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[Centaur]

The 74% illuminated waning gibbous Moon will occult magnitude +2.9 Mu Geminorum for observers in portions of North America and Europe during the night of 2010 OCT 27/28. The southern graze path will pass across some US Plains and Midwestern states during the evening before crossing the Atlantic and passing through France and Italy in the early morning. Observers on that path will be able to witness the star winking on and off as lunar hills and valleys pass by. Those located north of that path will see a full occultation. There will be no northern graze path since it would be in outer space above the North Pole. Mu Geminorum’s apparent equatorial coordinates at the time of the event will be RA 06:23:38.9 and Dec N 22°30’26”.

I’ve created graze maps for both North America and Europe. I’ve also made a preview graphic with data for observers at Chicago’s Adler Planetarium. They can be seen by clicking www.curtrenz.com/astronomical and then going to the Moon page.

Photos and descriptions of the event would be welcome additions to this thread. If you would like occultation or graze data specifically for your location, then please reply to this post with a longitude, latitude, time zone and altitude above sea level.

[Paulie pchris00]

10:32- 10:59 CDT? And just a little earlier for me? Nice. I might actually get to see this. I've never seen a lunar occultation of a star. I didn't realize Gemini was up so early.

[Centaur]

Oct 24, 2010 8:49:25 GMT -6 Paulie pchris00 said:

10:32- 10:59 CDT? And just a little earlier for me? Nice. I might actually get to see this. I've never seen a lunar occultation of a star. I didn't realize Gemini was up so early.

Paulie, for Valparaiso the immersion will come at 22:34:06 CDT and the emersion at 22:57:38. The Moon’s shadow sweeps from west to east, so observers to the east generally witness occultations later than those to the west. For you the emersion will occur slightly earlier than at the Adler because you are further south and nearer to the graze path which results in a shorter duration for the occultation.

Actually, I’ve only witnessed one occultation myself. That was serendipitous. It occurred on 1958 JUN 18 while I was attempting to spot the New Moon aged 1.75 days shortly before sunset with the 3-inch Moonscope reflector I had gotten for Christmas. That was for mag +3.6 Lamda Geminorum. Although it wasn’t until forty years later that I had written the software that told me which star it was and created an image of the event. Déjà vu!

[Paulie pchris00]

The weather is still questionable, but if it's clear, Hillary and I may cover the event from separate locations. Out of necessity, I will have to observe without her. I will give her a crash course in gathering data, and let her borrow my 60mm refractor. We will report tomorrow.

[RobbW]

Curt, I didn't realize that a lunar occultation was all that uncommon. I would think that with all the movement the moon has around our plant that it would cross in front of a star quite frequently. Of course, I'm a recent re-newb'd newb when it comes to astronomy. So I'm still trying to freshen up!

[Centaur]

Oct 28, 2010 0:18:09 GMT -6 RobbW said:

Curt, I didn't realize that a lunar occultation was all that uncommon. I would think that with all the movement the moon has around our plant that it would cross in front of a star quite frequently. Of course, I'm a recent re-newb'd newb when it comes to astronomy. So I'm still trying to freshen up!

Indeed, Rob, they happen every night if your star magnitude criterion is unlimited or you’re willing to travel to any location on Earth. However, I only provide alerts for nighttime lunar occultations of planets and stars brighter than magnitude 4.0 that will occur for Chicagoland observers. Within those criteria we average less than one occultation per month, although we will get two in November, if we allow for the Sun being close to setting during the immersion of the first star and preparing to rise during the emersion of the second one. The previews for those two occultations already appear on my website.

2011 will be an unusual drought year worldwide for the occultations of planets and first magnitude stars. There will be only three, and in all cases with planets. None will be visible from North America, not even during the daytime. The 2005-2010 series of Pleiades occultations will also have ended. Worldwide during 2007 there were 57 occultations of planets and first magnitude stars, not to mention the monthly occultations of the Pleiades.

[RobbW]

Thanks for the explanation, Curt. I was by no means questioning your astronomical forecasts. I truly am a dunce with regards to details such as these. I simply had no frame of reference for why these occultations were rare and special. Thanks!

[Paulie pchris00]

First of all Curt, thanks for the information about the next two occultations. Maybe I will have more success with one of them. the two day old Moon on the 8th will make that a challenge, dealing with lingering twilight. I'm happy to see I have another shot at Mu Geminorum on the 24th. The immersion on the daylight side of the fat gibbous Moon may make that a challenge, too, and morning twilight may thwart the emersion. Those are plans to be made later though. This thread is for last Wednesday's occultation of Mu (µ) Geminorum.

Maybe I'm crazy, but despite this week's unprecedented low pressure system refusing to move out, I tried my best to observe the occultation, and document it. We all know the Moon orbits Earth, and moves through the sky about half a degree an hour, but to catch it observationally is another matter. Sure, I see it move through the Zodiac constellations night to night, but I’ve never paid much attention to the hourly motion. When Curt posted that the Moon would occult the star Mu (µ) Geminorum, I knew it was my chance to see the Moon in action.

The occultation time between 22:34:06 CDST and 22:57:38 CDST meant that the only place I could observe it would be at work, and even then I would have to hurry to put the telescope away and clock in as soon as the star reappeared. (The times listed above are Curt's calculations for Valparaiso; I was observing from Portage, but they served as my baseline start/end times).

Hillary wanted to observe the occultation too, so I left my 60mm refractor for her to use. The Moon was rising when I left her house, behind a pair of trees in the distance. The trees complicated her efforts, as well as the bitter wind and scattered, but increasing cloud cover.






Hillary had to deal with the Moon behind the trees in addition to the fierce wind and clouds.


I arrived at work about 10:25 PM, but the Moon was behind a cloud. I didn't get a good look until 10:34. According to my notes, at that time the "clouds cleared somewhat." Whether it was already occulted, or the clouds were hiding it, Mu Geminorum was not visible. Hillary and I were texting each other while waiting for emersion, hoping the clouds would clear.

Hillary-10:23 PM: The Moon is behind the clouds.

Paulie-10:29 PM: I've got clouds too. Maybe they'll go in a few minutes.

Hillary-10:30 PM: I know. It is too windy.

Paulie-10:31 PM: The wind is worse here [than when I left her house].

Hillary: I can't see the star.

Paulie-10:48 PM: It's hidden behind the Moon. Should pop out around 10:55 .

Hillary-10:53 PM: Okay. After this I'm going to bed.

Hillary-11:00 PM: Hey. Too much clouds here.

Paulie-11:01 PM: Look again! The star is there!

Hillary-11:07 PM: OMG I see the star.


We missed the immersion due to clouds, and in fact neither one of us saw the star before immersion. While the cold, fierce wind made observing difficult, at least it was moving the clouds along and creating a few opportune sucker holes to peek through. At 10:57 another sucker hole opened up in front of the Moon, and I was waiting for the moment it cleared. I saw something. Mu Geminorum was off the dark limb. As the sky cleared a little more it became brighter, and I tried to get pictures, but by the time I was ready the next cloud was already stealing my last moment of observation. I was sure I faintly captured the star, but comparing my image to Curt's graphic, now I'm not so sure. What looks like a possible star is in the wrong place that Curt predicted.




Ready and waiting...




The Moon through a cloud veil at 10:36 PM.




Conditions improved at 10:44, but didn't last long.






The strong wind made it hard to hold my camera still.




At first I thought the spot circled was the star Mu Geminorum, but now I'm not so sure. Look again at the same image below, unedited.






This was my first attempt to observe a lunar occultation of a star, and I really wanted to gather good data to support Curt's predictions. I failed this round, but at least I lost the battle with Mother Nature, and didn't do something foolish (like oversleep). I will have another opportunity with the same star next month. Who want to place bets for the rematch? ;D

[Centaur]

Rob, as one astronomical sage once put it regarding the infrequency of lunar occultations, “There’s an awful lot of black out there!”

Paulie & Hillary, thank you for your fine efforts and reports. And thank you for discovering a bug in my subroutine for drawing images of the Moon during occultations. My deep apologies. The zenith angle of the star on the lunar limb in my preview graphic was correct. Congratulations, Paulie, you indeed imaged and circled Mu Geminorum in your inverted photograph! However, the zenith angle of the center of the lunar bright limb in my preview graphic was incorrect. I’ve corrected this on my website for the November occultations. Below is the correct graphic for the October 27 occultation as seen from Valparaiso.

[Paulie pchris00]

Wow! I actually gathered good science data then?

I was trying to prove Curt right. I guess that's why observations are needed to follow up on the predictions.

[patrickm]

Nice work Team Valpo!!

[Paulie pchris00]

Thank you, thank you! That nearly inconclusive speck of light in my picture was a hard won observation. I've been out on much colder nights, but the wind was the most brutal I've ever done serious observing in.

[hillimolly]

Paulie, It was great last night just looking at the stars and moons leaving and coming back..

[patrickm]