Astrophotography with small telescopes

Home Articles New Comets Gallery Southern Sky from Namibia Astronomie (Deutsch) Author + Equipment Other pages Service

Comet Photography

Many amateur astronomers in the world waited long for the comet of the century Hale-Bopp. And it gave us a great show at the northern sky for several months. It reached perihelion in April 1997 and was a fantastic comet. Many amateurs made images to remember this great comet. Months or years after Hale-Bopp disappeared from the norther sky we can just remember the last two big comets, appearing separated by only one year. Comet Hyakutake and Comet Hale-Bopp were the last really big shows. Both reached almost mag. -1 in late March 1996 and the early days of April 1997.

The next bright comet is on its way to the sun. Comet C/2012 S1 ISON hopefully reaches our expectations of a spectacular bright comet due to its orbit that takes it extremely near to the sun. A Comet with such an orbit is called Sungrazer. First observations after its conjunction with the sun were already made and it shows the expected brightness.

Equipment for imaging comets

To get a fast impression of the necessary equipment taking comet images I made a short table sorted by magnitude and the purpose someone might want to reach.

          Recommendation: Monochrome CCD camera, CCD without Anti-Blooming Gate           Result: Image of faint comets with tail

What to know ?

If you have already taken images from deep-sky objects you should also read this because taking photos from comets needs some special requirements.
Normally you guide on a star to compensate the earth rotation. As comets move it is necessary to know how fast it moves and how long you can expose until you get a short streak instead of a fine and sharp image.

To know how fast the comet moves you need a program that calculates the movement from the daily positions.
When you know how fast the comet moves in one hour you can calculate how much it moves during your exposure time.

Download the program Orbitaes for easy calculating. Do the following steps before you use the first time.

  1. Enter your location and geographic coordinates
  2. Select the parameters of your resolution in pixel size or FWHM
  3. Select the format of the result ( seconds or minutes )
  4. Load the latest orbital elements
Do the following steps before you want to take images.

  1. Load the latest orbital elements
  2. Restart the program
  3. Select the comet you want to calculate the possible exposure time

Brighter comets ( e.g. 7 mag. or brighter ) can be exposed a bit longer as calculated due to the larger coma. It depends on the movement and the focal ratio of the used telescope/lens. This needs some experience. If possible, take several images with different exposure times.

You can find more information about imageprocessing, software and data of CCD cameras in my publication "Image Processing for Comets"