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A grazing lunar occultation (also lunar grazing occultation, lunar graze, or just graze) is a

lunar occultation An occultation is an event that occurs when one object is hidden from the observer by another object that passes between them. The term is often used in astronomy, but can also refer to any situation in which an object in the foreground blocks ...

in which as the occulted star disappears and reappears intermittently on the edge of the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

. A team of many observers can combine grazes and reconstruct an accurate profile of the limb

lunar terrain Selenography is the study of the surface and physical features of the Moon (also known as geography of the Moon, or selenodesy). Like geography and areography, selenography is a subdiscipline within the field of planetary science. Historical ...

Since graze paths rarely pass over established

observatories An observatory is a location used for observing terrestrial, marine, or celestial events. Astronomy, climatology/meteorology, geophysical, oceanography and volcanology are examples of disciplines for which observatories have been constructed. His ...

amateur astronomer Amateur astronomy is a hobby where participants enjoy observing or imaging celestial objects in the sky using the unaided eye, binoculars, or telescopes. Even though scientific research may not be their primary goal, some amateur astronomers m ...

s use portable observing equipment and travel to sites along the shadow path limits. The goal is to report the UTC of each event as accurately as possible, and

GPS The Global Positioning System (GPS), originally Navstar GPS, is a Radionavigation-satellite service, satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of t ...

disciplined devices are frequently used as the time-base. Two methods are used to observe: * visual – the observer has an audible UTC beeping device (e.g. a shortwave radio tuned to WWV) and an audio recorder (e.g. a

tape recorder An audio tape recorder, also known as a tape deck, tape player or tape machine or simply a tape recorder, is a sound recording and reproduction device that records and plays back sounds usually using magnetic tape for storage. In its present- ...

) and watches the target through the telescope, and calls 'Gone' when the star disappears, and 'Back' when the star reappears. The audio recording is later analysed to extract the event times. *

video Video is an electronic medium for the recording, copying, playback, broadcasting, and display of moving visual media. Video was first developed for mechanical television systems, which were quickly replaced by cathode-ray tube (CRT) syste ...

– the observer uses a small video camera, usually mounted in the focuser of the telescope. A Video Time Inserter (VTI) is commonly used to insert a UTC time-stamp onto each frame of the recording. Either a

camcorder A camcorder is a self-contained portable electronic device with video and recording as its primary function. It is typically equipped with an articulating screen mounted on the left side, a belt to facilitate holding on the right side, hot-swa ...

, DVR or a

laptop A laptop, laptop computer, or notebook computer is a small, portable personal computer (PC) with a screen and alphanumeric keyboard. Laptops typically have a clam shell form factor with the screen mounted on the inside of the upper li ...

computer is used to record the video stream. The video recording is later analysed to extract event times. Such observations are useful for: * refining knowledge of the positions and motions of stars * examining limb topographical profile around the lunar polar region. * Measurement of the

Earth's rotation Earth's rotation or Earth's spin is the rotation of planet Earth around its own Rotation around a fixed axis, axis, as well as changes in the orientation (geometry), orientation of the rotation axis in space. Earth rotates eastward, in retrograd ...

References

External links

* , showing grazing occultation of Jupiter as seen from Melbourne, Australia *Astronomy Picture of Day for March 16, 2007, showing grazing occultation of Satur
International Occultation Timing Association
Predicted paths for future grazing occultations * Zodiacal Catalogue (XZ80Q) of stars that can be occulted by the moo

* *Predictions and analysis of Lunar Occultations and Grazing Lunar Occultations. Occult (Software), Lunar Occultation Workbench (LOW) an
GRAZEPREP
{{Portal bar, Astronomy, Stars, Spaceflight, Outer space, Solar System Astronomical events

See also

References

Further reading

External links