J/ApJS/219/27 Surveys of asteroid rotation periods using iPTF (Chang+, 2015)
Asteroid spin-rate study using the intermediate Palomar Transient Factory.
Chang C.-K., Ip W.-H., Lin H.-W., Cheng Y.-C., Ngeow C.-C., Yang T.-C.,
Waszczak A., Kulkarni S.R., Levitan D., Sesar B., Laher R., Surace J.,
Prince T.A.
<Astrophys. J. Suppl. Ser., 219, 27 (2015)>
=2015ApJS..219...27C 2015ApJS..219...27C (SIMBAD/NED BibCode)
ADC_Keywords: Minor planets ; Surveys ; Photometry, RI
Keywords: minor planets, asteroids: general; surveys
Abstract:
Two dedicated asteroid rotation-period surveys have been carried out
in the R band with ∼20 minute cadence using the intermediate Palomar
Transient Factory (iPTF) during 2014 January 6-9 and February 20-23.
The total survey area covered 174deg2 in the ecliptic plane.
Reliable rotation periods for 1438 asteroids are obtained from a
larger data set of 6551 mostly main-belt asteroids, each with ≥10
detections. Analysis of 1751, PTF-based, reliable rotation periods
clearly shows the spin barrier at ∼2hr for rubble-pile asteroids. We
found a new large super-fast rotator, 2005 UW163, and another five
candidates as well. For asteroids of 3<D<15km, our spin-rate
distribution shows a number decrease along with frequency after 5
rev/day, which is consistent with the results of the Asteroid Light
Curve Database. The discrepancy between our work and that of Pravec et
al. (update 2014 April 20) comes mainly from asteroids with
Δm<0.2mag, which could be the result of different survey
strategies. For asteroids with D<3km, we see a significant number drop
at f=6rev/day. The relatively short YORP effect timescale for small
asteroids could have spun up those elongated objects to reach their
spin-rate limit resulting in breakup to create such a number
deficiency. We also see that the C-type asteroids show a smaller
spin-rate limit than the S-type, which agrees with the general
impression that C-type asteroids have a lower bulk density than S-type
asteroids.
Description:
The Palomar Transient Factory (PTF) project, and its successor the
iPTF project, employs the Palomar 48 inch Oschin Schmidt Telescope
equipped with an 11-chip mosaic CCD camera to explore synoptically the
transient and variable sky. This configuration creates a field of view
of ∼7.26deg2 and a pixel scale of 1.01". Most PTF exposures are
taken in the Mould-R band, and the other available filters are the
Gunn-g' and two different Hα bands.
To collect a large sample of asteroid light curves to further our
previous asteroid spin-rate studies (Polishook et al.
2012MNRAS.421.2094P 2012MNRAS.421.2094P; Chang et al. 2014ApJ...788...17C 2014ApJ...788...17C), we conducted
two asteroid rotation-period surveys during 2014 January 6-9 and
February 20-23. The exposure time of each frame was 60s, and the
scanned sky coverage was ∼174deg2 in total.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 131 1438 *Synodic rotation periods of PTF-U2s
table3.dat 131 169 Asteroids with partial phase coverage
table4.dat 129 96 Bright asteroids with large light-curve variation
and without rotation-period determination
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Note on table2.dat: "PTF-U2s" = The 1438 Palomar Transient Factory
(PTF)-detected asteroids, with reliable (i.e., U≥2) rotation periods.
See section 4.
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See also:
B/astorb : Orbits of Minor Planets (Bowell+ 2014)
II/313 : Palomar Transient Factory (PTF) photometric cat. 1.0 (Ofek+, 2012)
J/A+A/556/A8 : 100 asteroids rotational parameters (Lhotka+, 2013)
J/ApJ/770/7 : WISE/NEOWISE Main Belt asteroids (Masiero+, 2013)
J/ApJ/743/156 : NEOWISE obs. of NEOs: preliminary results (Mainzer+, 2011)
J/ApJ/742/40 : Jovian Trojans asteroids with WISE/NEOWISE (Grav+, 2011)
J/ApJ/741/68 : Main Belt asteroids with WISE/NEOWISE. I. (Masiero+, 2011)
http://www.ptf.caltech.edu/iptf : Intermediate Palomar Transient Factory home
http://minorplanetcenter.net/ : IAU Minor Planet Center home page
http://www.minorplanet.info/lightcurvedatabase.html : Asteroid LC database
Byte-by-byte Description of file: table[234].dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- ID Object identifier (asteroid number or
MPC packed format)
9- 10 A2 --- f_ID Flag on ID (1)
12- 17 I6 --- Planet ? Asteroid number
19- 32 A14 --- Name Name or preliminary designation
34- 37 F4.2 AU a [1.3/5.3] Semi-major axis
39- 42 F4.2 --- e [0.01/0.5] Eccentricity
44- 48 F5.2 deg i [0.04/31] Inclination
50- 54 F5.1 deg Omega Longitude of ascending node
56- 60 F5.1 deg omega Argument of periapsis
62- 66 F5.1 km Diam [0.1/122.3] Diameter
68 A1 --- f_Diam [w] w: Diam derived from WISE/NEOWISE data
70- 73 F4.2 AU Delta [1/5.8] Heliocentric distance
75- 78 F4.2 AU r [0.1/4.8] Geodesic distance
80- 84 F5.2 deg alpha [0.2/20.6] Phase angle
86- 90 F5.2 mag HRmag [8.4/21.7] Absolute HR magnitude
92- 95 F4.2 mag e_HRmag [0.03/0.5] Uncertainty in HRmag
97 I1 --- Nn [1/4] Number of nights
99-101 I3 --- Ni [14/122] Number of images
103-107 F5.2 mag Rptf [13.9/21.1] PTF R band magnitude
109-112 F4.2 mag e_Rptf [0/0.2] Uncertainty in Rptf
114-118 F5.2 h Per [1.2/44]? Derived rotation period
(not for table 4)
120-124 F5.2 h e_Per [0/83.4]? Uncertainty in Per
126-129 F4.2 mag Amp [0.04/1.6] Lightcurve amplitude
131 I1 --- U [2/3]? Lightcurve quality code;
3=highly reliable (not for table 4) (2)
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Note (1): Flag as follows:
* = Asteroid available in the LCDB (asteroid light curve database:
http://www.minorplanet.info/lightcurvedatabase.html).
b = Lightcurves with large amplitudes and deep V-shape minima.
Note (2): Code as follows:
3 = highly reliable;
2 = some ambiguity;
1 = possible but may be wrong (Warner, Harris & Pravec 2009Icar..202..134W 2009Icar..202..134W);
0 = no acceptable lightcurve solution.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 28-Sep-2015