Thursday26 August 20044:53pm MDT2004-08-26 UTC 2253 last
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The Asteroid/Comet Connection's
daily news journal about
asteroids, comets, and meteors

Today's issue status: done

IndexyesterdayContentstomorrow

Cover: The “moose in the field,” a monsoon season comet discovered by Roy Tucker in this image Monday morning at Goodricke-Pigott Observatory in Arizona. See his discovery story below.

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Bits of luck   by Roy Tucker

With my system at Goodricke-Pigott Observatory, I do an all-night scan-mode image of a strip of sky 48 arcminutes wide centered at declination +02 degrees, 5 minutes with three 35-centimeter aperture f/5 Newtonian telescopes with 1K-squared CCDs at the foci. The telescopes are spread in the east-west direction so that they image the same sky but separated in time by about twenty minutes. Their aiming is centered about 40 minutes to the east of the meridian. During data acquisition, the scan is chopped into 1024x1024-pixel FITS images, each covering about 0.64 square degrees. Imaging begins in the evening twilight and continues until morning twilight.

Summer is not prime observing time in Tucson, Arizona. We have a seasonal monsoon from early July until mid-September like clockwork. I haven't seen Perseid meteors here in years. My first bit of luck was that I got four consecutive clear nights from the 20th through the 23rd of August.

The object announced yesterday in MPEC 2004-Q43 as comet C/2004 Q1 (Tucker) was actually recorded on the morning of the 22nd, but in an image triplet just a few fields from the end. After looking at blinking images for a couple of hours, I sometimes get a little eager to finish up. I actually did report a faint asteroid in another part of the field, but I was

so fixated on looking for faint moving objects that I missed the big moose wallowing across the field.

Fortunately, the 23rd was clear and the comet was well positioned near the middle of the field of view (in the cropped frame seen above). When I got to that image triplet, I immediately noticed it, but didn't think too much about it. I see known comets pass through my field fairly often and, indeed, had seen comet 53P/Van Biesbroeck pass through on the 20th and the 21st. I went to the Minor Planet Center's Web site and used the MPChecker function to find out what the object was. When it reported no known objects in that area, I became very interested.

I immediately composed an astrometry report for those observations and E-mailed them to the Minor Planet Center with the heading "comet" and inquired if this was a known object. After a bit of time, Kyle Smalley responded that this appeared to be an unknown object and requested a physical description. During the wait for this response, I realized that I should have recorded it the previous night. A short search revealed the previous images and I sent those astrometric measures to the MPC. So, although the formal discovery

concluded >>

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image was recorded on the 23rd of August, I was actually able to provide observations for the previous night within a short time. The object was then posted on the NEO Confirmation Page and other observers quickly verified it.

So, I was lucky three ways. 1) I had good weather at just the right time, 2) nobody else saw it between my observations of the 22nd and the 23rd, and 3) the other surveys were working mostly to the west. Of course, it helps to look at large numbers of images. Each clear night provides me 500 to 700 images to examine, depending upon season. I'll get perhaps 190 clear, dark nights per year, which means a little over 100,000 images per year.

Although the discovery was very exciting, the operation that produced it is very routine. MOTESS is a “discovery machine”; photons go in and discoveries come out. I don't actually do much except look at a lot of images. I go to bed pretty early and rise early to shut down the instrument and begin processing the data. It's a pleasant change from the usual astronomical observing in that I can get a good night's sleep and go to a day job refreshed.

Roy Tucker's day job is CCD engineer at the University of Arizona. See a previous article telling about how that sometimes leads to observing time on large telescopes.
      MOTESS is short for “Moving Object and Transient Event Search System,” a project that received a 2002 Planetary Society Eugene Shoemaker Grant (update). His other discoveries include NEA 2003 UY12 and PHA 2004 MP7.

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News briefs

Australian event:  There are reports today in southeastern Australia, “from the New South Wales central coast to Shepparton in Victoria,” that tell of a possible meteor witnessed as “an extremely bright light and two explosions about 11.30pm (AEST)” Wednesday night. See News.com.au for an Australian Associated Press story (with unfounded statements about “space junk”) and ABC Illawarra.

Marco Langbroek reports that “The meteoric fireball seen from eastern Australia at 25 August 1330 UTC (11:30pm local time) is not likely to have been man-made space junk.”

Rosetta news:  On cruise four light minutes out, the Rosetta mission has now gone to weekly communication passes. The August 23rd status report, the first in two weeks, has as its highlight that “the LGA threshold test first attempted on 1 June 2004 was repeated successfully.” Checking the earlier report, you will see that the “LGA TC threshold test could not be completed due to a problem in the New Norcia station” during “TTC commissioning.” Well, hmm. There is, thankfully, a Rosetta Project Glossary, but it only informs us that TC = telecommand. A little digging finds that LGA = low gain antenna (more about that), and TTC = telemetry, tracking, and command. Now you know.

2004 FU162 update:  SpaceRef.com posted an issue of David Morrison's NEO News E-mail newsletter yesterday telling about 2004 FU162's March 31st close passage (see A/CC news Sunday and Monday), and refers to an incident with “the object called AL00667,” properly referred to as 2004 AS1 (see Index). It reports “the population of NEAs with diameter of 6 m or more is a couple hundred million, with an expected impact frequency of one per several years.” One coming as close as 2004 FU162 “should be four times more frequent, or more than once per year. Thus this event is not particularly rare, except that LINEAR had the good fortune to notice it.” This report has spawned a Sky & Telescope news brief yesterday and an AFP wire story that appears at SpaceDaily today.

The Albuquerque Tribune gets the passage date wrong, but has some interesting comments today from LINEAR's Grant Stokes:

“We've been experimenting with different observation methods and improving the technology. One of the byproducts of that is that we're seeing objects that come closer to us.”
  . .
Last week's object [sic] probably didn't hit Earth, although if it did the atmospheric burn-up would have been hard to see because it happened in the daytime, Stokes said. 
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Risk monitoring 26 August

The Thursday Daily Orbit Update MPEC carries no observations of objects with impact solutions, although it does have positions from yesterday from Hunters Hill Observatory in Australia for 2004 QY2, for which all solutions were removed yesterday. The European Spaceguard Central Node campaigns page today pulled down observing campaigns for QY2 and 2004 QA2, while leaving 2004 PP97 and 2004 QZ2.

Overnight and this morning, JPL posted first 2004 QD14 and 2004 QF14, and later 2004 QB17. NEODyS has posted 2004 QD14 and 2004 QV16.

2004 QD14 was announced at five minutes after midnight UT in MPEC 2004-Q45 as discovered Tuesday by Rob McNaught and Gordon Garradd at the Siding Spring Survey (SSS) with its 0.5m Uppsala Schmidt Telescope in New South Wales. It was confirmed with the nearby Australian National University 1m telescope, from which McNaught followed the object for 4.41 hours and then picked it up 13.72 hours later and again 9.28 hours after that. Mt. John Observatory in New Zealand also confirmed it. JPL puts this object's diameter estimate at 260 meters/yards.

In contrast to many highly preliminary impact solutions for that object, JPL has only one for 2004 QF14, which was

Summary Risk Table - sources checked at 2205 UTC, 26 Aug

Object

Assessment

Years

VI
PS
cum
PS
max
T
S
Arc 
days
 2004 QZ2 NEODyS 8/252068-20792-6.65-6.8304.644
JPL 8/252068-20681-6.17-6.1704.644
 2004 QV16 NEODyS 8/262008-20081-5.70-5.7001.012
 2004 QJ7 NEODyS 8/252007-208071-3.44-4.0400.965
JPL 8/242009-2103107-3.23-3.9500.965
 2004 QF14JPL 8/262020-20201-8.46-8.4600.723
 2004 QD14 NEODyS 8/262028-20708-4.63-4.9601.297
JPL 8/262018-2098122-3.24-3.7501.297
 2004 QB17JPL 8/262012-209931-4.61-5.0400.979
 2004 PP97JPL 8/26R E M O V E D
 NEODyS 8/172029-20757-4.04-4.5500.987
 2004 FU162JPL 8/242006-2104824-5.38-6.3700.031
VI = count of "virtual impactors" (impact solutions)
See A/CC's Consolidated Risk Tables for more and maybe
  newer details, and check the monitors' links for latest info.
Note that only objects recently in view are shown here.

announced at about the same time in MPEC 2004-Q46. It was discovered by LINEAR in New Mexico yesterday morning and confirmed last night by Great Shefford and Highworth observatories, both in England. JPL puts the diameter at roughly 90 meters.

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MPEC 2004-Q51 today announced 2004 QB17, a half-kilometer size object discovered yesterday morning by Miwa Block with the Spacewatch 0.9m telescope in Arizona and confirmed this morning by Great Shefford, Three Buttes Observatory in Arizona, and Table Mountain Observatory in southern California.

NEODyS has a single low-rated, very preliminary impact solution less than four years away for 2004 QV16, which was announced today in MPEC 2004-Q47 as discovered yesterday by Brian Skiff at LONEOS in Arizona and confirmed last night by Great Shefford and this morning by Table Mountain, Sabino Canyon Observatory in Arizona, and Three Buttes. From its brightness, this object is estimated by standard formula to be on the order of 645 meters wide.

Update: JPL has removed its impact solutions for 2004 PP97, and a check of the MPC Last observations page is showing that this object was caught two days ago with the Australian National University 1m telescope. It hadn't been reported since its discovery MPEC on the 17th.

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