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Lunar Occultation Observations in 2003

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Lunar Occultation Observations in 2003 LUNAR OCCULTATION OBSERVATIONS IN 2003 Summary - In 2003, timing data of1001 lunar occultations of reliable quality, including 693 photoelectric observations, were obtained at four astronomical stations of JHOD. Reduction and analysis give the following results for the moon's longitude and latitude: ΔＬ ＝ ＋0.28″″ ±0.02 (m.e.) ΔＢ ＝ －0.17″″ ±0.02 (m.e.) for the epoch 2003.6 on the FK5 system. Key words: occultation - moon's coordinates This is a continuation of the report series of occultation observations made by the Hydrographic and Oceanographic Department of Japan (JHOD) and contains the data for 2003. The constants and data adopted in this reduction for the lunar occultation data in 2003 are accordant with the IAU (1976) system. 1. Observations Observations of occultations of stars by the moon were continued in 2003 at four astronomical stations of JHOD.One staff member of the Shirahama Hydrographic Observatory, three of the Shimosato Hydrographic Observatory, One of the Bisei Hydrographic Observatory were changed in April, 2003. In total,1001 timing data were acquired through the year, including 693 photoelectric data. The H2004 Catalogue was compiled by the stars in the HIPPARCOS(1997),TYCHO-2(2000), PPM( 1989, 1992),etc. Table A gives the individual numbers of observations accepted in this report. Parenthesized figures in the third column are the numbers of observations which are accompanied by simultaneous photoelectric timing. Table 1 shows the geodetic coordinates (WGS84 ) and geocentric rectangular coordinates (world geodetic datum) of the stations, the instruments and observers. Records of observations are listed on the left hand pages of Table 2 excepting the last column. Explanations of each column are given on pages9－ 11. Table A. Number of data acquisitions Station Photoelectric Visual Total Head Office, Tokyo 11(1)2 Shirahama Hydrogr. Obs. 144 92(53) 236 Shimosato Hydrogr. Obs. 73 8( 6) 81 Bisei Hydrogr. Obs.475 207(97) 682 2 LUNAR OCCULTATION OBSERVATIONS IN 2003 2. Reduction According to the recommendations of the International Astronomical Union (IAU) in 1976, new methods and theories have been adopted for the Japanese Ephemeris since the edition for 1985. (See Japanese Ephemeris 1986.) The reduction for occultations of stars by the moon was made using the Japanese Ephemeris (IAU 1976 system) for lunar position and a corresponding star coordinate system, FK5. For the geocentric coordinates of the observatories a coordinate system, Marine Geodetic Control Network, was used. Marine Geodetic Control Network was derived by the satellite laser ranging (SLR) at the Shimosato Hydrographic Observatory and other laser sites in the world (T. Tatsuno and M. Fujita, 1994). The detailed scheme of the reduction is in No.12 of this series. A. Constants and basic data a. Ephemeris the Japanese Ephemeris, 2003. b. Star place H2004 Catalogue. The H2004 Catalogue was compiled by the stars in the HIPPARCOS(1997),TYCHO-2(2000), PPM( 1989, 1992),etc. c. Moon Independent argument: TDT (TAI＋ 32S .184), sin σ０ Radius:ｋ ＝ ＝ 0.2725076(IAU,1984), sin π０ Limb correction: Watts' charts (1963). d. Earth Equatorial radius:a ｅ ＝ 6378140m (IAU,1976), Rotation axis (xyｐｐ, ) and UT1-UTC : IERS Annual Report for 2003. e. Station Earth centered coordinates (u,v,w ): Marine Geodetic Control Network Transformation parameters from the Tokyo Datum to this system: Δuvw ＝ －146.23, Δ ＝ ＋507.57, Δ ＝ ＋681.86m (T. Tatsuno and M. Fujita, 1994). Refraction heighthｒ for the standard atmosphere (Uniwa, unpublished): ２４ h ｒ ＝ 2.3 ＋ 2.20 cotaa － 0.0045 cot(m) , a : altitude of the star. B. Computations Computations are made with a work station（－ Hewlett Packard b2600) using the following programs. A39 41: arrangement of relevant data (Y. Ganeko, 1973 and M. Kawada, 1978), A39 42: main calculation (Y. Ganeko, 1973, M. Kawada, 1978 and A. Senda, 1985), A39 2 7 , A 3943 , A 3945 , A 3946 : preparation and rearrangement for limb correction (T. Kanazawa and M. Kawada, 1975, 1976), A3944 : Watts' charts reading (T. Kanazawa, 1975), A4126: inter-and extrapolations of the vertical profiles (M. Kawada, 1976), A3947 : least-squares calculations to be described in the next section (Y. Ganeko and M. Sasaki, 1973 and M. Kawada, 1978). Results of the reductions are tabulated in the last column of the left hand pages and in the columns of the right hand pages of Table 2. LUNAR OCCULTATION OBSERVATIONS IN 2003 3 3. Preliminary analysis The corrections to the moon's longitude (ΔΔＬＢ ) and latitude ( ) for the Japanese lunar ephemeris 2003 are derived by the following equation, ∂∂σσ Δ＋ＬＢ Δ＝Δ.σ ∂∂ＬＢ Δσ is a observational residual of angular distance between the Moon's center and the star. The least-squares calculations are made for every synodic month from lunation 990 to 1001 applying ２ the weightｗｗａａ whose square root is given in the column 23 of Table 2. When two or more timings have been obtained for a single event at a station, the following visual data are excluded from the analysis: ( i ) those obtained simultaneously with photoelectric timing, or (ii) those obtained later than another visual timing. The results for synodic months are listed in Table B. Table B. Solutions for lunations ２ Lunation No. of eq. SumｗＬａ ΔΔ m.e. Ｂ m.e. Epoch 990 111 1591.6 +0.19″″±± 0.05 -0.08 ″ 0.08 2003.04 991 52 650.1 +0.31 .07 +0.02 .09 .12 992 44 516.1 +0.46 .10 +0.09 .12 .21 993 38 237.6 +0.18 .07 +0.36 .08 .28 994 13 146.6 +0.38 .12 -0.06 .22 .35 995 15 116.1 +0.25 .13 -0.09 .17 .44 996 8 130.2 +0.37 .26 -0.92 .83 .54 997 46 679.1 +0.28 .05 -0.25 .07 .63 998 88 1104.6 +0.36 .04 -0.40 .04 .71 999 145 2187.3 +0.31 .04 -0.23 .05 .78 1000 77 1095.9 +0.37 .04 -0.24 .06 .86 1001 61 881.3 +0.26 .08 -0.17 .11 .94 Mean values ofΔΔＬＢ and through the year are also calculated using the same formula. The solution is given in Table C. Table C. Solution for the year ２ No. of eq. SumｗＬａ ΔΔ m.e. Ｂ m.e. Epoch 669 9354.6 +0.28″″±± 0.02 -0.17 ″″ 0.03 2003.56 A solution ofΔΔＬＢ and for photoelectric observations is: ΔＬ ＝ ＋0.29″″ ±0.02 ( m.e.) and ΔＢ ＝ －0.18″″ ±0.03( m.e.) for 2003.56, n ＝ 550. 4 LUNAR OCCULTATION OBSERVATIONS IN 2003 In Figure 1, values ofΔΔＬＢ and for the lunar ephemeris based on IAU 1976 system from 1972 to 2003 are exhibited. ⊿L 0.50" 0.48 0.46 0.44 0.42 0.40 0.38 0.36 0.34 0.32 0.30 0.28 0.26 0.24 0.22 0.20 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 Figure 1a. Values ofΔＬ (), vertical bar denotes mean error ⊿B 0.00" -0.02 -0.04 -0.06 -0.08 -0.10 -0.12 -0.14 -0.16 -0.18 -0.20 -0.22 -0.24 -0.26 -0.28 -0.30 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 Figure 1b. Values ofΔＢ ().v ertical bar denotes mean error LUNAR OCCULTATION OBSERVATIONS IN 2003 5 This reduction based on IAU 1976 system was made for the all occultation data obtained from 1972 to 2003. The solutions are given in Table D. Table D. Solution based on IAU 1976 system for 1972-2003 ２ Year No. of eq. SumｗＬａ ΔΔ m.e. Ｂ m.e. Epoch 1972 707 6833.0 +0.34″″±± 0.02 -0.15 ″″ 0.03 1972.50 1973 655 7474.2 +0.32 0.02 -0.19 0.03 1973.57 1974 643 7326.1 +0.33 0.02 -0.17 0.03 1974.53 1975 765 8350.6 +0.40 0.02 -0.14 0.02 1975.56 1976 808 8804.0 +0.42 0.02 -0.08 0.02 1976.51 1977 867 10221.8 +0.40 0.02 -0.18 0.02 1977.55 1978 818 9920.5 +0.37 0.02 -0.19 0.02 1978.51 1979 770 9039.1 +0.40 0.02 -0.12 0.02 1979.44 1980 807 7979.9 +0.33 0.02 -0.14 0.02 1980.52 1981 899 9504.2 +0.36 0.01 -0.16 0.02 1981.46 1982 860 10338.9 +0.44 0.01 -0.12 0.02 1982.46 1983 959 11120.8 +0.41 0.01 -0.21 0.02 1983.56 1984 849 10237.0 +0.37 0.01 -0.12 0.02 1984.62 1985 802 10525.1 +0.37 0.01 -0.13 0.02 1985.51 1986 652 9443.0 +0.37 0.02 -0.10 0.02 1986.47 1987 576 8045.8 +0.41 0.02 -0.08 0.02 1987.52 1988 576 6964.0 +0.43 0.02 -0.15 0.02 1988.49 1989 651 7351.7 +0.44 0.02 -0.04 0.02 1989.45 1990 628 7426.3 +0.39 0.02 -0.13 0.03 1990.46 1991 689 9154.0 +0.38 0.02 -0.10 0.03 1991.46 1992 958 11552.8 +0.43 0.01 -0.15 0.02 1992.56 1993 1031 12403.2 +0.45 0.01 -0.13 0.02 1993.54 1994 752 9919.0 +0.36 0.02 -0.10 0.02 1994.50 1995 1031 13898.0 +0.36 0.01 -0.14 0.02 1995.60 1996 805 10446.5 +0.34 0.02 -0.14 0.02 1996.50 1997 581 7864.0 +0.32 0.02 -0.16 0.02 1997.51 1998 627 7927.1 +0.30 0.02 -0.12 0.02 1998.45 1999 781 9346.0 +0.32 0.02 -0.11 0.02 1999.43 2000 861 12657.2 +0.29 0.01 -0.12 0.02 2000.51 2001 663 7616.2 +0.33 0.02 -0.16 0.02 2001.64 2002 533 6606.5 +0.35 0.02 -0.18 0.03 2002.63 2003 669 9354.6 +0.28 0.02 -0.17 0.03 2003.56 Calculations and compilation of this report have been made by M.
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