Télescope de Schmidt de 48 pouces, soit 122 cm, d'ouverture et de rapport d'ouverture F/D 2,5

POSSII

The STScI Digitized Sky Survey:

The Digitized Sky Survey ( DSS ) comprises a set of all-sky photographic surveys in E, V, J, R, and N bands conducted with the Palomar and UK Schmidt telescopes.

The Catalogs and Surveys Branch (CASB) is digitizing the photographic plates to support HST observing programs but also as a service to the astronomical community.

The 6.5-degree x 6.5-degree plates are scanned using a modified PDS microdensitometer to a pixel scale of about 1.7 arcseconds per pixel for the POSS, SERC,

and Palomar Quick-V surveys, and to about 1.0 arcseconds per pixel for the POSS-II surveys.

Images of any part of the sky may be extracted from the DSS, in either FITS or GIF format.

N.B. The DSS files extracted in FITS format cannot be read by FitsLiberator/Photoshop! They have to be reformated by MaximDL for example.

From "Photoshop for Astrophotographers"
by Jerry Lodriguss:

1) Registering the Images in RegiStar:

Open 2M78B.TIF and 2M78R.TIF in Picture Window.

Operations > Register Register the blue image to the red image.

Operations > Crop/Pad Image uncheck "Trim", and select "Match" and OK the dialog box.

Save the cropped and padded blue image as a 16-bit TIFF file with filename 3M78B.TIF.

Save the original 2M78R.TIF as a TIFF file with the filename 3M78R.TIF. No changes need to be made to this image except the file name.

2) Create a Synthetic Green Channel Image:

To create a color RGB image, the red and blue images must be combined to create a synthetic green image.Photoshop (the 8 bit images must be used):
Open the registered red and blue images, 3M78R.TIF, and 3M78B.TIF.
Copy the red image: Ctrl A, Ctrl C
Paste it on top of the blue image: Click on the blue image, Ctrl V
Open the Layers Palette (Window > Show Layers). Change the opacity of the top layer to 50%.
Flatten the Image with Layer > Flatten Image.
Save with the filename 3M78G.TIF