Pleiades Occultation: Celaeno Graze 1-Apr

During the recent passage of the Moon through the Pleiades a remarkable event was visible within the borders of N.Y.C. — something I hadn't seen before.

A group of us, Charlie, Kin, Peter & myself, headed down to a spot near the Staten Island Ferry terminal, on the Staten Island side, to attempt a grazing occultation of the star Celaeno (16 Tauri).

At magnitude 5.45 this Pleiad is not usually bright enough to be seen naked eye from within the city. With optics this star is rather bright.

Charlie Ridgway found a place for us to observe along a favorable portion of the graze path on Staten Island. All it took was a subway, a ferry trip and a short walk to the ‘Staten Island September 11 Memorial’.

Unfortunately partly cloudy skies ruled the night. We we able to observe a few of the occulations between cloud breaks but the main event was the graze of Celaeno around 7:15pm EST.

The wind was rather strong with gusts recorded at 33 mph in Central Park with sustained winds close to 15 mph. [weather history]

Software and the Celaeno Graze

There is an excellent piece of software for predicting lunar occultations including the viewing of these spectacular grazes. The name of the program is ‘Occult for Windows’.

The image below shows the contour of the Moon's limb at the time of the Celaeno graze for Staten Island. The time frame shown is roughly 6 minutes along the horizontal line starting on the right at 3m and continuing to the left at -3m.

Charlie found a place that was approximately 0.75 miles off the center-line shown by the yellow line on the chart. Looking along this line there are two gaps between the time of immersion and emergence. These represent two reappearances of Celaeno.

It's remarkable how well amateurs have coordinated the observation of grazes in order to produce these accurate profiles of the Moon's limb. It's impressive how accurate the software can place an observer along a path for viewing a grazing occultation.

For this graze, at our location, the distance between an occultation of Celaeno by a single mountain peak (at the northern limit) and a total occultation (at the southern limit) is nearly 0.65 miles or 3,400 feet. An even narrower path for the double reappearance we witnessed (excluding final emergence) is only two tenths of a mile wide!

Equipment Purchases

I made a few recent purchases to test my skills at taking photos through the Televue-76. Recording a video of the event was a missed opportunity. It will take a lot of practice getting it right. I'm looking forward to nights where the Moon is up with a few stars nearby to test exposures for still photos and short movies.

Here are some recent purchases:

• William Optic DCL-52 75mm focal length eyepiece
• 2 Televue extension tubes - one 2" and one 3"
• adapter ring to step down from the 55mm thread

Here are some pending purchases:

• shutter release for the FZ-30
• extra battery
• extra 2 gigabyte memory card

Conclusion

It was great that all four of us were able to witness this graze of Celaeno. The anticipation of not knowing when it would start or how many events would happen increased the excitement.

If there is ever an opportunity for you to view a grazing occultation of a bright star I highly recommend the experience.