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Hubble Top Star

Top Stars
           “Make an HST Photo”           
How Tocolor.html


In the spring of 2009, we offered an elective astronomy course where students used real astronomical images to conduct original research projects. Using data from a variety of small ground-based telescopes the students searched for asteroids, produced supernova lightcurves, and measured the distance modulus of open clusters. While working on these research projects, the students mastered the process of reducing, calibrating, and aligning astronomical images. For part of their final exam, I asked the students to take raw images from the Hubble Space Telescope and use them to produce a beautiful color image like the ones they have seen on posters and television. This final exam was not a recitation of facts or vocabulary terms, but rather was a formative opportunity for students to be like an astronomer working with the Hubble Space Telescope.


Our Top Stars entry is the final exam to a rather unusual course. This astronomy elective course was the second trimester of astronomy for most of the students. The entire course was centered around the goal of conducting original astronomical research projects with real data from telescopes. The first project that all students performed was making a color astronomical image. This project taught the students how to plan an observation, collect astronomical images, calibrate the images through dark subtraction and flat fielding, align the images, and combine multiple filters to make a "true color" image. You, too, can perform these steps to make a color astronomical image, or even try it as a class project. View this page for instructions. For my course, I asked the students to make a small webpage describing how they created their image as well as the science revealed through the picture. I used this rubric (pdf) to grade the student’s project.

After this initial project, the students broke into teams to conduct research projects of their choosing. Students hunted for asteroids (with great success), produced supernova lightcurves, measured the distance modulus of nearby open clusters, and even hunted for extrasolar planets. The students were able to make some exciting discoveries with one group even publishing their results in an astronomical journal.

Every day, the class met in our school computer lab where they used the open source program, ImageJ. Using the variety of astronomical functions within the program, the students mastered the techniques required to manipulate and analyze astronomical images. I could think of no greater application of their new-found mastery than to ask them to act as a professional astronomer and use images from the world-class Hubble Space Telescope. For their final exam, I asked the students to produce a beautiful color image from raw HST images.

The Final Exam

Below are the only instructions that were given to my students for their final exam.

I allowed them to use their individual research notebooks for support.

Make an HST Image
For your final project in astronomy class, I would like you to try your hand at making a beautiful color image from Hubble Space Telescope data. Below you will find links to download three raw images of the Ring Nebula (M57) from Hubble, one with each of Red, Green, and Blue filters.

Notice, there are no darks or flats. 
The data from the Hubble archive is available already reduced.

HST Images
(Note for Top Stars: The images are included here as .jpg files so that you can view them without special software.)

M 57 Blue.fits
M 57 Green.fits
M 57 Red.fits

You will need to adjust the three images, align them, and turn them into a beautiful color picture. Once you have completed your best version of the image, save it as a .jpg and email it to me.

Along with your email, I would like you to answer the following three questions.
1. What make the Hubble Space Telescope one of the most powerful telescopes at our disposal?
2. HST is located in the vacuum of space. How might this impact the need for calibration such as dark subtraction and flat fielding?
3. Look up an HST photo of the Ring Nebula (M 57) online (type "HST ring nebula" into a Google image search).
a) How do you think this photo compares to the one that you made?
b) Which do you feel is more realistic? Why?topstars_files/M%2057%20Blue.jpgtopstars_files/M%2057%20Green.jpgtopstars_files/M%2057%20Red.jpgshapeimage_5_link_0shapeimage_5_link_1shapeimage_5_link_2

Student Results


1. What make the Hubble Space Telescope one of the most powerful telescopes at our disposal?

"There is no air in space, so you don't get the same effects in space as you would in the Earth's atmosphere. The Earth's atmosphere moves in front of the camera causing scintillation which blurs the images and potentially ruins them. In the vacuum of space, the Hubble Space Telescope gets the sharpest images possible even though it isn't the biggest telescope."

2. HST is located in the vacuum of space. How might this impact the need for calibration such as dark subtraction and flat fielding?

"The fact that it is cold in space could negate the need for a dark subtraction because those tiny electrons won't be bounced around due to heat in the camera. This would eliminate those speckles that appear in the images from the electrons being dislodged. In the vacuum of space, there may also be no need for flat fielding because there will not be any unwanted dust or other particles floating around and landing on the telescope." (Note: Flat-fielding of HST images is still required to remove vignetting and sensitivity variations across the detector.)

3. Look up an HST photo of the Ring Nebula (M 57) online (type "HST ring nebula" into a google image search).

a) How do you think this photo compares to the one that you made?

"It looks nearly exactly the same. My picture has stronger, brighter colors, especially more blue. Their picture is rotated and the nebula is shown at a different angle, but this hardly makes a difference in the appearance of it. My picture seems to have a lower variety of colors because I've made them very bright. On their image, there appears to be 5 significant shades of color. On mine, it is pretty much just 3-4 shades. I will attempt to create this more multi-dimensional impression of the ring nebula with my extra time on this exam."

b) Which do you feel is more realistic? Why?

"Their pictures are probably more realistic as to what the nebula would look like to a human eye, but my picture looks way cooler cause the colors are so sweet and bright. What particularly makes their image more realistic is a shade of pink between the red and turquoise rings which I am so far unable to accomplish creating. On my images this shade appears more orange and I am unable to get it to look how they have it. Their image is also more realistic because the stars behind and in front of the nebula show up as bright white, whereas in my image they show up as slightly brighter blue specks."

National Standards Addressed

This project closely aligns with the inquiry-based recommendations of the National Science Education Standards. In particular, the following standards are addressed directly by this project:

NS.9-12.1: Science as Inquiry

            a. Abilities necessary to do scientific inquiry

            b. Understandings about scientific inquiry

NS.9-12.4: Earth and Space Science

            d. Origin and evolution of the universe

NS.9-12.5: Science and Technology

            b. Understandings about science and technology

NS.9-12.7: History and Nature of Science

            a. Science as a human endeavor

            b. Nature of scientific knowledge

NT.K-12.6: Technology Research Tools

            b. Students use technology to process data and report results.

NT.K-12.3: Technology Productivity Tools

            b. Students us productivity tools to collaborate in constructing technology-enhanced models, prepare publications, and produce other creative works.