Blinking and measurements
Once you have successfully matched your first image data with the star catalog
you can load other image data files.
Automatic matching is made with image data 2 and beyond.
If you have loaded all image files you can now proceed to blinking
stage by clicking on blink icon
.
You are now ready for detecting asteroids.
Clicking on "Automatic blinking"
will start the process of blinking
(alternate showing of all images).
Blinking speed can be changed by the up and down icon
found to the right of .
If you click on "Manual blinking" icon
you can see images one by one.
Look at blinking images very carefully and try to find moving objects.
You must not be confused by noise. For details on noise please refer to chapter 4.6.
You may find it easier to work with enlarged images. Use following icons.
Display whole image : Whole image is displayed (This is the default setting)
Please note that the displayed area may be limited by the display of your PC. If one whole image cannot be accommodated within your screen you can scroll your image by one of the following methods.
(1) Direct clicking on scroll bar or by dragging the bar itself.
(2) Pressing space bar will move the image across.
(3) Clicking in the grid which is shown upper left
(4) Use arrow keys.
On the blinking window itself you also have a display option icon 
.
Use it when trying to find dim objects.
You can selectively blink your images. Use following icon .
On the blinking window you can see the values of the right ascension and declination where your cursor is currently positioned. You can move your cursor about to see the scale of your images.
NB: Some examples of angular distance are as follows.
From the horizon to the Zenith : 90 degrees
Size of the Plough : Approx. 15 degrees
Three stars of the Orion : Approx. 2.5 degrees
Apparent diameter of the Sun and the Moon: Approx. 0.5 degrees (= 30 minutes)
Daily movement of asteroids : Approx. 0.2 degrees (= 12 minutes)
Apparent diameter of the Jupiter : Approx. 0.7 degrees (= 42 seconds)
Apparent diameter of Pluto : Approx. 0.1 second
Search for known asteroids
| You cannot use this function in this edition. This is because we would like you to enjoy detecting even known asteroids. Followings in this paragraph are just for your information. |
If there are known asteroids within your image their predicted positions will be displayed in a red frame and their names and predicted magnitudes will be displayed in red.
You can search for known asteroids by clicking on
NB 1: Asteroids' names are displayed as follows:. Also, if you click on
detailed information on the known asteroids will be displayed.
(1862) Asteroid registered as one thousand and eight hundred and sixty second 2000UV13 Asteroid registered with provisional designation 2000 UV13 3040P-L Asteroid registered with provisional designation 3040 P-L 5778T-3 Asteroid registered with provisional designation 5778 T-3
NB 2: Accuracy of predicted positions of asteroids
The accuracy of predicted positions of numbered asteroids is pretty high to within a few arc seconds. However, with asteroids with provisional designation numbers you may not find them at predicted locations because information on their orbits is insufficient for accurate prediction. The accuracy differs from one asteroid to another. All astronomical objects in our solar system are under mutual gravitational influence and their orbits are constantly changing by perturbation. Therefore, positional accuracy decreases with time.
Search for moving objects
If you click on this icon moving objects will be marked blue. However, it is you who must decide if they really are moving objects. Sometimes this function fails to mark moving objects. Use your own eyes to find them. (This function can only be used when you have loaded more than one image files.)
About stars
If you click on
objects recognized as stars will be marked red. If you click on
then the objects recognized as stars and those that match with the star catalog will be marked. If matched properly marking will be in red and if matching is not very good marking will be in blue.
Delete markings
All markings will be deleted if you click on this icon
.
If you find an object moving relative to stars in the background, you should measure its position. It is necessary to measure the position of the same asteroid for all the blinking image files. In order to measure the position, put the cursor at the center of the object and click. Its positional information will be displayed immediately at the top of your screen (Following figure).
Of the two lines displayed the lower line shows the positional information you just clicked for and its contents are as follows (From left to right):
| Measurement serial number |
|
Time of observation (Universal Time "UT"). (Hour, minute, second is converted into decimals in units of day) |
| Right ascension (Hour/minute/second. Year 2000 equinox) |
| Declination (Hour/minute/second. Year 2000 equinox) |
| Group name |
| Magnitude (V= Visual magnitude) |
| Observatory code |
| Standard deviation etc. |
The position of the selected objects are determined by using several sets of reference stars. The numbers such as (0.07 0.12) 12 in the right show the standard deviation and the number of times of determinations.
Pixel brightness map
The pixel brightness map is a sky brightness distribution of the objects and the surrounding sky recorded on the CCD camera. You may use the pixel brightness map in one of the following two cases.
(1) Objects are too dim and clicking on them does not give measurements (No red frame appears, which means that automatic measurements is impossible.)
(2) When you want to know detailed information on the pixel brightness and to determine the position manually.
In the case of (1) drag your mouse and draw a blue frame around the object you selected (Next figure), and release the right button of your mouse. It will show the pixel brightness map around the selected object.
In the case of (2) after clicking your object, click on "pixel brightness map" icon
.
Following figure is the pixel brightness map.
Pixel brightness map window
Each number within the cells gives the amount of light that fell on each pixel. Large numbers are bright stars and their surrounding areas.
When the pixel brightness map is displayed drag your mouse, with the left mouse button pressed down, to draw an area which you wish to recognize as a star. Selected area will turn blue and an asterisk is placed in front of the brightness value (following figure). This is the area you select as your star candidate. As soon as dragging stops the center coordinates of the star are calculated and the result will be shown at the top of the matrix.
Brightness matrix
Your drag will initially select a square, but you can make fine adjustments by clicking the left button of the mouse on each pixel (Each clicking corresponds to "on" and "off"). Just after each clicking, the star position will be calculated and the result will be displayed at the top.
You can also make automatic star recognition while on the pixel brightness map itself.
Put your cursor at the center of your target star and click the right button on it.
It will show the result.
If you want to cancel all pixel selection just click on the clear icon
.
This is how you make measurements on the blinking window or on the pixel brightness map. If you are satisfied with the results you then save them on a file.
6.4 Saving measured results on a file
In order to save the result of your measurements on a file, you click on
"Output measured data" icon 
.
Display will change to the following.
You will see the lastly measured data in the frame at the center. This data will be saved on a file.
Selecting astronomical object type
First, select unnumbered asteroid, numbered asteroid, or comet. However, it may be difficult to know what your discovery is. If you want to check the type of the object please use the method explained in chapter 7. If you find it difficult to check, you may just select "Unnumbered asteroid" and give it a personal code as follows.
Naming your object
Once you have selected an object type the next step is to name it and you may do so according to the format as follows.
Above is the case of unnumbered asteroids. In this case a personal code of "SCL001" is being given. Here, you can arbitrarily choose the portion corresponding to "SCL". "001" is a serial number. You can choose any name as you wish such as SCL001 when you cannot identify your object as one of the known astronomical objects.
If your discovery is an unnumbered asteroid with a temporary code just enter that code as the name of your discovery. If, for example, it is the asteroid 2001 AS you enter "2001 AS" or you can also enter just "01AS" and hitting the Enter key will convert that into a proper format.
In the case of a numbered asteroid you enter its registration number such as 1 or 2382. In the case of a comet you should enter the name of the comet according to the IAU formal format. This format is used by the Minor Planet Center.
NB: Please hit the return key (CR) after you have entered the object name. It will insert that name into the top of the data string.
Entering the file name
After you have entered the object name you must also enter a file name. You can use any file name as long as it makes sense to you. Unless you specify your own folder the file will be stored in the folder that was specified when you made your initial setting. You may also use a full path specification such as "C:\NEA\ObsData\AstObs.txt". (You find this file in your CD-ROM. This is a sample file for measurements.)
Finally, clicking on "OK" icon 
will save the result on
the specified file.
If a file already exists with the same name, then data will be added and
if not a new file will be created.
Examples of measurements [IAU format]
> 1 2 3 4 5 6 7 8
>12345678901234567890123456789012345678901234567890123456789012345678901234567890
>
>numbered asteroids ------------
>02382 C2000 06 19.51343 16 45 18.68 -07 01 35.3 300
>02382 C2000 06 19.51860 16 45 18.36 -07 01 28.6 300
>
>unnumbered asteroids ----------
> J87K00L C2000 06 19.50797 15 32 50.88 -19 36 34.3 300
> J87K00L C2000 06 19.51601 15 32 50.25 -19 36 45.7 300
> AB001 * C2000 06 04.66535 18 28 01.17 -10 47 47.9 17.3 V 300
> AB001 C2000 06 04.66762 18 28 00.11 -10 47 49.7 300
>
>periodic comets --------------
>0047P C2000 06 04.74766 20 50 14.30 -34 58 18.1 15.6 T 300
>0047P C2000 06 04.75455 20 50 14.41 -34 58 19.6 300
>
>non-periodic comets ------------
> CJ99S040 C2000 06 04.76306 02 08 06.90 +33 05 53.7 300
> CJ99S040 C2000 06 04.76645 02 08 07.10 +33 05 56.4 300
> CJ99S040 C2000 06 04.76747 02 08 07.07 +33 05 56.7 300
The data format used in AstCat is quite similar to the IAU format. IAU format consists of 80 columns of text with alphanumeric characters. However, with AstCat we added extra columns from 81 to record X and Y coordinates of the object and the name of the image file.
The first 80 columns from the left are as follows.(1) Name of the celestial body
(2) Asterisk at the 13th column indicates the new observation
(3) Date of image acquisition (Time as a fraction of one day)
(4) Right ascension and declination
(5) Magnitude
(6) Color band (V if CCD is used)
(7) Observatory code
Please take care that the same objects are measured more than once in the above example. This is because you must measure the position of the same object for every images that you blink to show that the objects that you find are moving objects.
