Lunar Transit through the Pleiades on 2007 December 21

and Favourable Grazing Occultations in Germany

 

Dear observer,

 

on Friday evening, December 21th, the moon will pass in front of the north-western part of the Pleiades cluster, causing several grazing occultations throughout  Europe. The limit lines of Celaeno (16 Tauri, 5.5mag) and Maia (20 Tauri, 3.9 mag) will run across Central Europe.

 

 

The limit lines intersect outside the extreme western coast of the Bretagne. Nevertheless the lunar profile allows to combine both events within a limited region.

 

 

 

 

Organized Expeditions in Germany

 

Throughout Germany no such twin observation is possible. Therefore you may join one of two IOTA/ES expeditions:

 

 

 

 

 

 

Position Angle and Profile for Celaeno

 

 

 

The graze of Celaeno takes place in a Cassini area of the lunar profile. Therefore the historical profile data by Watts (red dashed) are uncertain. Former graze observations indicate a profile depicted by the green line. Despite an unsatisfactory scatter of these data the green line is much more confident.

 

IMPORTANT:  If you observe from the theoretical linimt line, you probably will see a passage of the star without any occultation. The profile suggests to choose an observation site at least 1 to 1.5 km north of the predicted line. A strip up to 4 km north is favorable.

Please observe at least +/- 3 minutes around the time of central graze tabulated for your geographical position.

 

 

 

 

 

Position Angle and Profile for Maia

 

 

 

Path

 

The graze of Maia takes place in a Cassini area of the lunar profile. Therefore the historical profile data by Watts (red dashed) are uncertain. Former graze observations indicate a profile depicted by the green line. Despite an unsatisfactory scatter of these data the green line is much more confident.

 

IMPORTANT:  If you observe from the theoretical linimt line, you certainly will see a passage of the star without any occultation. The profile suggests to choose an observation site at least 2 km north of the predicted line. A strip up to 4 km north is favorable.

Please observe at least +/- 3 minutes around the time of central graze tabulated for your geographical position.

 

Grazing occultations help to improve the precise knowledge about the polar limb profiles of the moon. This is necessary to evaluate Baily's bead observations during solar eclipses for the determination of the sun’s diameter. Appearances and disappearances of beads are essential events, therefore probing the depth of valleys during grazing occultations is especially important.

 

 

 

 

 

Maps for Germany

 

The following maps show the limit lines for both grazing occultations across Germany allowing a rough orientation. Please take detailed path data and the times of central graze from tables linked in chapter “Organized Expeditions in Germany”. Do not forget to take into account the offset suggested in the preceeding chapter.

Additionally an adjustment for terrain elevation may be required in mountain ranges. With sufficient accuracy you can calculate this parallel southward offset by multiplying the elevation of you observation site with a factor of 0.62.

 

 

 

 

 

 

Transit through Pleiades Cluster

 

Anywhere else you may observe several regular or so-called total occultations of Pleiades stars, or you may just enjoy the transit. This overview, strictly valid for central Germany, gives you an impression what you will see:

 

 

 

 

 

Clear skies and successful observation!

 

 

 

Alfons Gabel

 

International Occultation Timing Association / European Section

http://www.iota-es.de