J/ApJ/743/156 NEOWISE observations of NEOs: preliminary results (Mainzer+, 2011)
NEOWISE observations of near-earth objects: preliminary results.
Mainzer A., Grav T., Bauer J., Masiero J., McMillan R.S., Cutri R.M.,
Walker R., Wright E., Eisenhardt P., Tholen D.J., Spahr T., Jedicke R.,
Denneau L., DeBaun E., Elsbury D., Gautier T., Gomillion S., Hand E.,
Mo W., Watkins J., Wilkins A., Bryngelson G.L., Del Pino Molina A.,
Desai S., Camus M.G., Hidalgo S.L., Konstantopoulos I., Larsen J.A.,
Maleszewski C., Malkan M.A., Mauduit J.-C., Mullan B.L., Olszewski E.W.,
Pforr J., Saro A., Scotti J.V., Wasserman L.H.
<Astrophys. J., 743, 156 (2011)>
=2011ApJ...743..156M 2011ApJ...743..156M
ADC_Keywords: Minor planets ; Infrared sources ; Surveys
Keywords: infrared: planetary systems - minor planets, asteroids: general -
planets and satellites: general - surveys
Abstract:
With the NEOWISE portion of the Wide-field Infrared Survey Explorer
(WISE) project, we have carried out a highly uniform survey of the
near-Earth object (NEO) population at thermal infrared wavelengths
ranging from 3 to 22um, allowing us to refine estimates of their
numbers, sizes, and albedos. The NEOWISE survey detected NEOs the same
way whether they were previously known or not, subject to the
availability of ground-based follow-up observations, resulting in the
discovery of more than 130 new NEOs. The survey's uniform sensitivity,
observing cadence, and image quality have permitted extrapolation of
the 428 near-Earth asteroids (NEAs) detected by NEOWISE during the
fully cryogenic portion of the WISE mission to the larger population.
We find that there are 981±19 NEAs larger than 1km and 20500±3000
NEAs larger than 100m. We show that the Spaceguard goal of detecting
90% of all 1km NEAs has been met, and that the cumulative size
distribution is best represented by a broken power law with a slope of
1.32±0.14 below 1.5km. This power-law slope produces ∼13200±1900
NEAs with D>140m. Although previous studies predict another break in
the cumulative size distribution below D∼50-100m, resulting in an
increase in the number of NEOs in this size range and smaller, we did
not detect enough objects to comment on this increase. The overall
number for the NEA population between 100 and 1000m is lower than
previous estimates. The numbers of near-Earth comets and potentially
hazardous NEOs will be the subject of future work.
Description:
WISE was launched on 2009 December 14. The WISE survey began on 2010
January 14, and the mission exhausted its primary tank cryogen on 2010
August 5. An augmentation to the WISE baseline data processing
pipeline, "NEOWISE", permitted a search for new moving objects to be
carried out using the WISE data in near-real time. Exhaustion of the
secondary cryogen tank occurred on 2010 October 1, and the survey was
continued as the NEOWISE Post-Cryogenic Mission using only bands W1
and W2 until 2011 February 1. As described in Wright et al.
(2010AJ....140.1868W 2010AJ....140.1868W) and Mainzer et al. 2011ApJ...731...53M 2011ApJ...731...53M, the
NEOWISE survey cadence resulted in most minor planets in the WISE
sample receiving an average of 10-12 observations over ∼36hr,
although some NEOs were observed dozens or even hundreds of times.
We have created preliminary thermal models for each NEO observed by
WISE Moving Object Processing System (WMOPS) during the fully
cryogenic portion of the survey. As described in Mainzer et al.
(2011ApJ...736..100M 2011ApJ...736..100M), we employ the spherical near-Earth asteroid
thermal model (NEATM) (Harris, A.W., 1998Icar..131..291H 1998Icar..131..291H).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 86 486 *NEATM results for the 428 Near-Earth Objects (NEOs)
detected by NEOWISE during the fully cryogenic
portion of the WISE mission
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Note on table1.dat: This table contains the preliminary thermal fit results
(NEATM = spherical Near-Earth Asteroid Thermal Model) based on the
First Pass version of the WISE data processing as described in the
text. The NEOWISE project plans to produce an updated final catalog
of physical properties based on the Second Pass processing of the WISE
data using the updated version of the WISE Science Data System, with a
goal of delivering this updated catalog to NASA's Planetary Data System.
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See also:
B/astorb : Orbits of Minor Planets (Bowell+ 2013)
II/311 : WISE All-Sky Data Release (Cutri+ 2012)
II/190 : IRAS Minor Planet Survey (IMPS) (Tedesco 1992)
VII/91 : IRAS Asteroid and Comet Survey (Veeder+ 1986)
J/ApJ/741/68 : Main Belt asteroids with WISE/NEOWISE. I. (Masiero+, 2011)
J/ApJ/742/40 : Jovian Trojans asteroids with WISE/NEOWISE (Grav+, 2011)
J/PASJ/63/1117 : Asteroid catalog using AKARI (AcuA). V1. (Usui+, 2011)
J/A+A/509/A94 : Lightcurves of 14 NEAs (Kwiatkowski+, 2010)
J/A+A/511/A49 : Lightcurves of 12 NEAs (Kwiatkowski+, 2010)
J/A+A/423/381 : Asteroidal I, J, K in the DENIS Survey (Baudrand+, 2004)
J/A+A/375/285 : Photometric observations of 9 NEOs (Szabo+, 2001)
http://wise.ssl.berkeley.edu/ : WISE home page
http://neo.jpl.nasa.gov/ : NASA Near Earth Object Program home page
http://www.minorplanetcenter.org/ : IAU Minor Planet Center home page
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- MPC Trojan asteroid name, in MPC packed format
9- 13 F5.2 mag HMag [9.4/24.2]?=-9.99 Absolute H band magnitude
15- 18 F4.2 --- G ?=-9.99 Magnitude slope parameter
20- 25 F6.3 km Diam [0.04/37.7] Diameter
27- 31 F5.3 km e_Diam Statistical error in Diam (1)
33- 38 F6.3 --- pV ?=-9.99 Optical geometrical albedo
40- 44 F5.3 --- e_pV Statistical error in pV (1)
46- 50 F5.3 --- eta Beaming parameter η (3)
52- 57 F6.3 --- e_eta ?=-9.99 Statistical error in eta (2)
59- 64 F6.3 --- pIR Infra-red geometrical albedo
66- 70 F5.3 --- e_pIR Statistical error in pIR (1)
72- 74 I3 --- N1 Number of WISE W1 (3.3um) observations
76- 78 I3 --- N2 Number of WISE W2 (4.6um) observations
80- 82 I3 --- N3 Number of WISE W3 (11.6um) observations
84- 86 I3 --- N4 Number of WISE W4 (22.1um) observations
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Note (1): Error values presented here represent the statistical errors on
the model fits, including Monte Carlo modeling of uncertainties for
the WISE magnitudes, H, G, and beaming and pIR when these two
parameters cannot be fit. Two calibration papers by Mainzer et al.
(2011ApJ...736..100M 2011ApJ...736..100M and 2011ApJ...737L...9M 2011ApJ...737L...9M) discuss the absolute
calibration of the WISE data for small Solar system bodies and should
be consulted before comparing with data derived from other sources.
The quoted precision for each parameter follows the object with the
most significant figures for the error on that value in the table.
H, G and albedo values of "-9.99" indicate that the objects have not
received visible light follow-up. Readers are encouraged to check the
WISE Explanatory Supplement by Cutri et al. 2011,
http://wise2.ipac.caltech.edu/docs/release/prelim/expsup/wise_prelrel_toc.html
for details and updates.
Note (2): Beaming value errors of "-9.99" indicate that the thermal fit
routine returned a maximum value of π or a minimum of 0.3, so
error cannot be properly determined.
Note (3): The beaming parameter η represents the deviation of the
thermal emission from that of a smooth non-rotating sphere due to
rotation and surface roughness, and is used to consolidate the
uncertainty in the values of the surface thermal properties, including
emissivity; in range [0,π].
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 15-May-2013