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De-Coding Starlight: From Pixels to Images - High School

#### Student Handout

The Scenario

You and your partner have just discovered a brilliant new supernova remnant using the Chandra X-ray Observatory. The Director of NASA Deep Space Research has heard of your discovery and wants a report of your results in her office in 45 minutes. Unfortunately, your computer crashed fatally while you were creating an awesome image of the supernova remnant from the numerical data. Because the NASA director always wants to see cool images (not numbers) of newly discovered objects, you and your partner will have to create, by hand, an image of the supernova remnant.

To create the image, you and your partner will have to use "raw" data processed from the Chandra satellite. You have tables of the data, but during the excitement of the computer crash, you spilled soda over some of the information and will have to recalculate some values.

In addition to the graph, you and your partner will have to prepare a written explanation of your discovery and answer a few of the Director's questions.

Before you are ready to present your findings to the NASA director, you will need to complete the following three tasks.

1. Your mission is to turn "boring" numbers into a super-cool picture. Before you can make the image, you will need to make some calculations.
2. The raw data for the destroyed "pixels" (grid squares containing a value and color) are listed in Table 1. Before making the image, you will need to fill in the last column of Table 1 by calculating average X-ray intensity for each pixel.
3. After you have determined average pixel values for the destroyed pixels, write the numerical values in the proper box (pixel) of the attached grid. Many of the pixel values are already on the grid, but you have to fill in the blank pixels. This is the grid in which you and your partner will draw the image.

Task B: Coloring the Image You and your partner will need to complete the following steps in coloring the image. Important Note: Read all the instructions carefully before you start coloring!

1. You are allowed to use five and only five colors in drawing your image.
2. Each of the five colors will represent a range of intensity values. You and your partner should select the range of intensities assigned to each color. Fill in these range values and associated colors on the legend at the bottom of the image grid sheet.
3. Hint: as you assign colors to ranges, it is best to pick colors that are "close" to each other as you move from one range to another. For example, in the range with the lowest intensities you may assign the color red. In the next lowest range, you would then assign the color orange, rather than indigo. Before proceeding, have the instructor check you assigned colors.
4. Using colored pencils, shade in the grid using your color legend.
1. On the back of the image, write a detailed description (1-2 paragraphs) of the prominent features of the supernova remnant. Be sure to describe how the image shows a neutron star, a fast outer shock wave, and a slower inner shock wave.
2. Include an artist's impression drawing of what the actual supernova remnant would "look" like.
3. The NASA director has the following specific questions about your findings. Answer these questions on the back of the image.
1. In the table, some of the data were missing. In 3-4 sentences, describe how you "handled" these missing data in making your calculations and coloring your image.
2. Because your computer crashed, you had to draw the image by hand. In 3-4 sentences, explain why would it have been easier to use a computer? (In your answer, consider that the Chandra satellite actually sends millions of data from each observation and how long it would take to process millions of data by hand.)

Table 1. "Raw" data of the newly discovered supernova remnant collected from the Chandra X-ray Observatory.

Missing Grid Coordinate Number of X-ray Photons Detected Average Number of Photons
Observation 1 Observation 2 Observation 3 Observation 4 Observation 5
A4 39 40 40 42 42
B6 59 61 62 60 58
B7 62 71 missing 63 missing
B8 64 68 71 71 72
C3 50 54 52 50 54
C6 33 missing missing 31 38
C10 64 63 61 64 missing
D2 41 missing missing missing 43
D6 104 missing 105 108 108
D7 140 144 142 141 137
D10 62 50 57 50 52
E7 41 43 43 36 40
E8 214 210 210 210 214
F2 missing 49 49 47 47
F4 153 missing 154 155 156
F6 148 135 missing missing 130
F8 152 141 147 145 144
G2 49 51 48 50 missing
G4 130 123 missing missing 124
H2 51 49 53 50 50
H3 34 25 38 31 26
H4 115 114 missing 128 123
H6 95 97 missing missing missing
H8 115 115 115 113 112
H10 73 83 missing 80 81
I3 missing 39 35 37 42
I5 58 69 54 missing 65
I9 68 77 80 81 missing
J6 46 49 55 missing 48
J7 61 69 79 74 54

Supernova Remnant Image Grid

A B C D E F G H I J K
1 0 1 1 1 1 1 1 1 1 1 1
2 2 5 35
48

46 18 7
3 23 36
35 30 27 21

13 0
4
43 24 8 216

54 21 3
5 36 58 37 44 36 20 33 105
23 4
6 32

12
18
24
17
7 24
32

17 12 126 64
21
8 18
36 237

155
22 74 6
9 16 75 38 34 26 12 14 21
37 4
10 8 71

42 23 64
31 16 2
11 3 3 2 1 0 0 2 0 1 0 0

Legend

Average number of photons

Color