Hi,
I recently was observing a (currently) 12mag asteroid 2003UV11, which featured a close flyby to earth some days ago on Oct 29./30.2010. Story:
http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/4078634/page/0/view/collapsed/sb/5/o/all/fpart/1
BUT:
The Guide 8.0 (version July 12, 2010) position plotted on the basis of new MPCORB.DAT data was WRONG by roughly 9' (9' offset to north of the truth), which is by far too much (in terms of normal ephemeris data). I cross-checked with the JPL Horizons ephemeris (calculated for the exact geo position on earth) - actually those were correct
(for proof see the foto + guide overlay below).
I used Guide for some other (weak 15mag) asteroids recently (also with MPCORB.DAT) and positions were perfectly accurate on DSS images ! So I guess (!) Guide has NO BUG here.
But does anyone know WHY MPCORB.DAT should be so inaccurate for this object specifically ??? (JPL Horizons and MPCORB astroid elements don't match, see the data at the bottom)
Thanks for any comments on this,
Peter
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Here comes the proof: a foto taken by a colleague on Oct 29, 21:40 CEST = 9:40pm CEST (see the detected asteroid path) with Guide chart overlaid with positions calculated by MPCORB. JPL Horizons prediction is given by green arrow (it fits on the actual asteroid track, OK.
http://www.eyes4skies.de/Internet/Astro/BeobachtungsReports/BeobachtungsReports_files/BB_2010_10_28/2003UV11/2003UV11_QuestionablePosition_Guide_w.jpg
Some details:
- No, Guide is NOT calculating for geo center here
- Geo Position (for foto + Guide) was 52.37° North, 9.72° east
- MPCORB.DAT was pretty NEW from MPC mirror Lulin Sky Survey, Taiwan
as described in
http://www.projectpluto.com/mpcorb.htm
- all equinox are 2000.0
- all times measured in CEST (= MESZ) central european summer time (yes, before the recent switch)
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MPCORB element data from Guide:
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2003 UV11 mag 12.0
Right ascension: 22h43m01.018s
Declination: +22 10' 40.05"
Mean position at current epoch:
Right ascension: 22h43m32.369s
Declination: +22 14' 04.99"
Apparent position at current epoch:
Right ascension: 22h43m33.987s
Declination: +22 14' 22.95"
Dist from home planet: 0.01403044 AU (2,098,924 km)
Heliocentric position: lon 35.60087 lat 0.37624
Heliocentric radius 1.00214 AU
81.92% illuminated
Phase angle: 50.33 degrees
Elongation from Sun 129.04 degrees (evening sky)
Speed of apparent motion: 2.317/hour at position angle 264.8
Motion is 55.36 degrees/day in RA, -5.11 degrees/day in dec
Assumed asteroid diameter 869 meters
Comments from the MPCORB database:
Designation: 2003 UV11
Absolute magnitude: 19.4
Slope parameter: 0.15
Orbital elements:
Semimajor axis: 1.4509401
Eccentricity: 0.7628815
Inclination of orbit: 5.95172
Argument of perihelion: 124.79508
Long. ascending node: 31.98953
Mean anomaly: 278.16305
Mean daily motion: 0.56393601 degrees/day
Epoch of elements: 23 Jul 2010
Uncertainty level: 2
457 observations made at 4 oppositions
Orbital arc: 1996-2010
Last observed: 2010 10 28
RMS residual: 0.47
Perturbing objects used in orbit: M-v
Orbit computed by MPCALB
Orbit based on the JPL DE403 positions and masses
Apollo
A potentially hazardous asteroid (PHA)
Reference: E2010-U50
Perihelion distance 0.3440447 AU
Aphelion distance 2.5578355 AU
Period of orbit 1.75 years (638.4 days)
Date of perihelion JD 2455545.61743 (15 Dec 2010 4:49)
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Element data by JPL Horizons:
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JPL/HORIZONS (2003 UV11) 2010-Oct-30 06:27:23
Rec #:452163 (+COV) Soln.date: 2010-Oct-18_15:08:29 # obs: 375 (1996-2010)
FK5/J2000.0 helio. ecliptic osc. elements (AU, DAYS, DEG, period=Julian yrs):
EPOCH= 2455502.5 ! 2010-Nov-02.00 (CT) Residual RMS= .45657
EC= .7630012693280119 QR= .3442960419731397 TP= 2455545.613788302
OM= 31.97059638220447 W= 124.7648929867429 IN= 5.928541742140045
A= 1.452733696070523 MA= 335.7315944584261 ADIST= 2.561171350167907
PER= 1.751 N= .562891977 ANGMOM= .013402128
DAN= 1.07446 DDN= .42297 L= 156.8795572
B= 4.8674563 TP= 2010-Dec-15.1137883
Physical parameters (KM, SEC, rotational period in hours):
GM= n.a. RAD= n.a. ROTPER= n.a.
H= 19.304 G= .150 B-V= n.a.
ALBEDO= n.a. STYP= n.a.
ASTEROID comments:
1: soln ref.= JPL#29, PHA OCC=0
2: source=ORB
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