Asteroid Occults Regulas

On Wednesday evening, March 19th, a rare astronomical event will take place. The asteroid Erigone will pass in front of the star Regulus in the constellation Leo. For people living in New York and eastern Canada this event will take place at 2:07 a.m. Eastern Daylight Time. They will actually see Regulus disappear for 14 seconds. Fortunately for us living here in California this event will take place between 11:06 – 11:36 p.m. The closest approach of Erigone too Regulus will take place at 11:20 according to my simulations.

Here are some useful facts that might help you see the event.

  • What size telescope do I need?

The limiting Magnitude of a 4″ scope is 11.8 so a 4″ scope might be able to see Erigone. I would recommend at least a 6″ or larger scope.

  • How much magnification do I need?

My simulation shows that you will need to have at least 203X magnification to split Erigone from Regulus. (200X is the maximum power for a 4″ scope)

  • How bright are Erigone and Regulus?

Erigone has an apparent magnitude of 11.47. This is right at the limit of a 4″ scope.
Regulus has an apparent magnitude of 1.34 which will really outshine Erigone. To top it off, Regulus is a double star and its companion star might confuse you a little. The companion star will not be moving. Erigone will.

Click on the link below to see a simulation of the event. It is moving 300X faster than the actual event and runs from 10:30 p.m. to 11:30 p.m. The blue lines are lines that outline the Constellation of Leo.

Erigone & Regulus (Converted)

Leo1

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Author


Greg Eckes

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I am a retired music teacher. I make custom violins and violas. I play violin in the Tulare County Symphony and fiddle in the Tule River Bluegrass Band. I like camping and astronomy.

One thought on “Asteroid Occults Regulas

  1. Greg Eckes
    Greg Eckes March 20, 2014 at 11:19 am

    I set up my scope at 7:00 p.m. to get it acclimated to the outside temperature. At 9:00, I got a call from my brother Dave, in Reno Nevada. He wanted to know what our sky condition was here in Visalia. I told him the sky was clear. Orion was shining bright and everything looked good. His sky had a lot of clouds. I went out at 10:20 to align my scope and start observing the event. I could not see Leo because it was covered by clouds. A thin layer of clouds covered Orion. I proceded to aligned my scope and hoped for the best. At 10:35, the clouds started to break up. By 10:45 I could see Leo. Regulus was a big bright fuzz ball. It would not focus to a point. The air was really turbulent.

    I called Dave back and asked him what he could see. He was having the same problem. Regulus was so
    big and boiling so bad that it would not come into focus. I stayed on the phone with him till about 11:30. We could not see Erigone. Regulus was too overpowering.

    I continued to observe until 12:00. I checked out Jupiter, which looked great. Mars was a little low to get a good image. I thought that I could see a polar ice cap. I checked out M51, (Whirlpool Galaxy). It looked good even with the moon shining brightly. I ended the night with Polaris. I wanted to compare it to Regulus. Polaris is a double star. Most people don’t even notice its companion. Polaris shines at magnitude of 2.1 and its companion has a magnitude of 9.1, so if you are not looking for the companion you will easily miss it. I think that was the problem with Regulus and Erigone. Regulus is way too bright and Erigone is too dim and small.

    The evening was not a waste. I had a great time sharing the event with my brother Dave and being out under the stars, on the first day of spring, was fantastic! I can’t wait for next weekend, which is the dark weekend, to do some spring time observing.

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