Observations of stars occultations by the Moon with the "Spalakh" television system
On the television observations of lunar occultations of the stars and reductions made in 2003–2004 at the Astronomical Observatory of the Kyiv National Taras Shevchenko University are reported. Observations are executed with the help of the “Spalakh” system with fixation Universal Time for each fram...
Збережено в:
| Опубліковано в: : | Кинематика и физика небесных тел |
|---|---|
| Дата: | 2005 |
| Автори: | , |
| Формат: | Стаття |
| Мова: | Англійська |
| Опубліковано: |
Головна астрономічна обсерваторія НАН України
2005
|
| Теми: | |
| Онлайн доступ: | https://nasplib.isofts.kiev.ua/handle/123456789/79688 |
| Теги: |
Додати тег
Немає тегів, Будьте першим, хто поставить тег для цього запису!
|
| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Цитувати: | Observations of stars occultations by the Moon with the "Spalakh" television system / V.V. Kleshchonok, M.I. Buromsky // Кинематика и физика небесных тел. — 2005. — Т. 21, № 5-додаток. — С. 405-408. — Бібліогр.: 4 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1860174751343837184 |
|---|---|
| author | Kleshchonok, V.V. Buromsky, M.I. |
| author_facet | Kleshchonok, V.V. Buromsky, M.I. |
| citation_txt | Observations of stars occultations by the Moon with the "Spalakh" television system / V.V. Kleshchonok, M.I. Buromsky // Кинематика и физика небесных тел. — 2005. — Т. 21, № 5-додаток. — С. 405-408. — Бібліогр.: 4 назв. — англ. |
| collection | DSpace DC |
| container_title | Кинематика и физика небесных тел |
| description | On the television observations of lunar occultations of the stars and reductions made in 2003–2004 at the Astronomical Observatory of the Kyiv National Taras Shevchenko University are reported. Observations are executed with the help of the “Spalakh” system with fixation Universal Time for each frame. On the exact moment of occultations is reported.
|
| first_indexed | 2025-12-07T17:59:48Z |
| format | Article |
| fulltext |
OBSERVATIONS OF STARS OCCULTATIONS BY THE MOON
WITH THE “SPALAKH” TELEVISION SYSTEM
V. V. Kleshchonok, M. I. Buromsky
Astronomical Observatory, National Taras Shevchenko University of Kyiv
3 Observatorna Str., 04053 Kyiv, Ukraine
e-mail: klev@observ.univ.kiev.ua
On the television observations of lunar occultations of the stars and reductions made in 2003–2004
at the Astronomical Observatory of the Kyiv National Taras Shevchenko University are reported.
Observations are executed with the help of the “Spalakh” system with fixation Universal Time for
each frame. On the exact moment of occultations is reported.
INTRODUCTION
More than 80 years the observations of star occultations have been performing at the Astronomical Observatory
of the Kyiv National University. The new television system “Spalakh” was created at the Astronomical Ob-
servatory [3] for improvement objectivity and accuracy of the occultations observation. The main parameters
of the system are: the time resolution is 40 ms, the accuracy time scale is 50 ms, the limit of star magnitude
is 12m. The original software for the system allow digital recording TV signal from sensitive CCD camera with
precision of link to UTC scale and processing the observation result.
γ VIRGO OCCULTATION
First observation of star occultation by the Moon with the television system was carried out on July 6, 2003
using the refractor of the Astronomical Observatory of the Kyiv National University. The CCD camera was
established in focus of the Repsold refractor guide. The occultation of the SAO 138917 star (29 γ Vir) was
observed during 2.9 min. The conditions of the observation are listed below: a dense layer of mobile clouds,
the unstable star image, dark limb of the Moon is invisible, a phase of the Moon of 46%, height above horizon 25◦,
the Sun under horizon at height −6◦. Precomputation moment [4] of double star γ Vir (mα = 3.65, mβ = 3.68)
occultation by the Moon is 18h 50m 13s ± 6s. For processing results of observation the original software was
used. It allows to derive the estimations of a star brightness on each frame. Photometric curve was obtained
and as a result a duality of the star (γ Vir) was confirmed [1] (see Fig. 1).
Initial maximum of brightness corresponded to a case when we saw two components. Intermediate bright-
ness value was observed for a case when the Moon closed one of the component. The final brightness value
corresponded to a case when we saw only background value. Photometric errors were calculated for each interval
of star brightness values. The designated ranges of confidential intervals for brightness, which were chosen at
the 2.5σ level, are showen as a dashed line in Fig. 1. All values of momentary estimations of brightness lay in
the ranges of the confidential intervals except for a point 18h 50m 11.00s UTC. It means that the occultation
was held during exposing this frame, and that its time needs to be accepted as occultation time of the first
component. Occultation time of the second component is 18h 50m 11.43s UTC. Time of 0.43 s between coverings
of stars corresponds to the bottom estimation of distance between components at 0.20 arcsec. For more exact
estimation of occultation conditions it is necessary to calculate distance between components and a positional
angle of direction center-to-center stars using the orbit elements of the double star. The calculated distance
between components of the double star (γ Vir) is equal to R = 0.74′′ at the moment of observation (2003.52).
Formulas (1), (2) were used for calculation of value R between components [2]:
R = ρ
cos(v + ω)
cos(θ − Ω)
, (1)
ρ =
a(1 − e2)
1 + e cos v
, (2)
c© V. V. Kleshchonok, M. I. Buromsky, 2004
405
Figure 1. Photometric curve of γ Vir double star occultation on July 6, 2003
M
P
Q
T
R
R
K
S
S
1
2
North Pole
Moon
movement
direction
0
Figure 2. Position of a double star (γ Vir) relatively a direction of the Moon movement
where a is the major semiaxis, e is the eccentricity, v is the true anomaly, ω is the angle between node and
periastron, Ω is the positional angle of the line of nodes.
Figure 2 shows the occultation conditions. Points S1, S2 are components of a double star. Line S1K shows
the position of the Moon limb at the moment of first component occultation. T is the positional angle of
the line S1K. The Moon moves with a velocity V in a direction with positional angle M . Distance R0 (equals
S2K) is determined by the time between coverings of components, and parallel to the Moon velocity vector.
It is equal to
R0 =
R sin(θ − T )
sin(M − T )
. (3)
T = P − 90◦ without taking into account a profile of a regional zone. Here P is an ephemeris positional angle
of occultation. For our case P = 157◦ and if to put T = 67◦ for difference 0.43 s in the moments of occultation
we shall derive a value of distance between components R = 0.48′′ that essentially differs from the ephemeris
data. It is possible to explain such difference by lunar limb profile. It is possible to observe the occultation
consistent with the ephemeris data if assume that the positional angle of lunar limb is equal to 53◦. It means
that in this place the lunar limb has an additional inclination in 14◦ to local horizon.
406
Figure 3. Part of frame during occultation of SAO 77 775 star (4.8 mag) by the Moon bright limb
Figure 4. Photometrical curve of occultation near reappearance of HIP 32663 star. The event time is determined with
a help combination of three criteria: drop signal assumption, median filtration, and noise level
SAO 77775 OCCULTATION
This observation is interesting because the disappearance not brilliant star (4.8m) on the bright limb was
registered. The conditions of observation are: a good atmosphere transparency, a strong sky background,
the phase of the Moon is equal to 47%, the height above horizon is equal to 60◦, the Sun height under horizon
is equal to −12◦. Figure 3 shows the part of recording frame near event. The star had been visible up to
the lunar limb without regard to a significant difference in brightness that has allowed getting sharp estimation
for occultation time. The estimation of event time was obtained by frame-accurate viewing of record. It was
equal to 02h 30m 52.44s UTC.
HIP 32663 OCCULTATION
This observation is interesting because it was managed to register the reappearance of extreme faint star (10m).
Conditions of observation were: a good atmosphere transparency, the dark limb of the Moon is well seen,
the phase of the Moon is equal to 37%, the height above horizon is equal to 42◦, the Sun height under horizon
is equal to −23◦. Figure 4 shows the part of occultation photometrical curve near star reappearance. In this
case, the moment of event approach is insufficiently evident, and application of special mathematical methods
of processing for its definition is required.
Three methods of event time definition at presence of strong fluctuations of a signal recommended themselves
well. The first method is approximation of measurements of the star brightness by drop function. Three
parameters have been finding from the least squares method: levels of a signal before and after event and
position of spasmodic change. Other method uses median filtration of photometric magnitude, as it does not
deform fronts at spasmodic changes of a signal level. This fact is very important to correct determination of
occultation time. The third method is a method of noise level measurement. It measures a dispersion of a signal
407
Table 1. Summary table of occultation observation with “Spalakh” television system
Ephemeris Star Measuring
N Data, Time, UTC Identification mag Spectral Event Telescope Remarks time, UTC
YMD hh mm ss class hh mm ss
1 20030706 18 50 11 SAO 138917 2.8; K7; DD R Double star 18 50 11.00;
3.5 F0 18 50 11.47
2 20030919 02 30 49 SAO 77775 4.8 K0 DB R 02 30 52.44
3 20030920 01 11 40 HIP 32663 10.0 K0 DD R Extremely faint star 01 11 41.58
4 20040402 19 29 19 SAO 99321 6.8 G5 DD R HD 93993 19 29 15.27
5 20040427 20 37 55 SAO 80456 9.1 G5 DD R BD +22 2004 20 37 52.43
6 20040428 18 57 17 DM +19 2239 9.6 G0 DD R 18 57 20.50
7 20040428 20 28 05 SAO 98724 9.6 A5 DD R Variability/Duplicity 20 28 07.04
8 20040428 21 12 48 SAO 98725 9.3 A DD R Variability/Duplicity 21 12 52.56
9 20040501 19 49 55 SAO 119245 6.1 K0 DD R Variability/Duplicity 19 49 54.36
10 20040504 21 30 41 SAO 158855 6.6 F6V DU A 21 19 44.40
11 20040625 19 29 07 SAO 119340 8.5 F5 DD R Variability/Duplicity 19 29 06.64
12 20040626 19 33 16 SAO 139178 8.0 F8 DD R Variability/Duplicity 19 33 16.74
Event:
First character shows the phenomenon:
D – disappearance; R – reappearance.
Second character shows the lunar limb:
D – dark limb event; B – bright limb event; U – event during an eclipse of the Moon.
Telescope:
A – the AZT-14 reflector (D =0.5 m, F = 7.7 m), Lisnyki;
R – the Repsold refractor (D = 0.2 m, F =4.0 m), Kyiv.
in a sliding window, which is centered on the given point. The combination of these three methods has allowed
identifying the moment of star reappearance confidently. Maximum time error is equal to 0.09 s. It consists of
accuracy of the system and an error of a frame number choice for which there comes event of star reappearance.
It was obtained values of time of the reappearance as 01h 11m 41.58s UTC.
SAO 158855 OCCULTATION
This occultation was observed during a full lunar eclipse time. Conditions of observation were: a not good
transparency of an atmosphere, a strong sky background, the height above horizon is equal to 28◦, the Sun
height under horizon is equal to −23◦. Unfortunately, the star image was essentially unstable. The estimation of
event time was received by frame-accurate viewing of record. It was equal to 21h 19m 44.40s UTC. Uncertainty
for choosing event frame is equal to 2 frames. The result error is 0.13 s.
Other observations of star occultations were typical, therefore, their detailed descriptions are not given.
The results of all observations are collected in the summary table (see Table 1).
DISCUSSION
First results of observation with a “Spalakh” system show significant potential of system. There are such
evidences about this: bad weather conditions and bright lunar limb, and a considerable part of faint stars in
observation. The software for occultation processing allow determining number frame of event better than one
frame and also the faint star for dark limb occultation. Accuracy for bright limb occultation strongly depends
on weather conditions. 80% of all observations have the maximal accuracy, which is determined by accuracy of
the “Spalakh” television system.
[1] Aitken R. G. New General Catalogue of Double Stars.–Washington: Carnegie Institution, 1932.–II.–P. 730–732.
[2] Couteau P. L’Observation des étoiles doubles visuelles.–Flammarion, 1978.
[3] Kleshchonok V. V., Buromsky M. I. First results of observations with astronomical television complex “Spalakh”
for fast processes registrations // Visnyk of Kyiv University.–2004.–42.
[4] The ephemeride lunar occultations.–Tokyo, International Lunar Occultation Centre, 2002.
408
|
| id | nasplib_isofts_kiev_ua-123456789-79688 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 0233-7665 |
| language | English |
| last_indexed | 2025-12-07T17:59:48Z |
| publishDate | 2005 |
| publisher | Головна астрономічна обсерваторія НАН України |
| record_format | dspace |
| spelling | Kleshchonok, V.V. Buromsky, M.I. 2015-04-03T19:21:18Z 2015-04-03T19:21:18Z 2005 Observations of stars occultations by the Moon with the "Spalakh" television system / V.V. Kleshchonok, M.I. Buromsky // Кинематика и физика небесных тел. — 2005. — Т. 21, № 5-додаток. — С. 405-408. — Бібліогр.: 4 назв. — англ. 0233-7665 https://nasplib.isofts.kiev.ua/handle/123456789/79688 On the television observations of lunar occultations of the stars and reductions made in 2003–2004 at the Astronomical Observatory of the Kyiv National Taras Shevchenko University are reported. Observations are executed with the help of the “Spalakh” system with fixation Universal Time for each frame. On the exact moment of occultations is reported. en Головна астрономічна обсерваторія НАН України Кинематика и физика небесных тел MS4: Positional Astronomy and Global Geodynamics Observations of stars occultations by the Moon with the "Spalakh" television system Article published earlier |
| spellingShingle | Observations of stars occultations by the Moon with the "Spalakh" television system Kleshchonok, V.V. Buromsky, M.I. MS4: Positional Astronomy and Global Geodynamics |
| title | Observations of stars occultations by the Moon with the "Spalakh" television system |
| title_full | Observations of stars occultations by the Moon with the "Spalakh" television system |
| title_fullStr | Observations of stars occultations by the Moon with the "Spalakh" television system |
| title_full_unstemmed | Observations of stars occultations by the Moon with the "Spalakh" television system |
| title_short | Observations of stars occultations by the Moon with the "Spalakh" television system |
| title_sort | observations of stars occultations by the moon with the "spalakh" television system |
| topic | MS4: Positional Astronomy and Global Geodynamics |
| topic_facet | MS4: Positional Astronomy and Global Geodynamics |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/79688 |
| work_keys_str_mv | AT kleshchonokvv observationsofstarsoccultationsbythemoonwiththespalakhtelevisionsystem AT buromskymi observationsofstarsoccultationsbythemoonwiththespalakhtelevisionsystem |