December 18

December 18 Leap Leap+1 Leap+2 Leap+3
1950 3 X SGR 3 X SGR 3 X SGR
HR 6628 SCO
2000 3 X SGR 56 Omicron SER

Use 3 X Sagittarius for Leap+3 years in the 1950 era. Use 56 Omicron Serpens or 3 X Sagittarius for Leap+1 and Leap+2 years in the 2000 era. In some cases you have a choice of stars for this date. Remember that a brighter star has a smaller magnitude number, if that is your choice.

Name: 56 Omicron SER
Birthday from Jack’s initial research: Dec 17
Magnitude: 4.3
Spectrum/Star type: White
Distance in Light Years: 170
Diameter compared to Sun: ~2x
Luminosity compared to Sun: 30x
Date best observed: Aug 1
Additional information: It is a double star, outside of the zodiac in the tail of the Serpent. Serpens is the only constellation divided into two parts-Head and Tail. It is separated by Ophiuchus.

Name: 3X SGR
Birthday from Jack’s initial research: Dec 18
Magnitude: 4.5, variable (4.2 to 4.8)
Spectrum/Star type: Light yellow to yellow
Distance in Light Years: 1000+
Diameter compared to Sun: About 60
Luminosity compared to Sun: 3100 including infra-red
Date best observed: Aug 2
Additional information: 3X is a Cepheid variable with a period of 7 days. It is very young, about 55 million years old. It is the naked-eye star nearest the direction of the Galactic Center. Every star you see in the night sky is part of our Milky Way Galaxy. The galactic center is 30,000 light-years away. X marks the spot(almost)!

Name: HR 6628 SCO aka HIP 87220 formerly BS 6628
Birthday from Jack’s initial research: Dec 19
Magnitude: 4.8
Spectrum/Star type: Blue Supergiant
Distance in Light Years: 610
Diameter compared to Sun: Close to 50x
Luminosity compared to Sun: tens of thousands x
Date best observed: Aug 3
Additional information: Near M6 & M7. Larger and more luminous, this star out-classes ours even though it appears quite dim!

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