The image shows Messier object number 51 or better known as the Whirlpool Galaxy (NGC 5194). It was observed on 25th of June with the 14" Maksutov-Cassegrain telescope on Schauinsland. The galaxy with an estimated diameter of about 50 000 lightyears lies in the constellation Canes Venatici. It is a spiral galaxy and recently encountered another dwarf galaxy (NGC 5195), which is visible next to it. The encounter is believed to have happened about 500 million years ago and is responsible for the pronounced spiral arms.
To obtain this image two special techniques were used. First, the image is a composite of four images: three color images with red, blue, and green filters (RGB), and one white light image. The white light image is also known as the luminance image (L) which helps to enhance the contrast. Each image was exposed for five minutes. The resulting image is then called a LRGB composite. This technique can help in obtaining color images for darker objects.
The second technique used is auto guiding, a common practice in astronomy. A second telescope mounted to the main telescope is used to observe a star, during observation. With the help of a camera and software these images are used to calculate and correct any drifts of the field of view. This is done by sending commands directly to the mount of the telescope which then moves to the correct position. With this technique it is possible to obtain minute long exposures even with telescopes of long focal lengths....