© Sierra College Astronomy Department1 Photographing the Sun and Moon (II-C) Prime Focus Photography

2 Additional Topic Slide, if needed Universal Time

Fun Solar Facts s As viewed from the Earth, the Sun has an average angular diameter of 31´ 59” and is at an average distance from the Earth of X 10 8 km which is defined as 1 Astronomical Unit (AU).

Safely viewing the Sun s Pinhole projection s Eyepiece projection on a piece of paper s Through a proper solar filter  Ex: Mylar; #14 or greater welder’s glass s Through a telescope with a solar filter in the front of the telescope

Calculating the Size of the Sun R Sun D d r s By using the solar projection device we can calculate the linear size of the sun Projection of sun Pinhole projector  = 1.50 x 10 8 km = 1 m

The Corona as seen during a total solar eclipse

Sun in Optical Sun in UV nm 28.4 nm

© Sierra College Astronomy Department8 Total Solar Eclipse Total Solar Eclipse on August 21, 2017

s One can also use the afocal method s Use a camera mount to attach the camera to the eyepiece or use a tripod to point a camera towards the eyepiece  Camera looks directly into the eyepiece, just like your eye would. u Vignetting can be an issue Vignetting  The effective focal length of the camera + telescope: Taking pictures of the Sun and Moon – using the afocal method

Afocal setup © Sierra College Astronomy Department10

Procedure - Terrestrial s Use Prime Focus to take pictures of something outside (the further away the better). Use the focal reducer. s Use the afocal method to take pictures of the same target. Use the smaller 50 mm lens and the 40 mm eyepiece. s Download pictures! s Answer questions #1 and #2 in Lab 11

Taking pictures of the Sun and Moon s USE A PROPER SOLAR FILTER TO VIEW THE SUN! s Even with a 400-mm telephoto lens, the image of the sun or moon on the digital camera sensor is still fairly small s Use the telescope as a telephoto lens: Connect a camera with T-adaptor and T-ring  Prime focus photography  T-adaptor connects to telescope  T-ring connects to T-adaptor and camera  Use Focal Reducer to get all of Sun onto digital sensor

Procedure - Solar s Set up telescope and align it North. s Go through the star alignment procedure up to the point before the telescope slews to the first alignment star (through step 8 on star alignment guide). s Put on solar filter and manually move telescope to look at sun (by minimizing the shadow). Lock down telescope and move telescope by hand control. Then….  Prime Focus: Take off diagonal and put on focal reducer. Then put on the T-adapter and T-ring attached to camera onto the focal reducer and then adjust the focus of the telescope THEN s Have afocal apparatus set up (eyepiece + camera mount) and place it into the telescope. Keep extended camera lens about 5 mm from the eyepiece.  Focus camera and then focus telescope. Use focal length of 50 mm fixed lens Adjust camera-eyepiece to avoid vignetting and seeing the secondary mirror.

Procedure - Solar s Use Prime Focus to take pictures of the sun. Use the focal reducer and solar filter. s Use the afocal method to take pictures of the sun. Use the smaller 50 mm lens and the 40 mm eyepiece. s Download pictures! s Answer question #3 in Lab 14

© Sierra College Astronomy Department15 Prime Focus with C-8 and focal reducer

The Sun afocal

Vignetting and seeing the secondary mirror afocal

The Sun afocal

Sun Halo

Sun Dogs

Anatomy of the Sun

© Sierra College Astronomy Department22 Sunspots and the Solar Activity Cycle s Dark spots on the Sun were first reported by the Chinese in the 5 th century B.C. s Galileo and Thomas Harriott were the first Europeans to report these sunspots in the early 17 th century. s Sunspots are about 1,500° cooler than the surrounding photosphere and hence appear to be black.

Lab II-C: Epilogue Calculating the Size of the Sun R Sun D d r s By using the solar projection device we can calculate the linear size of the sun Projection of sun Pinhole projector  = 1.50 x 10 8 km = 1 m Green Book Q #3: Using the solar projectors and knowing that the Sun is 1.50x10 ­ 8 km away from the Earth, what is the diameter of the Sun?