Meade Image Processing Instrukcja Użytkownika Pobierz pdf (Strona 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 been rotated in the time between. The

only way to be sure of that is to look up the “Notes” files, which indicate the camera

orientations for each night.

IV. The original files on the server cannot be changed, nor can students save anything in

this area (it is write protected). The correct place to put your files is the assigned work

area on the server. The “STUDENTS WORK HERE” shortcut opens the area on the server. (You

will see the path “\\Phys252.phy.olemiss.edu\astro\Student_Work” as the ADDRESS.) It is

advisable to put all your files there instead of some location directly on the computer,

because only when you work directly on the server will you be able to access your files

from a different computer. So start your work by creating a folder there with your and

your partner’s names (such as JaneDoe_JohnDoe), and copying all the original files you

might want to use into your folder.

V. Keep in mind that you should never double click on any picture (CCDOPS, CCDSOFT,

and PHOTOSHOP will be all mixed up if you do.) When you want to open an image, start

the software first, and then use the FILE→OPEN menu, or drag the file icon over the

software’s window.

VI. Your first step should be to make an inventory of all the images taken of your object.

You’ll have to open all the “Note” files, including those that were taken at different times

in the semester from your date, to see who else took images of the same object, and to

decide on which flat frames were taken with the same orientation as your images. Make a

table of all relevant files for yourself, and copy all these files into your folder. You may

want to rename some of these files (to avoid duplicate names), carefully recording the

changes.

VII. You will start with the standard basic processing of each image. Locate the

appropriate dark frames and flat frames to be used for your images. Unless you are using

darks from the library (recall that you need darks with the exposure time and temperature

matching the light frames’), use CCDOPS to median-average multiple dark frames. Inspect

your flat frames, and do not use those whose brightest parts have a pixel reading over

40,000 – these are overexposed and incorrect. Then each individual light frame must be

dark-subtracted, then flat-framed; then use hot and cold pixel removal; you can use either

CCDOPS or CCDSOFT for this. A routine of CCDOPS called “Remove blooming streaks”

comes in handy when there are overexposed stars on the image. Save each step under a

new name and keep order, so you can return to an erroneous step and correct it. The

resulting frames should look good with appropriate contrast settings.

VIII. The next step is aligning. Put a copy of all your images that will go into one

picture (multiple images, and different colors all together) in a new folder and call it

something like “Aligned”. Now open each of the images in your “Aligned” folder in

CCDSOFT. Use the “pin” to mark the centroid of the same star on each image. Then use

ALIGN CENTROIDS. You will see that the images are shifted for the star to match on each.

Save the images.

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Meade Image Processing Instrukcja Użytkownika Strona 24