How can I use my current camera whose zoom lens can't be removed behind an f/6 refractor for as an astrophotography? I am looking at an Astrotech AT60ED (60 mm f/6 with a field flattener) and a Digi-Kit telescope adapter to do astrophotography, mainly deep-sky and I'm wondering if I can use my current Panasonic DMC-FZ50 Type CCD camera body.

The problem is that it has a zoom lens that can't be detached which is why I am worried.
The AT60ED is a nice small refractor. However, its objective lens simply projects an image at the focal plane. Adding a field flattener mimimizes curvature that degrades sharpness at the edges of the image. The flattener requires a specific back-focus, or distance (about 57 mm for the AT60 FF) between its (T2, 42 mm thread) flange and the image plane where the sensor should be located.

If your camera has a non-removable lens, its sensor cannot be placed directly at the focal plane. You cannot just attach your lens to the telescope or field flattener to take an image.

I believe that the only alternative for a camera with lens is to use eyepiece projection, also called digi-scoping. An eyepiece magnifies the image at the refractor's focal plane and projects it, usually so the eye can then focus the image on the retina. Instead, if a camera is attached to the eyepiece using a suitable adapter, its lens can then focus the image.

Eyepiece projection also has disadvantages, including a small field of view, vignetting, and often balance issues due to the camera weight and adapter attached to a small eyepiece, rather than directly to the focuser of the telescope. However, lots of people use eyepiece projection just by holding their cell phone camera at the exit pupil of the eyepiece.

Edit:  Added some comments regarding deep-sky imaging.

Also, deep-sky imaging presents additional challenges. The Moon and planets can be photographed with short exposures. However, images of even the brightest nebulas and galaxies require long exposures. Astrophotographers usually take a large number of individual images, called sub-exposures, each typically lasting tens of seconds to many minutes. These are then aligned and stacked to improve signal to noise by averaging. Total integration time can often be several hours or more, depending on the brightness of the object.

A telescope mount that can accurately track a celestial object, compensating for the Earth's rotation, is necessary to prevent motion blur over these long exposures. The cost of a mount suitable for even a relatively short focal length refractor such as the AT60ED will be several times the cost of the telescope, and much more than a camera capable of prime focus astrophotography.