Science Lab - $20

The NED website entry page: http://nedwww.ipac.caltech.edu/

Choose “By Name” under “Objects” and this screen pulls-up:

Type in the object name, as listed in the date sheet (e.g. NGC 3310), and click “Submit query.” As an example, I have typed in LMC (Large Magellanic Cloud). The screen will look like:

Notice the blue box along the bottom of the above screen shot. To the left of it is a small image with the “Images” link underneath. Click on the link; this will open-up a new window/tab that will look something like this:

Scroll down and look at the thumbnail images along the left. Find one that is in color. If you find one, check the 5th column (Band, Wavelength) to see if the color on the image corresponds to visible light or if it is representative.

For example, sometimes an image is in color, but the color corresponds to the intensity of the light, or to different wavelengths outside of the visible light spectrum. Some color images are from the 2MASS, which stands for the 2 micron all-sky survey. The visible light we see has a wavelength of roughly 400 to 700 nanometers, or billionths of a meter. A micron is a millionth of a meter, or a thousand times larger in wavelength than visible light. This puts it in the infrared part of the spectrum. So the color in the 2MASS images are referring to differing infrared wavelengths.

Thus, when you find an image that appears to be in color, look in the 5th column, labeled “Band, Wavelength.” If there is a V with a number either between roughly 400 nm to 700 nm, OR 4000 Å to 7000 Å (Å = angstroms, or 1/10 nm), then it is within the visible part of the spectrum and can be used.

If there is a color image for the object, describe in the data sheet what colors you see in the column labeled “Your observed color”. If there is no image available, write “NA” on your data sheet.

Even if there is no color image, do look at the images of the galaxy. By looking at it, determine what type of galaxy you think it is: elliptical or spiral. Write that answer in the “Galaxy Type” column of your data sheet.

You are now done with this screen/page/tab/window and may navigate away from it by either closing it or just switching back to the previous screen shown on page 3.

Referring to the screen on page 3, notice the blue box along the bottom towards center. Click on that blue box. This will either open a new window/tab (if you closed the previous one) or change the “images” screen (if you only navigated away from it without closing it) found on page 4.

<scroll down to the next page>

This tab/window will look something like the one below:

Scroll down and you will see something like this:

In the 2nd column (Observed Passband), look for the BT and VT magnitudes (labeled as B (B_T) and V (V_T), respectively). Record these in the data sheet. (As an example, B (B_T) is in the 5th row.) Switch back to the first tab/window (on pg. 3) and click on “spectra (to the right of the blue box).

VERY strange that the LMC has no spectra!! Some of the objects on the data sheet may not, either. But those that do, record the number of emission lines you see and a short description of it. You may want to include the wavelength range (listed along the x-axis). Also, under the “Spectra?” column on the data sheet, type “yes” if it does have a spectra and “no” if it does not.