Last March 17, 2011 , the University of the Philippines Astronomical Society (UP AstroSoc) set up at the PAGASA Astronomical Observatory in UP Diliman to observe the occultation of the 3.3 magnitude star, Omicron Leonis (or Subra) by the 92% illuminated waxing gibbous Moon.
This event was headed by UP AstroSoc associate member and alumni, Anthony Urbano of EtenyWorks. Kuya Eteny, as the members fondly call him, was experienced in observing occultations.
During this observation, he brought his 6″ Newtonian Equatorial Reflecting Telescope (NERT) with a self-designed home-built clock drive attached to the telescope’s equatorial mount. To record the occultation event, a Canon S3IS connected to a laptop was mounted to the telescope’s eyepiece by means of a fabricated camera adapter. This modified camera can show it’s system time on its on-screen display. According to Kuya Eteny, the default precision of the on-screen timer is limited to 1 second, but a patch, currently made available only for Canon S3IS, increased the clock’s precision to 1/100 of a second — the maximum precision of the camera’s built-in clock.
You can learn more about this improvised clock drive project, the camera modification and the rest of observation set up by visiting his site where he posts a lot of cool stuff about observation and instrumentation. His inventions are most fit for those amateur astronomers interested in modifying their own telescopes and cameras especially for the purpose of doing astrophotography. 🙂
The event was from 10:20 UT (ingress) and ended at 11:10 UT (egress). Although it can be classified as a ‘bright star occultation’, the light coming from the target star wasn’t bright enough to pass through the thick clouds during the entire event. By around 11:50 UT, we decided to packed up since there was still no trace of the star near the Moon.
When the Moon passes in front of a background star during occultations, the shadow of the Moon cast by the star sweeps across the Earth. When the leading or trailing edge of the Moon’s shadow crosses an observer, the observer sees the star “disappear” or “reappear”. These events are usually very sudden, and timing the instant of occultation is an important astronomical measurement.
But why is it important to observe lunar occultations?
- Observing lunar occultations is important because the results improve our knowledge of the position and motion of the Moon. For example, when you time the disappearance of a star behind the edge of the Moon to 0.1 second accuracy (a value easily attainable), you are actually fixing the position of the Moon’s edge in space to an accuracy of about 80 metres. i.e. you are making a measurement with a precision of only 80 metres over a distance of 384,400 km. (This is one of the most accurate measurements an amateur observer can make in any branch of science!)
- Combining many such measurements of the Moon’s position over a long time gives astronomers new information about the Moon’s motion and orbit. For example, total occultation observations have shown that the Moon is spiralling away from the Earth at a rate of a few centimetres per year.
- Total lunar occultations have also been used to provide valuable information about star positions, about the hills and valleys on the edge of the Moon, and to discover new double stars.
Aside from occultations by the Moon, there were also Planetary Occultations and Asteroid Occultations. Just as the Moon passes in front of background stars, so too do planets and minor planets (also called asteroids).
Planetary occultations are occultations of stars by the passing of a planet in front of it. However planetary occultations occur less frequently than lunar occultations because the planets appear so much smaller in our sky than does the Moon. Nevertheless, observing occultations of stars by planets has yielded some stunning discoveries – for example, the rings of Uranus, and the atmosphere around Pluto.
On the other hand, Asteroid Occultations are occultations of stars by the passing of an asteroid in front of it. Asteroid occultations can occur anywhere on the surface of the earth. A few naked eye stars have been occulted during the past 20 years, but most occultations are of quite dim stars typically between magnitudes +9 and +12. An occultation might occur at any time of night, on any day of the week. More and more fainter asteroid occultations are being predicted, so that it is likely that at least 5 events will likely cross your area in the coming year.
While occultations of bright stars by major planets are very rare, occultations by asteroids are a little less so. This is not because any one asteroid has a greater chance of passing in front of a star. Rather, it is because there are so many more asteroids to choose from!
Anyway, asteroid occultations are the only way — apart from spacecraft missions to asteroids and radar observations of nearby objects — to determine the approximate size and shape of those bodies and are, of course, much cheaper.
If, as an amateur astronomer or telescope owner, you would like to be part of history, contribute something relevant to the study of astronomy, or would love to see sights that few have witnessed, then occultations are the thing for you. The occultation process offers discovery and research. It is possible for amateur astronomers to discover new companions of stars, help to improve the polar diameter of the sun and moon, identify the existence of possible satellites orbiting asteroids, to improve knowledge of heights of lunar mountain peaks and depths of valleys in the polar regions, determine corrections to ephemeris errors and assess star position errors, improve knowledge of the shape and sizes of asteroids, and more through occultation science. It does not matter where you live in the world. If you have access to a computer and possess a telescope of at least 4-6 inches, know your geodetic position either from GPS or a good topographic map, have a source of time signals and tape recorder, you can make your own observations of these rare and critical events.
The IOTA web site contains predictions that are updated frequently.
To be able to observe and correctly record an occultation event, you should first have knowledge to find your way about the sky. Most stars that are occulted by asteroids have average apparent visual magnitude of 10.
The program Win-OCCULT, authored by David Herald in Australia, provides accurate predictions of all types of occultations and related phenomena. You can obtain a copy of Win-OCCULT by downloading it from here.
Good luck! 🙂
I and my fellow UP AstroSoc members, Aaron Misayah and Bea Banzuela observed the Partial Lunar Eclipse at Moonrise last Dec. 21, 2010 from the roof deck of Bea’s house in Marikina City.
During this observation, I took pictures using my portable Galileoscope and Kodak C813 8.0 megapixel digicam while Bea used her Canon 400D DSLR camera .
The sky was about 70-80% cloudy when we set up and the northeastern horizon was blocked with haze and big clouds. At first, we thought that we may never witness this event because the whole phase visible in the Philippines will occur at a very low altitude (below 5 deg.) and one must have a very clear eastern horizon to see the rising eclipsed moon.
At 5:44 PM, all of us become ecstatic as we turned our gaze to a bright yellowish light (which we soon recognized as the eclipsed right limb of the Moon) emerging from behind the clouds above the mountains. We were so amazed by this spectacular view that we almost forgot to take pictures of it. 😀
This ‘celestial experience‘ was indeed an early Christmas gift from above 🙂
Due to a busy schedule, I was not able to observe the peak of the Leonid Meteor Shower last Nov. 17 to 18. According to Philippine Atmospheric Geophysical and Astronomical Services Administration (PAGASA), the best time to look for these fast moving meteors would be around two to three hours before dawn when the waxing gibbous Moon has already set and the constellation Leo is high in the Eastern sky.
I planned on observing the following night. However, I realized that aside from missing the peak of the meteor shower, I would probably have less chances to see the Leonids because the light from the nearly full Moon will wash out the fainter meteors. The angular difference of the plane of revolution of Earth around the Sun and that of the Moon around the Earth causes the Moon to rise and set about 50 minutes later each successive night, so I would have an even smaller chance of seeing a meteor every night I wait after the peak.
Nevertheless, because of my eagerness and keen determination to see even a single Leonid, I tried my luck during the night of Nov. 19-20. 🙂
Together with some friends and fellow orgmates, we drove home to Marikina City at around 2am. While on the way, I noticed the Moon shining brightly in the west. Jupiter was nowhere to be found as it has set earlier along with Uranus.
After arriving at my friend’s house, I immediately told her of my plan and we prepared to set up at the topmost part of the house. It was cold and a bit foggy outside during that time. We took a sleeping bag with us so we could lie down on the floor of the roof deck as we watch for meteors. Unfortunately, the floor was already wet – probably because of the dew – when we climbed upstairs. So instead, we spread out the sleeping bag across the roof just below the topmost deck and began our quest for that night. Below us, all the little houses and buildings stood silent as the little spots of light coming from the street lamps appeared to twinkle just like the stars above us.
We found the very conspicuous Leo, the constellation where the meteors seem to radiate from, lying high in the northeastern sky. As we started out to look for zooming meteors from other parts of the sky, we were stunned by the total beauty of the night sky surrounding us. Luna was already low and obstructed by a building to the west, which allowed the stars of the bright constellations to shine brightly against the dark sky. In the west, the Winter Triangle – which is composed of red Betelgeuse of the mighty Orion, Procyon of Canis Minor and Sirius of Canis Major – stood out together with Castor and Pollux of Gemini, Aldebaran of Taurus, Capella of Auriga, Mirphak of Perseus and Arneb of Lepus. Of course, the heavenly sisters, Pleiades and Hyades, could be easily noticed as well. In the south, bright Canopus greeted us with the other stars of the former Argo Navis. Looking northwards, I was surprised to see the famous seven stars comprising the Big Dipper in Ursa Major again. It has been a long time since this asterism, which serves as a guide in finding the North Star, became visible once again. The eastern horizon was practically covered with dark, low-lying clouds so it remained blank for a few hours.
After several minutes of searching the sky, I saw my very first Leonid – a swift yellow meteor with a long trail. 😀 As I traced back its path, it appeared to have come from the sickle of Leo which confirmed that it was indeed a Leonid! After that I saw 7 more meteors, 3 of which were big yellowish-orange with long trails. We were so astounded by their beauty that we screamed with delight every time we saw one. The best one I saw was very bright with a long, lingering, smoky tail behind it which lasted for about 5 seconds.
Meanwhile, we also saw several artificial satellites moving across the northwestern sky from 4am-5am.
At about 5:15 am, we decided to end our meteor counting and go inside because it’s getting too cold and our sleeping bag was already wet due to the morning dew. But before we went downstairs, we noticed this very bright apparition in the eastern sky. At first, we thought it was an airplane because of its intense luminosity. However, we noticed that it wasn’t moving at all. I thought that maybe it was another celestial object. Was it a big meteor that was about to hit Earth or a UFO? Or, was it a star that had just risen? I know that there’s only one celestial object that could shine that bright then – the planet Venus. After undergoing inferior conjunction with the Sun, Venus was now back to being a morning star. However, I wondered why we didn’t see it rising. I suddenly recalled that maybe it was covered by the thick clouds in the east that we saw a while ago as it rose up in the horizon.
Upon checking Stellarium, I realized that Venus was also perfectly placed near Saturn and the star Spica of Virgo then. My friend, Bea, had her Canon 400D DSLR camera with her that time so we decided to capture this remarkable view at that moment.
Though I caught a cold, got no sleep, and had itchy mosquito bites all over my arms and feet during this observation (such is the life of an amateur astronomer, ha ha), seeing all those beautiful sights of the heavens would always be more than enough for me to go to great heights for astronomy and continue on this passion of exploring the cosmos and sharing it to everyone . 🙂
“For astronomy is not only pleasant, but also very useful to be known: it cannot be denied that this art unfolds the admirable wisdom of God.” – John Calvin
In hope of observing the Orionids Meteor Shower, I and some UP Astrosoc friends planned to go to the south to avoid the unfavorable weather in Manila. Unfortunately, we were not able to pursue the plan due to the heavy rain. Instead, we went to Naic, Cavite, a town just a few kilometers outside Manila, a day after super typhoon Megi left the country to try our luck.
We arrived at the local beach resort and started setting up our things including our tent at around 11:00 PM. The sky was totally overcast, but the waning gibbous moon and a star, which I know was the planet Jupiter, were visible then.
After a few minutes of observing the two, we noticed a faint but full 22 degree lunar halo circling the moon. Jupiter was just within the circle. We even got more amazed as the halo became clearer when the moon reached the zenith. One of us took a shot of this stunning view using her Canon 400D Digital SLR camera.
Lunar halos are caused by sunlight being refracted by cirro-stratus clouds. Cirro-stratus clouds are thin clouds, very high in the atmosphere, and are composed of ice crystals. The shape of the ice crystals results in a focusing of the light into a ring. They bend light at a 22 degree angle, which creates a solar halo or lunar halo that is 44 degrees in diameter.
Since the ice crystals typically have the same shape, namely a hexagonal shape, the Moon ring is almost always the same size. Less typical are the halos that may be produced by different angles in the crystals. They can create halos with an angle of 46 degrees.
The sky remained overcast during the rest of the evening until twilight and so we were not able to see even a single fireball.
Nevertheless the attempt was worth a try, thanks to that wonderful halo which left us amazed and happy. 😀
Today is the “International Observe the Moon Night” when people in all parts of the globe are encouraged to wait till dark and go outside and pay attention to our closest neighbor in space — the Moon. 🙂 Me and my friends (and also fellow UP AstroSoc members) will set up our observation at the back of SM Mall of Asia in Pasay, near the Manila Bay. After watching the beautiful sunset by the bayside, we’ll focus on taking images of the moon for the InOMN Photo Contest. 😛
Alright, there’s really no special happening on the moon later tonight, no spacecraft impact or a UFO flyby. But the “event” is more of a reminder to look up and appreciate what we sometimes take for granted. It’s goal is also to raise the awareness and interest of the public on the recent lunar research and exploration which has brought us a lot of new information about our space companion.
Let’s all see the moon in a whole new light! Observe the moon with your telescopes, binoculars or even just with naked eyes. Appreciate its beauty — take note of it’s phase, the patterns and shades of it’s features. If you’re gonna use telescopes or binoculars, see its mountains and craters, Get involved and invite others! Why? Because so few people ever take the time to just look up and see the splendor of the creation stretching across the skies.
I have included here below some of the lunar photos which me and my fellow amateurs took before. 😀 Enjoy and clear skies!
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Some Quick Moon Facts…..
+ The distance From Earth is 363,301 kilometers (225,745 miles).
+ The radius of the moon is 1,738 kilometer (1,080 miles), the diameter is 3476 kilometers (2,160 miles).
+ Total weight: of the moon is 74 sextillion kilograms (81 Quintillion Tons).
+ The surface temperature at the equator during the day is 134oC (273o F), and at night is – 153o C (244o F)
+ Gravity at the surface of the moon is 1/6 that of the Earth.
+ The moon has no significant atmosphere or clouds.
+ Its surface is scarred from hundreds and thousands of meteors that have struck it over billions of years.
+ The Moon’s surface layer is called regolith.
+ The Moon’s orbit is inclined 5 degrees from the Earth’s ecliptic.
+ The face of the Moon is marked by regions, called mare, Latin for “sea”. A name given by Galileo who thought the dark featureless areas were bodies of water. We now know them to be basalt (a type of lava) filled impact basins.
+ The Moon’s magnetic field is 100 to 1000 times weaker than the Earth’s
The night sky on August 26 will be dominated by Jupiter and the waning gibbous moon. They can be seen in the east by mid-evening, after brilliant Venus has disappeared beyond the western horizon. Rising just an hour or two after sunset, Jupiter and the moon can be viewed for the rest of the night among the faint stars of the constellation Pisces the Fish.
With a bright moon passing near them, Pisces’ dim outline might not be visible except from very dark locations. Still, a prominent asterism – or noticeable pattern of stars – can be glimpsed near Jupiter and the moon on that night. It’s called The Circlet in Pisces.
Jupiter, is slowly increasing in brightness as it heads towards its opposition and closest approach to Earth in 12 years just next month, September 21 . This time is the best chance to view and photograph Jupiter and its moons. The giant planet will be as big and bright as it gets in the night sky. A medium-sized telescope should be able to show some of the details in Jupiter’s cloud bands.
For Philippine sky gazers, the planets Venus and Neptune will make their greatest appearance for this year on the evening of August 20 😀
The brightest planet in the solar system, Venus will appear especially prominent because it will climb to its highest point in the evening sky upon reaching its greatest elongation. It will lie 47° from the Sun, its maximum distance for this appearance.
Also on this night, the planet Mars will lie just 2° above Venus. (That’s approximately the width of one finger when held at arm’s length.) Using binoculars will help bring it to view because it glows less than 1 percent as Venus. The planet Saturn lurks approximately 10° to Venus’ right and the star Spica in the constellation Virgo sits 10° to Venus’ left. Both shine a little brighter than Mars but fall far short of dazzling Venus.
Although naked eyes and binoculars offer the best views of the evening scene, anyone with a small telescope will get a thrill from targeting Venus. At greatest elongation, Venus looks like a miniature version of a First Quarter Moon, with one half in sunlight and the other in darkness.
On the other hand, the planet Neptune will be in opposition (opposite the sun in the sky and closest to Earth) and will be highest in the sky at local midnight. This opposition is special because Neptune will be returning close to the spot where it was discovered in 1846, marking its first complete trip around the sun since its discovery.
To find Neptune, look for the large but faint triangle of Capricornus, to the left of Sagittarius and the Milky Way around 1 a.m. this week. The two stars at the left end of the triangle point the way to Neptune, just a little bit short of and above the star Iota in the neighboring constellation Aquarius.
In a small telescope or even binoculars, Neptune will look just like a star; what gives it away is its distinctive blue-green color.
Happy planet hopping! 😀
A lot of Filipino amateur astronomers including me 😀 are excited for this month’s sky display.
For Philippine observers, the annual Perseids Meteor Shower which often shows 50 meteors per hour will be observed with its peak on the late night of August 12-13. The Perseids appear to radiate out from the constellation Perseus, which is located in the eastern horizon during August.
2010 is a great year for the Perseids. This year, the slender waxing crescent moon will set at early evening, leaving a dark sky for this year’s Perseid show.
The Perseids tend to strengthen in number as late night deepens into midnight, and typically produce the most meteors in the wee hours before dawn. These meteors are often bright and frequently leave persistent trains. The Perseid Meteor Shower is famous for its Earthgrazers –meteors that approach from the horizon and skim the atmosphere overhead like a stone skipping the surface of a pond. Earthgrazers are long, slow and colorful; they are among the most beautiful of meteors.
The source of the shower is Comet Swift-Tuttle. Although the comet is nowhere near Earth, the comet’s tail does intersect Earth’s orbit. We glide through it every year in August. Tiny bits of comet dust hit Earth’s atmosphere traveling 132,000 mph. At that speed, even a smidgen of dust makes a vivid streak of light–a meteor–when it disintegrates.
Friday the 13th will never be unlucky for sky observers on this night. Those who plan to watch the Perseids will also have the chance to see a beautiful planetary grouping before the radiant rise in the East.
Coincidentally, on August 13 at around 7pm the crescent Moon will join the groupings of Mars, Venus, Saturn and Mercury in the western horizon.
Happy observing and Clear Skies to all!
Stargazing during the month will give fine displays of celestial bodies, stars and constellations after sunset and before sunrise. This is truly something to look forward to on July despite the cloud and rains that cover our skies 🙂
Here is a post from GMAnews.TV via Yahoo news Philippines to guide Filipino sky gazers this month.
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Can’t watch eclipse? At least watch the parade of stars
If we can’t watch the eclipse where we are, at least we can watch the nightly parade of stars.
No, it’s not a movie critic talking about the current Hollywood hit, “Eclipse.” It is what state astronomers said late Thursday, referring to a total solar eclipse that will occur on July 11 from 6 to 9 p.m. (Universal Time) but will not be visible in the Philippines, during which it will be July 12 from 2 to 5 a.m.
However, stargazers can still get some consolation gazing at a celestial parade of stars, as well as four planets that will dramatically line up on July 14, the Philippine Atmospheric Geophysical and Astronomical Services Administration (PAGASA) hastened to add.
“A total eclipse of the Sun will occur on August 12 [sic], however, it will not be visible in the Philippines. The eclipse will begin at exactly 1:09 p.m. (Philippine Standard Time). It will visible in the Cook Island, French Polynesia, and Southern tip of South America,” PAGASA said in its astronomical diary for July.
[Editor’s note: The date “August 12” in the PAGASA website entry is wrong. Other authoritative sites, such as that of the United States’ National Aeronautics and Space Administration and United Kingdom’s Nautical Almanac Office all include a solar eclipse event for July 11 but none on Aug. 12. We assume that the wrong date in the PAGASA website is a mere typist’s error.]
On the other hand, state astronomers said stargazing during the month will give fine displays of celestial bodies, stars and constellations after sunset and before sunrise.
It said the famous Summer Triangle of the stars Vega, Deneb and Altair of the constellations Lyra, Aquila and Cygnus, respectively, is being well placed above the eastern horizon.
The bowls of the Big and Small Dipper in Ursa Major and Minor stand high above the northern horizon with the body of the constellation Draco, the Dragon, winding between them.
Also, PAGASA said the grouping of a horseshoe shape stars of the constellation Corona Borealis, the Northern Crown, lies on the north-south meridian with the head of Draco below it.
“The constellation of Scorpio is positioned above the east-south eastern horizon, while the constellations of Centaurus, the Centaur and Acrux, the Southern Cross are just above the south direction after sunset,” it added.
July 14 lineup
On July 14, PAGASA said an evening line-up of naked-eye planets including the crescent Moon will parade before skywatchers as they will see Mercury, Venus, Mars and Saturn in the western horizon this month, 30 minutes after sunset.
The gap between these planets shrinks throughout the month of July, PAGASA said.
At midnight, Jupiter, Uranus and Neptune will be found at about 18, 21 and 44 degrees above the eastern horizon, respectively.
“Modest size binocular or telescope will be needed to view these planets,” PAGASA said.—JV, GMANews.TV
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Happy observing! 🙂
The partial lunar eclipse last June 26, 2010 was the first of two lunar eclipses in 2010. At maximum eclipse, 53.7% of the moon was covered by the earth’s shadow. Full details of the eclipse can be found in from my previous blog post. I and two of my UP Astrosoc colleagues decided to observe this event and take images from Marikina City.
At first, we were anxious that we would not be able to observe the partial lunar eclipse due to the thick rain clouds covering the whole observation area. The sky was overcast that day and it started raining at around 7pm. Using Stellarium, I located the moon in the western sky, but the clouds blocked even the slightest trace of moonlight.
We decided to transfer to another location within the same area where we could get a better view. There were no objects that could be seen through the thick clouds anyway so we just spent our time looking for a nice spot to observe when the rain stopped. While walking past the street corner, we saw this house that had a two-leveled roof deck, ideal for our observation and high enough not to be blocked by any other building that surrounds it. It was a good place for observation, however we are too shy to approach the owner of that house.
Driven by our willingness to observe this rare phenomenon, we overcame our hesitation and went to that house. Fortunately, the owner of the house allowed us to use the top deck. We had our equipment then, so I think we somewhat looked sincere with our request.
As we went up to the deck, we saw a beautiful view of the city with those little lights from below which reminded me of the stars on a dark night. We began to set up our equipment and prepared for the appearance of Luna. After several minutes, it rained. We stayed under an umbrella and used the spare ones to protect our camera and laptop. We just stayed there to wait though a slight shadow of desperation was coming over us then. The rain just seemed to drag on and on and we were soon thinking of packing up our things and going home.
Luckily, after more than an hour of waiting in the rain while holding on to our hopes by praying, the skies began to clear up. Venus appeared in the west, and the moon finally showed itself to us with its upper part still covered by the umbra. We immediately used the binoculars to make sure that it was not just clouds covering the moon. It was a few minutes past 8pm then, and according to the predicted eclipse activity, the moon would still be eclipsed though we had already missed the maximum.
We took several photos at different settings. We needed to adjust our camera’s settings every now and then because the clouds were moving fast in front of the moon. There were even times when we needed to wait for minutes for the clouds to pass. Good thing that despite the little time left for us to take photos and the thick clouds, we were still able to get nice shots.
We left the place a little past 10pm, when the penumbral eclipse was about to end.
Unfortunately, were not able to witness the maximum eclipse because of the rain. Nevertheless, I still feel so blessed to have been able to take images of this event 😀
We will surely never forget this experience for it deepened our love for astronomy and the sky. We are now more inspired to do astro imaging for the next astronomical event.
Photo details: We took the photos using Canon PowerShot SX20
Post-processing was done using Registax V.5.1 to enhance the lunar features.
Location: Marikina City, Philippines
Coordinates: 14°38’20″N 121°7’32″E