saberscorpx
27-02-2009, 08:36 PM
Extreme Crescents and Colongitude
A big piece of the puzzle concerning the appearance of a thin crescent's degree of segmentation may be predicted by its colongitude at New Moon which, not suprisingly, can vary by more than 10°, trumping the effects and cycling independently of the perigee-apogee lunar profiles. VMA simulations show New Moon colongs less than 270° to favor segmented waxing crescent durations while those over 270° favor segmented waning crescents.
Equally important to those hunting Saber's Beads, colongitude may also be used inversely to determine the best profiles and visibilities for personal record crescent spotting.
The table below shows the lunation, colongitude at New Moon, duration in hours of the most segmented waxing limb (-280° colongitude), and the duration in hours of the most segmented waning/preceding limb (+260° colongitude).
Data from thin crescent images and my own experiences with Saber's Beads also concur with a 260-280° colong window.
lun/colong/h-280/h+260
1067 275.5 08 30
1068 274.7 10 28
1069 273.0 13 25
1070 271.1 17 21
1071 269.3 20 18
1072 267.6 24 14
1073 266.0 27 11
1074 264.9 29 09
1075 264.7 29 09
1076 266.0 27 11
1077 268.5 22 16
1078 271.3 16 22
1079 273.5 12 26
1080 274.7 10 28
1081 274.9 09 29
1082 274.4 10 28
1083 273.3 12 26
1084 271.5 16 22
1085 269.3 21 17
1086 267.0 25 13
1087 265.3 28 10
1088 264.7 29 09
1089 265.3 28 09
1090 266.9 25 13
1091 268.9 21 17
1092 271.1 17 21
1093 273.1 13 25
1094 274.7 10 28
1095 275.3 08 30
Saber Does The Stars at
www.astronomyblogs.com/member/saberscorpx (http://www.astronomyblogs.com/member/saberscorpx)
A big piece of the puzzle concerning the appearance of a thin crescent's degree of segmentation may be predicted by its colongitude at New Moon which, not suprisingly, can vary by more than 10°, trumping the effects and cycling independently of the perigee-apogee lunar profiles. VMA simulations show New Moon colongs less than 270° to favor segmented waxing crescent durations while those over 270° favor segmented waning crescents.
Equally important to those hunting Saber's Beads, colongitude may also be used inversely to determine the best profiles and visibilities for personal record crescent spotting.
The table below shows the lunation, colongitude at New Moon, duration in hours of the most segmented waxing limb (-280° colongitude), and the duration in hours of the most segmented waning/preceding limb (+260° colongitude).
Data from thin crescent images and my own experiences with Saber's Beads also concur with a 260-280° colong window.
lun/colong/h-280/h+260
1067 275.5 08 30
1068 274.7 10 28
1069 273.0 13 25
1070 271.1 17 21
1071 269.3 20 18
1072 267.6 24 14
1073 266.0 27 11
1074 264.9 29 09
1075 264.7 29 09
1076 266.0 27 11
1077 268.5 22 16
1078 271.3 16 22
1079 273.5 12 26
1080 274.7 10 28
1081 274.9 09 29
1082 274.4 10 28
1083 273.3 12 26
1084 271.5 16 22
1085 269.3 21 17
1086 267.0 25 13
1087 265.3 28 10
1088 264.7 29 09
1089 265.3 28 09
1090 266.9 25 13
1091 268.9 21 17
1092 271.1 17 21
1093 273.1 13 25
1094 274.7 10 28
1095 275.3 08 30
Saber Does The Stars at
www.astronomyblogs.com/member/saberscorpx (http://www.astronomyblogs.com/member/saberscorpx)