Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://star.arm.ac.uk/~ambn/veritas.ps Äàòà èçìåíåíèÿ: Mon Dec 9 18:05:07 1996 Äàòà èíäåêñèðîâàíèÿ: Mon Oct 1 21:29:52 2012 Êîäèðîâêà: Ïîèñêîâûå ñëîâà: çàêîí âèíà

Veritas Asteroid Family: Remarkable
Spectral Differences Inside a Primitive
Parent Body 1
M. Di Martino y , F. Migliorini ] , V. Zappal`a y , A. Manara [ , C. Barbieri z
y Osservatorio Astronomico di Torino, strada Osservatorio 20, I--10025 Pino Torinese,
Italy
e­mail: dimartino@to.astro.it
tel. (39) 11 4619035
fax (39) 11 4619030
] Armagh Observatory, College Hill, Armagh BT61 9DG, Northern Ireland, UK
e­mail: pat@star.arm.ac.uk
[ Osservatorio Astronomico di Brera, via Brera 28, I--20121 Milano, Italy
e­mail: manara@brera.mi.astro.it
tel. (39) 2 72320308
fax (39) 2 72001600
z Dipartimento di Astronomia di Padova, Vicolo dell'Osservatorio 5, I--35122 Padova,
Italy
e­mail: barbieri@pd.astro.it
tel. (39) 49 8293434
fax (39) 49 8759840
1 Partially based on observations carried out at the European Southern Observatory
(ESO), La Silla, Chile.
1

Number of manuscript pages: 26
Number of tables: 3
Number of figures: 5
Keywords: asteroid -- spectroscopy -- composition
2

Running head: Spectroscopy of Veritas family
Send correspondence to:
M. Di Martino
Osservatorio Astronomico di Torino,
I--10025 Pino Torinese, Italy
e--mail: dimartino@to.astro.it; Tel.: 39--11--4619035; Fax: 39--11--4619030
3

Abstract
In this paper we report first optical reflectance spectra in the wave­
length range 3800--9000 š A for seven members of the Veritas asteroid
family, as determined by Zappal`a et al. (1994, Astron. J., 116, 291--
314). The observed asteroids are 490 Veritas, 844 Leontina, 1086 Nata,
2428 Kamenyar, 2934 Aristophanes, 5592 Oshima, and 1985 TQ 1 . In
addition, we observed also the object 5107 1987 DS 6 , which joins
the Veritas family when a slightly more relaxed criterion of selection
is adopted. The obtained spectra show a surprising slope gradient
spanning from 0 to about 8%, a range which includes the slopes char­
acteristics of all the low albedo, primitive bodies (from C to D--type).
Taking into account the very compact structure of the family -- the
probability of finding interlopers inside the defined clustering is prac­
tically zero --, this result seems to confirm the suggestion by Vilas and
Sykes (1996, Icarus, in press) about the presence of thermally altered
large asteroids inside the outer belt population. However, the hypoth­
esis of possible space weathering processes cannot completely ruled
out. A tentative representation of the post--impact velocity field has
been also obtained, showing a possible peculiar ejection of the frag­
ments.
4

1 Introduction
The evolution of the Solar System has been greatly dominated by high­energy
collisional impacts, leading to complete fragmentation of minor bodies as well
as to the cratering of the surface of the largest planets. However, while the
importance of catastrophic fragmentations is widely accepted, knowledge of
the physical mechanisms following an impact is still an open problem. Lab­
oratory experiments play an important role in defining the main parameters
involved in the process, but their exact quantification is very difficult to ob­
tain: this is mostly due to the unsolved ``scaling'' problem (Fujiwara et al.
1989). In fact, it is not obvious how to extrapolate the results obtained on
targets of few tens of centimeters to objects of some hundreds of kilometers in
size. On the other hand, in the Solar System there exists a quite large sam­
ple of fragments produced in high--velocity catastrophic impacts, in principle
able to clarify most of the unsolved problems related to the fragmentation
mechanisms. They are the so--called ``asteroid families'', clusterings of some
tens to hundreds of minor planets having quite similar orbital elements. They
represent the outcomes of mutual collisions among asteroids, which involved
objects whose sizes ranged from few tens to hundreds of kilometers. Even
though known from the beginning of this century, asteroid families have not
yet been conveniently studied from a detailed physical point of view, due the
low reliability of past procedures and techniques used to define them. Re­
cently some new and objective statistical identification methods have been
applied to a much larger sample of data (to date about 12,500 asteroids), to­
gether with the simultaneous improvements of the computation techniques of
asteroid proper elements (KneŸzevi'c and Milani 1994, and references therein).
The final result is the identification of a group of families (about 30) with a
very high statistical reliability, whose memberships appear stable versus the
method used for family identification (Zappal`a et al. 1995). Therefore, it is
possible now to start systematically quantitative investigations of the main
physical and chemical characteristics of these groupings, which represent the
best example of the outcomes of catastrophic fragmentations still observable
in the solar system. The main analyses include mass and velocity distribu­
tions, mineralogical surface compositions of the members, dependence of the
various parameters from the size of the target and from the impact energy,
etc..
Visible and near--infrared (up to wavelengths of about 3 ¯m) reflectance
5

spectroscopy is the most fruitful remote sensing technique for characterizing
many cosmically important mineral phases, and has been used extensively
to determine the likely surface compositions of the largest asteroids (Gaffey
et al. 1989). Thus, by comparing the optical properties and the inferred
surface compositions of several members of the same family, one can aim
at ``reconstructing'' the parent body like a 3--D jigsaw puzzle -- thus finding
out whether it was made of primitive, unheated material or it was melted
and differentiated, and in the latter case trying to obtain constraints on its
internal layering, and the compositions of its core/mantle/crust. Moreover,
spectroscopic data in turn would allow us to discriminate in many cases be­
tween the ``real'' members and the chance interlopers, which can affect the
reconstruction of the velocity field (Migliorini et al. 1995, Zappal`a et al.
1996).
In this paper we present the results obtained from visible spectroscopic obser­
vations of seven Veritas family members (plus one ``captured'' by the family
at 20 m/sec up the Quasi­Random­Level as defined by Zappal`a et al. 1995),
and we have outlined a possible representation of the post--impact velocity
field, showing a possible peculiar ejection of the fragments.
2 The Veritas Family
Veritas family is located in the outer part of the main belt with an average
proper semimajor axis of about 3.17 AU. Veritas membership, from a statisti­
cal point of view, has a very high level of reliability, it is well defined and very
compact in the proper elements space (Zappal`a et al. 1994, 1995); We recall
that some members of the present family were already enclosed in family 106
as defined by Williams (1979). Figure 1 shows the family membership in the
planes a 0 \Gamma e 0 , a 0 \Gamma sin i 0 , and e 0 \Gamma sin i 0 , where the size of the different circles
is proportional to the diameter of the corresponding objects and the black
dots refer to objects observed in this survey. The available data for Veritas
family members are summarized in Table 1, which lists, from column 1 to 8,
the asteroid number, the proper semimajor axis, eccentricity and sine of the
inclination (Milani and KneŸzevi'c 1994), the IRAS albedo, and, as computed
taking into account different sources of error in the absolute magnitude, the
diameter and the relative 2oe error. For the asteroids not observed by IRAS
6

the diameters have been estimated by assuming an albedo of 0.069, which is
the average value of the IRAS observed objects.
As shown in Table 1, the Veritas family, determined by Zappal`a et al. (1995),
is composed of 22 objects; ten of them are numbered and only three have a
diameter larger than the completeness limit, i.e. the diameter beyond which
all the existing bodies are likely to have been already discovered. This limit
has been estimated by Zappal`a and Cellino (1994) to be 27.5 km. According
to Migliorini et al. (1995) it's very unlikely that any of the family members
can be chance interlopers, in fact in the diameter range 0 \Gamma 28 km, apply­
ing Poisson statistical analysis, the probability that no interlopers exist is
73%. In the 28--75 km range we expect no interlopers with a probability of
92%. In the last range, i. e. 75--130 km, no background objects are available
near the family proper element space for a correct estimation of interlopers.
Until now, only few physical data about the Veritas family members have
been available. Besides the IRAS albedos of some objects, we know that
490 Veritas belongs to the C taxonomic class (Tholen 1989), but no other
objects have been yet classified. For 490 Veritas a 24­colors spectrum is also
available (Chapman and Gaffey 1979).
Recently Milani and Farinella (1994) have analysed the stability of the orbits
of the Veritas family members, integrating them back for 72 million years,
and conclude that ú 5 \Theta 10 7 years after the birth of the family, the proper
elements of two objects become widely dispersed. 490 Veritas' orbit has been
proved to be very chaotic as well as that of 3542 on timescales of 50 million
years. Therefore they concluded that this timescale would be comparable
with the age of the family, making it very probably one of the youngest in
the belt. The other family members are sometimes slightly chaotic, but they
remain well inside the borders of the family. Due to the practically void area
around the family, the above considerations do not affect the reliability and
compactness of the clustering.
3 Observations and Data Reduction
The observations have been carried out from April 1994 to November 1995 in
three different sites: European Southern Observatory (ESO, La Silla, Chile)
by the 1.52--m telescope, Bologna Observatory (Loiano observing station,
7

Italy) by the 1.5--m telescope and Padova--Asiago Observatory (Cima Ekar
observing station, Italy) by the 1.82--m telescope. The circumstances of the
observations and the aspect data of the observed asteroids are listed in Table
2 and Table 3, respectively.
The ESO telescope was equipped with a Boller & Chivens spectrograph and
as detector a CCD 2048 \Theta 2048 (windowed at about 300 \Theta 2048). The CCD
has a 15 ¯m square pixel, yielding a dispersion of 4.9 š A/pixel in the wave­
length direction. The grating used was a 225 grooves/mm with a dispersion
of 330 š A/mm in the first order. The useful spectral range is from about 5000
š A to 9000 š A with an instrumental FWHM of 9.8 š A. At the Bologna Observa­
tory the Bologna Faint Spectrograph and Camera (BFOSC) has been used. It
is equipped with a 1024 \Theta 1024 Thomson coated CCD with a pixel dimension
of 19 ¯m, yielding a dispersion of 4.2 š A/pixel in the wavelength direction.
The spectral range is from about 5200 š A to 9000 š A, with an instrumental
FWHM of 8.4 š A. At Padova--Asiago Observatory we have used a Boller &
Chivens spectrograph and as detector a CCD Thomson TH7882 thick UV--
coated 580 \Theta 388 pixels, each of them with dimensions of 23¯m\Theta23¯m, giving
a dispersion of about 7:8 š A/pixel . The grating had 150 grooves/mm with
a dispersion of 339 š A/mm in the first order. In order to prevent the second
order contamination, a yellow filter was used (– T ( š A) ? 6200 š A) to perform
the observations at ESO and Padova--Asiago observatories. The 490 Veritas
spectrum has been obtained in a different wavelength range, namely from
3800 š A to 7500 š A. Observations of solar--analog stars (Hardorp 1978), as si­
multaneously as possible with those of asteroids, have been made in order to
calibrate the asteroid relative reflectance spectra (when possible we used 16
Cyg B and 64 Hyades) and of spectrophotometric standard stars to monitor
changes in atmospheric extinction. Wavelength calibration was performed
by using He--Ar or Fe--Ar lamp spectra.
Data reduction has been performed by using IRAF package following the
standard procedure, as described in Di Martino et al. (1995), which includes
subtraction of bias level, flattening of data, removal of the cosmic rays, sub­
traction of sky, wavelength calibration, collapsing the two--dimensional spec­
tra, extinction correction, and division of the asteroid spectrum by the solar
analogs spectra.
The spectra obtained are shown in Fig. 2, in which to the spectrum of 490
Veritas the 24--colors spectrum, taken from Chapman and Gaffey (1979), has
been overlapped.
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4 Spectroscopic Results
Considering that the Veritas family is one of the more compact and statisti­
cally reliable grouping of asteroids, a surprising result of this study consists
in the wide range of slopes (from 0 to about 8%, the values typical of C--type
to D--type) shown by the spectra of the observed objects. We really expected
a more similar slope for each member considering the primitive taxonomic
type of the largest remnant as well as of the region where the clustering is
located. To check this finding, we have compared in Fig. 3 the spectra of the
family members with the available 8--colors spectra (Zellner et al. 1985) of
background asteroids having sizes comparable with that of the Veritas parent
body (i.e., larger than about 100 km) and semimajor axes included between
3.1 to 3.3 AU. We considered only asteroids belonging to low albedo taxo­
nomic classes (in accord with the taxonomic type of 490 Veritas), excluding
the objects belonging to other families located in the same region (Themis,
Hygiea, and Meliboea). The result is very intriguing: Veritas members show
a much greater slope range with respect to that shown by the background
asteroids. Trying to add some more information to this problem, in Fig.
3 we have plotted also the 8­colors spectra of background objects having
sizes smaller than 100 km. They should represent more likely fragments of
relatively recent impacts. Indeed, they show a dispersion of spectral slopes
more similar to that shown by the Veritas family members. An inspection of
SMASS survey spectra performed by Xu et al. (1995) confirms these results.
Therefore, we can outline a general scenario for the whole outer region of the
main belt, which takes into account the previous observational evidences: the
large majority of the ``old'' large asteroids seem to show a surface composi­
tion which fit quite well a spectrum typical of C--type (very probably this was
also the case of the Veritas parent body). Then, more or less catastrophic
impacts produce fragments, which are smaller, ``younger'' (their age depends
obviously on the age of the break­up event) and come -- for the most -- from
the interior of their parent bodies. There is an evidence that these younger,
smaller, and ``core'' fragments show a wide variety of spectral slopes, ranging
from C-- to D--types.
In order to explain this scenario, we hazard two possible hypotheses: i) as in
9

the case of S­type asteroids, in which supposed space weathering processes
have been confirmed by Gaspra and Ida observations by the Galileo space­
craft (Chapman 1996), also in the case of low albedo, carbonaceous objects
similar processes could be effective, as some preliminary laboratory studies
seem to show (Korochantsev et al. 1996, Moroz et al. 1992). In this view,
``core'' fragments, which have been originated in different break--ups, can
show a different spectral slope depending on the age of the event. However,
we have to take into account that some small fragments can also come from
the parent body surface and therefore they could partly show the original
weathering suffered by the parent body itself. ii) the original parent bod­
ies have been already altered in their interior by extended thermal episodes
(Vilas and Sykes 1996, and reference therein). In this case, the role of the
impact has been only that of exposing pieces coming from different regions
inside the target, which suffered different degrees of thermal metamorphism
leading to different spectrum signatures.
The first hypothesis can be applied to non--altered parent bodies, the differ­
ent spectral signatures of the fragments being only due to their corresponding
exposure age. The second one can be applied to altered parent bodies with­
out any weathering processes affecting the fragment surfaces. Obviously, the
two mechanisms can work together.
The Veritas case, which very probably refers to a single episode, implying
the same exposure age for all the fragments, seems to fit better the second
hypothesis and it is in good agreement with the conclusions by Vilas and
Sykes (1996), who suggest that fragments coming from the interior of a large
parent body should exhibit a greater range of compositional diversity than
the large asteroids. However, as already pointed out, the first one cannot
be completely ruled out, since one can assume that some pieces come from
the parent body surface and therefore can partly have an older exposure age
with respect to that of the ``core'' fragments. Among the 8 observed objects,
3 of them, namely 1086 Nata, 2934 Aristophanes, and 1985 TQ1, appear to
have a practically flat spectrum, i.e. a trend very typical of C­type aster­
oids. Vilas et al. (1993,1994) have shown that objects belonging to this class
present a shallow and wide absorption band centered around 7000 š A, which
is attribuited to an F e 2+ ! F e 3+ charge transfer transition in oxidized iron
in phyllosilicates. Vilas and Sykes (1996) discussed deeply the presence of
this feature in terms of primordial heating events. In particular, they con­
cluded that at a given heliocentric distance the fraction of C--asteroids that
10

possess this feature should decrease with decreasing size. This absorption
band is well recognizable in the spectrum of 1086 Nata, while is less evident
in the spectrum of 1985 TQ 1 . The same band could be also present in the
spectrum of 2934 Aristophanes, but the spectrum it is too noisy to reveal a
feature as weak as that present in the 1086 Nata spectrum. Figure 4 shows
these spectra, where for evidencing the feature the method described by Vi­
las et al. (1993) has been applied. These results are not in conflict with the
conclusion of Vilas and Sykes (1996) quoted before, if we consider the C--
type fragments of the family as survivor pieces of the surface of the original
larger parent body. However, it remains hard to explain why the largest rem­
nant of the family (490 Veritas) does not present the same feature. May be
that the catastrophic disruption which originated the family has been ``core--
type'' (Fujiwara et al. 1989), i.e. a shattering process in which the outer
layers of the target are spalled off leaving a large central core, followed by
a considerable reaccumulation. Anyway, to confirm this hypothesis, it could
be very interesting to perform spectroscopic observations of 490 Veritas at
different rotational phases, in order to check the possibility of a composi­
tional diversity in its surface. More in general, we have to say that future
spectroscopic observations under 5000 š Aand in the IR spectral domain, as
well as laboratory experiments on space weathering processes on primitive
materials, are highly reccommended for drawing more definitive conclusions
on a topic which appears of the highest importance for the understanding of
the thermal history and the collisional evolution of the asteroidal population
as a whole.
5 A Possible Collisional Model
In order to understand what kind of catastrophic event could have formed
the Veritas family, we try to reconstruct the original velocity field of the
family applying the method described in Zappal`a et al. (1996). Unfortu­
nately, a major problem prevents us from drawing any definitive conclusion.
In fact, due to the chaotic motion of 490 Veritas itself (containing more than
80 percent of the total mass) as described by Milani and Farinella (1994), the
position of the barycenter of the family (i.e., the origin of the velocity field)
cannot be determined. It follows that no really quantitative conclusion about
the relative velocities of the fragments can obviously be obtained. However,
11

some information about the qualitative behaviour of the overall velocity field
can still be extracted by the present data. Let us assume that the position
of 490 Veritas is the real one, not affected by any kind of chaotic motion.
It means that the barycenter of the family turns out to be very close to the
position of Veritas itself. Under this assumption we apply the method by
Zappal`a et al. (1996) and we obtain (with some very large uncertainty on
the computed angles due to the peculiar structure of the velocity field) that
the true anomaly f and the argument of perihelion w + f at the moment
of breakup should be about 70 deg and 45 deg respectively. Identifying the
direction of the projectile (i.e., the direction of the impact) with the axis of
symmetry of the overall velocity field [see Zappal`a et al. (1996) for a more
detailed discussion of the procedure to adopt], we obtain the representation
of the velocity field reported in Fig. 5. Apart from quantitative conclusions
(unrealistic due to the inescapable uncertainty connected with the barycen­
ter, as stated before), an interesting result appears: the velocity field is well
represented by a kind of ``jet--like'' structure lying in the plane v imp \Gamma v norm1 .
This behaviour is not affected by changing the angles f and w + f by some
20­30 deg as well as by changing the barycenter of the family. In the latter
case what we can obtain is to alter the shape of the ``jet'', but we cannot
avoid the fact that almost all the fragments are located in a well defined
plane. It is very interesting to note that this kind of planar ejecta (even if
not very common) has been obtained in some laboratory simulation of hy­
pervelocity impacts (Martelli et al. 1993). Finally, we have to note that the
second largest object of the family (844 Leontina) seems to be not connected
with the rest of the fragments. However, its ``isolated'' position could be due
to the chaotic motion of Veritas and consequently to the adopted barycenter
of the family.
6 Conclusion
We have performed spectroscopic observations in the visual band of 8 mem­
bers of the Veritas family and the result we obtained is quite unexpected. In
fact, considering that this family is one of the more compact and statistically
reliable grouping of asteroids, the slope of the spectra we obtained shows a
slope gradient ranging from 0 to 8% within which the slope characteristics
of the major low albedo asteroid types (C, P and D--types) are included.
12

The family slope range shows a larger gradient when it is compared with the
available 8--colors spectra of background asteroids larger than 100 km. On
the contrary, the slope range of background asteroids smaller than 100 km,
which at least in part are fragments of catastrophic fragmentations, is quite
similar to the family one. These observational evidences allow us to outline
the following two alternative hypotheses, which can be applied to the whole
population of the outer main belt asteroids:
ffl the parent bodies had an already altered interior, due to local or ex­
tended thermal episodes, and its fragmentation exposed pieces of dif­
ferent composition. This hypothesis fits well the case of Veritas' family.
ffl low albedo asteroids can be affected, as S--type objects, by some kind
of ``space weathering'', so spectral differences among smaller, collision­
ally generated asteroids could be related to the different age of the
catastrophic impact that originated the fragments.
Three of the observed asteroids (1086 Nata, 2934 Aristophanes, and 1985
TQ 1 ) show flat spectra characteristic of the C--type taxonomic type objects.
At least two of them (1086 Nata and 1985 TQ 1 ) show a shallow and wide
absorption band centered around 7000 š A, which is attributed to the presence
of aqueous alteration products on the asteroid surface. These results can
anyway agree with the conclusions drawn by Vilas and Sykes (1996), if we
consider that these objects are fragments coming from the parent body sur­
face. These evidences and the fact that the spectrum of the largest remnant
of the family do not present the same feature suggest the hypothesis that the
catastrophic fragmentation that originated the family has been ``core--type''.
More definitive issues can be drawn by further spectroscopic observations in
the UV and IR domains and by laboratory studies on the space weathering
of carbonaceous materials.
7 Acknowledgements
We are grateful to C. Chapman and F. Vilas for thoughtful reviews, thanks
to which the paper has been greatly improved. This work has been partly
supported by Italian Space Agency (ASI), contract number 94­RS­69, and
by the EEC grant number CHRX--CT94--0445.
13

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Figure Captions
Figure 1. Veritas family asteroids in the proper element space. Filled cir­
cles show the observed objects (excluded 5107), whereas empty circles show
not--observed members. The dimension of the circles is proportional to the
asteroid diameter.
Figure 2. Spectra of the observed asteroids (normalized at 7000 š A). To the
spectrum of 490 Veritas the 24--colors spectrum, taken from Chapman and
Gaffey (1979), has been overlapped.
Figure 3. (Top) Spectra of background asteroids having sizes larger than 100
km and semimajor axis included between 3.1 and 3.3 AU. (Center) Spectra
of Veritas family members. (Bottom) Spectra of background asteroids hav­
ing sizes smaller than 100 km and semimajor axis included between 3.1 and
3.3 AU. The objects belonging to other families located in the Veritas region
(Themis, Hygiea, and Meliboea) have been excluded from background pop­
ulation.
Figure 4. Residual spectra of asteroids 1086 Nata, 2934 Aristophanes, and
1985 TQ 1 created as a result of the smoothing with a five--point running
box average of the original ones and divided by the linear backgrounds with
overlapped the continuum in order to evidence the absorption band centered
around 7000 š A.
Figure 5. Velocity field of the Veritas family as computed by using the
method developed by Zappal`a et al. (1996).
17

Table 1: Membership, proper elements, absolute magnitude (H), albedo (p v ),
and diameter of the Zappal`a Veritas family member asteroids.
Number a' e' sin i' p v D(km) 2oe D
490 3.17504 0.0646 0.1576 0.0622 115.53 12.24
844 3.19689 0.0687 0.1605 --- 60.79 26.18
1086 3.16589 0.0603 0.1616 0.0767 60.42 25.65
2147 3.17137 0.0632 0.1607 0.0439 26.45 11.04
2428 3.17068 0.0620 0.1617 0.0864 26.02 10.81
2934 3.16743 0.0597 0.1596 0.0780 24.98 10.49
3090 3.16983 0.0618 0.1604 --- 17.53 7.55
3542 3.17484 0.0638 0.1609 --- 19.22 8.28
5107 3.13628 0.0724 0.1559 --- 18.31 7.62
5592 3.16905 0.0589 0.1630 --- 24.20 10.42
5594 3.16880 0.0575 0.1617 --- 22.07 9.50
1976 QL 2 3.17075 0.0626 0.1626 --- 15.99 6.89
1981 ES 9 3.16529 0.0595 0.1626 --- 7.31 3.15
1985 TQ 1 3.16652 0.0616 0.1604 --- 21.08 2.61
1981 EE 4 3.17507 0.0573 0.1617 --- 6.64 2.88
1981 EM 10 3.17225 0.0602 0.1631 --- 10.47 1.29
1981 ER 34 3.16584 0.0582 0.1592 --- 6.54 0.81
1991 PW 9 3.16492 0.0612 0.1615 --- 11.58 4.99
2123 PL 3.17613 0.0672 0.1611 --- 7.62 0.94
4573 PL 3.17328 0.0688 0.1622 --- 8.38 0.98
4107 T 1 3.16442 0.0604 0.1617 --- 13.12 1.62
1118 T 3 3.17811 0.0681 0.1616 --- 5.81 2.50
1122 T 3 3.18297 0.0527 0.1603 --- 7.65 3.30
18

Table 2: Circumstances of the observations.
Object Place Date UT [Start] T exp Airmass
490 Ekar 11--04--95 19h 10m 32 min. 1.44
844 ESO 17--04--94 06h 21m 40 min. 1.00
1086 ESO 18--04--94 09h 18m 50 min. 1.28
2428 Ekar 27--10--94 01h 00m 32 min. 1.67
2934 Loiano 30--10--94 19h 36m 45 min. 1.48
5107 ESO 09--11--95 00h 15m 120 min. 1.07
5592 ESO 18--04--94 06h 21m 40 min. 1.12
1985 TQ 1 ESO 18--04--94 02h 23m 60 min. 1.20
Table 3: Aspect data of the observed asteroids at 0 h UT of the observation
day.
Object R.A. Decl. Long. Lat. r \Delta Phase V
[2000] [2000] [AU] [AU] [deg] [mag]
(490) Veritas 07 h 55: m 9 +13 ffi 44: 0 3 117: ffi 5 \Gamma6: ffi 9 3.28 3.00 17: ffi 6 14.2
(844) Leontina 15 h 09: m 3 \Gamma28 ffi 19: 0 4 231: ffi 9 \Gamma10: ffi 2 3.24 2.32 8: ffi 26 14.4
(1086) Nata 20 h 54: m 4 \Gamma20 ffi 24: 0 1 309: ffi 6 \Gamma2: ffi 8 3.33 3.40 17: ffi 11 15.5
(2428) Kamenyar 01 h 01: m 0 +10 ffi 17: 0 7 17: ffi 2 +3: ffi 5 2.91 1.94 5: ffi 33 15.2
(2934) Aristophanes 00 h 46: m 7 +05 ffi 42: 0 4 12: ffi 2 +0: ffi 6 3.20 2.26 7: ffi 10 16.0
(5107) 1987 DS 6 22 h 12: m 1 \Gamma09 ffi 12: 0 6 330: ffi 9 +1: ffi 7 3.19 2.77 17: ffi 43 17.6
(5592) Oshima 19 h 11: m 7 \Gamma16 ffi 45: 0 5 286: ffi 5 +5: ffi 6 3.03 2.68 18: ffi 98 16.9
1985 TQ 1 11 h 58: m 2 +3 ffi 53: 0 9 177: ffi 3 +3: ffi 3 3.39 2.48 8: ffi 51 17.1
19