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J/A+A/511/A49       Lightcurves of 12 NEAs                  (Kwiatkowski+, 2010)

Photometric survey of the very small near-Earth asteroids with the SALT telescope. III. Lightcurves and periods for 12 objects and negative detections. Kwiatkowski T., Polinska M., Loaring N., Buckley D.A.H., O'Donoghue D., Kniazev A., Romero Colmenero E. <Astron. Astrophys. 511, A49 (2010)> =2010A&A...511A..49K
ADC_Keywords: Surveys ; Solar system ; Minor planets ; Photometry, CCD Keywords: techniques: photometric - minor planets, asteroids: general Abstract: Very small asteroids (VSAs) are thought to be the building blocks of larger asteroids and, as such, are interesting to study. Many of these monolithic or deeply fractured objects display rapid rotations with periods as short as several minutes. Observations of such asteroids can reveal their spin limits, which can be related to the tensile strength of their interiors. The evolution of the spins of these objects is primarily shaped by the YORP effect, the theory of which needs comparison with observations. With the 10m SALT telescope, we observed VSAs belonging to near-Earth asteroids. The obtained lightcurves were used to derive synodical periods of rotation, amplitudes, and elongations of these bodies. Results for 14 rapidly rotating asteroids were reported in the first paper in this series. Here we show lightcurves of 2 fast rotators, 9 objects with periods ≥1h, and a possible non-principal axis rotator. We also list negative detections that most probably indicate asteroids with long periods and/or low amplitudes. Combining our results with the data from the literature, we obtain a set of 79 near-Earth VSAs with a median period of 0.25h (15min). By adjusting the spin limits predicted by theory to those observations, we find tentative evidence that the tensile strengths of VSAs, after scaling them to the same size, are of the same order as the minimum tensile strengths of stony meteoroids that undergo fragmentation under the atmospheric load. Description: Time-series relative photometry for 12 near-Earth asteroids is presented as well as the aspect data, the observing log, and the derived rotation parameters. Objects for which no brightness variations was recorded are also listed. For most asteroids several lightcurves are reported, each of which was measured with a different comparison star. For each asteroid a composite lightcurve is included, obtained with the specified synodic rotation period. The period, together with the shifts in magnitude of the individual data sets used in the composite lightcurve, were obtained in a least-square fit of the Fourier series of the specified order. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 88 23 Aspect data and observing log table2.dat 37 12 Summary of the results list.dat 62 37 List of all light curves lc/* 22 27 Individual light curves clc/* 19 10 Composite light curves
See also: J/A+A/509/A94 : Lightcurves of 14 NEAs (Kwiatkowski+, 2010) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 10 A10 --- Ast Designation of the asteroid 12- 15 F4.1 mag Hmag Absolute magnitude 17- 26 A10 "YYYY/MM/DD" Obs1.Date Date of observation 28- 32 A5 "h:m" Obs1.Time Observing time (beginning) (1) 34- 38 A5 "h:m" Obs2.Time Observing time (end) (1) 40- 45 F6.4 AU r Asteroid-Sun distance (2) 46- 51 F6.4 AU Delta Asteroid-Earth distance (2) 52- 55 F4.1 deg alpha Solar phase angle (2) 57- 61 F5.1 deg ELON Geocentric, ecliptic longitude (2) 63- 67 F5.1 deg ELAT Geocentric, ecliptic latitude (2) 69- 72 F4.1 mag Vmag Apparent magnitude 74- 77 F4.1 arcsec/min SkyMov Asteroid movement on the sky 79- 80 I2 s Exp Exposure time 82- 84 I3 --- N1 Number of exposures taken 86- 88 I3 --- N2 Number of exposures used
Note (1): Observing runs which started on the next UTC night have hours greater than 24 h. Note (2): Coordinates given for the middle of the observation
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 10 A10 --- Ast Asteroid designation 12- 16 F5.3 h Per Rotation period 18- 22 F5.3 h e_Per Period uncertainty (max error/sigma) 24- 27 F4.2 mag Amp Peak-to-peak lightcurve amplitude 29- 31 F3.1 --- a/b Maximum elongation (1) 33- 37 F5.3 km Diam Effective diameter
Note (1): Actual a/b elongation is not greater than the given value
Byte-by-byte Description of file: list.dat
Bytes Format Units Label Explanations
1- 10 A10 --- Ast Asteroid name 13- 26 A14 --- FileName Name of the file containing the light curve 31- 62 A32 --- Title Title of the file
Byte-by-byte Description of file: lc/*
Bytes Format Units Label Explanations
1- 15 F15.7 d Time Julian date (1) 17- 22 F6.3 mag mag Relative magnitude
Note (1): not corrected for the light travel time
Byte-by-byte Description of file: clc/*
Bytes Format Units Label Explanations
1- 13 F13.7 d Phase Rotation phase 15- 19 F5.3 mag mag Relative magnitude
Acknowledgements: Tomasz Kwiatkowski, tkastr(at)vesta.astro.amu.edu.pl References: Kwiatkowski et al., Paper I 2010A&A...509A..94K, Cat. J/A+A/509/A94 Kwiatkowski, Paper II 2010A&A...509A..95K
(End) T. Kwiatkowski [Poznan Obs., Poland], Patricia Vannier [CDS] 05-Mar-2010
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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