1 Image taking with a CCD camera Dr. Tibor Torma This booklet introduces how to take images with the SBIG ST-10 camera at the University of Mississipp

10 - = The first issue you will face it is the contrast settings of an image. Each image is an array of 2184 × 1472 pixels, eac

11 / = The various parts of the resulting dark-subtracted images are not equally bright. There are many optical surfaces in a telescope system, and

12 Now you are ready to add images of the same color together. Effectively you will produce a longer exposure image out of a few shorter

13 Review questions It is now time to make sure that the reader understands and remembers the important points of astronomical imaging. The foll

14 6. Learning how to use the camera ● The imaging math In recent years the price of CCD cameras dropped dramatically. Before that, only the lead

15 clipped. It is good practice (whenever doable) to avoid collecting more electrons than that in any one pixel, and one can do that by limiting the e

16 Resolution and image size The resolution of long-exposure images is always limited by seeing. In our circumstances, seeing on good nigh

17 Optional mathematical treatment of dark subtraction and flat fielding 1. The reading on each pixel is N = D + S × L, with dark current D,

18 ● The imaging hardware There is one 12-inch Meade Schmidt-Cassegrain telescope (with a built-in focal reducer f = 1800 mm, f/5.9) reserve

19 (iii) The ST10 camera comes with two built-in chips. The large imaging chip is used to take pictures, and the little tracking CCD (

2 1. Introduction Students in some of the introductory astronomy courses at Ole Miss will be doing a semester project, which introduc

20 (iv) Grab: this is how you take individual images. You can select if you also want dark frames taken and automatically subtract

21 click “yes” when asked.) Use the TELESCOPE tab in the OBJECT panel to PARK the telescope before you switch it off. (v) There is a button for

22 Start up CCDOPS; on the SETUP tab, set the temperature 30oC below ambient temperature and start the cooling. Start up TheSky, establish the link to

23 7. Real-life image processing The basic steps of image processing have already been explained in the section entitled “Introduction to image proces

24 appropriate flats. Recall that the flats must have been taken with the same color filter as the light images; and the camera must not have

25 IX. Now co-add the multiple exposures of the same color (if any) either in CCDOPS or in CCDSOFT. When the same exposure time was used fo

26 RGB channel to bring out the faint parts of deep-sky objects, while keeping the bright stars still colorful. It will take much experimenta

27 The report Students are asked, within two weeks after all raw images are taken and darks and flats are available, to write and turn in a two-three

28 NGC 6946: a spiral galaxy Located in the constellation of Cygnus, NGC 6946 is a 9-g face-on spiral galaxy. In a 12-inch telescope under very da

29 Galaxies are the main building blocks of the Universe. They are congregates of hundreds of billion stars; the whole universe is built of

3 2. Generalities: why CCD? The single most important challenge facing all of astronomy is how to extract information from the little ligh

4 images), it is black and white (which increases sensitivity to faint light), it is stable and linear (so it does not lose electrons d

5 3. A tour of the sky The only way to really appreciate the achievement that the use of CCD’s represents is to look at the sky first the way everyone

6 the glasses getting in the way. Get rid of them: always take off your glasses for telescopic observation, and use the telescope’s focuser to correct

7 4. Observations and weather Atmospheric conditions matter much in astronomical observations. It is absolutely necessary for students to und

8 but not dark blue; grey toward the horizon; and the setting Sun is yellow but it does not vanish behind clouds long before set

9 5. Basics of image processing When an astronomical CCD camera is used to record light, it always comes in the form of a digital image on a com