Astronomical Ephemeris

Explanation of the Astronomical Ephemeris Tables

These tables are intended to provide the astronomical data necessary to plan an observing program. Unlike the data typically published in the news media and on calendars, these tables are night oriented. That is to say, a single line in this table refers to a single night, rather than a single day as is more conventional. Times and dates are all in terms of local time. The date at the beginning of the night is given on the left side of the table, the date at the end of the night is given on the right side. In general, these tables should be simple to apply^[1]. Just read across the appropriate line for the various event times for that night. Times in the range 12^h00 to 23^h59 refer to the first half of the night (prior to midnight). Times in the range 00^h00 to 11^h59 refer to the second half of the night.

After the date and day-of-week at the start of the night, the truncated Julian Date^[2] and local sidereal time at midnight are given. Next are given the times of sunset, dusk and dawn , and sunrise. These are followed by moonrise and moonset^[3]. The dates of new moon and full moon are denoted by the letters N and F respectively following the moonset time. The penultimate entries are for the duration in hours and minutes of astronomical darkness (from dusk to dawn) and total darkness (astronomical darkness when the moon is down as well)^[4]. The final data column gives the day-of-week and date at the end of the night.

The algorithms used will typically be accurate to about 1 minute of time for all values except moonrise and moonset which may have errors of several minutes. Rising and setting are based on the first sight and last sight of the refracted sun or moon. Dusk and dawn are defined for astronomical twilight when the sun is less than 18 degrees below the horizon. The tables switch between standard and daylight time on the last Sunday in April and the last Sunday in October.

^[1] The exception may be when comparing these tables with other data. One must be very careful to compare the proper dates. This is especially true of the moon data. If these times seem to be about one hour off, the incorrect date is almost certainly being compared.

^[2] To get the complete Julian Date, add 2,440,000 to the number tabulated for dates between May 24, 1968 and October 9, 1995. Add 2,450,000 from October 10, 1995 onwards.

^[3] Note that since the moon rises approximately 50 minutes later each night, there is one date each month when there is no moonrise. This will be the night following that date when the moon has risen just before 12:00 noon. The next rising will be more than 24 hours later. Similarly, there will be one date each month with no moonset. Such dates are indicated by a series of dashes in the tables.

^[4] Near full moon, there may be several nights when the moon is up continuously between astronomical dusk and dawn. These nights are indicated by a series of dashes.

January

____________________ ________________________ _____________ duration _______

| 2002 JD ST |___________SUN__________|_____MOON____| of | no | |

| 1 Tue 2276.7 06h16|17h43 19h07 06h00 07h25|20h19 10h17 |1052|0111|Wed 2 |

| 2 Wed 2277.7 06h20|17h43 19h08 06h00 07h25|21h27 10h59 |1052|0218|Thu 3 |

| 3 Thu 2278.7 06h24|17h44 19h09 06h01 07h25|22h34 11h37 |1052|0325|Fri 4 |

| 4 Fri 2279.7 06h28|17h45 19h09 06h01 07h25|23h38 ----- |1051|0428|Sat 5 |

| 5 Sat 2280.7 06h32|17h46 19h10 06h01 07h25|00h42 12h13 |1051|0531|Sun 6 |

| 6 Sun 2281.7 06h36|17h46 19h11 06h01 07h26|01h44 12h49 |1050|0633|Mon 7 |

| 7 Mon 2282.7 06h39|17h47 19h11 06h01 07h26|02h46 13h24 |1050|0734|Tue 8 |

| 8 Tue 2283.7 06h43|17h48 19h12 06h02 07h26|03h48 14h02 |1049|0835|Wed 9 |

| 9 Wed 2284.7 06h47|17h49 19h13 06h02 07h26|04h49 14h42 |1048|0936|Thu 10 |

| 10 Thu 2285.7 06h51|17h49 19h13 06h02 07h26|05h48 15h27 |1048|1034|Fri 11 |

| 11 Fri 2286.7 06h55|17h50 19h14 06h02 07h26|06h45 16h16 |1047|1047|Sat 12 |

| 12 Sat 2287.7 06h59|17h51 19h15 06h02 07h26|07h36 17h09 N|1047|1047|Sun 13 |

| 13 Sun 2288.7 07h03|17h52 19h16 06h02 07h26|08h23 18h04 |1046|1046|Mon 14 |

| 14 Mon 2289.7 07h07|17h53 19h16 06h02 07h25|09h03 19h00 |1045|1045|Tue 15 |

| 15 Tue 2290.7 07h11|17h54 19h17 06h02 07h25|09h40 19h56 |1044|1006|Wed 16 |

| 16 Wed 2291.7 07h15|17h54 19h18 06h02 07h25|10h12 20h50 |1044|0911|Thu 17 |

| 17 Thu 2292.7 07h19|17h55 19h19 06h02 07h25|10h43 21h43 |1043|0818|Fri 18 |

| 18 Fri 2293.7 07h23|17h56 19h19 06h02 07h25|11h12 22h36 |1042|0725|Sat 19 |

| 19 Sat 2294.7 07h27|17h57 19h20 06h01 07h24|11h41 23h28 |1041|0633|Sun 20 |

| 20 Sun 2295.7 07h31|17h58 19h21 06h01 07h24|----- 00h20 |1040|0540|Mon 21 |

| 21 Mon 2296.7 07h35|17h59 19h21 06h01 07h24|12h11 01h15 |1039|0446|Tue 22 |

| 22 Tue 2297.7 07h39|18h00 19h22 06h01 07h24|12h43 02h11 |1038|0349|Wed 23 |

| 23 Wed 2298.7 07h43|18h00 19h23 06h01 07h23|13h19 03h10 |1037|0250|Thu 24 |

| 24 Thu 2299.7 07h46|18h01 19h24 06h00 07h23|14h01 04h12 |1036|0148|Fri 25 |

| 25 Fri 2300.7 07h50|18h02 19h24 06h00 07h22|14h49 05h15 |1035|0045|Sat 26 |

| 26 Sat 2301.7 07h54|18h03 19h25 06h00 07h22|15h45 06h16 |1034|----|Sun 27 |

| 27 Sun 2302.7 07h58|18h04 19h26 06h00 07h21|16h48 07h14 |1033|----|Mon 28 |

| 28 Mon 2303.7 08h02|18h05 19h27 05h59 07h21|17h57 08h06 F|1032|----|Tue 29 |

| 29 Tue 2304.7 08h06|18h05 19h27 05h59 07h20|19h07 08h52 |1031|----|Wed 30 |

| 30 Wed 2305.7 08h10|18h06 19h28 05h58 07h20|20h18 09h34 |1030|0049|Thu 31 |

| 31 Thu 2306.7 08h14|18h07 19h29 05h58 07h19|21h26 10h12 |1029|0157|Fri 1 |

|____________________|___________SUN__________|_____MOON____|____|____|_______|

Times twixt 00h00 and 11h59 refer to the date at the end of the night.

Times twixt 12h00 and 23h59 refer to the date at the start.

Dusk and Dawn are for astronomical twilight.