Saturday14 August 20046:19pm MDT2004-08-15 UTC 0019 back top next  

The Asteroid/Comet Connection's
daily news journal about
asteroids, comets, and meteors

Today's issue status: done

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Cover: This is a stack of all the frames used to report two positions in this morning's Daily Orbit Update MPEC for 2004 PU42 from either side of midnight 11-12 August by the Visnjan School of Astronomy (VSA) NEO group using a remote-controlled Observatorio Astronomico de Mallorca (OAM) 0.3m telescope. This is from during the confirmation period, but the faint fast-moving object wasn't located in the imagery until a better calculation of its motion became available, as Reiner Stoss explains below, and also see below about this object's current impact risk assessment. (The faint trail at lower left is a satellite.)

Chasing 2004 PU42 – panel 1/1 Major News for 14 August 2004 back top next  

Chasing 2004 PU42   by Reiner Stoss

Using a remote-controlled Observatorio Astronomico de Mallorca (OAM) 0.3m telescope, the Visnjan School of Astronomy (VSA) NEO group imaged 2004 PU42 while it was AP01598 on the Near-Earth Object Confirmation Page (NEOCP), but we were not able to detect it reliably. Why? The prediction on the NEOCP was based on the discovery set of observations only, and thus the predicted position as well as the predicted motion of this fast-moving object (FMO) certainly had some degree of uncertainty.

We imaged the field centered on the predicted position and stacked images on the predicted motion, but couldn't see the object. So there were two possible explanations for this negative observation:
 1.  The object was outside the imaged field.
 2.  The applied motion for the stacking, as predicted on the NEOCP for the nominal position, was too far off from the real one, making the object trail on the stack and thus not reaching a signal-to-noise ratio (SNR) above the background noise.

We thought we saw something at that position, but it was ahead of the prediction and too noisy, and we did not restack the images for different motions to see if the signal increased. We should have done that, but we had a lot of easier

images for other objects to reduce, so we postponed it, hoping the next day to get an updated ephemeris.

We awoke Thursday to find that the object was already MPEC'd, so someone else had managed to detect it (see news). Yesterday we went back to our images and, with the accurately predicted motion for the time of our images, we were now able to see it clearly. We reported the set of measurements to the MPC, especially since the object has impact solutions and so the positions could prove valuable.

A check of residuals on the MPC Minor Planet Ephemeris Service (MPES) shows that our measurements are pretty accurate, with residuals below one arcsecond, especially when compared with observations made with much larger telescopes. This is the result of applying advanced techniques for data reduction, which are taught here to the students. When searching for new objects, a decrease in quality for the gain of more area can be justified. Not so, however, when doing follow-up observations which, with all the issues involved, such as virtual impactors, should be precise enough to allow a good determination of the orbit.

See cover above for a stack of all the frames used to report a position from each side of midnight 11-12 August. Reiner Stoss wrote Tuesday about the VSA NEO group, and see below about 2004 PU42's risk assessment.

News briefs – panel 1/1 Major News for 14 August 2004 back top next  
News briefs

Naming:  Timed for tomorrow's 58th Indian Independence Day, Vishnu Reddy has a news release about his naming of 78118 Bharat (2002 NT), which came in the July namings. The IAU citation states that “Bharat is the native name of India and derives from the wise and pious King Bharata of ancient Hindu mythology.” There are reports today at the Times of India, Hindustan Times, and Sify.

Vishnu Reddy tells A/CC that he was with Roy Tucker at Goodricke-Pigott Observatory in Arizona when he made this discovery on July 4th. “It was my dream to discover an asteroid and I came to U.S. in 2002 just to do that with the help of Roy.” After that, back in India, “[I] continued my work with Roy by reducing data he sends through CDs via USPS [mail]. It's amazing how the surveys don't pick up asteroids. I discovered over 10 asteroids from those CDs which take up to 15 days to get to India.” Since then “I have given up my job as a news journalist in India and am now a grad student in space studies at [the University of North Dakota]. My main research area is near-IR spectroscopy of olivine-rich asteroids [using] the 3-meter NASA IRTF on Mauna Kea.”

Meteor news:  Sandia National Labs today posted new pairs of JPEG flight composites and QuickTime movies for 39 bright meteors caught between early on July 31st and yesterday morning. (Files are kept in that ftp folder for only a month or so.)

Risk monitoring - panel 1/1 Major News for 14 August 2004 back top next  
Risk monitoring 14 August

The Saturday Daily Orbit Update MPEC (DOU) has observation of 2004 PU42 from Marxuquera Observatory in Spain Thursday night, Sormano Observatory in Italy last night, and early today from Pla D'Arguines Observatory in Spain and Great Shefford Observatory in England. Also in the DOU are two positions from the 2004 PU42 confirmation period, on either side of midnight Wednesday, from the Visnjan student NEO group via the Observatorio Astronomico de Mallorca (OAM). Today NEODyS slightly lowered its low risk assessment for this tiny object, and cut from 13 to six impact solutions, now only in the years 2071-77. (At last check, at 5pm in Pasadena, JPL hadn't yet updated its 2004 PU42 risk assessment.)

Summary Risk Table - sources checked at 0000 UTC, 15 Aug

Object

Assessment

Years

VI
PS
cum
PS
max
T
S
Arc 
days
 2004 PU42 NEODyS 8/142071-20776-6.25-6.6502.915
JPL 8/132053-210327-5.55-6.4901.826
2004 ME6JPL 6/282017-209943-5.64-6.3500.873
 NEODyS 6/272044-20637-7.29-7.7600.873
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.
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