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Photometric lightcurves of 21 asteroids
ICARUS 64, 37-52 (1985)
Photometric Lightcurves of 21 Asteroids CARL D. V E S E L Y AND RONALD C. TAYLOR Lunar and Planetary Laboratory, The University of Arizona, Tucson, Arizona 85721 Received M a r c h 22, 1985; revised M a y 1, 1985 Forty-three lightcurves of 21 asteroids obtained in Arizona b e t w e e n 1968 a n d 1978 are p r e s e n t e d with a brief d i s c u s s i o n of each. Included are four asteroids not previously observed: 34 Circe, 138 Tolosa, 162 Laurentia, and 1058 Grubba. Rotation periods are at least 12 hr for Circe, either 6.42 or 12.98 hrs for Laurentia, and m o r e than 18 hr for Grubba. Magnitudes and colors for 12 of the asteroids are given. It appears that 10 Hygiea has lightcurves which s o m e t i m e s have two m a x i m a per rotation cycle a n d s o m e t i m e s three. A strong relation b e t w e e n amplitude and solar p h a s e angle is seen for 39 Laetitia. The first direct evidence of an opposition effect for 89 Julia is given. 511 Davida is d i s c u s s e d in an effort to u n d e r s t a n d the pole orientation using photometric astrometry. © 1985AcademicPress, Inc.
son star observation exceeds three times the nightly average. All the observations were made using the V filter of the Johnson UBV system, with the exception of Aug. 9, 1973 which was done in the y filter of the Strrmgren system. Table I lists the aspect data for the asteroids and the figure number for each lightcurve. The aspect data are for the midtime of the lightcurves. Table II lists the comparison stars and the quality of the night; " s c a t t e r " is the average deviation from a smooth curve of comparison star magnitude versus time. If UBV photometry was done, the V magnitude and B - V color of each comparison star are given. Table III gives the magnitudes and colors of the asteroids. V0(l,o0 is the V magnitude of the observed lightcurve maximum corrected to unit distances from Sun and Earth. V(I,a) is the mean magnitude of the asteroid, defined as the magnitude of the asteroid corrected to the line through the middle of the lightcurve which divides the area above and below equally. In all cases the errors associated with the magnitudes and colors of the asteroids are either the mean residuals of the standard stars of the night or one standard deviation from the mean of the in-
I. I N T R O D U C T I O N
We present 43 photoelectric lightcurves of 21 asteroids that were observed during the period 1968-1978. Four of the asteroids, to our knowledge, have not had their periods previously reported: 34 Circe, 138 Tolosa, 162 Laurentia, and 1058 Grubba. V magnitudes and colors were also obtained for 12 of the asteroids and are included. Of those there are f o ur - - 42 Isis, 162 Laurentia, 747 Winchester, and 1058 G r u b b a - - f o r which we give new V0 magnitudes. Also, the first UBV colors of Grubba are given. These lightcurves were obtained to increase the data base for studies in shapes, spin periods, and the orientation of the rotation axes. This paper gives the remainder of usable lightcurves from our files. One exception is asteroid 45 Eugenia whose lightcurves will be published separately. The lightcurves appear in Figs. 1-23; in the legends the various observers and the telescopes involved are acknowledged. The lightcurves are not corrected for light time. The observing and reducing routines have been described by Gehrels and Owings (1962). Open circles are used when the deviation from the mean of a single compari37
0019-1035/85 $3.00 Copyright © 1985by Academic Press, Inc. All rights of reproduction in any form reserved.
38
VESELY
AND
TAYLOR
'FABLE 1 ASPECT DATA Asteroid
2 2 8 10 10 10 10 10 I0 12 15 18 20 23 23 34 39 39 42 60 89 89 89 89 89 113 129 129 129 129 138 162 162 162 404 404 511 511 511 511 747 747 1[)58
Obs. date UT (yr.mo.dayl
Phase angle
Distance ..... from from Sun Earth (AU) (AU)
RA (1950)
Dec (1950)
73.05.13 73.06.16 70.04.19 70.01.02 70.01.03 73.06.24 73.06.25 73.06.26 73.06.27 71.06.14 70.03.07 74.08.15 70.03.28 73.04.23 73.06.24 78.04.04 77.06.10 78.10.15 70.04.12 70.05.31 68.08.13 68.08.14 68.08.15 68.08.22 68.08,24 70.04.12 71.05.29 71.05.30 71.06.13 71.06.16 78.10.13 70.01.31} 70.02.08 70.03.01 74.04.27 74.04.28 68.12.29 68.12.30 70.03.21 72.08.07 70.03.29 73.08.09 74.08.25
+14.°8 + 19.0 - 10.7 + 10.6 + 10.8 - 15.9 - 15.7 - 15.5 - 15.3 -15.8 - 6.2 + 3.4 + 2.6 + 10.7 +23.7 + 15.8 + 6.1 + 5.7 + 6.9 + 1.8 - 5.5 - 5.1 -- 4.7 + 4.4 + 4.9 + 5.7 + 12.8 +13.1 + 17.3 +18.2 +11.1 - 6.7 - 4.1 + 9.3 + 12.9 + 13. I 1.7 - 1.6 - 7.8 + 3.6 + 9.8 - 8.1 + 4.5
2,759 2.837 2.541 3.494 3.494 2.967 2.968 2.969 2.970 1.859 3.006 1.958 2.348 2.326 2.481 2.415 2.798 2.475 2.682 2.741 2.135 2.134 2.132 2.126 2.123 2.17[) 2.264 2.263 2.259 2.258 2.164 2.495 2.492 2.448 2.tt59 2.059 2.672 2.672 3.259 3.523 3.252 2.476 1.796
1.941 2.261 1.612 2.688 2.698 2.245 2.235 2.225 2.216 0.908 2.052 0.949 1.353 1.380 2.091) 1.570 1.811 1.496 1.714 1.729 1.133 1.131} 1.128 1.121 1.122 1.1811 1.327 1.3311 1.397 1.421 1.222 1.536 1.515 1.549 I. 112 I. 114 1.69/) 1.691} 2.336 2.539 2.373 1.500 0.789
14h54".'3 14 3 6 . 0 15 3 8 . 2 3 52.1 3 51.7 21 4 8 . 5 21 4 8 . 4 21 4 8 . 3 21 4 8 . 1 1920.5 I1 2 5 . 9 21 1 8 . 5 12 4 6 . 8 12 5 8 . 6 12 5 6 . 5 10 1 5 . 3 17 4 1 . 7 I 56.7 12 4 8 . 4 16 3 1 . 2 21 5 4 . 5 21 5 3 . 5 21 5 2 . 4 21 4 4 . 3 21 4 2 . 1 13 1 . 3 15 1 6 . 4 15 1 5 . 7 15 8 . 2 15 7 . 3 23 4 8 . 1 959.8 952.5 9 34.4 13 5 9 . 5 13 5 8 . 6 642.7 641.8 13 2 9 . 5 20 3 1 . I I1 (I.8 22 3 9 . 3 22 4 . 0
+25035 ' + 2 5 14 1042 + 2 2 55 + 2 2 52 --1051 -1050 1049 -1048 1057 .... 1 2 4 3 I1 49 5 23 + 7 27 + 037 ~- 8 21 7 50 I 41 + 837 17 I 450 444 439 4 5 3 56 + 3 5 + 3 37 + 3 35 + 240 + 223 -- 6 01 + 2 2 36 + 2 3 15 + 2 4 10 + 1 3 18 + 1 3 16 +19 4 + 1 9 I1 + 1 4 31 26 32 + 2 2 36 18 15 - 3 27
± 0.1
+0.002
+0.002
+_(}.2
± 1
Ecliptic Long. 11950)
Lat. (1950)
211°.4 206.6 234.8 60.8 60.7 325.6 325.6 325.6 325.6 290.1 177.3 318.4 192.9 191}.5 192.8 152.7 265.3 26.5 187.7 248.7 329.1 328.9 328.7 326.9 326.5 192.9 225.6 225.4 223.8 223.6 354.9 144.2 142.3 138.1 202.7 202.5 100.1 99.9 194.9 303.6 157.5 334.5 331.8
+4071 +38.1 + 8.5 + 2.7 + 2.6 + 2.3 + 2.3 + 2.3 + 2.3 +11.1 15.0 + 3.7 .... 0.3 + 12.6 + 6.1 2.3 15.5 12.8 +12.7 + 4.8 + 7.4 + 7.6 + 7.8 4 9.0 + 9.3 + 8.9 +21.0 +20,9 +19,5 +19,2 4,3 + 9~7 + 9,7 + 9,2 +23.8 +23.7 - 4.() 3.9 +22.1 - 7.4 +15.0 9.0 + 7.9
Fig.
I I 2 3 3 4 4 4 4 5 6 7 8 9 9 10 II I1 12 13 14 14 14 14 14 15 16 16 16 16 17 18 18 18 19 19 21) 20 21 21 22 22 23
39
ASTEROIDS LIGHTCURVES TABLE
11
C O M P A R I S O N STARS A N D Q U A L I T Y OF NIGHTS
Asteroid
2 2 8 10 10 10 10 10 10 12 15 18 20 23 23 34 39 39 42 60 89 89 89 89 89 113 129 129 129 129 138 162 162 162 404 404 511 511 511 511 747 747 1058
Obs. date (UT) (yr.mo.day) 73.05.13 73.06.16 70.04.19 70.01.02 70.01.03 73.06.24 73.06.25 73.06.26 73.06.27 71.06.14 70.03.07 74.08.15 70.03.28 73.04.23 73.06.24 78.04.04 77.06.10 78.10.15 70.04.12 70.05.31 68.08.13 68.08.14 68.08.15 68.08.22 68.08.24 70.04.12 71.05.29 71.05.30 71.06.13 71.06.16 78.10.13 70.01.30 70.02.08 70.03.01 74.04.27 74.04.28 68.12.29 68.12.30 70.03.21 72.08.07 70.03.29 73.08.09 74.08.25
RA (1950)
14h55.m0 14 36.1 15 39. 1 3 52.6 3 52.0 21 4 8 . 5 21 4 8 . 4 21 4 8 . 3 21 48. 1 19 2 0 . 5 11 2 6 . 0 21 18.6 12 4 6 . 7 12 5 9 . 0 o o o ~ 16 3 1 . 3 21 5 3 . 7 21 5 3 . 5 21 5 2 . 6 21 4 4 . 3 21 4 2 . 0 13 0 . 7 15 16.1 15 16.1 15 7 . 6 15 7 . 7 23 4 6 . 7 9 59.4 9 52.0 10 0 . 2 13 5 9 . 7 13 5 8 . 3 642.6 641.9 ~ 20 3 0 . 9 11 I .0 22 3 8 . 9 22 3 . 9 -+0.2
Dec 11950)
Scatter (mag)
+25°32 ' +25 19 -- 10 38 + 2 2 51 + 2 2 56 --10 51 -- 10 50 -- 10 48 -- 10 46 --10 55 --12 43 --11 49 -- 5 28 + 7 28
-+0.005 -+0.005 -+0.004 -+0.011 -+0.013 -+0.023 -+0.027 -+0.024 -+0.017 -+0.011 -+0.009 -+0.021 -+0.004 -+0.010
V (mag)
7.31 9.11
-+0.04 -+0.04
B-V (mag)
+0.66 0.65
-+0.01 -+0.02
Remarks
Clouds at end Clouds at end Variable seeing
10.61
-+0.01
+1.31
-+0.01
Clouds about Cirrus all about Clear 10.07 7.82 9.37
-+0.02 -+0.03 -+0.02
+0.56 +0.44 +0.70
-+0.02 -+0.02 -+0.01
D u s t y winds
Some clouds Seeing poor
-17 1 - 4 50 - 4 44 - 4 39 - 404 - 3 56 + 3 5 + 3 51 + 3 51 + 2 46 + 3 00 - 5 51 +22 40 +23 19 +22 29 +13 9 +13 11 +19 2 +19 8 -26 +22 - 18 - 3
27 40 23 27 -+1
-+0.015 -+0.011 -+0.006 -+0.020 ±0.011 ---0.017 -+0.012 -+0.024 -+0.009 -+0.018 -+0.008 -+0.024 -+0.005 +-0.013 -+0.012 -+0.009 -+0.040 -+0.007 -+0.008 -+0.006 -+0.010 -+0.008 -+0.018 -+0.013 -+0.004
12.22
-+0.03
+0.68
-+0.03
9.70 10.59 10.61 10.19
-+0.02 -+0.01 -+0.03 -+0.02
+1.06 +0.49 +1.26 +0.54
-+0.01 -+0.01 -+0.02 -+0.01
Clouds at end
10.32
-+0.02
+0.60
-+0.02
10.99
-+0.03
+0.64
-+0.02
Windy Telescope drift Clouds about
11.26
-+0.02
+0.73
-+0.01
5.32 10.36 11.55 10.01 13.01
-+0.02 -+0.02 -+0.02 -+0.03 -+0.03
+ 1.25 +0.38 +0.91 +0.47 +0.53
-+0.02 -+0.02 -+0.02 -+0.03 -+0.05
13.41
-+0.02
---0.82
-+0.01
Variable seeing
Clouds at end Clouds at end Clouds at end
Clouds. h a z y
Clouds
o Not available.
dividual magnitudes of the object, whichever is poorer. The second method is applied for the comparison star errors. II. DISCUSSION OF EACH ASTEROID Lightcurves of five asteroids, 8 Flora, 15 Eunomia, 18 Melpomene, 42 Isis, and 747 Winchester, are presented in Figs. 2, 6, 7, 12, and 22, respectively, without comment.
2 Pallas
Photoelectric lightcurves of Pallas were made by Groeneveld and Kuiper (1954b), Wood and Kuiper (1963), Burchi (1972), and Chang and Chang (1963). Schroll et al. (1976), using their many observations and the then-unpublished observations of I. van Houten-Groeneveld (1981), determined a period of 7.807 hr and preliminary pole co-
40
VESELY A N D TAYLOR "FABLE 111 MAGNITUDES
Asteroid
Obs. date (UT)
Phase angle
2 2 10 15 18 20 42 89 89 89 89 129 129 162 511 51 l 511 511 747 1058
73.05.13 73.06.16 70.01.03 70.03.07 74.08.15 70.03.28 70.04.12 68.08.14 68.08.15 68.08.22 68.08.24 71.05.29 71.06.13 70.02.08 68.12.29 68.12.30 70.03.21 72.08.07 70.03.29 74.08.25
17°8 19.0 10.8 6.2 3.4 2.6 6.9 5.1 4.7 4.4 4.9 12.8 17.4 4.1 1.7 1.6 7.8 3.6 9.8 4.5
AND COLORS
V0(l,a) (mag) 4.92 5.19 5.96 5.52 6.65" 6.65 8.02 6.95 6.95 6.91 6.91 7.41 7.58 9.15 6.37 6.33 6.82 6.48 8.28 12.34"
~)(l,c0 (mag)
±0.04 +0.04 ±0.01 ÷0.02 ±0.03
B-V (mag)
4.94 5.21 6.04 5.72 6.72 6.73 8.17 7.05 7.05 7.01 7.01 7.61 7.78 9.29 6.41 6.37 6.95 6.52 8.34 12.38
+-0.02
+0.03 +0.02
+-0.02 ±11.02 +0.02 ±0.04 +0.02 ±0.03 ±0.04 +0.03 ±:0.02 +0.03 +11.05 ±0.05
+0.66 +0.60 +0.71 +0.82 +0.85 +0.82 +0.88 +0.85 +0.87 +0.86 +0.85 +0.70 +0.72 +0.70 +0.69 +0.68 +0.73 +0.70 +0.72 +0.88
U-B (mag)
+0.01 -+0.02 -+0.04 -+0.01 -+0.02 -+0.02 -+0.02 -+0.02 ±0.01 -+0.02 +0.01 -+0.02 -+0.02 +0.02 -+0.02 +0.02 -+0.02 -+0.03 -+0.03 -+0.02
+0.27 -+0.35 +0.43 +0.37 +0.40 +0.43 +0.42 +0.43 4-0.42 +0.42 +0.27 4-0.27 +0.32 +0.39 +0.36 +0.36 +0.37 +0.32 +0.50
±0.02 -±0.03 +0.01 ±0.02 -+0.02 -+0.03 +0.02 +0.01 -+0.02 -+0.02 ±0.04 +0.02 -+0.02 -+0.02 +0.03 -+-0.04 -+0.04 +0.03 -+0.03
" T h e m a g n i t u d e at the m a x i m u m o f the a v a i l a b l e l i g h t c u r v e w h i c h might not be a true V0.
ordinates o f 228 °, +43 °. Chang et al. (19811 reevaluated their o w n 1963 lightcurves and utilized s o m e 1965 observations to derive a period o f 7.815 hr. Burchi and Milano (1983) a n a l y z e d their 1973 and 1974 observations using the Schroll et al. period and found the pole to be at 211 °, +38 °. Carlsson and Lagerkvist (1983) s h o w a short 1982 lightcurve o f very l o w amplitude. Binzel
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(1984) presents his 1982 and 1983 lightcurves in c o m p o s i t e form based on Schroll's period. He used these and all other available lightcurves to determine a n e w pole solution o f 200 ° , +37 ° . Figure 1 gives two near pole-on lightcurves o f Pallas from 1973. Lustig and Hahn (1976) s h o w a Pallas lightcurve from the same opposition that has a "spiked"
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FIG. 1. L i g h t c u r v e s o f 2 Pallas, o b s e r v e d in 1973 by R. C. C a p e n at the Kitt P e a k 41-cm No. 3 t e l e s c o p e o n M a y 13 and at the S t e w a r d 5 1 - c m t e l e s c o p e on June 16.
ASTEROIDS m~_ I .00
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Fl6. 2. L i g h t c u r v e o f 8 Flora, o b s e r v e d in 1970 by R. C. C a p e n at the Kitt Peak 41-cm No. 3 telescope.
maximum which enhances the amplitude by 50%. Our lightcurves do not confirm such a feature. The 1982 lightcurves of Binzel (1984) are at the same longitude and do not show the spiked maximum either. We suggest that the spiked maximum may have been caused by a star passing through their field. 10 Hygiea
The first observations of Hygiea, on consecutive nights totaling nearly 15 hr, by Groeneveld and Kuiper (1954b) did not cover the entire period, which they gave provisionally as 18 hr. Harris and Young I
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41
(1983) reported a preliminary period of 17.495 hr from the unpublished 1977 lightcurves of E. Bowell. Our 1970 and 1973 lightcurves (Figs. 3 and 4), when combined with the other Hygiea lightcurves, present a dilemma. There is no period that satisfies the present collection of lightcurves. That is, the composite lightcurve from any opposition will not superpose on the composite lightcurve from any other opposition. We suggest the following: The period of Hygiea is 18.4 _+ 0.01 hr; the composite lightcurves of 1953-1954 and 1973, which are 180° apart in longitude, display only one maximum and one minimum; and, the composite lightcurve of 1970 displays two maxima and two minima. Zappal~ et al. (1983a) observed a similar phenomenon with the lightcurves of 52 Europa, as did Harris and Young (1979) with 532 Herculina. 12 Victoria
The only previous photoelectric observations of Victoria were made during the 1968
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FIG. 3. L i g h t c u r v e s of 10 Hygiea, o b s e r v e d in 1970 by C. D. Vesely and J. L. Dunlap on J a n u a r y 2 and by C. D. Vesely on J a n u a r y 3 at the Kitt Peak 41-cm No. 3 telescope.
42
VESELY AND TAYLOR
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FIG. 4. Lightcurves of 10 Hygiea, observed in 1973 by C. D. Vesely on June 24 and by M. L. Howes on June 25-27 at the Steward 51-cm telescope.
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period of 8.65 hr. Our 1971 lightcurve (Fig. 5) is consistent with their results.
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FIG. 5. Lightcurve of 12 Victoria, observed in 1971 by E. Dobosh at the Kitt Peak 41-cm No. 3 telescope.
opposition by Tempesti and Burchi (1969) and produced lightcurves with two different maxima, an amplitude of 0.33 mag, and a
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The first photoelectric observations of Massalia by Gehrels (1956) were extensive and a synodic period of 8.098 hr was determined with a maximum amplitude of 0.27. It was that set of data which led to the discovery of the opposition effect--a brightness surge at small solar phase angles. Subsequent observations by Gehrels and • wings (1962), Chang and Chang (1962), Lupishko et al. (1982), Zhou et al. (1983),
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FIG. 6. Lightcurve of 15 Eunomia, observed in 1970 by R. G. Thomas at the Kitt Peak 41-cm No. 3 telescope.
ASTEROIDS L I G H T C U R V E S '
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FIG. 7. Lightcurve of 18 Melpomene, observed in 1974 by R. C. Capen at the Kitt Peak 41-cm No. 3 telescope.
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FIG. 8. Lightcurve of 20 Massalia, observed in 1970 by C. D. Vesely at the Kitt Peak 41-cm No. 3 telescope.
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Fit;. 9. Lightcurves of 23 Thalia, observed in 1973 by R. C. Capen on April 23 and by M. L. Howes on April 24 at the Steward 51-cm telescope.
B a r u c c i et al. (1985), and o u r 1970 o b s e r v a tion (Fig. 8) are in a g r e e m e n t with that period and a m p l i t u d e .
O u r 1970 l i g h t c u r v e is within l0 ° ecliptic longitude and 1° p h a s e angle o f the April l, 1955, lightcurve o f G e h r e l s (1956). In T a b l e
44
VESELY AND TAYLOR I
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FIG. 10. Lightcurve of 34 Circe, observed in 1978 by J. Degewij at the Catalina 154-cm telescope.
magnitude is equivalent to V0(I,c0 -- 6.69 -+ 0.01. Lupishko e t al. (1982) give an analytic expression for the opposition effect of Massalia. According to that relation our 1970 magnitude should be 0.05 mag brighter than that of 1955, which it is.
II1 we give V0(i,a) = 6.65 + 0.02 for the 1970 observation. It is not intuitively obvious, but this is in agreement with the 1955 results: The 1955 magnitude is given in mean V; that is, the magnitude is corrected to the midline of the lightcurve. The 1955
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FIG. 11. Lightcurves of 39 Laetitia, observed in 1977 by J. Degewij on June 10 at the Steward 230-cm telescope and in 1978 by E. F. Tedesco on October 15 at the Catalina 102-cm telescope.
ASTEROIDS LIGHTCURVES m
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FIG. 12. Lightcurveof 42 Isis, observed in 1970by T. Kunkle at the Steward 91-cm telescope.
23 Thalia
Yang et al. (1965) were the first to observe Thalia and they calculated a period of 12.308 hr, assuming a lightcurve with two different maxima and minima. Van HoutenGroeneveld et al. (1979) proposed that Thalia had a single maximum that varied in appearance with the phase angle. They suggested a period of 6.150 hr. Observations by Harris and Young (1983) tend to support the period of Yang et al. (1965), but they caution that the number of extrema per rotation period may still be in question. Our 1973 lightcurves (Fig. 9) are consistent with the composite by Harris and Young. Thalia is included in the list of asteroids having ambiguous periods (Zappal~ et al. 1983a). Further observations at a suitable range of phase angles are needed to resolve the question of the number of maxima. 34 Circe
No other observation of Circe has been reported. Our partial lightcurve (Fig. 10) suggests a period of at least 12 hr if the two maxima differ, and an amplitude of at least 0.25 mag. A. W. Harris has unpublished data from 1983 which are consistent with these results (personal communication).
van Houten-Groeneveld and van Houten (1958), Gehrels and Owings (1962), Yang et al. (1965), Wamsteker and Sather (1974), Sather (1976), Chang et al. (1981), McCheyne et al. (1984), and McCheyne et al. (1985). In Fig. 11 we present lightcurves from two additional years. We see a clear example of the phase affect amplitude by comparing our Oct 15, 1978, lightcurve (longitude 26 °, latitude - 1 3 °) with the Dec 18, 1955, lightcurve (longitude 26° , latitude - 1 2 °) of van Houten-Groeneveld and van Houten (1958). The former has an amplitude of 0.34 mag at 6° phase and the latter 0.50 mag at 20 ° phase. 60 E c h o
The first published observation of Echo by Gehrels and Owings (1962) indicates a period on the order of 30 hr and amplitude of 0.07 mag. Harris and Young (1983) reported unpublished 1978 observations by Schober that make a period of 52 hr seem likely. Their own 1979 observations, which
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Lightcurves of Laetitia had been observed in 15 different years and are reported in Groeneveld and Kuiper (1954a),
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FIG. 13. Lightcurveof 60 Echo, observedin 1970by C. D. Vesely at the Kitt Peak 127-cmtelescope.
46
VESELY AND TAYLOR
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FIG. 14. L i g h t c u r v e s o f 89 Julia, o b s e r v e d in 1968 by J. L. Dunlap on August 13, by R. C. Taylor and J. L. Dunlap on A u g u s t 14 and 15, and by J. L. Dunlap and R. E. Sather on August 22 and 24 at the Kitt Peak 41-cm No. 4 telescope.
are as yet unpublished because of complications with a variable comparison star (see Harris and Young, 1983), seem to confirm this approximation. Florence and Zeigler (1984) composite 13 nights of 1984 data to a period of 25.208 hr. Zappal~ et al. (1983b) show a short 1979 lightcurve of about 0.08 mag amplitude. Our 1970 lightcurve (Fig. 13) also suggests a long period and shows an amplitude of at least 0.14 mag. 89 J u l i a
Veverka (1970) made the first determination of a period of 11.3 hr for Julia from five nights that had a lightcurve variation of less than 0.20 mag. Schober and Lustig (1975) composited lightcurves from nine nights in Aug 1972 to refine the synodic period to
11.387 hr with an amplitude of 0.25 mag. Our five 1968 lightcurves (Fig. 14) are from the same opposition as Veverka's and agree nicely with the period of Schober and Lustig. Veverka's and our lightcurves are about 17° in longitude from those of Schober and Lustig. Both sets show lightcurves with a broad maximum, but unfortunately our lightcurves were obtained when the broad maximum could not be seen from Earth. The 1968 magnitudes of Julia in Table III are corrected to V0 and mean V by overlaying each lightcurve with the one of Aug 24 and applying the appropriate corrections. An inspection of the V phase curve of Julia (Veverka, 1970) does not clearly show an opposition effect. Our four magnitudes,
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FIG. 15. Lightcurve of 113 Amalthea, observed in 1970 by R. G. Thomas at the Kitt Peak 41-cm No. 3 telescope.
each observed at less than 6° phase, when included in the phase curve of Veverka clearly indicate an opposition effect for Julia in 1968. 113 Amalthea
Harris and Young (1983) observed Amalthea over I0 nights in 1979 and derived a period of 9.935 hr with an amplitude of about 0.19 mag. Surdej et al. (1983) reported 1981 observations showing two dis_'
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In 1976, Antigone was extensively observed by Scaltriti and Zappal~ (1977) who Ii
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FIG. 16. Lightcurves of 129 Antigone, observed in 1971 by R. G. Thomas on May 29 and 30 at the Kitt Peak 41-cm N o . 4 telescope and by J. L. Dunlap and E. Dobosh on June 13 and by E. D o b o s h on June 16 at the Kitt Peak 41-cm N o . 3 telescope.
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No previous observations of Tolosa have been published. Our partial lightcurve from 1978 (Fig. 17) suggests the amplitude exceeds 0.28 mag. A. W. Harris, E. Bowell, and J. Young have five nights of unpublished photometry from the Table Mountain and Lowell Observatories during January and February 1984. Their lightcurves of Tolosa have an amplitude of 0.4 mag and suggest a period of about 10.1 hr (A. W. Harris, personal communication).
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These are the first published lightcurves of Laurentia (Fig. 18). Assuming one maximum and one minimum per rotation the period is 6.490 +0.005 hr and the amplitude at least 0.29 mag. The period could be doubled to 12.98 hr with two maxima and two minima. In Table III we include what we believe to be the first V0 magnitude for Laurentia.
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FIG. 19. Lightcurves of 404 Arsinoe, observed in 1974 by R. E. Sather at the Kitt Peak 41-cm No. 3 telescope.
maximum of June 13 is really 0.02 mag fainter than indicated by the 0.00-mag line in Fig. 16. That adjustment has been made in both the V0 and mean V magnitudes in Table III. The magnitude of Antigone, corrected to unit distance from Sun and Earth, as well as to the maximum of the lightcurve, is about 0.24 mag brighter in 1971 than in 1976. This can be seen by entering the magnitudes of Table III on the magni-
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FIG. 20. Lightcurves of511 Davida, observed in 1968 by J. L. Dunlap and R. E. Sather on December 29 and by R. E. Sather and R. C. Taylor on December 30 at the Kin Peak 41-cm No. 4 telescope.
50
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FIG. 21. Lightcurves of511 Davida, observed in 1970 by J. L. Dunlap on March 21 at the Steward 91cm telescope and in 1972 on August 7 at the Mauna Kea 61-cm telescope.
511 Davida
Observatory answered an urgent appeal for lightcurves of Davida which was then visible in the southern skies just 20° in longitude from the low-amplitude lightcurve of 1972 (Fig. 21). He obtained two iightcurves and made them available to us. Their amplitudes are both 0.13 +0.02 mag, which is larger than one would expect. Seven lightcurves of Davida were obtained in 1979 by Zappal/t and Knezevic
Davida lightcurves from 1952 and 1953 were obtained by Groeneveld and Kuiper (1954a), from 1958 by Gehrels and Owings (1962), and from 1962 by Chang and Chang (1963). Figure 20 gives two Davida lightcurves from 1968 and Fig 21 lightcurves from 1970 and 1972. In 1983 P. V. Birch of the Perth
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FIG. 22. Lightcurves of 747 Winchester, observed in 1970 by J. L. Dunlap on March 29 at the Steward 91-cm telescope and in 1973 by R. C. Capen on August 9 at the Mauna Kea 61-crn telescope, The latter observation was done in the y filter of the Str6mgren system.
ASTEROIDS LIGHTCURVES
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tude in order to have an internally consistent amplitude-aspect relation. The pole of Davida was calculated by Zappal~t and Knezevic (1985) to be at longitude 302 °, latitude 29° using an amplitudemagnitude method and by Drummond and Hege (1985) at longitude 291 °, latitude 37° using speckle interferometry. In their paper Drummond and Hege suggest that Davida may have a gradient in albedo from the equator to the pole. If true, such an albedo variation over the surface of the asteroid might affect the lightcurve features enough to cause the PA problems discussed above.
1
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FIG. 23. Lightcurve of 1058 Grubba, observed in 1974 by J. L. Dunlap at the Steward 230-cm telescope.
(1985) who derived a period of 5.13 hr. It is curious that the amplitudes for the Nov I 112, 1979, lightcurve (Zappalh, 1984, personal communication) and the Dec 5, 1962, lightcurve (Chang and Chang, 1963) are not the same (0.18 and 0.12 mag, respectively) when the geometry of the observations are so similar: The aspect differences are only 4° in longitude, 3° in latitude, and I ° in solar phase angle. The pole orientation routine, called photometric astrometry (PA), was attempted by Taylor using the above lightcurves. Only the three same-longitude sets of lightcurves (1953-1970, 1962-1979, and 1952-1968) were applied in PA so as to eliminate the problem of being unable to superpose the lightcurves--the same longitude sets can be accurately overlayed and time intervals between similar features calculated. When the three time intervals are altered by their estimated uncertainties, the pole solution varies within a circle of radius 22 -+ 10° (1 SD). The center of the circle lies near 285 ° longitude and 45 ° latitude. Such high uncertainties are not unexpected when there are so few intervals but even so this result should not be taken too seriously. A baffling thing happens to the pole when just one other interval (not at the same longitude) is inserted in the analysis: The pole is thrown back to longitudes between 180 and 240°. For Davida a pole in that region would not be possible under normal circumstances, meaning, if it is assumed that Davida is a single-body system, is shaped somewhere between a triaxial ellipsoid and a sphere, and is spinning at a constant rate then the pole must be near 300° longi-
1058 Grubba Our 1974 lightcurve (Fig. 23) is the only known observation of Grubba. The lightcurve shows an amplitude of at least 0.10 mag and a period that appears to exceed 18 hr. We also believe that the UBV colors and V0 magnitude in Table III are the first for Grubba. ACKNOWLEDGMENTS We thank the many observers mentioned in the figure legends, and T. Gehrels, E. F. Tedesco, and L. Doose for helpful suggestions. We also thank R. E. Sather for help with data reduction. P. V. Birch gathered data on short notice and J. D. Drummond helped to decipher 511 Davida. We thank V. Zappal& for supplying six individual lightcurves of Davida in advance of publication. We thank M. A. Barucci and R. P. Binzel who, as referees, offered many constructive suggestions. This work is supported by the National Aeronautics and Space Administration. REFERENCES BARUCCI, M. A., M. FULCHIGNONI, R. BURCHI, AND V. D'AMBROSlO (1985). Rotational properties of ten main belt asteroids: Analysis of the results obtained by photoelectric photometry. Icarus 61, 152-162. BINZEL, R. P. (1984). 2 Pallas: 1982, 1983 lightcurves and a new pole solution. Icarus 59, 456-461. BURCHI, R., AND L. MILANO (1983). 2 Pallas pole revisited. Moon Planets 28, 17-21. BURCm, R. (1972). Some photometric parameters of the minor planet 2 Pallas. Mere. Soc. Astron. ltal. 42, 27-32. CARLSSON, M., AND C.-I. LAGERKVIST (1983). Physical studies of asteroids. XI. Photoelectric observations of the asteroids 2, 161, 216 and 276. Astron. Astrophys. Suppl. 53, 157-159.
52
VESELY AND TAYLOR
CHANG, Y. C., AND C. S. CHANG (1962). Photometric investigations of seven variable asteroids. Acta AstroD. Sin. 10, 101-111. CHANG, Y. C., AND C. S. CHANG (1963). Photometric observations of variable asteroids, II. Acta Astron. Sin. 11, 139-149. CHANG, Y. C., X. H. ZHOU, X. Y. YANG, Y. W. ZHANG, X. Q. LI, AND Z. X. WU (1981). Light curves of asteroids (IV). Chin. Astron. Astrophys. 5, 434-437. Dt MARTINO, M., AND S. CACCIATORI (1984). Photoelectric photometry of 14 asteroids. Icarus 60, 7582. DRUMMOND, J. D., AND E. K. HEGE (1985). Speckle lnterferometry o f Asteroids. Ill. 511 Davida. In preparation. FLORENCE, W. B., AND K. W. ZEIGLER (1984). Photoelectric photometry of asteroid 60 Echo. Minor Planet Bull. 11, 33-34. GEHRELS, T. (1956). Photometric studies of asteroids. V. The lightcurve and phase function of 20 Massalia. Astrophys. J. 123, 331-338. GEHRELS, T., AND D. OWINGS (19621. Photometric studies of the asteroids. IX. Additional lightcurves. Astrophys. J. 135, 906-924. GROENEVELD, |., AND G. P. KUIPER (1954a). Photometric studies of asteroids. I. Astrophys. d. 120, 200-220. GROENEVELD, 1., AND G. P. KUIPER (1954b). Photometric studies of asteroids. II. Astrophys. J. 120, 529-546. HARRIS, A. W., AND J. YOUNG (19791. Photoelectric lightcurves of asteroids 42 Isis, 45 Eugenia, 56 Melete, 103 Hera, 532 Herculina, and 558 Carmen. Icarus 38, 100-105. HARMS, A. W., AND J. W. YOUNG (19831. Asteroid rotation. IV. 1979 observations. Icarus 54, 59-1119. LUPISHKO, D. F., I. N. BEL'SKAYA, F. A. TUPtEVA, AND G. P. CHERNOVA (1982). Photometry of asteroid 20 Massalia and 110 Lydia. Vestn. Kharkov. Gos. Univ. 232, 54-58. LUST1G, G., AND G. HAHN (19761. Photoelektrische Lichtkurven der Planetoiden (2) Pallas und (704) Interamnia. Acta Phys. Austr. 44, 199-205. McCHEYNE, R. S., N. EATON, S. F. GREEN, AND A. J. MEADOWS (1984). B and V lightcurves and pole positions of three S-class asteroids. Icarus 59, 286295. McCHEYNE, R. S., N. EATON, AND A. J. MEADOWS (1985). Visible and near-infrared lightcurves of eight asteroids. Icarus 61, 443-460. RIGOLLET, R. (1950). Short period brightness variations of minor plants. C. R. Acad. Sci. Paris 230, 2077-2078. SATHER, R. E. (1976). Minor planets and related objects. XIX. Shape and pole orientation of 39 Laetitia. Astron. J. 81, 67-73. SCAH'RITL F., AND V. ZAPPALA ~19771. Photoelec
tric photometry of the minor planets 41 Daphne and 129 Antigone. Astron. Astrophys. 56, 7-11. SCHOBER, H. J. (1981). Photoelectric photometry of the asteroids 404 Arsinoe and 628 Christine. Astron. Astrophys. 100, 311-313. SCHOBER, H. J., AND G. LUSTIG (19751. A photometric investigation of the asteroid (89) Julia. Icarus 25, 339-342. SCHROLL, A., H. F. HAUPT, AND H. M. MA1TZEN (1976). Rotation and photometric characteristics of Pallas. Icarus 27, 147-156. SURDEJ, J., A. SURDEJ, AND B. LOUIS (1983). UBV photometry of the minor planets 86 Semele, 521 Brixia, 53 Kalypso and l l3 Amalthea. Astron. Astrophys. Suppl. 52, 203-211. TAYLOR, R. C., AND E. F. TEDESCO(1983). Pole orientation of asteroid 44 Nysa via photometric astrometry, including a discussion of the method's application and its limitations. Icarus 54, 13-22. TEMPESTI, P., AND R. BURCHI (1969). A photometric research on the minor planet 12 Victoria. Mere. Soc. Astron. Ital. 40, 415-432. VAN HOUTEN-GROENEVELD, I. (1981). Photoelectric lightcurve of Pallas. Astron. Astrophys. 98, 203204. VAN HOUTEN-GROENEVELD, I., AND C. J. VAN HOUTEN (1958). Photometric studies of asteroids. VII. Astrophys. J. 127, 253-273. VAN HOUTEN-GROENEVELD, I., C. J. VAN HOUTEN, AND V. ZAPPALA (19791. Photoelectric photometry of seven asteroids. Astron. Astrophys. Suppl. 35, 223-232. VEVE~KA, J. (1970). Photometric and Polarimetric Studies o f Minor Planets and Satellites. Ph.D. dissertation, Harvard University. WAMSTEKER, W., AND R. E. SATHER (19741. Minor planets and related objects. XVII. Five-color photometry of four asteroids. Astron. J. 79, 14651470. WOOD, H. J., AND G. P. KUIPER (19631. Photometric studies of asteroids. X. Astrophys. J. 137, 12791285. WANG, X. Y., Y. Y. ZHANG, AND X. Q. LI (1965). Photometric observations of the variable asteroids, III. Acta Astron. Sin. 13, 66-74. ZAPPALA, V., M. Dl MARTINO, AND S. CACCIATORI (1983a). On the ambiguity of rotational periods of asteroids: The peculiar case of 52 Europa. Icarus 56, 319-324. ZAPPAL/~, V., AND Z. KNEZEVIC (1985). Pole coordinates o f the asteroid 511 Davida via amplitudemagnitude method. In preparation. ZAPPAL,~, V., F. SCALTRITI, AND M. DI MARTINO (1983b). Photoelectric photometry of 21 asteroids. Icarus 56, 325-344. ZHOU, X. H., X. Y. YANG, AND Z. X. WU (19831. Lightcurves of asteroids. V. Chin. Astron. Astrophys. 7, 129-131.
Photometric Lightcurves of 21 Asteroids CARL D. V E S E L Y AND RONALD C. TAYLOR Lunar and Planetary Laboratory, The University of Arizona, Tucson, Arizona 85721 Received M a r c h 22, 1985; revised M a y 1, 1985 Forty-three lightcurves of 21 asteroids obtained in Arizona b e t w e e n 1968 a n d 1978 are p r e s e n t e d with a brief d i s c u s s i o n of each. Included are four asteroids not previously observed: 34 Circe, 138 Tolosa, 162 Laurentia, and 1058 Grubba. Rotation periods are at least 12 hr for Circe, either 6.42 or 12.98 hrs for Laurentia, and m o r e than 18 hr for Grubba. Magnitudes and colors for 12 of the asteroids are given. It appears that 10 Hygiea has lightcurves which s o m e t i m e s have two m a x i m a per rotation cycle a n d s o m e t i m e s three. A strong relation b e t w e e n amplitude and solar p h a s e angle is seen for 39 Laetitia. The first direct evidence of an opposition effect for 89 Julia is given. 511 Davida is d i s c u s s e d in an effort to u n d e r s t a n d the pole orientation using photometric astrometry. © 1985AcademicPress, Inc.
son star observation exceeds three times the nightly average. All the observations were made using the V filter of the Johnson UBV system, with the exception of Aug. 9, 1973 which was done in the y filter of the Strrmgren system. Table I lists the aspect data for the asteroids and the figure number for each lightcurve. The aspect data are for the midtime of the lightcurves. Table II lists the comparison stars and the quality of the night; " s c a t t e r " is the average deviation from a smooth curve of comparison star magnitude versus time. If UBV photometry was done, the V magnitude and B - V color of each comparison star are given. Table III gives the magnitudes and colors of the asteroids. V0(l,o0 is the V magnitude of the observed lightcurve maximum corrected to unit distances from Sun and Earth. V(I,a) is the mean magnitude of the asteroid, defined as the magnitude of the asteroid corrected to the line through the middle of the lightcurve which divides the area above and below equally. In all cases the errors associated with the magnitudes and colors of the asteroids are either the mean residuals of the standard stars of the night or one standard deviation from the mean of the in-
I. I N T R O D U C T I O N
We present 43 photoelectric lightcurves of 21 asteroids that were observed during the period 1968-1978. Four of the asteroids, to our knowledge, have not had their periods previously reported: 34 Circe, 138 Tolosa, 162 Laurentia, and 1058 Grubba. V magnitudes and colors were also obtained for 12 of the asteroids and are included. Of those there are f o ur - - 42 Isis, 162 Laurentia, 747 Winchester, and 1058 G r u b b a - - f o r which we give new V0 magnitudes. Also, the first UBV colors of Grubba are given. These lightcurves were obtained to increase the data base for studies in shapes, spin periods, and the orientation of the rotation axes. This paper gives the remainder of usable lightcurves from our files. One exception is asteroid 45 Eugenia whose lightcurves will be published separately. The lightcurves appear in Figs. 1-23; in the legends the various observers and the telescopes involved are acknowledged. The lightcurves are not corrected for light time. The observing and reducing routines have been described by Gehrels and Owings (1962). Open circles are used when the deviation from the mean of a single compari37
0019-1035/85 $3.00 Copyright © 1985by Academic Press, Inc. All rights of reproduction in any form reserved.
38
VESELY
AND
TAYLOR
'FABLE 1 ASPECT DATA Asteroid
2 2 8 10 10 10 10 10 I0 12 15 18 20 23 23 34 39 39 42 60 89 89 89 89 89 113 129 129 129 129 138 162 162 162 404 404 511 511 511 511 747 747 1[)58
Obs. date UT (yr.mo.dayl
Phase angle
Distance ..... from from Sun Earth (AU) (AU)
RA (1950)
Dec (1950)
73.05.13 73.06.16 70.04.19 70.01.02 70.01.03 73.06.24 73.06.25 73.06.26 73.06.27 71.06.14 70.03.07 74.08.15 70.03.28 73.04.23 73.06.24 78.04.04 77.06.10 78.10.15 70.04.12 70.05.31 68.08.13 68.08.14 68.08.15 68.08.22 68.08,24 70.04.12 71.05.29 71.05.30 71.06.13 71.06.16 78.10.13 70.01.31} 70.02.08 70.03.01 74.04.27 74.04.28 68.12.29 68.12.30 70.03.21 72.08.07 70.03.29 73.08.09 74.08.25
+14.°8 + 19.0 - 10.7 + 10.6 + 10.8 - 15.9 - 15.7 - 15.5 - 15.3 -15.8 - 6.2 + 3.4 + 2.6 + 10.7 +23.7 + 15.8 + 6.1 + 5.7 + 6.9 + 1.8 - 5.5 - 5.1 -- 4.7 + 4.4 + 4.9 + 5.7 + 12.8 +13.1 + 17.3 +18.2 +11.1 - 6.7 - 4.1 + 9.3 + 12.9 + 13. I 1.7 - 1.6 - 7.8 + 3.6 + 9.8 - 8.1 + 4.5
2,759 2.837 2.541 3.494 3.494 2.967 2.968 2.969 2.970 1.859 3.006 1.958 2.348 2.326 2.481 2.415 2.798 2.475 2.682 2.741 2.135 2.134 2.132 2.126 2.123 2.17[) 2.264 2.263 2.259 2.258 2.164 2.495 2.492 2.448 2.tt59 2.059 2.672 2.672 3.259 3.523 3.252 2.476 1.796
1.941 2.261 1.612 2.688 2.698 2.245 2.235 2.225 2.216 0.908 2.052 0.949 1.353 1.380 2.091) 1.570 1.811 1.496 1.714 1.729 1.133 1.131} 1.128 1.121 1.122 1.1811 1.327 1.3311 1.397 1.421 1.222 1.536 1.515 1.549 I. 112 I. 114 1.69/) 1.691} 2.336 2.539 2.373 1.500 0.789
14h54".'3 14 3 6 . 0 15 3 8 . 2 3 52.1 3 51.7 21 4 8 . 5 21 4 8 . 4 21 4 8 . 3 21 4 8 . 1 1920.5 I1 2 5 . 9 21 1 8 . 5 12 4 6 . 8 12 5 8 . 6 12 5 6 . 5 10 1 5 . 3 17 4 1 . 7 I 56.7 12 4 8 . 4 16 3 1 . 2 21 5 4 . 5 21 5 3 . 5 21 5 2 . 4 21 4 4 . 3 21 4 2 . 1 13 1 . 3 15 1 6 . 4 15 1 5 . 7 15 8 . 2 15 7 . 3 23 4 8 . 1 959.8 952.5 9 34.4 13 5 9 . 5 13 5 8 . 6 642.7 641.8 13 2 9 . 5 20 3 1 . I I1 (I.8 22 3 9 . 3 22 4 . 0
+25035 ' + 2 5 14 1042 + 2 2 55 + 2 2 52 --1051 -1050 1049 -1048 1057 .... 1 2 4 3 I1 49 5 23 + 7 27 + 037 ~- 8 21 7 50 I 41 + 837 17 I 450 444 439 4 5 3 56 + 3 5 + 3 37 + 3 35 + 240 + 223 -- 6 01 + 2 2 36 + 2 3 15 + 2 4 10 + 1 3 18 + 1 3 16 +19 4 + 1 9 I1 + 1 4 31 26 32 + 2 2 36 18 15 - 3 27
± 0.1
+0.002
+0.002
+_(}.2
± 1
Ecliptic Long. 11950)
Lat. (1950)
211°.4 206.6 234.8 60.8 60.7 325.6 325.6 325.6 325.6 290.1 177.3 318.4 192.9 191}.5 192.8 152.7 265.3 26.5 187.7 248.7 329.1 328.9 328.7 326.9 326.5 192.9 225.6 225.4 223.8 223.6 354.9 144.2 142.3 138.1 202.7 202.5 100.1 99.9 194.9 303.6 157.5 334.5 331.8
+4071 +38.1 + 8.5 + 2.7 + 2.6 + 2.3 + 2.3 + 2.3 + 2.3 +11.1 15.0 + 3.7 .... 0.3 + 12.6 + 6.1 2.3 15.5 12.8 +12.7 + 4.8 + 7.4 + 7.6 + 7.8 4 9.0 + 9.3 + 8.9 +21.0 +20,9 +19,5 +19,2 4,3 + 9~7 + 9,7 + 9,2 +23.8 +23.7 - 4.() 3.9 +22.1 - 7.4 +15.0 9.0 + 7.9
Fig.
I I 2 3 3 4 4 4 4 5 6 7 8 9 9 10 II I1 12 13 14 14 14 14 14 15 16 16 16 16 17 18 18 18 19 19 21) 20 21 21 22 22 23
39
ASTEROIDS LIGHTCURVES TABLE
11
C O M P A R I S O N STARS A N D Q U A L I T Y OF NIGHTS
Asteroid
2 2 8 10 10 10 10 10 10 12 15 18 20 23 23 34 39 39 42 60 89 89 89 89 89 113 129 129 129 129 138 162 162 162 404 404 511 511 511 511 747 747 1058
Obs. date (UT) (yr.mo.day) 73.05.13 73.06.16 70.04.19 70.01.02 70.01.03 73.06.24 73.06.25 73.06.26 73.06.27 71.06.14 70.03.07 74.08.15 70.03.28 73.04.23 73.06.24 78.04.04 77.06.10 78.10.15 70.04.12 70.05.31 68.08.13 68.08.14 68.08.15 68.08.22 68.08.24 70.04.12 71.05.29 71.05.30 71.06.13 71.06.16 78.10.13 70.01.30 70.02.08 70.03.01 74.04.27 74.04.28 68.12.29 68.12.30 70.03.21 72.08.07 70.03.29 73.08.09 74.08.25
RA (1950)
14h55.m0 14 36.1 15 39. 1 3 52.6 3 52.0 21 4 8 . 5 21 4 8 . 4 21 4 8 . 3 21 48. 1 19 2 0 . 5 11 2 6 . 0 21 18.6 12 4 6 . 7 12 5 9 . 0 o o o ~ 16 3 1 . 3 21 5 3 . 7 21 5 3 . 5 21 5 2 . 6 21 4 4 . 3 21 4 2 . 0 13 0 . 7 15 16.1 15 16.1 15 7 . 6 15 7 . 7 23 4 6 . 7 9 59.4 9 52.0 10 0 . 2 13 5 9 . 7 13 5 8 . 3 642.6 641.9 ~ 20 3 0 . 9 11 I .0 22 3 8 . 9 22 3 . 9 -+0.2
Dec 11950)
Scatter (mag)
+25°32 ' +25 19 -- 10 38 + 2 2 51 + 2 2 56 --10 51 -- 10 50 -- 10 48 -- 10 46 --10 55 --12 43 --11 49 -- 5 28 + 7 28
-+0.005 -+0.005 -+0.004 -+0.011 -+0.013 -+0.023 -+0.027 -+0.024 -+0.017 -+0.011 -+0.009 -+0.021 -+0.004 -+0.010
V (mag)
7.31 9.11
-+0.04 -+0.04
B-V (mag)
+0.66 0.65
-+0.01 -+0.02
Remarks
Clouds at end Clouds at end Variable seeing
10.61
-+0.01
+1.31
-+0.01
Clouds about Cirrus all about Clear 10.07 7.82 9.37
-+0.02 -+0.03 -+0.02
+0.56 +0.44 +0.70
-+0.02 -+0.02 -+0.01
D u s t y winds
Some clouds Seeing poor
-17 1 - 4 50 - 4 44 - 4 39 - 404 - 3 56 + 3 5 + 3 51 + 3 51 + 2 46 + 3 00 - 5 51 +22 40 +23 19 +22 29 +13 9 +13 11 +19 2 +19 8 -26 +22 - 18 - 3
27 40 23 27 -+1
-+0.015 -+0.011 -+0.006 -+0.020 ±0.011 ---0.017 -+0.012 -+0.024 -+0.009 -+0.018 -+0.008 -+0.024 -+0.005 +-0.013 -+0.012 -+0.009 -+0.040 -+0.007 -+0.008 -+0.006 -+0.010 -+0.008 -+0.018 -+0.013 -+0.004
12.22
-+0.03
+0.68
-+0.03
9.70 10.59 10.61 10.19
-+0.02 -+0.01 -+0.03 -+0.02
+1.06 +0.49 +1.26 +0.54
-+0.01 -+0.01 -+0.02 -+0.01
Clouds at end
10.32
-+0.02
+0.60
-+0.02
10.99
-+0.03
+0.64
-+0.02
Windy Telescope drift Clouds about
11.26
-+0.02
+0.73
-+0.01
5.32 10.36 11.55 10.01 13.01
-+0.02 -+0.02 -+0.02 -+0.03 -+0.03
+ 1.25 +0.38 +0.91 +0.47 +0.53
-+0.02 -+0.02 -+0.02 -+0.03 -+0.05
13.41
-+0.02
---0.82
-+0.01
Variable seeing
Clouds at end Clouds at end Clouds at end
Clouds. h a z y
Clouds
o Not available.
dividual magnitudes of the object, whichever is poorer. The second method is applied for the comparison star errors. II. DISCUSSION OF EACH ASTEROID Lightcurves of five asteroids, 8 Flora, 15 Eunomia, 18 Melpomene, 42 Isis, and 747 Winchester, are presented in Figs. 2, 6, 7, 12, and 22, respectively, without comment.
2 Pallas
Photoelectric lightcurves of Pallas were made by Groeneveld and Kuiper (1954b), Wood and Kuiper (1963), Burchi (1972), and Chang and Chang (1963). Schroll et al. (1976), using their many observations and the then-unpublished observations of I. van Houten-Groeneveld (1981), determined a period of 7.807 hr and preliminary pole co-
40
VESELY A N D TAYLOR "FABLE 111 MAGNITUDES
Asteroid
Obs. date (UT)
Phase angle
2 2 10 15 18 20 42 89 89 89 89 129 129 162 511 51 l 511 511 747 1058
73.05.13 73.06.16 70.01.03 70.03.07 74.08.15 70.03.28 70.04.12 68.08.14 68.08.15 68.08.22 68.08.24 71.05.29 71.06.13 70.02.08 68.12.29 68.12.30 70.03.21 72.08.07 70.03.29 74.08.25
17°8 19.0 10.8 6.2 3.4 2.6 6.9 5.1 4.7 4.4 4.9 12.8 17.4 4.1 1.7 1.6 7.8 3.6 9.8 4.5
AND COLORS
V0(l,a) (mag) 4.92 5.19 5.96 5.52 6.65" 6.65 8.02 6.95 6.95 6.91 6.91 7.41 7.58 9.15 6.37 6.33 6.82 6.48 8.28 12.34"
~)(l,c0 (mag)
±0.04 +0.04 ±0.01 ÷0.02 ±0.03
B-V (mag)
4.94 5.21 6.04 5.72 6.72 6.73 8.17 7.05 7.05 7.01 7.01 7.61 7.78 9.29 6.41 6.37 6.95 6.52 8.34 12.38
+-0.02
+0.03 +0.02
+-0.02 ±11.02 +0.02 ±0.04 +0.02 ±0.03 ±0.04 +0.03 ±:0.02 +0.03 +11.05 ±0.05
+0.66 +0.60 +0.71 +0.82 +0.85 +0.82 +0.88 +0.85 +0.87 +0.86 +0.85 +0.70 +0.72 +0.70 +0.69 +0.68 +0.73 +0.70 +0.72 +0.88
U-B (mag)
+0.01 -+0.02 -+0.04 -+0.01 -+0.02 -+0.02 -+0.02 -+0.02 ±0.01 -+0.02 +0.01 -+0.02 -+0.02 +0.02 -+0.02 +0.02 -+0.02 -+0.03 -+0.03 -+0.02
+0.27 -+0.35 +0.43 +0.37 +0.40 +0.43 +0.42 +0.43 4-0.42 +0.42 +0.27 4-0.27 +0.32 +0.39 +0.36 +0.36 +0.37 +0.32 +0.50
±0.02 -±0.03 +0.01 ±0.02 -+0.02 -+0.03 +0.02 +0.01 -+0.02 -+0.02 ±0.04 +0.02 -+0.02 -+0.02 +0.03 -+-0.04 -+0.04 +0.03 -+0.03
" T h e m a g n i t u d e at the m a x i m u m o f the a v a i l a b l e l i g h t c u r v e w h i c h might not be a true V0.
ordinates o f 228 °, +43 °. Chang et al. (19811 reevaluated their o w n 1963 lightcurves and utilized s o m e 1965 observations to derive a period o f 7.815 hr. Burchi and Milano (1983) a n a l y z e d their 1973 and 1974 observations using the Schroll et al. period and found the pole to be at 211 °, +38 °. Carlsson and Lagerkvist (1983) s h o w a short 1982 lightcurve o f very l o w amplitude. Binzel
.oo
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o4
I 400
J
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olalqo~e~oeeB I 5:00
I
(1984) presents his 1982 and 1983 lightcurves in c o m p o s i t e form based on Schroll's period. He used these and all other available lightcurves to determine a n e w pole solution o f 200 ° , +37 ° . Figure 1 gives two near pole-on lightcurves o f Pallas from 1973. Lustig and Hahn (1976) s h o w a Pallas lightcurve from the same opposition that has a "spiked"
• OoeD e°e°eleea~o oem°o°o • e me
15 Moy 1975 1 , I 6:00 7:00
,
I 8:00
~
I
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o
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FIG. 1. L i g h t c u r v e s o f 2 Pallas, o b s e r v e d in 1973 by R. C. C a p e n at the Kitt P e a k 41-cm No. 3 t e l e s c o p e o n M a y 13 and at the S t e w a r d 5 1 - c m t e l e s c o p e on June 16.
ASTEROIDS m~_ I .00
' o
I
'
I
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• o•
I
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19 Apr 1970
°°oo°°°o
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LIGHTCURVES
~O•e• O
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I
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,
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I1:00
12:0OUT
Fl6. 2. L i g h t c u r v e o f 8 Flora, o b s e r v e d in 1970 by R. C. C a p e n at the Kitt Peak 41-cm No. 3 telescope.
maximum which enhances the amplitude by 50%. Our lightcurves do not confirm such a feature. The 1982 lightcurves of Binzel (1984) are at the same longitude and do not show the spiked maximum either. We suggest that the spiked maximum may have been caused by a star passing through their field. 10 Hygiea
The first observations of Hygiea, on consecutive nights totaling nearly 15 hr, by Groeneveld and Kuiper (1954b) did not cover the entire period, which they gave provisionally as 18 hr. Harris and Young I
m
'
I
'
I
'
41
(1983) reported a preliminary period of 17.495 hr from the unpublished 1977 lightcurves of E. Bowell. Our 1970 and 1973 lightcurves (Figs. 3 and 4), when combined with the other Hygiea lightcurves, present a dilemma. There is no period that satisfies the present collection of lightcurves. That is, the composite lightcurve from any opposition will not superpose on the composite lightcurve from any other opposition. We suggest the following: The period of Hygiea is 18.4 _+ 0.01 hr; the composite lightcurves of 1953-1954 and 1973, which are 180° apart in longitude, display only one maximum and one minimum; and, the composite lightcurve of 1970 displays two maxima and two minima. Zappal~ et al. (1983a) observed a similar phenomenon with the lightcurves of 52 Europa, as did Harris and Young (1979) with 532 Herculina. 12 Victoria
The only previous photoelectric observations of Victoria were made during the 1968
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2 don 1970
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FIG. 3. L i g h t c u r v e s of 10 Hygiea, o b s e r v e d in 1970 by C. D. Vesely and J. L. Dunlap on J a n u a r y 2 and by C. D. Vesely on J a n u a r y 3 at the Kitt Peak 41-cm No. 3 telescope.
42
VESELY AND TAYLOR
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FIG. 4. Lightcurves of 10 Hygiea, observed in 1973 by C. D. Vesely on June 24 and by M. L. Howes on June 25-27 at the Steward 51-cm telescope.
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period of 8.65 hr. Our 1971 lightcurve (Fig. 5) is consistent with their results.
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FIG. 5. Lightcurve of 12 Victoria, observed in 1971 by E. Dobosh at the Kitt Peak 41-cm No. 3 telescope.
opposition by Tempesti and Burchi (1969) and produced lightcurves with two different maxima, an amplitude of 0.33 mag, and a
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The first photoelectric observations of Massalia by Gehrels (1956) were extensive and a synodic period of 8.098 hr was determined with a maximum amplitude of 0.27. It was that set of data which led to the discovery of the opposition effect--a brightness surge at small solar phase angles. Subsequent observations by Gehrels and • wings (1962), Chang and Chang (1962), Lupishko et al. (1982), Zhou et al. (1983),
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FIG. 6. Lightcurve of 15 Eunomia, observed in 1970 by R. G. Thomas at the Kitt Peak 41-cm No. 3 telescope.
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FIG. 7. Lightcurve of 18 Melpomene, observed in 1974 by R. C. Capen at the Kitt Peak 41-cm No. 3 telescope.
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FIG. 8. Lightcurve of 20 Massalia, observed in 1970 by C. D. Vesely at the Kitt Peak 41-cm No. 3 telescope.
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Fit;. 9. Lightcurves of 23 Thalia, observed in 1973 by R. C. Capen on April 23 and by M. L. Howes on April 24 at the Steward 51-cm telescope.
B a r u c c i et al. (1985), and o u r 1970 o b s e r v a tion (Fig. 8) are in a g r e e m e n t with that period and a m p l i t u d e .
O u r 1970 l i g h t c u r v e is within l0 ° ecliptic longitude and 1° p h a s e angle o f the April l, 1955, lightcurve o f G e h r e l s (1956). In T a b l e
44
VESELY AND TAYLOR I
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FIG. 10. Lightcurve of 34 Circe, observed in 1978 by J. Degewij at the Catalina 154-cm telescope.
magnitude is equivalent to V0(I,c0 -- 6.69 -+ 0.01. Lupishko e t al. (1982) give an analytic expression for the opposition effect of Massalia. According to that relation our 1970 magnitude should be 0.05 mag brighter than that of 1955, which it is.
II1 we give V0(i,a) = 6.65 + 0.02 for the 1970 observation. It is not intuitively obvious, but this is in agreement with the 1955 results: The 1955 magnitude is given in mean V; that is, the magnitude is corrected to the midline of the lightcurve. The 1955
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FIG. 11. Lightcurves of 39 Laetitia, observed in 1977 by J. Degewij on June 10 at the Steward 230-cm telescope and in 1978 by E. F. Tedesco on October 15 at the Catalina 102-cm telescope.
ASTEROIDS LIGHTCURVES m
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FIG. 12. Lightcurveof 42 Isis, observed in 1970by T. Kunkle at the Steward 91-cm telescope.
23 Thalia
Yang et al. (1965) were the first to observe Thalia and they calculated a period of 12.308 hr, assuming a lightcurve with two different maxima and minima. Van HoutenGroeneveld et al. (1979) proposed that Thalia had a single maximum that varied in appearance with the phase angle. They suggested a period of 6.150 hr. Observations by Harris and Young (1983) tend to support the period of Yang et al. (1965), but they caution that the number of extrema per rotation period may still be in question. Our 1973 lightcurves (Fig. 9) are consistent with the composite by Harris and Young. Thalia is included in the list of asteroids having ambiguous periods (Zappal~ et al. 1983a). Further observations at a suitable range of phase angles are needed to resolve the question of the number of maxima. 34 Circe
No other observation of Circe has been reported. Our partial lightcurve (Fig. 10) suggests a period of at least 12 hr if the two maxima differ, and an amplitude of at least 0.25 mag. A. W. Harris has unpublished data from 1983 which are consistent with these results (personal communication).
van Houten-Groeneveld and van Houten (1958), Gehrels and Owings (1962), Yang et al. (1965), Wamsteker and Sather (1974), Sather (1976), Chang et al. (1981), McCheyne et al. (1984), and McCheyne et al. (1985). In Fig. 11 we present lightcurves from two additional years. We see a clear example of the phase affect amplitude by comparing our Oct 15, 1978, lightcurve (longitude 26 °, latitude - 1 3 °) with the Dec 18, 1955, lightcurve (longitude 26° , latitude - 1 2 °) of van Houten-Groeneveld and van Houten (1958). The former has an amplitude of 0.34 mag at 6° phase and the latter 0.50 mag at 20 ° phase. 60 E c h o
The first published observation of Echo by Gehrels and Owings (1962) indicates a period on the order of 30 hr and amplitude of 0.07 mag. Harris and Young (1983) reported unpublished 1978 observations by Schober that make a period of 52 hr seem likely. Their own 1979 observations, which
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Lightcurves of Laetitia had been observed in 15 different years and are reported in Groeneveld and Kuiper (1954a),
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FIG. 13. Lightcurveof 60 Echo, observedin 1970by C. D. Vesely at the Kitt Peak 127-cmtelescope.
46
VESELY AND TAYLOR
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FIG. 14. L i g h t c u r v e s o f 89 Julia, o b s e r v e d in 1968 by J. L. Dunlap on August 13, by R. C. Taylor and J. L. Dunlap on A u g u s t 14 and 15, and by J. L. Dunlap and R. E. Sather on August 22 and 24 at the Kitt Peak 41-cm No. 4 telescope.
are as yet unpublished because of complications with a variable comparison star (see Harris and Young, 1983), seem to confirm this approximation. Florence and Zeigler (1984) composite 13 nights of 1984 data to a period of 25.208 hr. Zappal~ et al. (1983b) show a short 1979 lightcurve of about 0.08 mag amplitude. Our 1970 lightcurve (Fig. 13) also suggests a long period and shows an amplitude of at least 0.14 mag. 89 J u l i a
Veverka (1970) made the first determination of a period of 11.3 hr for Julia from five nights that had a lightcurve variation of less than 0.20 mag. Schober and Lustig (1975) composited lightcurves from nine nights in Aug 1972 to refine the synodic period to
11.387 hr with an amplitude of 0.25 mag. Our five 1968 lightcurves (Fig. 14) are from the same opposition as Veverka's and agree nicely with the period of Schober and Lustig. Veverka's and our lightcurves are about 17° in longitude from those of Schober and Lustig. Both sets show lightcurves with a broad maximum, but unfortunately our lightcurves were obtained when the broad maximum could not be seen from Earth. The 1968 magnitudes of Julia in Table III are corrected to V0 and mean V by overlaying each lightcurve with the one of Aug 24 and applying the appropriate corrections. An inspection of the V phase curve of Julia (Veverka, 1970) does not clearly show an opposition effect. Our four magnitudes,
ASTEROIDS I
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FIG. 15. Lightcurve of 113 Amalthea, observed in 1970 by R. G. Thomas at the Kitt Peak 41-cm No. 3 telescope.
each observed at less than 6° phase, when included in the phase curve of Veverka clearly indicate an opposition effect for Julia in 1968. 113 Amalthea
Harris and Young (1983) observed Amalthea over I0 nights in 1979 and derived a period of 9.935 hr with an amplitude of about 0.19 mag. Surdej et al. (1983) reported 1981 observations showing two dis_'
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In 1976, Antigone was extensively observed by Scaltriti and Zappal~ (1977) who Ii
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FIG. 16. Lightcurves of 129 Antigone, observed in 1971 by R. G. Thomas on May 29 and 30 at the Kitt Peak 41-cm N o . 4 telescope and by J. L. Dunlap and E. Dobosh on June 13 and by E. D o b o s h on June 16 at the Kitt Peak 41-cm N o . 3 telescope.
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tude-phase relation given in Fig. 8 of Scaltriti and Zappalh (1977).
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No previous observations of Tolosa have been published. Our partial lightcurve from 1978 (Fig. 17) suggests the amplitude exceeds 0.28 mag. A. W. Harris, E. Bowell, and J. Young have five nights of unpublished photometry from the Table Mountain and Lowell Observatories during January and February 1984. Their lightcurves of Tolosa have an amplitude of 0.4 mag and suggest a period of about 10.1 hr (A. W. Harris, personal communication).
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162 Laurentia
These are the first published lightcurves of Laurentia (Fig. 18). Assuming one maximum and one minimum per rotation the period is 6.490 +0.005 hr and the amplitude at least 0.29 mag. The period could be doubled to 12.98 hr with two maxima and two minima. In Table III we include what we believe to be the first V0 magnitude for Laurentia.
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FIG. 19. Lightcurves of 404 Arsinoe, observed in 1974 by R. E. Sather at the Kitt Peak 41-cm No. 3 telescope.
maximum of June 13 is really 0.02 mag fainter than indicated by the 0.00-mag line in Fig. 16. That adjustment has been made in both the V0 and mean V magnitudes in Table III. The magnitude of Antigone, corrected to unit distance from Sun and Earth, as well as to the maximum of the lightcurve, is about 0.24 mag brighter in 1971 than in 1976. This can be seen by entering the magnitudes of Table III on the magni-
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Schober (1981) derived a period of 8.93 hr and an amplitude of 0.36 mag from his 1979 observations of Arsinoe. Our 1974 partial lightcurves (Fig. 19) are of the two different minima.
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FIG. 20. Lightcurves of511 Davida, observed in 1968 by J. L. Dunlap and R. E. Sather on December 29 and by R. E. Sather and R. C. Taylor on December 30 at the Kin Peak 41-cm No. 4 telescope.
50
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FIG. 21. Lightcurves of511 Davida, observed in 1970 by J. L. Dunlap on March 21 at the Steward 91cm telescope and in 1972 on August 7 at the Mauna Kea 61-cm telescope.
511 Davida
Observatory answered an urgent appeal for lightcurves of Davida which was then visible in the southern skies just 20° in longitude from the low-amplitude lightcurve of 1972 (Fig. 21). He obtained two iightcurves and made them available to us. Their amplitudes are both 0.13 +0.02 mag, which is larger than one would expect. Seven lightcurves of Davida were obtained in 1979 by Zappal/t and Knezevic
Davida lightcurves from 1952 and 1953 were obtained by Groeneveld and Kuiper (1954a), from 1958 by Gehrels and Owings (1962), and from 1962 by Chang and Chang (1963). Figure 20 gives two Davida lightcurves from 1968 and Fig 21 lightcurves from 1970 and 1972. In 1983 P. V. Birch of the Perth
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FIG. 22. Lightcurves of 747 Winchester, observed in 1970 by J. L. Dunlap on March 29 at the Steward 91-cm telescope and in 1973 by R. C. Capen on August 9 at the Mauna Kea 61-crn telescope, The latter observation was done in the y filter of the Str6mgren system.
ASTEROIDS LIGHTCURVES
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51
tude in order to have an internally consistent amplitude-aspect relation. The pole of Davida was calculated by Zappal~t and Knezevic (1985) to be at longitude 302 °, latitude 29° using an amplitudemagnitude method and by Drummond and Hege (1985) at longitude 291 °, latitude 37° using speckle interferometry. In their paper Drummond and Hege suggest that Davida may have a gradient in albedo from the equator to the pole. If true, such an albedo variation over the surface of the asteroid might affect the lightcurve features enough to cause the PA problems discussed above.
1
UT
FIG. 23. Lightcurve of 1058 Grubba, observed in 1974 by J. L. Dunlap at the Steward 230-cm telescope.
(1985) who derived a period of 5.13 hr. It is curious that the amplitudes for the Nov I 112, 1979, lightcurve (Zappalh, 1984, personal communication) and the Dec 5, 1962, lightcurve (Chang and Chang, 1963) are not the same (0.18 and 0.12 mag, respectively) when the geometry of the observations are so similar: The aspect differences are only 4° in longitude, 3° in latitude, and I ° in solar phase angle. The pole orientation routine, called photometric astrometry (PA), was attempted by Taylor using the above lightcurves. Only the three same-longitude sets of lightcurves (1953-1970, 1962-1979, and 1952-1968) were applied in PA so as to eliminate the problem of being unable to superpose the lightcurves--the same longitude sets can be accurately overlayed and time intervals between similar features calculated. When the three time intervals are altered by their estimated uncertainties, the pole solution varies within a circle of radius 22 -+ 10° (1 SD). The center of the circle lies near 285 ° longitude and 45 ° latitude. Such high uncertainties are not unexpected when there are so few intervals but even so this result should not be taken too seriously. A baffling thing happens to the pole when just one other interval (not at the same longitude) is inserted in the analysis: The pole is thrown back to longitudes between 180 and 240°. For Davida a pole in that region would not be possible under normal circumstances, meaning, if it is assumed that Davida is a single-body system, is shaped somewhere between a triaxial ellipsoid and a sphere, and is spinning at a constant rate then the pole must be near 300° longi-
1058 Grubba Our 1974 lightcurve (Fig. 23) is the only known observation of Grubba. The lightcurve shows an amplitude of at least 0.10 mag and a period that appears to exceed 18 hr. We also believe that the UBV colors and V0 magnitude in Table III are the first for Grubba. ACKNOWLEDGMENTS We thank the many observers mentioned in the figure legends, and T. Gehrels, E. F. Tedesco, and L. Doose for helpful suggestions. We also thank R. E. Sather for help with data reduction. P. V. Birch gathered data on short notice and J. D. Drummond helped to decipher 511 Davida. We thank V. Zappal& for supplying six individual lightcurves of Davida in advance of publication. We thank M. A. Barucci and R. P. Binzel who, as referees, offered many constructive suggestions. This work is supported by the National Aeronautics and Space Administration. REFERENCES BARUCCI, M. A., M. FULCHIGNONI, R. BURCHI, AND V. D'AMBROSlO (1985). Rotational properties of ten main belt asteroids: Analysis of the results obtained by photoelectric photometry. Icarus 61, 152-162. BINZEL, R. P. (1984). 2 Pallas: 1982, 1983 lightcurves and a new pole solution. Icarus 59, 456-461. BURCHI, R., AND L. MILANO (1983). 2 Pallas pole revisited. Moon Planets 28, 17-21. BURCm, R. (1972). Some photometric parameters of the minor planet 2 Pallas. Mere. Soc. Astron. ltal. 42, 27-32. CARLSSON, M., AND C.-I. LAGERKVIST (1983). Physical studies of asteroids. XI. Photoelectric observations of the asteroids 2, 161, 216 and 276. Astron. Astrophys. Suppl. 53, 157-159.
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