[IAN] Prechod planet

[Ondrej Pejcha]

Zdravim,

podle teto zpravy z AAVSO (kraceno) lze spatrit zakryt
hvezdy IL Aqr jejimi planetami s amplitudou az 0.4 mag.
Zajimave, ale narocne na cas.

Ondra Pejcha


----- Pùvodní zpráva -----
Od: AAVSO <aavso na aavso...>
Komu: AAVSO <aavso na aavso...>
Odesláno: 11. kvìtna 2001 21:44
Pøedmìt: AAVSO Alert Notice 281


> POSSIBLE PLANETARY TRANSITS OF 2248-14 IL AQUARII = GLIESE
876
>
> AAVSO member and observer Frederick West, Hanover, PA,
gave a presentation
> at the 89th Annual Meeting of the AAVSO in October 2000 in
which he
> suggested that amateur astronomers monitor the variable
star IL Aqr =
> Gliese 876 in order to observe transits by either or both
of its
> recently-discovered Jovian planets. [The text of his
presentation, with
> calculations, will appear in June as a Letter to the
Editor in Journal
> AAVSO, Vol. 29, No. 2.]
>
> High-precision (CCD or photoelectric photometry) transit
observations
> could improve our information about the radii, mass,
density, and orbital
> elements of both Gliese 876 and its planets and about the
limb darkening
> of the star.  The first window of opportunity to look for
these transits
> is May 16 - 27, 2001.
>
> Gliese 876 = IL Aqr is a red dwarf star (RA = 22h 53m 20s,
Decl. = -14deg
> 13.2min (2000), M4V, range 10.15-10.19 V, (B-V)=1.58,
(R-I)=1.22),
> possible periods = 20.2 and 28.7 days).  Geoffrey Marcy,
University of
> California at Berkeley, and his colleagues (Marcy et al.
1998; Cowen 2001)
> found two giant planets orbiting Gliese 876:  Gliese 876b
and Gliese 876c.
> Using the information in these references and in Delfosse
et al. (1998),
> MacRobert (2001), Burrows et al. (1997), Sterne (1960),
and West (1996),
> West calculated approximate dates and times of predicted
transits of
> Gliese 876 by its planets; they are given in the table
below.
>
> Uncertainties in the orbital elements make the times
uncertain by several
> days, so Gliese 876 should be monitored for transits
during "opportunity
> windows" lasting ten days or longer.  These windows will
occur on the same
> days of the calendar year for many years.  Gliese 876
rises at sidereal
> time 17:42 and sets at 4:04 for an observer at 40 N
latitude. Thus,
> morning observations are feasible from late May to
September and evening
> observations September to late January.  For Gliese 876b a
transit may
> last as long as 3.53 hours and have an amplitude as much
as 0.20
> magnitude. For Gliese 876c a transit could last as long as
2.2 hours.  If
> the planets simultaneously transit, Gliese 876 could be
dimmed by as much
> as 0.45 magnitude.
>
>  Transit Number    ----Predicted Time of Transit----
Opportunity Window
>   876b   876c          JD             Date and UT
>            58      2452050.8     2001 May  21  07:12
2001 May  16-27
>    29              2452079.97    2001 Jun. 19  11:17
2001 Jun. 14-26
>            59      2452080.9     2001 Jun. 20  09:36
2001 Jun. 14-26
>            60      2452111.0     2001 Jul. 20  12:00
2001 Jul. 15-26
>    30              2452140.97    2001 Aug. 19  11:17
2001 Aug. 14-25
>            61      2452141.1     2001 Aug. 19  14:24
2001 Aug. 14-25
>            62      2452171.2     2001 Sep. 18  16:48
2001 Sep. 13-24
>            63      2452201.3     2001 Oct. 18  19:12
2001 Oct. 13-25
>    31              2452201.97    2001 Oct. 19  11:17
2001 Oct. 13-25
>            64      2452231.4     2001 Nov. 17  21:36
2001 Nov. 12-23
>            65      2452261.5     2001 Dec. 18  00:00
2001 Dec. 12-24
>    32              2452262.97    2001 Dec. 19  11:17
2001 Dec. 12-24
>            66      2452291.6     2002 Jan. 17  02:24
2002 Jan. 11-23
>
> Observations should be made every 5 minutes.  Observers
should have access
> to an accurate time source and record the time of their
observations to
> the nearest second, if possible.  Accompanying is an AAVSO
Preliminary 'd'
> scale chart of Gliese 876 with comparison stars suitable
for CCD or
> photoelectric observing.  Please use this chart to make
your observations
> and REPORT ALL OBSERVATIONS DIRECTLY TO Dr. Frederick
West, 520 Diller
> Road, Hanover, PA 17331-4805, USA. (Do not report
observations to the
> AAVSO.)
>
> References
> Burrows, A., et al. 1997, in: Planets Beyond the Solar
System and The Next
>   Generation of Space Missions (D.R. Soderblom,ed.), Ast.
Soc. Pacific Conf.
>   Series, Vol. 119, pp. 9-17.
> Cowen, R. 2001, Science News, 159, No. 2, 22.
> Delfosse, X., et al. 1998. Astron. and Astrophys. Lett.,
338, L67.
> Marcy, G.W., et al. 1998, Astrophys. J. Lett., 505, L147.
> MacRobert, A. 2001, Sky & Telescope, 101, No. 4, 20.
> Sterne, T.E. 1960, An Introduction to Celestial Mechanics,
Interscience,
>    New York, pp. 8-14.
> Weis, E.W. 1994, Astron. J., 107, 1135.
> West, F.R. 1996, J. Amer. Assoc. Var. Star Obs., 24, 19.
> West, F.R. 1999, J. Amer. Assoc. Var. Star Obs., 27, 77.