# Analyzing Photographs

We will analyze the photographs you took of constellations. Form the same groups as you made that week.

• Identify the pictures
• Find the cardinal directions
• Compare with your visual charts
• How many degrees does your picture cover?
• List the constellations falling within each picture
• Can you find stars of different colors?
• What is the faintest star you can identify?
• What is the maximum stellar density?
• Any interesting features? Clusters? Nebulae?

First, figure out which slide goes with each exposure you took last week. Make sure you know the direction, exposure time, and time at which each picture was taken. What was the target of each?

Question 1: Make a table of your exposures.

Figure out which way is north in the picture, and which way is east. You may have to re-orient the slide in the projector. When you've figured it out, mark North and East on the slide's mount, using ink and very careful penmanship.

Question 2: Determine the field of view the slides, in degrees.

Compare each photograph with the charts you made by hand.

Question 3: Which one shows more stars?

Using the Edmund Sky Chart, or Sky Map Pro, find other constellations which appear in each picture. If there are bright stars from other constellations, identify them.

Compare your pictures against each other, and against those taken by some other group.

Question 4: Which one has the darkest background? Which has the brightest? What are the factors which affect the brightness of the background? What exposure time would you recommend for future nights?

Look for stars of different colors in your pictures. Find the reddest star, the bluest star, and the yellowest star in the best of your pictures.

Question 5: For each of these colored stars, give
• the name
• the magnitude
• the spectral class
Based on the spectral class of each star, what color would you expect it to be, and why? How does that compare with the actual color?

Using either your Edmund Sky Guide, or Sky Map Pro, find the magnitude of the faintest star(s) you can see in each one of your images.

Question 6: List the name and magnitude of the faintest star you can identify in each photograph, and the faintest star that appears in your drawing. How does this magnitude depend on exposure time?

Are there any additional interesting features in your pictures? Clouds? Clusters of stars? Galaxies? Planets? Airplanes? If star charts show any galaxies, clusters, or other objects in your fields of view, try to find them.

Question 7: Describe in detail any interesting objects in your photographs. Provide information on each object (name, magnitude, class, etc.), and describe its visual appearance in your photograph.