Barbara Burtscher Switzerland Asteroids Sky Watch

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Barbara Burtscher University Zurich Switzerland Observations and analysis of Asteroids with theoretical reflections (Asteroid 2017 Wesson and the Trans-Neptunian Object 2003 UB313)

A) What is an asteroid?: 

A) What is an asteroid? Asteroids are large rocks without atmospheres that orbit the sun but are too small to be classified as planets. They are thought to be primordial material prevented by Jupiter's strong gravity from accreting into a planet-sized body when the solar system was born 4.6 billion years ago. Asteroids are classified into different types according to their albedo, composition derived from spectral features in their reflected sunlight and inferred similarities to known meteorite types. A white, perfectly reflecting surface has an albedo of 1.0; a black, perfectly absorbing surface has an albedo of 0.0. Many tens of thousands of asteroids have been discovered so far and more than 12,000 of these have been officially named. Most asteroids are found in the Asteroid Belt, between Mars and Jupiter. (http://www.solarviews.com/eng/eros.htm) © Nasa Attention: This presentation contains animated gifs which can only be seen by playing the presentation in Power Point © Nasa page 2

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NEA‘s come near to the earth so it is possible that a large NEA may hit the Earth in the future. Astronomers are trying very hard to find as many NEA‘s as possible and study their orbits to see if they might hit us. Unlike most meteorites, NEA’s can be quite big and could cause a lot of damage if they were to hit the earth. If astronomers can find big earth-colliding NEA’s early enough, it should be possible to change the orbit in order to avoid a crash. B) Why observe asteroids? Reasons for observing asteroids: to find a possible "killer-asteroid" To discover and study asteroids, in particular ones that might come close to the Earth (NEA‘s) © Nasa (http://impact.arc.nasa.gov/gallery_main.cfm) Asteroids with orbits that bring them within 1.3 AU (195million kilometers) of the sun are known as Near-Earth-asteroids (NEA‘s). page 3

C) Objective : 

C) Objective Asteroids "2017" Wesson and "2003 UB313" For my project, I decided to analyse the Sky-Watch-photographs of the Asteroid 2017. The tasks are; to identify the asteroid on the CCD-Images to create an animated gif to see the asteroid moving to calculate the rotation duration with photometry to calculate the speed to estimate the size Furthermore I am observing the new discovered trans-neptunian object 2003 UB313 which is vying with Pluto in size (IAU Circular 8577 announced on July 29, 2005) (http://www.iau.org/IAU/FAQ/2003_UB313.html ) page 4

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The patterns of stars in the sky do not change from night to night since stars do move very slowly. However, planets and asteroids are all orbiting around the sun and so do move. If you take two pictures of a particular part of the night sky some time apart (say, a few hours) and then compare them, the stars will not have moved, but any planets or asteroids will have. Then astronomers can work out a detailed orbit for the asteroids. With these observed orbits it is possible to calculate the future orbiting of the asteroids and planets. With these information, astronomers are able to crate a map of all orbits. And so detecting possible future collisions. D) Practical observation of Asteroids page 5

Equipment used: 

Equipment used Sky-Watch-CCD-Images: -The Andreas Michalitsianos telescope -Location: Mount Ainos, Kefallonia Island, Greece -Type: 60cm Cassegrain (Night observation) -Camera: Apogee (27microns pixel size) -Optics: f/6 (focal length: f=3600mm) -Operation: Remote, Autonomous Control My observations: -School observatory at the secondary school -Location: Heerbrugg (Switzerland) -Type: Meade LX-200 (40cm diameter) -Camera: CCD ST-10E -Optics: focal length f=4000mm page 6

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Algorithm to the observation of asteroids First, calculate or find the ephemerides from the asteroids. Download reference pictures from the Digital Sky Survey to find the asteroids during the observation. Focus a known bright star near the asteroid (it‘s important that the star isn‘t far away so that the main mirror doesn‘t change, in order that the focusing remains). Move the star into the middle of the ccd-image and match the coordinates. Go to the calculated coordinates of the asteroid. Choose an appropriate guiding star in the second ccd-chip. Take as many ccd-images as possible with an adapted exposure time. page 7

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Algorithm to the analysis of the CCD-Images Reduction of the images (Flatfield (FF), Dark, Bias). Find out the parameters for „Astrometrica“ in order to astrometry the images (Right ascension and Declination). Photometry with the software „Maxim DL“ (choose some reference stars and the asteroid as a moving object). Calculate the rotation duration of the asteroid using the light curve and reference stars. To calculate which part of the sky is visible on the photographs (how many degrees chip-size they are). etc. 1.) Reduction: Because there is always some dust on the CCD-chip, the different sensitivity of the individual pixels of the CCD-chip has to be compensated by reducing a Flatfield-photograph (FF) from the original photo. One has to make an appropriate Dark-photograph of the original photo for the HOT-pixels (glowing pixels) in the photographs to disappear. Dark FF page 8

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2.) Astrometry: With the programme “Astrometrica” using the focal length and the pixel size in microns, one can astrometry the images. To arrange the position of the stars in the ccd-images (Right ascension and Declination). animation by B.Burtscher page 9

E.1) Result of the analysis of 2017 Wesson: 

E.1) Result of the analysis of 2017 Wesson Speed of 2017: (2004-06-09) between the pictures at 22:59:20 UT and 23:53:00 UT (difference of 220 seconds), the asteroid covered a distance of about 0.000581° 0.0059 ’/min Estimation of the size: 2017 Wesson has a diameter of about 256.8 km With the distance to the asteroid of 0.974 AU one comes to a speed of approximate 6.711km/s. Using that the earth has a speed of 29.3 km/s, I came to a speed of about 22.589 km/s (reference value: 22.5km/s) ccd-images: © Sky-Watch animation: by B.Burtscher page 10

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Rotation duration and Magnitude of the Asteroid 2017 Wesson I calculated a rotation duration of: 1h 55min 47s With the magnitude of the reference star2 (Ref 2) of 12.5mag, I calculated an average brightness of the asteroid of 14.42 mag (on the 9th of July 2004). page 11 The illumination of the asteroid regularly changes because of its rotation.

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E.2) 2003 UB313 (http://news.bbc.co.uk/1/hi/sci/tech/4730061.stm#map) IAU Circular 8577 announced on July 29, 2005 the discovery of three relatively bright trans-neptunian objects by M. E. Brown, C. A. Trujillo, and D. Rabinowitz using the Palomar 1.2-m Schmidt telescope. One of these objects, 2003 UB313, appears to be as big as or slightly bigger than the planet Pluto. The object's distance from the Sun varies between about 38 AU (1 AU is 150 million kilometers) and 98 AU, which is also close to its current distance. Its orbit has a period of about 560 years and is even more elongated and more inclined than the orbit of Pluto. © Mike Brown ( http://www.gps.caltech.edu/~mbrown ) page 12

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The discovery of 2003 UB313 has precipitated the need for a precise definition of a planet in order to decide whether 2003 UB313 is to be classified as a planet or not. Until then the object will not be given an official name by the IAU. © Mike Brown ( http://www.gps.caltech.edu/~mbrown ) 2003 UB313 – asteroid or the tenth planet? page 13

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To continue my work, I could analyse more images of the asteroids in order to specify the rotation duration as well as their size more precisely. F) Future Work It could also be very interesting to analyse the spectroscopy of the two asteroids to compare it with reference values. (By looking at the reflected sunlight, one can study the composition of the objects.) © Mike Brown ( http://www.gps.caltech.edu/~mbrown ) page 14

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F) Future Work Therefore I would like to get more observations of the asteroid 2003 UB313 in order to calculate the rotation duration with photometry calculate the speed estimate the size And I also would like to get spectroscopic analysis of the asteroids in order to study their compositions. During the next months, I am observing the new discovered trans-neptunian object 2003 UB313 as well as other asteroids on the school observatory in Heerbrugg (Switzerland). To compare the results with reference values. This would help me learn more about these two asteroids and of which matter they are composed. page 15