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Photoelectric photometry of 14 asteroids
ICARUS 60, 75--82 (1984)
Photoelectric Photometry of 14 Asteroids M. DI MARTINO AND S. CACCIATORI Astronomical Observatory. of" Torino, 10025 Pino Torinese, Turin, Italy Received January 18, 1984; revised April 19, 1984 Results of observations of 14 asteroids are reported; all o f them, except 181 Eucharis, have been previously o b s e r v e d at least once. V photoelectric lightcurves were obtained from S e p t e m b e r 1982 to June 1983 at the Astronomical O b s e r v a t o r y of Torino and at the Astrophysical O b s e r v a t o r y of Catania. Part of this program aims to obtain complete lightcurves and, when possible, p h a s e c u r v e information and to determine amplitudes and V magnitudes at different longitudes for a selected group of asteroids, in order to enlarge the set o f known rotational axis directions. ~ 1984Academic Press, Inc.
of one asteroid from our list (181 Eucharis) has not been previously observed. Aspect and magnitude data (determined by a computer program, starting from the orbital elements taken from the Ephemerides o f Minor Planets, identification of comparison stars, and telescope employed are listed in Table I. In Table II are summarized the opposition dates, the taxonomic types and diameters (Bowell et al., 1979), the rotational periods, the observed amplitudes, and the number(s) of the corresponding figure(s) for the observed asteroids. Single-night curves as well as composite lightcurves are shown in Figs. 1 to 14; in the first case the ordinate is the instrumental magnitude, in the second we adopt the average maximum brightness as zero point of the scale. The abscissae are always UT, not corrected for light-time, and, when composite curves are presented, they refer to one night, the date of which is reported in the figure. Open symbols represent repeated observations. For a summary of previous observations, we consulted the "Asteroid Lightcurve Catalogue" by Lagerkvist et al. (1983).
INTRODUCTION
In this paper we present the results obtained for 14 asteroids observed during the interval September 1982 to June 1983, using the 45-cm reflector telescope of the Torino Observatory and the 91-cm telescope of the Catania Astrophysical Observatory, using a single-channel photometer in the pulsecounting mode. The observing procedure consisted of comparing an asteroid's brightness with that of a comparison star suitably chosen along the minor planet's path. Reductions were made by a computer program which takes account of differential extinction between the target object and the comparison star, using extinction coefficients determined nightly. Transformations to the standard UBV systems were made for all the asteroids, except 6 Hebe, by means of groups of standard stars taken from Johnson and Morgan (1953), Landolt (1973), Sanders (1966), and Blanco et al. (1968). Part of our observational program aims to obtain, at different oppositions and at small phase angles (~ < I0°), complete lightcurves of selected minor planets (Zappalh and Kne~evid, 1984) and to determine, using the amplitude and the magnitude at maximum brightness, the rotational axis direction and a rough indication of the shape (Zappalh et al., 1983a). Only the lightcurve
OBSERVATIONS AND RESULTS
6 Hebe
This asteroid has previously been observed during eight apparitions. Our obser75 0019-1035/84 $3.00 Copyright ~ 1984by AcademicPress, Inc. All rights of reproduction in any form reserved.
76
DI M A R T I N O A N D C A C C I A T O R I TABLE
1
ASPEC1 I ) A I A FOR 1HE OBSERVED ASTEROIDS
Date (0hUT)
6 Hebe 1983 06 10 06 I 1 06 15
Phase
V0(l,(~)
Comparison star
Tele~copc (crn)
BD 3+4182 BD 3°4182 BI) -3+'4168
45 45 45
B D --6°110
91
RA (1950)
Dec, 11950)
Long (1950)
Lal 11950)
r (AU)
~ (AU)
17h48m0 17h47".'0 17h43ml
3°23 ' 3°24 ' ....3029 '
266?8 266.6 265.5
+20?0 20.<1 +19.9
2.5396 2.5375 2.5292
1.5687 1.5646 1.5510
8'.'5 8.4 7.9
00h36".'6
--4°51 '
6?5
871
2,2105
1.2448
8?5
6".'67
12h01"75
+21032 '
17174
+ 1978
2.9791
2,11288
6?7
6"?86
00h39".'6
+ IIF37'
13?3
5?8
2.1874
1.1994
4'.'7
8"718
B D + 10+73
91
()2NB".'2
+ 190113'
3572
+6'71
2.3918
1.419<1
577
7'!'99
B D + 18°268
45
08h36"76
+23048 '
12574
+ 5?0
2.6375
1.6562
2?1
7".'47
B D + 24'+1971
45
08h22"?0
+ I 1°112'
12572
8?2
2.2227
1.2598
6.°9
8~738
B D + I 1°1834
45
03~14".'4
÷ 23+tt5 '
5071
~575
2.7822
1.8048
~77
7'!'34
BD +22"437
45
01n27'~'2
-7+45 '
1772
1577
3.2376
2.27~4
5'?3
7"731
BI)
8"257
91
(13h46m4
-(1°(12 ,
54?3
1974
2.3650
1.6779
21173
8~?80
BD
0°606
45
09hl6'!'3
+ 14°40 '
137711
I?1
2.5971
1.6229
4?7
8".'17z'
B D + 15°2112<)
45
12h38".~0 12h20m8
+ 2'+22 ' + 2 49
18778 183.6
+ 5?9 +4?6
3.1347 3.1604
_.14.~ 2.21168
2?2 6.8
7+Y64 7.93
BI) + 3 " 2 6 3 5 '
45 45
12h04':'6
+21°33 '
17271
._ ~'~(1°v
~,.3601
2.4993
11172
7".'11
...4411 B D + '~'~°'~
45
110h37"29
+6°53 '
I (1?I
1.96(14
0.9957
I (172
10".'61
BD
91
9 Metis 1982 10 18 22 Kalliope 1983 03 08 43 Ariadne 1982 I 0 16
"
45
55 Pandora 1982 I I 11 63 Ausonia 1983 01 24 79 Eurynome 1983 01 13 88 Thisbe 1982 t I 22 129 Antigone 1982 10 19 173 l n o 1983 01 I0 181 Eucharis 1983 02 19 250 Bettina 1983 03 26 04 16 471 Papagena 1983 04 14 852 Wladilena 1982 10 18
" S t a r is not cataloged, Chg~0
6711
6 +I I 0
12h(11'!'2. 81,~,0 ~ +21o22 '.
M a x i m u m was not observed. ' Star is not cataloged, cr~+~0 12h36".~4. 8=,or : + 2 ° 1 7 '-
vations were made over three nights, from which we have deduced a rotational period P = 7.h277 _+_ 0h.002 which is in very good agreement with the values obtained by A h m a d 119541 and Yang et al. 11965). The lightcurve shape and the amplitude (A 0.m19 +- 0m01) are practically the same as those obtained in the 1968 opposition (Gehrels and Taylor, 1977), the observations being made at about 15 ° of longitude apart. Figure I s h o w s the c o m p o s i t e lightcurve
o f this large asteroid, for which the value of the reduced magnitude at m a x i m u m brightness V0(l,a) was not obtained. 9 Metis
Metis was observed in a single night together with the minor planet 852 Wladilena, using the same comparison star. The resulting lightcurve is s h o w n in Fig. 2. The amplitude of A = 0.m05 -+ 0.m01 is the smallest obtained hitherto. The lightcurve s h o w s t w o well-defined maxima and minima. It is
77
P H O T O M E T R Y OF 14 A S T E R O I D S TABLE lI OPPOSITION DATES, PHYSICAL PARAMETERS, AND CORRESPONDING FIGURE(S) FOR THE ASTEROIDS PRESENTED
Asteroid
Opposition date
Taxonomic type
Diameter (km)
Perio& (hr)
Amplitude (mag)
Figure
6 Hebe 9 Metis 22 Kalliope 43 Ariadne 55 Pandora 63 Ausonia 79 Eurynome 88 Thisbe 129 Antigone 173 Ino 181 Eucharis 250 Bettina 471 Papagena 852 Wladilena ~
Jan. 17, 1983 Oct. 6, 1982 Mar. 19, 1983 Oct. 7, 1982 Oct. 30, 1982 Jan. 26, 1983 Jan. 22, 1983 Nov. 13, 1982 Oct. 17, 1982 Nov. 27, 1982 Feb. 8, 1983 Mar. 30, 1983 Mar. 26, 1983 Oct. 8, 1982
S S M S CMEU S S C U C S CMEU S S+
206 168 175 78 185 94 80 214 113 169 81 211 145 30
7.277 5.064 4.147 5.751 4.804 9.297 5.979 6.042 4.957 5.930 >7 5.105 7.105 4.611
0.19 0.05 0.07 0.31 0.08 0.15 0.24 0.14 0.25 -0.11 >0.08 0.60 0.11 0.30
I 2 3 4 5 6 7 8 9 10 II 12 13 14
" The rotational periods, except for 6 Hele, 181 Eucharis, and 250 Bettina, were not determined by the authors. b Assigned to S-type class for its eliocentric distance a < 2.6 AU. The diameter was computed assuming Pv = 0.16 and (B-V) = 0.87. i n t e r e s t i n g to n o t e that w h e n this a s t e r o i d w a s o b s e r v e d with a d i f f e r e n c e in l o n g i t u d e o f a b o u t 180 ° ( C h a n g a n d C h a n g , 1962; G e h r e l s an d O w i n g s , 1961), i.e., w h e n it had a c o m p l e m e n t a r y a s p e c t , t h e s e c o n d a r y m i n i m u m c o u l d n o t be d i s t i n g u i s h e d .
an a b r u p t rise to the p r i n c i p a l m a x i m u m a n d w i t h a n o t - w e l l d ef i n ed m i n i m u m . A s in t h e c a s e o f 9 M e t i s , the a m p l i t u d e (A = 0.m07 -+ 0m01) is less c o m p a r e d to t h o s e o b t a i n e d in t h e five p r e v i o u s a p p a r i t i o n s .
43 A r i a d n e 22 Kalliope
The complete lightcurve of o b t a i n e d in o n e night, is s h o w n is v e r y s y m m e t r i c a l , w i t h o u t larities that c h a r a c t e r i z e d the
T h e l i g h t c u r v e o b t a i n e d f o r this M t y p e , r a p i d l y r o t a t i n g a s t e r o i d is r e p r e s e n t e d in Fig. 3. It a p p e a r s r a t h e r a s y m m e t r i c , with
-o.~o
(~) •
-0.10
o g ~, o
.... o
:
m
•
% ,-;• . ' ; . 7..
,,
.
this o b j e c t , in Fig. 4. It t h e irregulightcurves
•
;
¢~:~,
Ib.*
•
....~
:'< .gl.
-0.20
Jun 9-10,1983 UT
21 h 1
I
23 I
1 I
I
3 I
I
(n.c.)
5 I
i
FIG. 1. Composite lightcurve of 6 Hebe (with P = 7.277) obtained on June 9 - 1 0 (IlL June 10-11 and June 14-15 ( 0 ) , 1983.
(0),
78
D1 M A R T I N • AND CACCIATORI
o
:(,:
o,0
" °%
-073
h 19 I
o
%
Oct 17-18,1982 23 I J
55 Pandora This object was previously o b s e r v e d only during the 1977 apparition (Schober, 1978), when the lightcurve was very regular in shape and had an amplitude of about 0.24 mag. Our observations, performed in a single night, are represented in Fig. 5. The lightcurve, with a m a x i m u m amplitude of 0.m06 --+ 0m01, is characterized by the different slopes of the increasing and decreasing branches of the maxima. 63 Ausonia Because of its proximity, this minor planet was o b s e r v e d simultaneously with 21 Lutetia (Zappal~t et al., 1983) but using different c o m p a r i s o n stars. A u s o n i a ' s lightcurve, shown in Fig. 6, has an amplitude of
I
•
• ..
o.44 ",C'.." :"
!
• 1.30
", __
V"
..."
O
Oh I
Mar 7-8,1983
I
2 i
ee°
21
L
i
23
i
4 I
UT(n.c.) L
FIG. 3. Lightcurve of 22 Kalliope obtained on March 7-8, 1983.
]
I
i
79 E u r y n o m e This object was also o b s e r v e d in a single night, and the lightcurve (Fig. 7) shows a very irregular secondary m a x i m u m containing a dip of 0.05 mag during a 40-min interval. A similar feature was recognized in the lightcurve of N o v e m b e r 9-10, 1974 (Schober, 1976), but with amplitude less than 0.01 mag. It could be attributed to topographic reliefs on a scale of several kilometers.
~ •
,.8~
F-
.
o•
•
."
•
i
Nov 10-11.1982
L
2 o"
~Oo~ o° o~o~
eell,
oo
%
'.'~-.a
%•
~'
~
..o
o
• •
ee
i
UT(n.clO °
about 0.15 mag and exhibits a similar difference in brightness (about 0.07 mag) of the primary and secondary minima, as already noted in the iightcurves from 1976 (Scaltriti and Zappal~t, 1977a), 1980 (Lagerkvist, 1981), and 1983 (Zappal~ et al., 1983).
~..
•
Oo
Fl~. 4. Lightcurve of 43 Ariadne obtained on October 15-16, 1982.
"~,:~'"o. ~ . ~
o
I
lg h i
oO
II
•
It
o
8
;.
Oct 15-18, lg82
8
o%
¢
• •
,. "e'~"
• o
•
~ 40
:
~
I
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;
ee~
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~o $o ..
8o •
-1.20
":
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(~)
~0
•
I
obtained in 1965 (Van H o u t e n - G r o e n e v e l d and Van Houten, 1979) and 1972 (Burchi and Milan•, 1974; Lustig and Dvorak, 1975). The e x t r e m a are well defined; prim a r y and secondary m a x i m a and minima are almost at the same level.
•• tflP~ ..
:.
UT(n.c
FiG. 2. Lightcurve of 9 Metis obtained on October 17-18, 1982.
I-0.~8
?;.'.: -1.10
oil 21 J
~
o¢
• 22
0
UT (n.c)
,2
FiG. 5. Lightcurve of 55 Pandora obtained on November 10-11, 1982.
PHOTOMETRY OF 14 ASTEROIDS
(~
r~o 0.05
.:
:.,! a =
i ~.
f:
•
•
79
)
o o
~.... "
ooo
t Jan 23-24,1983
? -o.os
UT(..~.)
•
I L" h
20 L
22
J
I
0
l
I
2
I
I
l
l
FroG. 6. Lightcurve of 63 Ausonia obtained on January 23-24, 1983.
Zappal~t (1977b) during the 1976 opposition. The trend of our lightcurve, shown in Fig. 9, is quite regular and very similar to those previously obtained, except for the amplitude, now smaller by about 0.06 mag.
88 Thisbe
This large asteroid exhibits a lightcurve (Fig. 8) with the same features (at 22.h7 and 02.h2) recognized in the lightcurves obtained during the 1977 opposition (Schober e t a / . , 1979; Choloniewski, 1979). From considerations similar to those of Goguen et al. (1976) it is possible to establish that the irregularities in the lightcurve are produced by topographic features about 20 km across.
173 Ino
The observation of this minor planet covers only about 70% of the rotational period found by Schober (1978). The minimum is missing, but we can easily estimate an amplitude close to 0.11 mag. The lightcurve, shown in Fig. 10, is asymmetrical, with a discontinuous rise to the maximum, which seems to mask the secondary extrema well evident in the 1977 lightcurves.
129 Antigone
This rapidly spinning asteroid was observed for the first time by Scaltriti and
/*" .-...
, •
:--"
#
~.,
.'
o
-# : ~oo°o 4
72oo
•
.B
•
•
o
Jan 12-13.1983
I t30 i 210h
UT(~.¢.) I
212
I
0m
2 I
I
I
4
I
FIG. 7. Lightcurve of 79 Eurynome obtained on January 12-13, 1983.
80
D1 MARTINO AND CACCIATORI
I2To
®
m e. -0,~."
%
4,0
.e e•
• ~,r
.,.2
•, .
"
.4,-~,2=,982
"~ 215
.; 2
181 Eucharis
No previous observations of this asteroid have been published. Our single night's observation covered about 7 hr. However, from the lightcurve obtained, shown in Fig. 1 l, we can only state that the rotational period is greater than 7 h. 250 Bettina
The period of this large CMEU asteroid was determined by Lagerkvist and Rickman (1981) from a single night's lightcurve. We have observed this object on two nights separated by 21 days, thereby improving the determination of the rotational period, 5.h105 --+ 0.h001. The amplitude is about 0.60 mag, implying that this large and rapidly spinning object belongs to the L A S P A class of asteroids (Farinella et al., 1981). From a tentative amplitude-longitude plot we find that the amplitude at equatorial aspect would be about 0.70 mag. Therefore, asm
..'. •
• •
~o9o : Oe : "
~o
oe i J ~1.00
•
o
"
•
.I • •
~
18h
oGO o o
20
22
UT(n.c:)
oo
•
-."•
Fl(;. I(1 Lighlcurve of 173 Ino obtained on January 10, 1983.
suming 250 Bettina to be a triaxial ellipsoid in hydrostatic equilibrium (Farinella et al., 1981) and taking into account the predicted maximum amplitude, we obtain a density of about 1.8 g/cm ~. Applying the multiple-scattering theory of Boweli and L u m m e (1979), we obtain a multiple-scattering factor Qv 0.09 -+ 0.01, corresponding to/3v = 0.034 + 0.001, in agreement with the phase coefficient of objects belonging to the CMEU taxonomic class. For Bettina, however, the Qv and/3,, values may be subject to variations at different aspect angles because of its highly nonspherical shape. The composite lightcurve is shown in Fig. 12. 471 Papagena
The lightcurve of this S-type asteroid, observed in a single night's observation, is shown in Fig. 13. It presents, as did the lightcurve from the 1976 apparition, three
i o~o
(~
IIo9c'."-:"':'= .';:.,'.:. ":'"" i
o:
O c t 18-19,1982 F 1"10 ~t__
0
b l~; 9. Lightcurve of 129 Antigone obtained on ()ctober 18-19, 1982.
i
- 1O0
o
-,,.
* ;,o~
' ";:'. ".."': •
Feb 18-19,1983 UT(n.c)
212
I
0
o
i
~
o
• •~•
Jan 10,1983
Po so • •
L ~ 2 l Oh
o oo o
~2 •
•° •
.•. ;
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°°
•
•
o
ee • • • •=p
•
-2.20
m
•
4
FIG, 8. Lightcurve of 88 Thisbe obtained on Novemher .:1-,_, 1982.
I
%
" • 8~," %,o ~
•
0
P
•
...
• t==• •
UT(n.c.)
h 22
(~
~o
21h
213
:V J-
~.•
UT(.c:)
1;1(; I I l.ightcurvc o f 181 Eucharis obtained on February 1 8 - { 9 1983
PHOTOMETRY OF 14 ASTEROIDS AV - (1~0
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•
0
-2.~o
o
I o
..
o
oo
=e I eem
file
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81
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im
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h 19
o
I
0
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21
I
I
I
23 l
1
FIG. 14. Lightcurve of 852 Wladilena obtained on October 1 7 - 1 8 , 1983. •
mm
o
•
O
Apr 15-16,1983
•
-o.eo
o o
Z •
21 h
o o
UTCn~)
1
23 I
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I
852 Wladilena
I
The lightcurve (Fig. 14) of this rapidly rotating asteroid shows two completely different maxima, differing in magnitude by about 0.14 mag. N o information is available on taxonomic type and diameter; however, from the orbital semimajor axis value we can infer an S taxonomic type and therefore a diameter of about 30 km. The amplitude, about 0.30 mag, is practically the same as that obtained during the 1977 opposition (Tedesco, 1979).
FIG. 12. Composite lightcurve of 250 Bettina (with P = 5.105) obtained on March 2 5 - 2 6 (11) and April 1 5 - 1 6 ( O ) , 1983.
well-defined maxima and minima and an amplitude of about 0.11 mag. Other asteroids (29 Amphitrite, 51 Nemausa, 75 Eurydike, 77 Frigga, etc.) have similar lightcurves, implying very irregular shapes and/or the existence of albedo spots on their surfaces. -I.~5
e• 4be qbo
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em
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FIG. 13. Lightcurve of 471 Papagena obtained on April 1 3 - 1 4 , 1983.
82
DI M A R T 1 N O
AND CACCIATOR|
ACKNOWLEDGMENTS The authors are very grateful to the Astrophysical O b s e r v a t o r y of Catania for granting observing time and technical assistance and to Dr. V. Zappali[ for useful d i s c u s s i o n s and c o m m e n t s . Moreover, the authors thank E. B o w e l l for his help in improving the English and for his suggestions. This work was partially supported by the National Research Council o f Italy (CNR). REFERENCES AtlMAD, l, I. 119541. Photometric studies of asteroids: IV. The lightcurves of Ceres, Hebe, Flora and Kalliope. Astrophys. J. 120, 551 559. BI ANCO, V. M., S. DEMERS. G. G. I)out;l ASS, ANI) M. P. FIrZGERALD ( 1 9 6 8 ) . Photoelectric Catalogue. Publ. U.S. Nawd Obs., Second Series XII. BOWELL, E., AND K. [AJMME 119791. Colorimetry and magnitudes of asteroids. In Asteroids (T. Gehrels, Ed.L pp. 132-169. Univ. of Arizona Press. Tucson. BOWEI.I., E.. T. GEHREI,S, AN[) B. ZEII NER 119791. Magnitudes, colors, types and adopted diameters of lhe asteroids. In Asteroids (T. Gchrels. Ed.), pp. 1108-1129. Univ. of Arizona Press, T u c s o n . BURCtlI. i . , ANI) l~. MII.ANO (19741. Photoelectric lightcurves of the minor planel 43 Ariadne during the 1972 opposition. Astmm. A.strop/ly.~. Suplfl. 15, 173-180. ('HAN(i, Y. ('., AND C.-S. CHAN(; (19621. Photometric investigation of seven variable asteroids. Acta As trott. Sin. 10, I111-111. CHOLONIEWSKL J. 119791. Photoelectric lighcurves of lhc asteroid 88 Thisbe during the 1977 opposilion. Aria Astron. 29, 1115-11"18. EARINEI I.A, P., P. PAOI.ICCItl, E. 1~'. TEDFS( O, AND V. ZAPPAI k (19811. Triaxial equilibrium ellipsoids a m o n g the asteroids? Icarus 46, 114-123. ( ; e H a E l s , T., AND D. ()WIN(~S 119621. Pholometric studies of asteroids: IX. Additional lightcurves. A~ trophys. J. 135, 906-924. (}ti]lrl 1 S, T., AND R. C. TAYLOR (19721. Minor planets and related objects: X X I I . Phase flmclion for {6) Hebe. Astron. ,I. 82, 229-237. (IOGUFN, J., ,I. VI-VERKA. J. l,. EI IIOI, ANI) ('. CHURCH (1976). The lightcurve and rolafion period of asteroid 139 ,luewa. h'arus 29, 137-142. JOIINSON, H. L., AND W. W. MORGAN (1953). Fundamental stellar photometry for standards of spectral type on the revised s y s t e m of thc Yerkes Spectral Alias. Astrophys. J. 117, 313-352. [,A(;Et',KVlSl. C.-I. 11981`1. Physical studies of asteroids: 11: Photoelectric observations of the asteroids 63. 93, 135 and 409. Astron. Astr,*phv.~. Suppl. 44, 345-347. LAGERKVIS1 , C.-I., AND H. RICKMAN t 1981 t. The spin periods of M asteroids. Moon Plain'Is 24, 437-440.
LAGERKVIST, C.-[., E. SCAI_TRITI, AND V. ZAPPAI.A (19831. Asteroid lightcurve catalogue. In Asteroids. Cornels. Meteors (C.-l. Lagerkvist and H. Rickman, Eds.), pp. 27-30. Uppsala Universitet Repocentralen, Uppsala. IJANDOH, A. U. 11973). UBV photoelectric seq u e n c e s in the celestial equatorial selected areas 92115. Astron. J, 78, 959-1020. LUSTIG, G., AND g. DVORAK 119751. Photometrische U n t e r s u c h u n g e n der Planetoiden (43) Ariadne and 1711 Niobe. A('ta Phys. Austr. 43, 89-97. SANDERS, W. L. 119661. UBV photometry of 1055 stars. A s m m . J. 7 1 , 7 1 9 - 7 2 9 . S(AI,TRITI, F., ANI) V. ZAPPAI.,~ (1977a). A pholomelric study of the minor phmet (63) Ausonia. Icarus 31, 498-51t2. S('AI_3RI1L F., -XND V. ZAPPALA (1977b). Photoelectric pholomelry of the minor planets 41 Daphne and 129 Antigone. Aslroll. Aslrophy,s. 56, 7 - I I . S ( H O B E R , H. J. (19761. The period of rotation and the photoelectric lightcurve of the minor phme! 79 Eurynome. lcaru,~ 28, 415-4211. ~('IlOBfR, 11. J. ( 19781. Photometric variations of the minor planets 55 Pandora and 173 Ino during the opposition in ]977: Lightcurves and rotation periods. A s t r o , . A.~lrophvs. 34, 377-381. S('HOBER, H. J., F. SCALIRI[I, AND V. ZAPPAIA 11979). Pholoelectric photomelry and rotation periods of three large and dark asteroids: 49 F'alcs, 88 Thisbe and 92 Undina. Astron. Astrophys. Suppl. 36, I-8. TtDESCO. E. f". (1979). Phi) thesis, New Mexico Slale University. V A N HOUTEN-GROI~.NI-:VEI.D, I., ('. J. VAN HOUTI-:N, AND V. ZAPPAL,~ (19791. Photoelectric photometry o f seven asteroids. Astron. Astrophys. Suppl. 35, 223-232. YAN(;, X.-Y.. Y.-Y. ZHAN(i, AND X.-Q. l,l 119651, Photometric observations of variable asteroids, I11. Aria. Astron. Sin. 13, 66-74. ZAPPM A, V., M. DI MARNNO, P. FORINELLO, AND P. PAOI.IC(HJ (1983a). An analytical method for the determination of the rotational direction of asteroids. In Asteroids, Comets, Meteors (C.-I. Lagerkvis! and H. Rickman, Eds.), pp. 73-76. Uppsala Universitet, Repocentralen HSC. Uppsala. ZAePAI M V., M. DJ MARTINO, Z. KNEZEW(, AND (;. I)JURAgEW(" (1983b). New evidence for the effect of phase angle on asteroid lightcurve shape: 21 I,utetia. Astron. Astrophys. 130, 208-210, ZAPPAI A, V., ANI)Z. KNE2EVI(" (1984). Rotation axis of asteroids: rcstdts for 14 objects, h ' a r u s 59, 436 455. ZAPPAI*'~, V., ~. S(AI.'IRITI. AND M. DI MARTINO (19841. Photoelectric photometry of 21 asleroids. h'arus 56, ~25 344.
Photoelectric Photometry of 14 Asteroids M. DI MARTINO AND S. CACCIATORI Astronomical Observatory. of" Torino, 10025 Pino Torinese, Turin, Italy Received January 18, 1984; revised April 19, 1984 Results of observations of 14 asteroids are reported; all o f them, except 181 Eucharis, have been previously o b s e r v e d at least once. V photoelectric lightcurves were obtained from S e p t e m b e r 1982 to June 1983 at the Astronomical O b s e r v a t o r y of Torino and at the Astrophysical O b s e r v a t o r y of Catania. Part of this program aims to obtain complete lightcurves and, when possible, p h a s e c u r v e information and to determine amplitudes and V magnitudes at different longitudes for a selected group of asteroids, in order to enlarge the set o f known rotational axis directions. ~ 1984Academic Press, Inc.
of one asteroid from our list (181 Eucharis) has not been previously observed. Aspect and magnitude data (determined by a computer program, starting from the orbital elements taken from the Ephemerides o f Minor Planets, identification of comparison stars, and telescope employed are listed in Table I. In Table II are summarized the opposition dates, the taxonomic types and diameters (Bowell et al., 1979), the rotational periods, the observed amplitudes, and the number(s) of the corresponding figure(s) for the observed asteroids. Single-night curves as well as composite lightcurves are shown in Figs. 1 to 14; in the first case the ordinate is the instrumental magnitude, in the second we adopt the average maximum brightness as zero point of the scale. The abscissae are always UT, not corrected for light-time, and, when composite curves are presented, they refer to one night, the date of which is reported in the figure. Open symbols represent repeated observations. For a summary of previous observations, we consulted the "Asteroid Lightcurve Catalogue" by Lagerkvist et al. (1983).
INTRODUCTION
In this paper we present the results obtained for 14 asteroids observed during the interval September 1982 to June 1983, using the 45-cm reflector telescope of the Torino Observatory and the 91-cm telescope of the Catania Astrophysical Observatory, using a single-channel photometer in the pulsecounting mode. The observing procedure consisted of comparing an asteroid's brightness with that of a comparison star suitably chosen along the minor planet's path. Reductions were made by a computer program which takes account of differential extinction between the target object and the comparison star, using extinction coefficients determined nightly. Transformations to the standard UBV systems were made for all the asteroids, except 6 Hebe, by means of groups of standard stars taken from Johnson and Morgan (1953), Landolt (1973), Sanders (1966), and Blanco et al. (1968). Part of our observational program aims to obtain, at different oppositions and at small phase angles (~ < I0°), complete lightcurves of selected minor planets (Zappalh and Kne~evid, 1984) and to determine, using the amplitude and the magnitude at maximum brightness, the rotational axis direction and a rough indication of the shape (Zappalh et al., 1983a). Only the lightcurve
OBSERVATIONS AND RESULTS
6 Hebe
This asteroid has previously been observed during eight apparitions. Our obser75 0019-1035/84 $3.00 Copyright ~ 1984by AcademicPress, Inc. All rights of reproduction in any form reserved.
76
DI M A R T I N O A N D C A C C I A T O R I TABLE
1
ASPEC1 I ) A I A FOR 1HE OBSERVED ASTEROIDS
Date (0hUT)
6 Hebe 1983 06 10 06 I 1 06 15
Phase
V0(l,(~)
Comparison star
Tele~copc (crn)
BD 3+4182 BD 3°4182 BI) -3+'4168
45 45 45
B D --6°110
91
RA (1950)
Dec, 11950)
Long (1950)
Lal 11950)
r (AU)
~ (AU)
17h48m0 17h47".'0 17h43ml
3°23 ' 3°24 ' ....3029 '
266?8 266.6 265.5
+20?0 20.<1 +19.9
2.5396 2.5375 2.5292
1.5687 1.5646 1.5510
8'.'5 8.4 7.9
00h36".'6
--4°51 '
6?5
871
2,2105
1.2448
8?5
6".'67
12h01"75
+21032 '
17174
+ 1978
2.9791
2,11288
6?7
6"?86
00h39".'6
+ IIF37'
13?3
5?8
2.1874
1.1994
4'.'7
8"718
B D + 10+73
91
()2NB".'2
+ 190113'
3572
+6'71
2.3918
1.419<1
577
7'!'99
B D + 18°268
45
08h36"76
+23048 '
12574
+ 5?0
2.6375
1.6562
2?1
7".'47
B D + 24'+1971
45
08h22"?0
+ I 1°112'
12572
8?2
2.2227
1.2598
6.°9
8~738
B D + I 1°1834
45
03~14".'4
÷ 23+tt5 '
5071
~575
2.7822
1.8048
~77
7'!'34
BD +22"437
45
01n27'~'2
-7+45 '
1772
1577
3.2376
2.27~4
5'?3
7"731
BI)
8"257
91
(13h46m4
-(1°(12 ,
54?3
1974
2.3650
1.6779
21173
8~?80
BD
0°606
45
09hl6'!'3
+ 14°40 '
137711
I?1
2.5971
1.6229
4?7
8".'17z'
B D + 15°2112<)
45
12h38".~0 12h20m8
+ 2'+22 ' + 2 49
18778 183.6
+ 5?9 +4?6
3.1347 3.1604
_.14.~ 2.21168
2?2 6.8
7+Y64 7.93
BI) + 3 " 2 6 3 5 '
45 45
12h04':'6
+21°33 '
17271
._ ~'~(1°v
~,.3601
2.4993
11172
7".'11
...4411 B D + '~'~°'~
45
110h37"29
+6°53 '
I (1?I
1.96(14
0.9957
I (172
10".'61
BD
91
9 Metis 1982 10 18 22 Kalliope 1983 03 08 43 Ariadne 1982 I 0 16
"
45
55 Pandora 1982 I I 11 63 Ausonia 1983 01 24 79 Eurynome 1983 01 13 88 Thisbe 1982 t I 22 129 Antigone 1982 10 19 173 l n o 1983 01 I0 181 Eucharis 1983 02 19 250 Bettina 1983 03 26 04 16 471 Papagena 1983 04 14 852 Wladilena 1982 10 18
" S t a r is not cataloged, Chg~0
6711
6 +I I 0
12h(11'!'2. 81,~,0 ~ +21o22 '.
M a x i m u m was not observed. ' Star is not cataloged, cr~+~0 12h36".~4. 8=,or : + 2 ° 1 7 '-
vations were made over three nights, from which we have deduced a rotational period P = 7.h277 _+_ 0h.002 which is in very good agreement with the values obtained by A h m a d 119541 and Yang et al. 11965). The lightcurve shape and the amplitude (A 0.m19 +- 0m01) are practically the same as those obtained in the 1968 opposition (Gehrels and Taylor, 1977), the observations being made at about 15 ° of longitude apart. Figure I s h o w s the c o m p o s i t e lightcurve
o f this large asteroid, for which the value of the reduced magnitude at m a x i m u m brightness V0(l,a) was not obtained. 9 Metis
Metis was observed in a single night together with the minor planet 852 Wladilena, using the same comparison star. The resulting lightcurve is s h o w n in Fig. 2. The amplitude of A = 0.m05 -+ 0.m01 is the smallest obtained hitherto. The lightcurve s h o w s t w o well-defined maxima and minima. It is
77
P H O T O M E T R Y OF 14 A S T E R O I D S TABLE lI OPPOSITION DATES, PHYSICAL PARAMETERS, AND CORRESPONDING FIGURE(S) FOR THE ASTEROIDS PRESENTED
Asteroid
Opposition date
Taxonomic type
Diameter (km)
Perio& (hr)
Amplitude (mag)
Figure
6 Hebe 9 Metis 22 Kalliope 43 Ariadne 55 Pandora 63 Ausonia 79 Eurynome 88 Thisbe 129 Antigone 173 Ino 181 Eucharis 250 Bettina 471 Papagena 852 Wladilena ~
Jan. 17, 1983 Oct. 6, 1982 Mar. 19, 1983 Oct. 7, 1982 Oct. 30, 1982 Jan. 26, 1983 Jan. 22, 1983 Nov. 13, 1982 Oct. 17, 1982 Nov. 27, 1982 Feb. 8, 1983 Mar. 30, 1983 Mar. 26, 1983 Oct. 8, 1982
S S M S CMEU S S C U C S CMEU S S+
206 168 175 78 185 94 80 214 113 169 81 211 145 30
7.277 5.064 4.147 5.751 4.804 9.297 5.979 6.042 4.957 5.930 >7 5.105 7.105 4.611
0.19 0.05 0.07 0.31 0.08 0.15 0.24 0.14 0.25 -0.11 >0.08 0.60 0.11 0.30
I 2 3 4 5 6 7 8 9 10 II 12 13 14
" The rotational periods, except for 6 Hele, 181 Eucharis, and 250 Bettina, were not determined by the authors. b Assigned to S-type class for its eliocentric distance a < 2.6 AU. The diameter was computed assuming Pv = 0.16 and (B-V) = 0.87. i n t e r e s t i n g to n o t e that w h e n this a s t e r o i d w a s o b s e r v e d with a d i f f e r e n c e in l o n g i t u d e o f a b o u t 180 ° ( C h a n g a n d C h a n g , 1962; G e h r e l s an d O w i n g s , 1961), i.e., w h e n it had a c o m p l e m e n t a r y a s p e c t , t h e s e c o n d a r y m i n i m u m c o u l d n o t be d i s t i n g u i s h e d .
an a b r u p t rise to the p r i n c i p a l m a x i m u m a n d w i t h a n o t - w e l l d ef i n ed m i n i m u m . A s in t h e c a s e o f 9 M e t i s , the a m p l i t u d e (A = 0.m07 -+ 0m01) is less c o m p a r e d to t h o s e o b t a i n e d in t h e five p r e v i o u s a p p a r i t i o n s .
43 A r i a d n e 22 Kalliope
The complete lightcurve of o b t a i n e d in o n e night, is s h o w n is v e r y s y m m e t r i c a l , w i t h o u t larities that c h a r a c t e r i z e d the
T h e l i g h t c u r v e o b t a i n e d f o r this M t y p e , r a p i d l y r o t a t i n g a s t e r o i d is r e p r e s e n t e d in Fig. 3. It a p p e a r s r a t h e r a s y m m e t r i c , with
-o.~o
(~) •
-0.10
o g ~, o
.... o
:
m
•
% ,-;• . ' ; . 7..
,,
.
this o b j e c t , in Fig. 4. It t h e irregulightcurves
•
;
¢~:~,
Ib.*
•
....~
:'< .gl.
-0.20
Jun 9-10,1983 UT
21 h 1
I
23 I
1 I
I
3 I
I
(n.c.)
5 I
i
FIG. 1. Composite lightcurve of 6 Hebe (with P = 7.277) obtained on June 9 - 1 0 (IlL June 10-11 and June 14-15 ( 0 ) , 1983.
(0),
78
D1 M A R T I N • AND CACCIATORI
o
:(,:
o,0
" °%
-073
h 19 I
o
%
Oct 17-18,1982 23 I J
55 Pandora This object was previously o b s e r v e d only during the 1977 apparition (Schober, 1978), when the lightcurve was very regular in shape and had an amplitude of about 0.24 mag. Our observations, performed in a single night, are represented in Fig. 5. The lightcurve, with a m a x i m u m amplitude of 0.m06 --+ 0m01, is characterized by the different slopes of the increasing and decreasing branches of the maxima. 63 Ausonia Because of its proximity, this minor planet was o b s e r v e d simultaneously with 21 Lutetia (Zappal~t et al., 1983) but using different c o m p a r i s o n stars. A u s o n i a ' s lightcurve, shown in Fig. 6, has an amplitude of
I
•
• ..
o.44 ",C'.." :"
!
• 1.30
", __
V"
..."
O
Oh I
Mar 7-8,1983
I
2 i
ee°
21
L
i
23
i
4 I
UT(n.c.) L
FIG. 3. Lightcurve of 22 Kalliope obtained on March 7-8, 1983.
]
I
i
79 E u r y n o m e This object was also o b s e r v e d in a single night, and the lightcurve (Fig. 7) shows a very irregular secondary m a x i m u m containing a dip of 0.05 mag during a 40-min interval. A similar feature was recognized in the lightcurve of N o v e m b e r 9-10, 1974 (Schober, 1976), but with amplitude less than 0.01 mag. It could be attributed to topographic reliefs on a scale of several kilometers.
~ •
,.8~
F-
.
o•
•
."
•
i
Nov 10-11.1982
L
2 o"
~Oo~ o° o~o~
eell,
oo
%
'.'~-.a
%•
~'
~
..o
o
• •
ee
i
UT(n.clO °
about 0.15 mag and exhibits a similar difference in brightness (about 0.07 mag) of the primary and secondary minima, as already noted in the iightcurves from 1976 (Scaltriti and Zappal~t, 1977a), 1980 (Lagerkvist, 1981), and 1983 (Zappal~ et al., 1983).
~..
•
Oo
Fl~. 4. Lightcurve of 43 Ariadne obtained on October 15-16, 1982.
"~,:~'"o. ~ . ~
o
I
lg h i
oO
II
•
It
o
8
;.
Oct 15-18, lg82
8
o%
¢
• •
,. "e'~"
• o
•
~ 40
:
~
I
":
;
ee~
• .'.
~o $o ..
8o •
-1.20
":
" ~'"
(~)
~0
•
I
obtained in 1965 (Van H o u t e n - G r o e n e v e l d and Van Houten, 1979) and 1972 (Burchi and Milan•, 1974; Lustig and Dvorak, 1975). The e x t r e m a are well defined; prim a r y and secondary m a x i m a and minima are almost at the same level.
•• tflP~ ..
:.
UT(n.c
FiG. 2. Lightcurve of 9 Metis obtained on October 17-18, 1982.
I-0.~8
?;.'.: -1.10
oil 21 J
~
o¢
• 22
0
UT (n.c)
,2
FiG. 5. Lightcurve of 55 Pandora obtained on November 10-11, 1982.
PHOTOMETRY OF 14 ASTEROIDS
(~
r~o 0.05
.:
:.,! a =
i ~.
f:
•
•
79
)
o o
~.... "
ooo
t Jan 23-24,1983
? -o.os
UT(..~.)
•
I L" h
20 L
22
J
I
0
l
I
2
I
I
l
l
FroG. 6. Lightcurve of 63 Ausonia obtained on January 23-24, 1983.
Zappal~t (1977b) during the 1976 opposition. The trend of our lightcurve, shown in Fig. 9, is quite regular and very similar to those previously obtained, except for the amplitude, now smaller by about 0.06 mag.
88 Thisbe
This large asteroid exhibits a lightcurve (Fig. 8) with the same features (at 22.h7 and 02.h2) recognized in the lightcurves obtained during the 1977 opposition (Schober e t a / . , 1979; Choloniewski, 1979). From considerations similar to those of Goguen et al. (1976) it is possible to establish that the irregularities in the lightcurve are produced by topographic features about 20 km across.
173 Ino
The observation of this minor planet covers only about 70% of the rotational period found by Schober (1978). The minimum is missing, but we can easily estimate an amplitude close to 0.11 mag. The lightcurve, shown in Fig. 10, is asymmetrical, with a discontinuous rise to the maximum, which seems to mask the secondary extrema well evident in the 1977 lightcurves.
129 Antigone
This rapidly spinning asteroid was observed for the first time by Scaltriti and
/*" .-...
, •
:--"
#
~.,
.'
o
-# : ~oo°o 4
72oo
•
.B
•
•
o
Jan 12-13.1983
I t30 i 210h
UT(~.¢.) I
212
I
0m
2 I
I
I
4
I
FIG. 7. Lightcurve of 79 Eurynome obtained on January 12-13, 1983.
80
D1 MARTINO AND CACCIATORI
I2To
®
m e. -0,~."
%
4,0
.e e•
• ~,r
.,.2
•, .
"
.4,-~,2=,982
"~ 215
.; 2
181 Eucharis
No previous observations of this asteroid have been published. Our single night's observation covered about 7 hr. However, from the lightcurve obtained, shown in Fig. 1 l, we can only state that the rotational period is greater than 7 h. 250 Bettina
The period of this large CMEU asteroid was determined by Lagerkvist and Rickman (1981) from a single night's lightcurve. We have observed this object on two nights separated by 21 days, thereby improving the determination of the rotational period, 5.h105 --+ 0.h001. The amplitude is about 0.60 mag, implying that this large and rapidly spinning object belongs to the L A S P A class of asteroids (Farinella et al., 1981). From a tentative amplitude-longitude plot we find that the amplitude at equatorial aspect would be about 0.70 mag. Therefore, asm
..'. •
• •
~o9o : Oe : "
~o
oe i J ~1.00
•
o
"
•
.I • •
~
18h
oGO o o
20
22
UT(n.c:)
oo
•
-."•
Fl(;. I(1 Lighlcurve of 173 Ino obtained on January 10, 1983.
suming 250 Bettina to be a triaxial ellipsoid in hydrostatic equilibrium (Farinella et al., 1981) and taking into account the predicted maximum amplitude, we obtain a density of about 1.8 g/cm ~. Applying the multiple-scattering theory of Boweli and L u m m e (1979), we obtain a multiple-scattering factor Qv 0.09 -+ 0.01, corresponding to/3v = 0.034 + 0.001, in agreement with the phase coefficient of objects belonging to the CMEU taxonomic class. For Bettina, however, the Qv and/3,, values may be subject to variations at different aspect angles because of its highly nonspherical shape. The composite lightcurve is shown in Fig. 12. 471 Papagena
The lightcurve of this S-type asteroid, observed in a single night's observation, is shown in Fig. 13. It presents, as did the lightcurve from the 1976 apparition, three
i o~o
(~
IIo9c'."-:"':'= .';:.,'.:. ":'"" i
o:
O c t 18-19,1982 F 1"10 ~t__
0
b l~; 9. Lightcurve of 129 Antigone obtained on ()ctober 18-19, 1982.
i
- 1O0
o
-,,.
* ;,o~
' ";:'. ".."': •
Feb 18-19,1983 UT(n.c)
212
I
0
o
i
~
o
• •~•
Jan 10,1983
Po so • •
L ~ 2 l Oh
o oo o
~2 •
•° •
.•. ;
~
°°
•
•
o
ee • • • •=p
•
-2.20
m
•
4
FIG, 8. Lightcurve of 88 Thisbe obtained on Novemher .:1-,_, 1982.
I
%
" • 8~," %,o ~
•
0
P
•
...
• t==• •
UT(n.c.)
h 22
(~
~o
21h
213
:V J-
~.•
UT(.c:)
1;1(; I I l.ightcurvc o f 181 Eucharis obtained on February 1 8 - { 9 1983
PHOTOMETRY OF 14 ASTEROIDS AV - (1~0
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o
oo
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FIG. 14. Lightcurve of 852 Wladilena obtained on October 1 7 - 1 8 , 1983. •
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The lightcurve (Fig. 14) of this rapidly rotating asteroid shows two completely different maxima, differing in magnitude by about 0.14 mag. N o information is available on taxonomic type and diameter; however, from the orbital semimajor axis value we can infer an S taxonomic type and therefore a diameter of about 30 km. The amplitude, about 0.30 mag, is practically the same as that obtained during the 1977 opposition (Tedesco, 1979).
FIG. 12. Composite lightcurve of 250 Bettina (with P = 5.105) obtained on March 2 5 - 2 6 (11) and April 1 5 - 1 6 ( O ) , 1983.
well-defined maxima and minima and an amplitude of about 0.11 mag. Other asteroids (29 Amphitrite, 51 Nemausa, 75 Eurydike, 77 Frigga, etc.) have similar lightcurves, implying very irregular shapes and/or the existence of albedo spots on their surfaces. -I.~5
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FIG. 13. Lightcurve of 471 Papagena obtained on April 1 3 - 1 4 , 1983.
82
DI M A R T 1 N O
AND CACCIATOR|
ACKNOWLEDGMENTS The authors are very grateful to the Astrophysical O b s e r v a t o r y of Catania for granting observing time and technical assistance and to Dr. V. Zappali[ for useful d i s c u s s i o n s and c o m m e n t s . Moreover, the authors thank E. B o w e l l for his help in improving the English and for his suggestions. This work was partially supported by the National Research Council o f Italy (CNR). REFERENCES AtlMAD, l, I. 119541. Photometric studies of asteroids: IV. The lightcurves of Ceres, Hebe, Flora and Kalliope. Astrophys. J. 120, 551 559. BI ANCO, V. M., S. DEMERS. G. G. I)out;l ASS, ANI) M. P. FIrZGERALD ( 1 9 6 8 ) . Photoelectric Catalogue. Publ. U.S. Nawd Obs., Second Series XII. BOWELL, E., AND K. [AJMME 119791. Colorimetry and magnitudes of asteroids. In Asteroids (T. Gehrels, Ed.L pp. 132-169. Univ. of Arizona Press. Tucson. BOWEI.I., E.. T. GEHREI,S, AN[) B. ZEII NER 119791. Magnitudes, colors, types and adopted diameters of lhe asteroids. In Asteroids (T. Gchrels. Ed.), pp. 1108-1129. Univ. of Arizona Press, T u c s o n . BURCtlI. i . , ANI) l~. MII.ANO (19741. Photoelectric lightcurves of the minor planel 43 Ariadne during the 1972 opposition. Astmm. A.strop/ly.~. Suplfl. 15, 173-180. ('HAN(i, Y. ('., AND C.-S. CHAN(; (19621. Photometric investigation of seven variable asteroids. Acta As trott. Sin. 10, I111-111. CHOLONIEWSKL J. 119791. Photoelectric lighcurves of lhc asteroid 88 Thisbe during the 1977 opposilion. Aria Astron. 29, 1115-11"18. EARINEI I.A, P., P. PAOI.ICCItl, E. 1~'. TEDFS( O, AND V. ZAPPAI k (19811. Triaxial equilibrium ellipsoids a m o n g the asteroids? Icarus 46, 114-123. ( ; e H a E l s , T., AND D. ()WIN(~S 119621. Pholometric studies of asteroids: IX. Additional lightcurves. A~ trophys. J. 135, 906-924. (}ti]lrl 1 S, T., AND R. C. TAYLOR (19721. Minor planets and related objects: X X I I . Phase flmclion for {6) Hebe. Astron. ,I. 82, 229-237. (IOGUFN, J., ,I. VI-VERKA. J. l,. EI IIOI, ANI) ('. CHURCH (1976). The lightcurve and rolafion period of asteroid 139 ,luewa. h'arus 29, 137-142. JOIINSON, H. L., AND W. W. MORGAN (1953). Fundamental stellar photometry for standards of spectral type on the revised s y s t e m of thc Yerkes Spectral Alias. Astrophys. J. 117, 313-352. [,A(;Et',KVlSl. C.-I. 11981`1. Physical studies of asteroids: 11: Photoelectric observations of the asteroids 63. 93, 135 and 409. Astron. Astr,*phv.~. Suppl. 44, 345-347. LAGERKVIS1 , C.-I., AND H. RICKMAN t 1981 t. The spin periods of M asteroids. Moon Plain'Is 24, 437-440.
LAGERKVIST, C.-[., E. SCAI_TRITI, AND V. ZAPPAI.A (19831. Asteroid lightcurve catalogue. In Asteroids. Cornels. Meteors (C.-l. Lagerkvist and H. Rickman, Eds.), pp. 27-30. Uppsala Universitet Repocentralen, Uppsala. IJANDOH, A. U. 11973). UBV photoelectric seq u e n c e s in the celestial equatorial selected areas 92115. Astron. J, 78, 959-1020. LUSTIG, G., AND g. DVORAK 119751. Photometrische U n t e r s u c h u n g e n der Planetoiden (43) Ariadne and 1711 Niobe. A('ta Phys. Austr. 43, 89-97. SANDERS, W. L. 119661. UBV photometry of 1055 stars. A s m m . J. 7 1 , 7 1 9 - 7 2 9 . S(AI,TRITI, F., ANI) V. ZAPPAI.,~ (1977a). A pholomelric study of the minor phmet (63) Ausonia. Icarus 31, 498-51t2. S('AI_3RI1L F., -XND V. ZAPPALA (1977b). Photoelectric pholomelry of the minor planets 41 Daphne and 129 Antigone. Aslroll. Aslrophy,s. 56, 7 - I I . S ( H O B E R , H. J. (19761. The period of rotation and the photoelectric lightcurve of the minor phme! 79 Eurynome. lcaru,~ 28, 415-4211. ~('IlOBfR, 11. J. ( 19781. Photometric variations of the minor planets 55 Pandora and 173 Ino during the opposition in ]977: Lightcurves and rotation periods. A s t r o , . A.~lrophvs. 34, 377-381. S('HOBER, H. J., F. SCALIRI[I, AND V. ZAPPAIA 11979). Pholoelectric photomelry and rotation periods of three large and dark asteroids: 49 F'alcs, 88 Thisbe and 92 Undina. Astron. Astrophys. Suppl. 36, I-8. TtDESCO. E. f". (1979). Phi) thesis, New Mexico Slale University. V A N HOUTEN-GROI~.NI-:VEI.D, I., ('. J. VAN HOUTI-:N, AND V. ZAPPAL,~ (19791. Photoelectric photometry o f seven asteroids. Astron. Astrophys. Suppl. 35, 223-232. YAN(;, X.-Y.. Y.-Y. ZHAN(i, AND X.-Q. l,l 119651, Photometric observations of variable asteroids, I11. Aria. Astron. Sin. 13, 66-74. ZAPPM A, V., M. DI MARNNO, P. FORINELLO, AND P. PAOI.IC(HJ (1983a). An analytical method for the determination of the rotational direction of asteroids. In Asteroids, Comets, Meteors (C.-I. Lagerkvis! and H. Rickman, Eds.), pp. 73-76. Uppsala Universitet, Repocentralen HSC. Uppsala. ZAePAI M V., M. DJ MARTINO, Z. KNEZEW(, AND (;. I)JURAgEW(" (1983b). New evidence for the effect of phase angle on asteroid lightcurve shape: 21 I,utetia. Astron. Astrophys. 130, 208-210, ZAPPAI A, V., ANI)Z. KNE2EVI(" (1984). Rotation axis of asteroids: rcstdts for 14 objects, h ' a r u s 59, 436 455. ZAPPAI*'~, V., ~. S(AI.'IRITI. AND M. DI MARTINO (19841. Photoelectric photometry of 21 asleroids. h'arus 56, ~25 344.