During this period the moon will reach its full phase on Saturday December 22nd. At this time the moon will lie above the horizon all night long for observers in the northern hemisphere. This will make viewing meteor activity difficult at the very least. If your sky is transparent you may wish to try and view some activity from the Ursid shower on the morning of December 22nd. Just be certain to face northward with the bright moon at your back. The estimated total hourly meteor rates for evening observers this week is near 3 as seen from mid-northern latitudes (45N) and 2 as seen from tropical southern locations (25S). For morning observers the estimated total hourly rates should be near 12 as seen from mid-northern latitudes and 5 from the southern tropics. The actual rates will also depend on factors such as personal light and motion perception, local weather conditions, alertness and experience in watching meteor activity. Rates are reduced during this period due to moonlight. Note that the hourly rates listed below are estimates as viewed from dark sky sites away from urban light sources. Observers viewing from urban areas will see less activity as only the brighter meteors will be visible from such locations.
The radiant (the area of the sky where meteors appear to shoot from) positions and rates listed below are exact for Saturday night/Sunday morning December 22/23. These positions do not change greatly day to day so the listed coordinates may be used during this entire period. Most star atlases (available at science stores and planetariums) will provide maps with grid lines of the celestial coordinates so that you may find out exactly where these positions are located in the sky. A planisphere or computer planetarium program is also useful in showing the sky at any time of night on any date of the year. Activity from each radiant is best seen when it is positioned highest in the sky, either due north or south along the meridian, depending on your latitude. It must be remembered that meteor activity is rarely seen at the radiant position. Rather they shoot outwards from the radiant so it is best to center your field of view so that the radiant lies near the edge and not the center. Viewing there will allow you to easily trace the path of each meteor back to the radiant (if it is a shower member) or in another direction if it is a sporadic. Meteor activity is not seen from radiants that are located far below the horizon. The positions below are listed in a west to east manner in order of right ascension (celestial longitude). The positions listed first are located further west therefore are accessible earlier in the night while those listed further down the list rise later in the night.
Radiant Positions at 7:00pm Local Standard Time
Radiant Positions at 12:00am Local Standard Time
Radiant Positions at 5:00am Local Standard Time
These sources of meteoric activity are expected to be active this week.
Details on each source will be available next week when viewing conditions are more favorable.
| SHOWER | DATE OF MAXIMUM ACTIVITY | CELESTIAL POSITION | ENTRY VELOCITY | CULMINATION | HOURLY RATE | CLASS |
| RA (RA in Deg.) DEC | Km/Sec | Local Standard Time | North-South | |||
| Anthelion (ANT) | – | 06:52 (103) +23 | 30 | 00:00 | 2 – 1 | II |
| Monocerotids (MON) | Dec 13 | 07:26 (112) +07 | 41 | 01:00 | <1 – <1 | II |
| alpha Hydrids (AHY) | Jan 03 | 07:42 (116) -06 | 43 | 01:00 | <1 – <1 | IV |
| c Velids (CVE) | Dec 29 | 09:00 (135) -53 | 39 | 02:00 | <1 – <1 | IV |
| December Leonis Minorids (DLM) | Dec 21 | 10:44 (161) +29 | 63 | 04:00 | 1 – <1 | II |
| Coma Berenicids (COM) | Dec 31 | 11:36 (174) +18 | 70 | 05:00 | <1 – <1 | II |
| December chi Virginids (XVI) | Dec 19 | 13:04 (196) -13 | 69 | 06:00 | 1 – 1 | IV |
| December sigma Virginids (DSV) | Dec 13 | 13:52 (208) +03 | 66 | 07:00 | <1 – <1 | IV |
| Ursids (URS) | Dec 22 | 14:24 (216) +75 | 33 | 07:00 | 3 – <1 | I |
| Quadrantids (QUA) | Jan 04 | 14:56 (224) +53 | 41 | 08:00 | <1 – <1 | I |
Source link
Комментариев нет:
Отправить комментарий