J/ApJS/237/19 KMTNet LCs of ∼1000 main-belt asteroids (Erasmus+, 2018)
Taxonomy and light-curve data of 1000 serendipitously observed main-belt
asteroids.
Erasmus N., McNeill A., Mommert M., Trilling D.E., Sickafoose A.A.,
van Gend C.
<Astrophys. J. Suppl. Ser., 237, 19 (2018)>
=2018ApJS..237...19E 2018ApJS..237...19E
ADC_Keywords: Minor planets; Photometry, VRI
Keywords: minor planets, asteroids: individual (Main-Belt Asteroids) ; surveys ;
techniques: photometric
Abstract:
We present VRI spectrophotometry of 1003 main-belt asteroids (MBAs)
observed with the Sutherland, South Africa node of the Korea
Microlensing Telescope Network (KMTNet). All of the observed MBAs were
serendipitously captured in KMTNet's large 2°x2° field of view
during a separate targeted near-Earth Asteroid study. Our broadband
spectrophotometry is reliable enough to distinguish among four
asteroid taxonomies and we confidently categorize 836 of the 1003
observed targets as either a S-, C-, X-, or D-type asteroid by means
of a machine learning algorithm approach. Our data show that the ratio
between S-type MBAs and (C+X+D)-type MBAs, with H magnitudes between
12 and 18 (12km≳diameter≳0.75km), is almost exactly 1:1.
Additionally, we report 0.5-3hr (median: 1.3hr) light-curve data for
each MBA and we resolve the complete rotation periods and amplitudes
for 59 targets. Of the 59 targets, 2 have rotation periods potentially
below the theoretical zero-cohesion boundary limit of 2.2hr. We report
lower limits for the rotation periods and amplitudes for the remaining
targets. Using the resolved and unresolved light curves we determine
the shape distribution for this population using a Monte Carlo
simulation. Our model suggests a population with an average elongation
b/a=0.74±0.07 and also shows that this is independent of asteroid
size and taxonomy.
Description:
Observations were made with the Sutherland, South Africa node of the
Korea Microlensing Telescope Network (KMTNet).
Observations were originally performed for a near-Earth asteroid study
that took place between 2016 October 25-2017 February 20 over four
observing weeks (Erasmus+ 2017AJ....154..162E 2017AJ....154..162E). However, the large
field of view of KMTNet meant that the 31 fields observed in that
study also included many serendipitously observed main-belt asteroids
(MBAs).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 134 1003 Observations and results
fig2/* . 1004 Individual CSV files for each object
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Description of file: On the FTP, the directory fig2/ contains 1003 tab
delimited data table containing the light curve photometry of the objects
in Figure Set 2.
The naming convention for each file follows name_jd.csv where "name" is the
source identifier, e.g. 2002_GG or Vadimsimona, and "jd" is the julian date
around the first observation in the file.
The first row gives the column labels (Observation time (JD),
V band magnitude (mag) and 1σ error in V band magnitude (mag).
Note that the data is the V magnitude data points with the adjusted I and R
magnitude data points included. Adjustments of I and R to V magnitudes are
done by adding the derived colors.
See also:
B/astorb : Orbits of Minor Planets (Bowell+, 2014)
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/578/A42 : Main Belt asteroids observed by Spitzer (Ryan+, 2015)
J/A+A/596/A40 : Main-belt asteroids optical light curves (Szabo+, 2016)
J/ApJS/234/37 : R-band K2 photometry of main-belt asteroids (Molnar+, 2018)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Seq [1/1003] Internal index number (1)
6- 20 A15 --- Name Object identifier
22- 34 F13.5 d JD Julian Date of observation start
36- 39 A4 "h:m" Dur [0/3] Observation duration
41- 44 F4.1 mag Hmag [8.1/19.7] H magnitude (2)
46- 50 F5.2 mag Vmag [13.26/21.13] V band magnitude
52- 56 F5.2 mag V-R [-0.95/0.39] The (V-R) color index (3)
58- 61 F4.2 mag e_V-R [0.01/0.27] Uncertainty in V-R
63- 67 F5.2 mag V-I [-0.46/0.54] The (V-I) color index (3)
69- 72 F4.2 mag e_V-I [0.02/0.36] Uncertainty in V-I
74- 77 A4 --- l_Amp Limit flag on Amp (4)
79- 82 F4.2 mag Amp [0.02/1.4] Amplitude
84- 87 F4.2 mag e_Amp [0.0/0.17]? Uncertainty in Amp
89- 92 A4 --- l_Per Limit flag on Per (4)
94- 96 I3 min Per [26/350] Rotational period
98- 99 I2 min e_Per [0/85]? Uncertainty in Per
101-105 F5.3 --- S-type [0.0/1.0] Probability of S-type
107-111 F5.3 --- X-type [0.0/0.931] Probability of X-type
113-117 F5.3 --- C-type [0.0/1.0] Probability of C-type
119-123 F5.3 --- D-type [0.0/0.787] Probability of D-type
125 A1 --- Tax Taxonomy
127-129 F3.1 --- a [2.1/3.2] Semi-major axis (2)
131-134 F4.1 deg i [0.2/28.1] Orbital inclination (2)
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Note (1): This table has 1003 entries but there are four main-belt asteroids
that were by chance observed twice. They are 1981 SU2, 1999 RE190,
2000 UM3 and Miahelena.
See Section 6.4 for more detail on duplicate observations.
Note (2): Obtained from http://ssd.jpl.nasa.gov/horizons.cgi
Note (3): Colors have been corrected for solar colors by subtracting
the respective V-R=0.41 and V-I=0.75 solar colors
(Binney & Merrifield 1998gaas.book.....B 1998gaas.book.....B).
Note (4): Lower limit shown in cases where observational duration was
insufficient to observe entire light-curve period.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 07-Sep-2018