are favored."
Risk monitoring: Today's Daily Orbit Update MPEC carries observations of three objects with impact solutions. 2004 MN4 was reported from Reedy Creek Observatory in Australia from yesterday and the day before, 2004 XM29 from Begues and Great Shefford observatories last night in Spain and England, and 2004 XP14 from Farpoint Observatory in Kansas last night.
Today JPL posted significantly lower risk ratings for 2004 MN4, but revised them upward later, and now the JPL and NEODyS assessments appear to be converging. Both risk monitors lowered their risk assessments for the small object, 2004 XM29, and JPL slightly lowered its assessment for 2004 XP14.
Dec.
2004
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29 December 2004 - Wednesday
Risk monitoring: Today's Daily Orbit Update MPEC reports observation of four objects with impact solutions. 2004 MN4, 2004 VD17, 2004 XM29, and 2004 XP14. Farpoint Observatory in Kansas caught all but 2004 XP14, which was picked up by Robert Hutsebaut in Belgium using Rent-A-Scope at New Mexico Skies. Jornada Observatory in New Mexico and LONEOS in Arizona observed 2004 MN4, and Great Shefford Observatory in England reported positions for 2004 XM29.
Today NEODyS slightly, and JPL very slightly, lowered overall risk ratings for 2004 MN4. Although differing in other assessment details, both risk monitors now have just one 2004 MN4 impact solution rated at Torino Scale 1 (a routine alert that an object "merits special monitoring"), in the year 2053.
The two monitors are closer on their 2004 VD17 assessments, which today they raised slightly while cutting impact solution counts. Both have one solution at TS-1, in the year 2091.
With 2004 XM29, both risk monitors lowered their overall risk ratings today. And, about 2004 XP14, which only JPL still lists, its risk assessment was raised slightly.
Associated Press has a wire story about 2004 MN4 that appears at many news outlets, such as at CNN today, "Asteroid Earth impact in 2029 ruled out." It notes that, "Scientists also ruled out an impact with the moon." Sky & Telescope has an article from yesterday, with the somewhat premature headline, "Earth Safe from Asteroid 2004 MN4." And Astronomy.com updated its Monday article yesterday, going to a new headline, "2004 MN4: swing and a miss."
Dec.
2004
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28 December 2004 - Tuesday
Risk monitoring: Today's Daily Orbit Update MPEC reports observation of three objects with impact solutions: 2004 MN4 by Powell Observatory in Kansas early today UT, 2004 VD17 from Marxuquera Observatory in Spain last night, and, within its existing observation arc, 2004 XP14 from Camarillo Observatory in southern California on December 11th.
Only JPL still has 2004 XP14 listed, and today very slightly raised it low overall risk ratings for this object estimated at roughly 420 meters/yards wide. NEODyS and JPL have lowered their ratings for 2004 VD17, an even larger object (on the order of 580 meters wide), that has stubbornly held its place in the risk listings since November 9th.
There was discussion overnight on the Minor Planet Mailing list (MPML) about the "missing observations" not used in JPL's latest risk assessments for 2004 MN4 (see below). It seems that some observatories, perhaps thinking it would be helpful due to the elevated concern over 2004 MN4, submitted large numbers of astrometric positions. David Dixon commented that there is no difference between this and "any other minor planet," and only "3 to 5 observations within an hour's time" should be reported. "Large sets of observations ... from one site probably don't improve the orbit, they just slow the impact monitors calculations, and whatever systematic error is present from the site (due to timing, catalog, measurement errors) just takes longer to be damped out of the solution by observations from other sites." Reiner Stoss said, "Why report 30 noisy positions (with low centroiding performance) when you can report 3 with high internal accuracy, after stacking the images in 3 independent sets?"
Andrea Milani at NEODyS informed the list that "We are actually discussing right now what is the correct procedure to delete some of the observations of the people reporting more than 10 observations per night. Please do not do this at all. And Steve Chesley at the JPL NEO Program Office said, "Reiner is absolutely right. Stacking to get a better SNR [signal-to-noise ratio] and submitting only about five observations is far preferable to getting a dozen or more observations with high noise. We are winnowing down to five observations in such cases." And Chesley made this special request to observers:
“ If you have submitted astrometry for 2004 MN4, please send me a short note indicating the catalog used. Also, the SNR of the target, a summary of the RMS of the star fits, etc., and perhaps a few words on your general impression of the accuracy of your batch would be helpful. ”
This is a good time to note that, in addition to the Minor Planet Center's Guide to Minor Body Astrometry, which is frequently updated (most recently on December 22nd), Tim Spahr recently posted a Most Common Problems tip sheet.
Update: NEODyS and JPL have updated their 2004 MN4 risk assessments. NEODyS, which had some catching up to do with recent observations (from today's DOU and yesterday's last 2004 MN4 MPEC), raised overall ratings very slightly, and JPL just barely raised its ratings. Both now show two impact solutions rated at Torino Scale 1 (a routine alert that an object "merits special monitoring") in the years 2044 and 2053, but they differ on solution counts and the year of their first solutions.
NEODyS, in its changing commentary on the situation, notes today that "The asteroid 2004 MN4 will have a very close approach to Earth in 2029." David Tholen told the MPML today that "the 2029 close approach will make the asteroid visible to the naked eye as seen from South Africa (using H=19.6, which may be on the faint side). I'm showing an ephemeris magnitude of 5.0." For comparison, the dimmest dipper corner in the Little Dipper is magnitude 5.0, 2.5 times brighter than magnitude 6.0, which is about the faintest the human eye can see under optimum viewing conditions.
Update #2: Still on the 28th local time but after midnight UTC, JPL has revised its 2004 MN4 risk assessment, which rejects the observations reported in this morning's DOU. The result is just five impact solutions, and only the first, in 2053, is rated at TS-1.
Dec.
2004
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27 December 2004 - Monday
Naming: The Chinese government news agency Xinhua reported yesterday that Main Belt asteroid 10388 Zhuguangya (1996 YH3) has been named for Zhu Guangya, "one of the leaders and organizers of the China's development programs for the A-bomb and the H-bomb." This was in the namings batch of November 22nd (news).
Mission technology: An article at the Albuquerque, New Mexico Tribune today, "'Coffee can' might find life's brew on Mars," comes to our attention because the new instrument, the Chemistry/Mineralogy analyzer (CheMin), "has been proposed for two other upcoming NASA Discovery missions, one to explore the moon and another to explore a comet... Neither has been approved." This device, which performs X-ray diffraction and fluorescence on minute samples, is mentioned in a Los Alamos National Lab December 22nd news release that also tells about another instrument that does laser-induced breakdown spectroscopy "from as far as 13 meters away."
Risk monitoring: Today's Daily Orbit Update MPEC is a short one, which isn't unusual during the time of the bright Moon. It reports observation of one object that has impact solutions, 2004 XM29, from Great Shefford Observatory in England last night. Today NEODyS slightly, and JPL very slightly, lowered their overall risk ratings for this small object.
The Minor Planet Center has issued three MPECs today for 2004 MN4, time-stamped 0315, 1413, and 1840 UT. The first reports observations from Jeffrey Sue in Hawaii using Rent-A-Scope at New Mexico Skies early yesterday and today. The second has 51 positions spanning 1.85 hours last night reported from the 1.0m telescope at Wise Observatory in Israel. And the third has observations from Marxuquera Observatory tonight in Spain.
NEODyS and JPL have updated their 2004 MN4 risk assessments today, although at last check they haven't yet incorporated the observations from the second MPEC or the just released third circular. Both slightly raised their overall risk ratings, while NEODyS no longer has a solution in 2067 rated at Torino Scale 1 (a routine alert). JPL has put two more solutions at TS-1, and now, like NEODyS, has five TS-1 ratings in the years 2030, 2031, and 2042-2044.
It is clear from a question received from a new reader that it needs to be stated that 2004 MN4 remains rated at Torino Scale 4 ("merits concern" for "A close encounter, with 1% or greater chance of a collision capable of causing regional devastation"), something that hasn't changed since December 24th. This is for an impact solution (not a prediction but a possibility that hasn't yet been eliminated) in the year 2029. Other solutions have their own lower Torino Scale ratings, from 0 to 1, which have been changing from day to day.
This A/CC news page is a stack of accumulated information, which readers can follow to see how news on a topic has progressed, which in the case of 2004 MN4 goes back daily to December 23rd below. To view a single report on 2004 MN4 along with the latest key details, and links to yet more information, see A/CC's Consolidated Risk Tables page (CRT).
Space.com has an article today, "Worrisome Asteroid Underscores Planetary Defense Mission."
Update: MPEC 2004-Y70 today reports that 2004 MN4 has been found in observations from the Spacewatch 0.9m telescope in Arizona from March 15th. This adds a very significant 96.060 days to the observing arc.
 2004 MN4 caught at Sandlot Observatory in Kansas yesterday by Gary Hug, who explains: "I combined 21 images in Astrometrica and further processed a little in CCDOPS and Photoshop to attain this image. At the time the object was ~20 degrees above my southern horizon." |
Update #2, expanded: MPEC 2004-Y71 carries observations from tonight from Wise Observatory and, all in Spain, from Pla D'Arguines, Begues, and Marxuquera observatories.
JPL has updated its 2004 MN4 risk assessment, dropping its Torino Scale rating to zero ("no likely consequences"), and completely eliminating all impact solutions before the year 2037. Overall impact probability is put at one in 55,556. This assessment is based on all reported observations except those in the latest MPEC, 2004-Y71.
Space.com has a second 2004 MN4 article today, "Asteroid Watch: Odds of 2029 Collision Stuck at 1-in-40."
Update #3: After midnight UTC, NEODyS has updated its 2004 MN4 risk assessment to remove all solutions before 2044, and has lowered its overall ratings to Torino Scale 1 for two solutions in the years 2044 and 2053. As with JPL's latest, this assessment is based on observations reported through all but the last of five MPECs issued for this object today.
About JPL's assessment, sharp-eyed reader Mikael Kinnunen asks, "The number of observations is now 118 and it was ~173 [176] when the TS rating was 4. What happened to the 55 observations?" The NEODyS assessment reports there are 243 positions reported for the period both monitors used in their current assessments, and "0 are rejected as outliers" by NEODyS. A mistake would be unusual, so it appears that JPL had to reject 67 observations in order to arrive at its current best orbit solution.
Astronomy.com has an article today, "Between 2004 MN4 and a hard place," by NASA astronomer Bille Cooke.
Update #4: JPL has revised its new 2004 MN4 risk assessment using the same observation arc as before, raising this object to Torino Scale 1 due to a 2053 impact solution.
Update #5: JPL has issued a new assessment for 2004 MN4 that incorporates the observations reported in MPEC 2004-Y71, and now, like NEODyS, JPL has solutions at TS-1 in the years 2044 and 2053.
JPL has issued a statement, "Possibility of an Earth Impact in 2029 Ruled Out for Asteroid 2004 MN4," and NEODyS has changed its statement, now headlined "Near-Earth Asteroid 2004 MN4: improved situation." Space.com has a report, "Whew! Asteroid Won't Hit Earth in 2029, Scientists Now Say."
Dec.
2004
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26 December 2004 - Sunday
Risk monitoring: The Minor Planet Center put out two special MPECs with new observations of 2004 MN4, dated 0357 and 0434 UT this morning, and had more in the Daily Orbit Update (DOU) MPEC at 0710 UT. Together the three circulars carry positions reported from Friday night from Observatorio Astronomico de Mallorca (OAM) and from this morning from, in time order, Sandlot Observatory in Kansas, Jornada Observatory in New Mexico, Jeffrey Sue in Hawaii and Robert Hutsebaut in Belgium independently using Rent-A-Scope at New Mexico Skies, Goodricke-Pigott Observatory in Arizona, Grasslands Observatory in Arizona, and Desert Moon Observatory in New Mexico.
Today NEODyS and JPL very slightly lowered their overall risk ratings for 2004 MN4. JPL went from a count of 38 impact solutions in the years 2029-2079 to 44 solutions during 2029-2092, and now has three solutions rated at Torino Scale 1 (a routine alert) in 2030, 2042, and 2043 (before this, JPL had three in 2030, 2031, and 2042). NEODyS went from 58 to 68 solutions within its 2080 time horizon, and, in addition to five solutions rated at TS-1 in the years 2030, 2031, and 2041-2043, now also has one in 2067.
Today's DOU carries observations of one other object with impact solutions. 2004 XM29 was caught yesterday morning by Desert Moon and last night by Great Shefford Observatory in England, adding 3.942 days to what had been a 10.749-day observing arc. Both risk monitors have lowered their overall ratings for this small object.
Finally, in a bit of news for people who thought we only had to worry about potentially hazardous objects circling the Sun, Australian media outlets are reporting that "NASA has issued its highest threat warning giving asteroid '2004 MN4' a rating of four on the 10-point Torino Scale used to rate intergalactic threats."
Dec.
2004
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25 December 2004 - Saturday
FMOP news: The Peoria, Illinois Journal Star has an article today, "Retiree spots close asteroid," telling about FMOP volunteer Stan Pope's discovery of Earth-buzzing 2004 YD5: "At 1 a.m. Monday, a retired computer specialist from Caterpillar Inc., working at home in Morton, spotted an asteroid passing so close to Earth it was below the orbits of some satellites." To be precise, it was below the altitude at which the highest satellites orbit Earth, but those (geosynchronous) satellites inhabit a ring around the equator, and 2004 YD5 passed well south of, rather than inside, that ring. So it was never below any satellites. Learn more in a news thread below.
Comet news: Yesterday's comet P/2004 Y1 (Christensen) update MPEC 2004-Y57 shows that this object has been found in observations from NEAT's former U.S. Air Force telescope on Haleakala in Hawaii from 24 January 1998, and from LONEOS in Arizona from April 18th of that same year. The MPEC also carries more prediscovery observations from LINEAR in New Mexico, from 19 and 21 October and November 19th, as well as new observations. See below about this comet's discovery.
Sky & Telescope has a 22 December article telling that "Being near the celestial equator, [C/2004 Q2 (Machholz)] is currently visible during evening from all the inhabited parts of the globe," and, when and where skies are dark, can be seen with the unaided eye. It will be at its best after tomorrow's full Moon wanes.
Risk monitoring: Observation of minor objects (asteroids and comets) slows during the time of the bright Moon, but today's Daily Orbit Update Minor Planet Electronic Circular (DOU MPEC) carries astrometric positions for two of the seven asteroids in recent view that have impact solutions, 2004 MN4 and 2004 YZ23. And, in an unusual move on any day, let alone on a major holiday, the Minor Planet Center at Harvard in Cambridge, Massachusetts, issued a follow-up 7.25 hours after the DOU with additional 2004 MN4 observations.
Sandlot Observatory in Kansas reported 2004 YZ23 from yesterday morning. Of the two risk monitors, only NEODyS still had this large object listed, and today it removed all of its impact solutions.
2004 MN4 was reported in the two MPECs as observed from LONEOS in Arizona yesterday morning UT (Universal Time, very similar to UTC and GMT), last night from the Observatorio Astronomico de Mallorca (OAM), and this morning by Jeffrey Sue in Hawaii using a remote-controlled Rent-A-Scope at New Mexico Skies, and from Goodricke-Pigott Observatory in Arizona and Desert Moon Observatory in New Mexico.
Today NEODyS in Pisa, Italy and the JPL NEO Program in Pasadena, California very slightly raised their overall risk ratings for 2004 MN4.
While it is almost always true that impact solutions will be removed with sufficient further observation, it is common for risk ratings to increase as the night-and-day cycle of observation and analysis progresses. Ratings will often subside for some period after reaching a peak, but the peak can be followed quickly by complete elimination. (And please note that the only risk ratings that matter are the current ratings. An object's previous ratings have absolutely no relevance, and are interesting only for studying how the risk monitoring process works.)
JPL sometime yesterday updated its December 23rd statement with a bottom paragraph noting 2004 MN4's elevation to Torino Scale 4. And Space.com has revised its December 24th article and updated its report on the 2004 MN4 situation.
The CRT has more details on current risk monitoring, and the information used in this report appeared there earlier today. If you use the A/CC news frame as your main access point, you can easily switch between the current general news stack (what you are reading now) and the running updates on the CRT page.
Readers new to impact risk monitoring will be interested to learn that observatories that participate in observing near-Earth objects (NEOs) are a mix of professional and amateur facilities. Amateur astronomers play such a vital scientific role in the process that A/CC's reporting rarely makes a distinction between them and professionals, but you can tell, and you can learn a lot, from visiting observatory links.
Update: JPL has posted a new 2004 MN4 risk assessment, and has very slightly lowered its overall risk ratings. This appears to be based on observations received ahead of tomorrow's DOU, adding 1.2 hours to the observing arc.
Update #2: NEODyS has now also updated its 2004 MN4 risk ratings, very slightly lowering them and now having only one TS-1 impact solution in the year 2031, but increasing its solution count by almost a third.
Dec.
2004
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24 December 2004 - Friday
Meteor news: The journal Nature reported December 22nd a finding that "there is a yearly global input of 14 +/- 5 kilotonnes of [ablated] meteoroid material to the Earth," and most of it appears to be "carried to the polar regions by the prevailing winds above 60 km before funnelling down to the surface." This conclusion comes from studying "a record of iridium and platinum fluxes on a climatic-cycle timescale, back to 128,000 years ago, from a Greenland ice core."
Mission news: Floriday Today has a brief item from yesterday, "Comet probe in final check," about the Deep Impact comet mission scheduled for launch January 12th. Just noticed is a JPL December 13th item about "Observing The Deep Impact Mission Target Comet."
JAXA's Institute of Space and Astronautical Science has a report dated December 9th, "Hayabusa's ion engines achieved 20,000 hours Space Operation," about the MUSES-C Hayabusa asteroid mission.
Deep space comms: NRAO has a December 22nd news release, "Radio Telescopes Will Add to Cassini-Huygens Discoveries." While this isn't about minor object news, it does tell a lot about deep space communication capabilities that someday could play a role in minor object science. The positional accuracy anticipated is "like being able to sit in your back yard and watch the ball in a ping-pong game being played on the Moon." See also the in "Obervatory news" October 18th (second paragraph) about participation in the Huygens effort by "The Dish" in Australia.
Miner objects: Also not about minor objects, but telling about related technologies for off-Earth mining and building a space-based economy, is a long and nicely illustrated piece, "Cosmochemistry and Human Exploration," posted yesterday at Planetary Science Research Discoveries.
Risk monitoring: Today's Daily Orbit Update (DOU) MPEC carries observation of two objects with impact solutions. 2004 YZ23 is reported from the Siding Spring Survey (SSS) in Australia yesterday, and JPL removed all of its impact solutions, while NEODyS posted this large object with preliminary solutions from 2009 through 2080.
The DOU restates the 19-20 June 2004 MN discovery observations from Tucker et al. with the 90" Bok telescope at Kitt Peak in Arizona (see A/CC's report yesterday, below), and report observations from yesterday from LINEAR in New Mexico and SSS that went into the monitors' second risk assessment, as well as apparently further observations from SSS yesterday. From early today UT (last night MST), positions are reported from Roy Tucker at his own Goodricke-Pigott Observatory in Arizona.
About the restatement of the discovery observations, the NEODyS Risk page reports:
“ [The discovery was made with] an instrument never previously used to find asteroids. As a result, the processing of the astrometry and photometry had some problems (distortions and clock errors). When the asteroid was rediscovered from Australia by Gordon Garradd of the Siding Spring Survey, it was soon found to be the same as 200A MN4 but the fit was very poor for the June data... Dave Tholen has remeasured the June observations of 2004 MN4, correcting the problems with ad hoc software. ”
That report indicates that the impact possibility was recognized around the time that MPEC 2004-Y25 was issued on December 20th, but this was considered "dubious" without "new and/or corrected data."
The public schedules for planetary radar observations at last check are not showing any attempt to ping 2004 MN4, which JPL reports was at its closest, for this time around, at 0.0964 AU = 37.5 lunar distances three days ago. Goldstone may not be available due to maintenance, and Arecibo doesn't have radar work scheduled until late January.
Space.com has a report about 2004 MN4 today, "Asteroid Has Outside Chance of Hitting Earth in 2029."
Update: NEODyS has updated its 2004 MN4 assessment, slightly raising its overall ratings, elevating the 13 April 2029 impact solution to an unprecedented Torino Scale 4 ("merits concern" for "A close encounter, with 1% or greater chance of a collision capable of causing regional devastation"), and elevating six other April impact solutions, from 2030, 2031 (two), and in the years 2042-2044, to TS-1 (a routine alert that an object "merits special monitoring").
Update #2: JPL has now raised its overall risk ratings for 2004 MN4 and has also elevated the 13 April 2029 impact solution to TS-4 while elevating solutions in 2030, 2031, and 2042 to TS-1.
Roy Tucker tells A/CC that he has been informed that a formal request is being made for Arecibo to "attempt radar astrometry of 2004 MN4 in January." And, if "successful, that will pretty much determine what 2004 MN4 is going to do."
Editor's note: I reported yesterday that the risk monitor's second 2004 MN4 risk assessments slightly lowered ratings, when actually they were slightly raised, as knowledgeable readers could see for themselves in the running risk rating tallies on the CRT. There's an explanation, but what only matters is that it was a mistake which is now corrected
Update #3: NEODyS has changed its Risk page statement about the 2004 MN4 situation to explain the new TS-4 rating.
Dec.
2004
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23 December 2004 - Thursday
Risk monitoring: (posted at 2023 UTC) JPL and NEODyS today posted 2004 MN4 and put it at a first-ever Torino Scale 2 rating ("merits concern" for "A somewhat close, but not unusual encounter. Collision is very unlikely.") for an impact solution for Friday the 13th in April 2029. See JPL's news release today:
“ The flyby distance is uncertain and an Earth impact cannot yet be ruled out. The odds of impact, presently around 1 in 300, are unusual enough to merit special monitoring by astronomers, but should not be of public concern... In all likelihood, the possibility of impact will eventually be eliminated as the asteroid continues to be tracked by astronomers around the world. ”
More info on 2004 MN4: (posted at 2220 UTC) Note the JPL statement about "In all likelihood, the possibility of impact will eventually be eliminated as the asteroid continues to be tracked." This object as of today has only 35 observations reported. The observing arc spans a long 186.3 days, but most of that is empty, with one end 0.999 days long, and, more recently, the other end 5.11 days long.
This object is estimated at roughly 400 meters wide, or about a quarter mile. That's not a "dinosaur killer," but it is ten times the theoretical diameter of the objects that made Meteor Crater in Arizona and knocked down a Siberian forest at Tunguska. JPL reports that it "was discovered on 19 June 2004 by Roy Tucker, David Tholen and Fabrizio Bernardi of the NASA-funded University of Hawaii Asteroid Survey (UHAS), from Kitt Peak, Arizona, and observed over two nights. On 18 December, the object was rediscovered from Australia by Gordon Garradd of the Siding Spring Survey, another NASA-funded NEA survey." See Roy Tucker's report, "A sweet position," for more about that observing run with the 90" Bok Telescope on Kitt Peak in Arizona. The temporary discovery designations on the NEO Confirmation Page were SSS 4X4E25A and UHAS58. The 2004 MN4 official IAU designation was assigned in early July, although a discovery MPEC was not issued.
The Minor Planet Center issued its first MPEC for 2004 MN4 on December 20th, MPEC 2004-Y25, linking to the 19-20 June observations and reporting "Additional Observations" from the Siding Spring Survey (SSS) on the 18th and confirmation from Sabino Canyon Observatory in Arizona and Mt. John Observatory in New Zealand on the 19th and from Table Mountain Observatory in southern California on the 20th. The next observation reported was in today's DOU, from SSS yesterday. And the European Spaceguard Central Node Priority List notes it will be visible until next May 18th.
Late news: While finishing this news update, it was noticed that NEODyS and JPL have slightly raised their 2004 MN4 risk assessments [not lowered, as originally reported–Ed.], based apparently on 20 new observations received ahead of tomorrow's DOU that have added 1.44 hours to the observing arc.
Update #2: In apparently the first breaking of the 2004 MN4 news via mainstream media outlets, many news sites are running an Associated Press wire story in various lengths, such as the long version at Arizona Central, "Asteroid gets elevated risk rating, but impact unlikely." Some of the other headlines in common use for this story include "Asteroid Given Highest Potential Impact Rating So Far" and, on CBS outlets, "Asteroid Could Hit Earth."
Other risk monitoring news: Today JPL posted 2004 YZ23 with highly preliminary impact solutions in 2010 and 2015. Its discovery was announced today in MPEC 2004-Y50 as found yesterday by Rob McNaught with the SSS 0.5m Uppsala Schmidt Telescope in Australia, and confirmed only by him in additional observations yesterday and today. At absolute magnitude (brightness) H=15.5, this is one of the year's larger discoveries, estimated by JPL at 2.61 km. (1.62 miles) in diameter.
Besides 2004 MN4, today's DOU reports observation of two objects with impact solutions — 2004 XG29 from Verona Observatory and 2004 XN14 from SSS. Both objects were only listed currently by JPL, and today JPL removed both as risks.
Dec.
2004
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22 December 2004 - Wednesday
Numbering & namings: The Minor Planet Center's Periodic Comet Numbers page was updated yesterday to show that comet P/2004 V4 (NEAT) has been numbered 163P/NEAT. And the MPC's Discovery Circumstances page was updated yesterday with 102 new namings, all for objects discovered by LINEAR in New Mexico, from 20586 Elizkolod (1999 RR160) to 21398 Zengguoshou (1998 FX55). There were also 16 other changes involving discovery credits, including two date changes. The previous most recent asteroid namings and comet numberings came in late November.
Comet news: MPEC 2004-Y47 today announces the discovery of P/2004 Y1 (Christensen), found by Eric Christensen at the Catalina Sky Survey (CSS) in Arizona yesterday morning and linked with observations from LINEAR in New Mexico from December 9th and 15th. Jim Young at Table Mountain Observatory in southern California and CSS confirmed the discovery this morning. This object travels a path from near the orbit of Mars to slightly past Jupiter, and the first preliminary calculation has perihelion last June 21st at 1.646 AU.
Observatory news: The Joint Astronomy Centre at the University of Hawaii has a news release today, "World's most powerful infrared camera opens its eyes on the heavens," telling about first light for the new Wide Field Camera (WFCAM) on the U.K. Infrared Telescope (UKIRT). It "has the largest field of view of any astronomical infrared camera in the world... an area ... equal to that of the full moon," and can produce more than 200Gb of imagery per night. The camera is "5.4 metres (18 feet) long," weighs 1,500 kg. (1.7 tons), and operates "below -200C
Astronomy.com has an article from yesterday reporting that test flights of the "SOFIA 747-SP aircraft, complete with a 98.4-inch (2.5 meter) infrared telescope [are] slated to begin in late February 2005." An additional delay has come from a late FAA requirement that the telescope door have a fail-safe closing mechanism, and door work should be finished in January. "Astronomers expect to begin using SOFIA in August 2006," after testing is completed, and after the flying observatory spends part of 2005 "in a stand-down configuration" due to a budget shortfall. See also a recent SOFIA news item, "SOFIA's Upper Rigid Door Installed."
Intruder: We have posted a report by Marco Langbroek about what might have happened if tiny 2004 YD5 had entered Earth's atmosphere. And accompanying that is an animation by Pasquale Tricarico showing the view from 2004 YD5 as it passed Earth on December 19th.
It was reported yesterday below that 2004 YD5 passed "slightly less than the altitude of geostationary satellites, but well above other satellite orbits." To clarify that point, geostationary satellites inhabit a ring around the Earth's equator, north of YD5's path, and we asked Pasquale Tricarico to explain the encounter circumstances. He reports that YD5 did not pass inside the ring, and in fact came closer to the GPS satellite constellation, although passing well clear, than to geostationary satellites. "The minimum orbit intersection distance (MOID) between a GPS sat (GPS BIIA-19) and the asteroid was of 1.88 Earth radii (ER). The MOID with geosynchronous sats was about 2.4 ER." Update: An illustration from Pasquale Tricarico demonstrates the 2004 YD5 asteroid-satellite encounter geometry
Space.com has a report today about 2004 YD5's passage.
At last check today, no further observations have been reported.
Risk monitoring: Today's Daily Orbit Update MPEC reports observation of three objects that have impact solutions. Sormano Observatory in Italy caught 2004 VD17, 2004 XM29, and 2004 XP14 last night, and Desert Moon Observatory in New Mexico observed 2004 XM29 yesterday morning.
Today NEODyS and JPL today very slightly lowered their risk assessments for 2004 VD17. NEODyS raised, and JPL slightly raised, overall risk ratings for 2004 XM29. And JPL slightly raised its ratings for 2004 XP14.
Dec.
2004
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21 December 2004 - Tuesday
Comet news: Comet C/2004 X3 (LINEAR) was announced today in MPEC 2004-Y36. The first observations from LINEAR in New Mexico are shown from the morning of December 15th, and it was confirmed by LINEAR and ten other U.S. and European observing facilities through this morning. The first preliminary calculation has perihelion next June 9th at 4.429 AU, almost as far from the Sun as Jupiter on a path nearly perpendicular to the ecliptic (i=80.9°).
Observation via SOHO of comet C/2004 V13 (SWAN) from 16-20 December was reported today in MPEC 2004-Y34, with old observations restated and new observations. The MPEC also makes the correction that this comet's LASCO discovery was made by J. Sachs. The new orbit calculation has perihelion this morning at about 0342 UT at a sizzling 0.18087 AU. See also news yesterday.
Intruder: MPEC 2004-Y35 dated "2004 Dec. 21, 17:02 UT" announces the discovery of 2004 YD5 and reports that it "passed 0.00023 AU from the Earth on Dec. 19.86 UT" (JPL puts the time at 2037 UT = 3:37pm EST). That's about 8.95% of the distance between Earth and Moon, or about 5.39 Earth radii — slightly less than the altitude of geostationary satellites, but well above other satellite orbits. According to the Minor Planet Center's Closest Approaches page, it is the second closest passage ever observed by telescope. (The closest, 2004 FU162, buzzed Earth last March, but wasn't announced until August. See the news thread.)
This is the object discovered yesterday morning by FMO Project online volunteer Stan Pope in Illinois and temporarily designated SW40Jh. He was reviewing images from the Spacewatch 0.9m telescope in Arizona with Robert McMillan at the telescope. The MPEC shows that they kept after the object, with six positions reported over a 3.83-hour period, during 0516-0906 UT (10:16pm to 2:06am local time). Confirmation positions began at 2319 UT, when KLENOT in the Czech Republic picked up the object. The Spacewatch 1.8m telescope followed it during 0418-0518 UT this morning, and Table Mountain Observatory in southern California closed out the confirmation process with positions reported up until 0614 UT.
At absolute magnitude (brightness) H=29.3, a standard but inexact formula estimates this object's size to be roughly 5 meters/yards wide. If it had entered Earth's atmosphere, it would have exploded harmlessly at high altitude. [news posted at 2027 UTC]
More details: Pasquale Tricarico tells A/CC that 2004 YD5 passed under the Earth, over Antarctica, coming from the Sun side of Earth's orbit, and would have been first visible in "the night sky of Africa, southern Europe, and western Asia." Using the orbit published in the MPEC, he calculates its passage at 0.0002265 AU = 5.31 Earth radii at Dec 19.86. The closest it came to the Moon was 0.0024 AU = 0.93 lunar distance at about 1.44 hours after passing the Earth.
Stu Megan and Marco Langbroek point out that this is the second smallest asteroid ever assigned an IAU designation. JPL today calculates H=29.26 for 2004 YD5, putting it between the nominally smallest, 2003 SQ222 at H=29.99, and the next largest, 2003 SW130 at H=29.12. (Assuming equal surface reflectivity in the absence of contrary knowledge, a higher H value means less light is reflected and thus the object's diameter is calculated to be smaller than for objects having lower H.) 2003 SW130 was discovered with the Spacewatch 1.8m telescope, and 2003 SQ222 was discovered during work on a prototype FMOP-like educational program associated with LONEOS (see Peter Birtwhistle's 2003 SQ222 page for images and links). Both of these tiny objects also intruded into the Earth-Moon system.
Megan and Langbroek note that Stan Pope is new to the FMOP program and he now holds the record for making a first discovery that received an MPEC, accomplished after reviewing only 35 images. The best previous was around 950 images, and it can take a lot more. Josep Julia Gomez's recent first discovery, for instance, came after viewing 4452 images. There are about 50 people presently involved with the program. [update posted at 2228 UTC]
Risk monitoring: Today's Daily Orbit Update MPEC reports observation of five objects with impact solutions, including two for which impact solutions had been eliminated recently but were reposted today by JPL — the small objects 2004 XG29 and 2004 XO63. About 2004 XP14, which was elevated yesterday by NEODyS and JPL to Torino Scale 1 (a routine alert that an object "merits special monitoring"), today NEODyS removed its only impact solution for this object, and JPL returned its assessment to TS-O ("no likely consequences").
Today both risk monitors very slightly raised their ratings for 2004 XM29, and JPL slightly raised its low assessment for 2004 XN14. Not reported today observed was 2004 VD17.