4. Hints for asteroid detection
There are almost limitless number of stars in the night sky. However, there are many more objects, which are too dim to be viewed with naked eyes. They are asteroids. They are so dim that even the use of telescopes will not allow you to see them.
How do we detect them?With this Asteroid Catcher B-612 anybody can find asteroids. We hope you will enjoy finding asteroids !
They are literally small planets. The largest asteroid is the Ceres and its diameter is approximately 910 km. However, most of asteroids are much smaller in diameter and range from a mere few hundred meters to a few kilometers. The smaller the size the greater the number of such asteroids exist.
Currently, we have accurate orbital information on nearly 30,000 asteroids. In addition, we have orbital information less accurate on more than 100,000 of them. If we include those which we have observed only once, the number will jump up to more than 200,000. They are small in size, but they are the main players in our solar system.
The first asteroid was found on 1st January 1801 at an astronomical observatory in Palermo on the island of Sicily in Italy. It was named after the Goddess of the island, Ceres. It was found halfway between the orbits of the Mars and the Jupiter. Subsequently, many more have been found in similar orbits.
The orbit in which we find most of asteroids between the Mars and the Jupiter is called the asteroid belt. However, some asteroids are found outside the belt, sometimes even outside the orbit of the Jupiter or inside the orbit of the Mars. We pay particular attention to those that orbit inside the Mars orbit as they may collide with the Earth. They are major targets for the observation at Bisei Spacegurad Center.
Until recently, we observed asteroids only through telescopes, but today we can send space probes to asteroids and get close up photographs. Some asteroids have been found to be shaped like potatoes.
The world of asteroids is still surrounded in mystery. We remain very interested in further discoveries.
4.3 From Detection to Registration
Just as the pocket monster grows from "peechyu" to "peekachyu", then to "reichyu" asteroids are also called with different names throughout the stage of being detected. (The names of pocket monsters mentioned here are Japanese ones.)
Asteroid detection process is as follows.
Stage 1 ---- Personal designation (just discovered)
The discoverer or discovering group of the newly found asteroid can give a sorting code. Normally, it is a combination of alphabets and serial numbers.
In the project using Asteroid Catcher B-612 it is assumed that the personal designation is an alphanumeric of less than seven digits. For example, you may use any arbitrary combination of 4 alphabetical characters of your own choice followed by a 3 digit serial number.
Examples: BSGC001, BSGC002, BSGC003 etc, or UFO800, UFO801, UFO802 etc.
Stage 2 ---- Provisional designation (unnumbered asteroids)
This is the sorting code given by the Minor Planet Center. It is given to an asteroid whose orbit is not yet clear. Asteroids at this stage are called "unnumbered asteroids". You need a minimum of two night's observation in order to get this code.
Examples: 1998 RX25, 2000 UV13 etc.
Stage 3 ---- Registration number (numbered asteroids)
This is the registration number given by the Minor Planet Center and is given to asteroids whose orbital information is accurately known. They are called "numbered asteroids".
Examples: (1), (1862), etc.
Stage 4 ---- Unique name (numbered asteroids)
This is a unique name is given by the Minor Planet Center. Advice on naming from the discoverer is considered. Naming can be made once a registration number has been assigned.
Examples: Ceres, Apollo, etc.
As you can see personal designation can be freely given by the discoverer or discovering group. However, beyond that stage all subsequent sorting codes will be given by the Minor Planet Center, and once given they become formal names. Unique names are also supposed to be given by the Minor Planet Center. However, it is customary that discoverer's advice is accepted after an assessment if there is no reason for objection. This is meant to pay respect to the effort made by the discoverer.
In early days when the number of asteroids found was small names with origins in the Greek myth were frequently used. Nowadays we seem to encounter many unique names. Usually, those named asteroids with corresponding registration numbers are denoted like (1) Ceres, (1862) Apollo. On the other hand those properly registered without names are often denoted like (17286) 2000 NB6.
Asteroid Catcher B-612 is designed to help you find asteroids with ease. It uses more than one sky images of the same area and displays them in quick succession (blinking) alternately so that objects moving against the background of stars such as asteroids and comets can be found with accurate positional information. You can get the image data either via Internet or on CD-ROMs from Bisei Spaceguard Center. The method of obtaining data will be different from one project to another. Once you have the image data you are ready to use Asteroid Catcher B-612. Please note that the CD-ROM, which contains "Asteroid Catcher B-612" also, contains sample images for your practice.
Asteroids circulate in elliptical orbits around the Sun, and when viewed from the Earth they appear to traverse the night sky against the background of stars. Thus, blinking more than one images with respect to reference stars will show up asteroids as moving objects. If you use more than two images you will be able to see the motion of asteroids more clearly.
That is how "Asteroid Catcher B-612" works. We hope that you will be able to find as many asteroids as you can and have some fun in doing so.
Example of moving objects
Beware of excessive viewing for your own health!
The motion of normal planets and asteroids is, when viewed from the Earth, from the west to the east. However, some may move in the opposite direction and some may even appear stationary before changing directions.
The relative motion of asteroids against the background can be very small or very large depending on the distance from the Earth, relative positions of the asteroids as well as the characteristics of the imaging device. In some cases you cannot detect motion at all due to the short time intervals used.
As you may see from the figure below the distance to an asteroid becomes least as the Earth overtakes them. At this stage it is located at the opposite end from the Sun. The asteroid is then fully reflecting the light from the Sun and is very visible. This is the best time for detecting usually very dim asteroids.
4.5 You may find other interesting objects
Long time ago people thought that the universe was stationary. Today, we know that it is not and in fact we know that the universe is constantly changing. It is therefore only natural that "some previously undetected moving (or changing) objects are recorded" on the vast amount of image data obtained by the Bisei Spaceguard Center.
Such objects other than asteroids are usually comets, supernovae and variable stars.
Comets move about the Sun just like asteroids, and usually they appear as fuzzy blobs like galaxies at a large distance. As they approach the Sun and become brighter they appear to have long tails. If you find fuzzy moving objects on your image data please suspect that they are new comets.
However, it is possible that they are known comets or simply noise due to the cryogenic CCD camera. You must be careful. You can obtain orbital information on known comets from magazines on astronomy. You can also obtain information from the home page of the Minor Planet Center.
Supernovae are explosive phenomena at the end of evolution of stars. They are rare and are found on average once in a few hundred years within any one galaxy. In fact, with our own galaxy no supernova has been detected since 1604 when a supernova called Kepler's supernova was detected in Ophiuchus.
However, there is almost limitless number of galaxies on your image data. Even if, with any one galaxy, it is rare to observe supernovae you can still expect to find them with other galaxies. Checking for supernovae is easy. All you need to do is to compare the images of the same galaxy taken at different times and look out for a new bright star in or around the galaxy. You can find the images of galaxy, for example, by clicking here.
Variable stars are the stars whose apparent brightness changes with time. There are different reasons for changing brightness. In some cases stars are periodically swelling and shrinking. In other cases they may be a binary with one star rotating around the other so that they appear like eclipsing when viewed from the Earth.
Their brightness usually do not change overnight. Therefore it is not easy to find them from a series of images taken at short time intervals. However, with care and patience you may find them if you compare images separated by a few days.
Digital CCD cameras are very popular these days. For serious astronomical use we also use cryogenic CCD cameras so that we can record astronomical objects over a long exposure time. Long exposure leads to an increased amount of noise. However, cooling the CCD chip reduces noise.
Unfortunately, cooling does not completely remove the noise. CCD chip consists of a large number of photo receptors called "pixels". For example, each image on your CD-ROM consists of a collection of some 4.19 million pixels. Some of these pixels are more photosensitive than others. Some may be faulty and do not respond to light at all.
These may be regarded as "noise". Noise is a nuisance when we examine our image data. Sometimes they appear just like asteroids. We need to be very careful.
