J/A+A/578/A42 Main Belt asteroids observed by Spitzer (Ryan+, 2015)
The kilometer-sized Main Belt asteroid population revealed by Spitzer.
Ryan E.L., Mizuno D.R., Shenoy S.S., Woodward C.E., Carey S.J.,
Noriego-Crespo A., Kraemer K.E., Price S.D.
<Astron. Astrophys. 578, A42 (2015)>
=2015A&A...578A..42R 2015A&A...578A..42R
ADC_Keywords: Minor planets ; Photometry, infrared
Keywords: minor planets, asteroids: general - infrared: general
Abstract:
Multi-epoch Spitzer Space Telescope 24um data is utilized from
the MIPSGAL and Taurus Legacy surveys to detect asteroids based on
their relative motion. Infrared detections are matched to known
asteroids and average diameters and albedos are derived using the Near
Earth Asteroid Model (NEATM) for 1865 asteroids ranging in size from
0.2 to 169km. A small subsample of these objects was also detected by
IRAS or MSX and the single wavelength albedo and diameter fits derived
from these data are within the uncertainties of the IRAS and/or MSX
derived albedos and diameters and available occultation diameters,
which demonstrates the robustness of our technique. The mean geometric
albedo of the small Main Belt asteroids in this sample is pV=0.134
with a sample standard deviation of 0.106. The albedo distribution of
this sample is far more diverse than the IRAS or MSX samples. The
cumulative size-frequency distribution of asteroids in the Main Belt
at small diameters is directly derived and a 3σ deviation from
the fitted size-frequency distribution slope is found near 8km.
Completeness limits of the optical and infrared surveys are discussed.
Description:
Mid-infrared photometry at 24 microns of 1865 asteroids are presented.
For each asteroid detection, the equatorial J2000 coordinates, time of
observation, heliocentric and geocentric distance, visual absolute
magnitude and 24 micron flux is reported. Photometry was obtained with
the Spitzer Space Telescope and photometry tool MOPEX. Thermal fitting
is used to determine asteroid diameters and albedos using the Near
Earth Asteroid Model for objects on a single detection basis and
average values are also reported.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 137 3486 24µm fluxes and observing circumstance for
survey asteroids
table2.dat 105 3479 Thermal model fits by individual asteroid sighting
table3.dat 110 1865 Mean albedo and diameter for all known asteroids
detected in survey data
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See also:
J/A+A/498/313 : Photometry of 3 main belt asteroids (Marciniak+, 2009)
J/A+A/508/1503 : Photometry of 3 main belt asteroids (Marciniak+, 2009)
J/A+A/529/A107 : Photometry of 4 main belt asteroids (Marciniak+, 2011)
J/A+A/545/A131 : Photometry of 8 main belt asteroids (Marciniak+, 2012)
J/A+A/539/A115 : Main-belt asteroids polarimetric survey II (Gil-Hutton+, 2012)
J/A+A/542/A11 : Main-belt asteroids polarimetry III (Canada-Assandri+, 2012)
J/A+A/569/A122 : Main-belt asteroids polarimetry IV (Gil-Hutton+, 2014)
J/ApJ/741/68 : Main Belt asteroids with WISE/NEOWISE. I. (Masiero+, 2011)
J/ApJ/759/L8 : Main Belt asteroids with WISE/NEOWISE. II. (Masiero+, 2012)
J/ApJ/770/7 : Main Belt asteroids with WISE/NEOWISE. III. (Masiero+, 2013)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name Asteroid name/provisional designation
17- 24 I8 --- Reqkey Spitzer reqkey of observation
26- 35 A10 "YYYY-MM-DD" Obs.date Date of reqkey of observation (YYYY-MM-DD)
37- 47 A11 "h:m:s" Obs.time Time of reqkey start (hh:mm:ss.ss)
49- 57 F9.5 deg RApdeg Predicted right ascension of asteroid at
beginning of AOR from Horizons (J2000)
59- 67 F9.5 deg DEpdeg Predicted declination of asteroid at
beginning of AOR from Horizons (J2000)
69- 77 F9.5 deg RAdeg Right ascension of asteroid detection in
AOR (J2000)
79- 87 F9.5 deg DEdeg Declination of asteroid detection in AOR
(J2000)
89 I1 --- q_Flux [1/4] Flux quality flag, 1=good (1)
91- 99 F9.3 mJy Flux [1/24506] Measured 24µm flux
101-108 F8.3 mJy e_Flux [0.2/3676] Error in 24µm flux
110-113 F4.2 AU rh [1.1/5.8] Heliocentric distance at time of
observation
115-118 F4.2 AU delta [0.3/5.6] Spitzer to asteroid distance
δ at time of observation
120-124 F5.2 deg phase [2.5/62] Asteroid phase angle
126-131 F6.3 mag H [7/27] Absolute magnitude of asteroid
133-137 F5.3 --- G [0.15] Asteroid Slope Parameter
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Note (1): Flux quality flags
1 = good flux
2 = flux which varies >30% between epochs
3 = nearby bright source
4 = saturated source
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name Asteroid name/provisional designation
17- 24 I8 --- Reqkey Spitzer reqkey of observation
26- 30 F5.3 --- Alb1 [0/1.6] Geometric Albedo for η=0.8
32- 36 F5.3 --- e_Alb1 [0.002/0.4] Error in Alb1
38- 44 F7.3 km Diam1 [0.2/152] Asteroid Diameter for η=0.8
46- 51 F6.3 km e_Diam1 [0.05/37] Error in Diam1
53- 57 F5.3 --- Alb2 [0/1.5] Geometric Albedo for η=1.07
59- 63 F5.3 --- e_Alb2 [0.002/0.4] Error in Alb2
65- 71 F7.3 km Diam2 [0.2/169] Asteroid Diameter for η=1.07
73- 78 F6.3 km e_Diam2 [0.05/41] Error in Diam2
80- 84 F5.3 --- Alb3 [0/1.4] Geometric Albedo for η=1.34
86- 90 F5.3 --- e_Alb3 [0.002/0.4] Error in Alb3
92- 98 F7.3 km Diam3 [0.2/184] Asteroid Diameter for η=1.34
100-105 F6.3 km e_Diam3 [0.05/45] Error in Diam3
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 7 I7 --- Number [1/362345]?=0 Asteroid number assigned by the MPC
9- 23 A15 --- Name Asteroid name/provisional designation
25- 29 F5.3 --- Alb1 [0.01/1.4] Mean Geometric Albedo for η=0.8
31- 35 F5.3 --- e_Alb1 [0.002/0.4] Error in Alb1
37- 43 F7.3 km Diam1 [0.2/152] Mean Asteroid Diameter for η=0.8
45- 50 F6.3 km e_Diam1 [0.05/26] Error in Diam1
52 I1 --- Nobs1 [1/6] Number of solutions with η=0.8 averaged
54- 58 F5.3 --- Alb2 [0.01/1.2] Mean Geometric Albedo for η=1.07
60- 64 F5.3 --- e_Alb2 [0.002/0.4] Error in Alb2
66- 72 F7.3 km Diam2 [0.2/169] Mean Asteroid Diameter for η=1.07
74- 79 F6.3 km e_Diam2 [0.05/29] Error in Diam2
81 I1 --- Nobs2 [1/6] Number of solutions with η=1.07 averaged
83- 87 F5.3 --- Alb3 [0.01/1.1] Mean Geometric Albedo for η=1.34
89- 93 F5.3 --- e_Alb3 [0.002/0.4] Error in Alb3
95-101 F7.3 km Diam3 [0.2/183] Mean Asteroid Diameter for η=1.34
103-108 F6.3 km e_Diam3 [0.05/32] Error in Diam3
110 I1 --- Nobs3 [1/6] Number of solutions with η=1.34 averaged
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Acknowledgements:
Erin Ryan, erinleeryan(at)gmail.com,
University of Maryland, United States
(End) Erin Ryan [University of Maryland], Patricia Vannier [CDS] 06-Apr-2015