Figure 1. Looking east in the Spring the brightest star is Vega, in the constellation Lyra, shown connected by lines. The image is 26x39 degrees, with north to the upper-left. More stars are present in this image than can be seen by the unaided eye. This picture was taken from a site in the mountains nearby, a mere 2200 feet higher than Santa Barbara, yet the sky was so much darker (being above the "boundary layer") that more stars can be seen. The resolution of the original image is much better than this web page version, as shown by the "detail" image below. [Minolta 35-mm camera strapped to a Meade ETX125EC for tracking and occasional manual guiding adjustments, 50mm f/1.7 lens, Kodak Elite Chrome ISO 400 pushed to 800, 4.2-minute exposure.]
Figure 2. Zooming in by a factor of 4 reveals detail of just the Lyra portion of the previous image (rotated so that north is at the top). Along the southern-most leg of Lyra is a pair of lines indicating the location of the Ring Nebula, M57. The faintest stars are magnitude 9.5, but M57 is visible even though it's magnitude is 9.7 - due to its unusual color. The image is 11 degrees on each side, north up. The "full-width at half-maximum" for stars that are not overexposed is 160 "arc (2.7 'arc), which is pretty good for a 50mm focal length, f/1.7 lens. (The original image still has slightly better resolution than this web page version. Below each bright star is a dark ghost, caused by my film scanner's detector recovery from brief saturation after sampling a transparent portion of the slide film.)
Figure 2. Zoom factor of 2.2, showing the Ring Nebula as a "green dot." The faintest stars visible in this image are magnitude 13.7. [2001.04.24, Nikon F3 camera, 400 mm f/5.6 lens, attached to Meade LX200 10-inch telescope for tracking and guiding adjustments, 11-minute exposure, Fujicolor Superia 400 film]
Figure 3. Zoom factor of 2.4, showing that the Ring Nebula is more like a "donut" than a "dot" - but it certainly is green! The faintest stars visible in this image are magnitude 14.1. [2001.04.24, Nikon F3 camera, 400 mm f/5.6 lens, attached to Meade LX200 10-inch telescope for tracking and guiding adjustments, average of two 5.3-minute exposures, Fujicolor Superia 400 film]
Figure 4. A zoom factor of 4.4 now shows the donut shape clearly. North is to the upper-right. [Nikon Coolpix 990 digital camera, attached to a Meade LX200 10-inch Schmidt-Cassegrain telescope with a 1-inch FL eyepiece for a series of four 8-second exposures, which were averaged to obtain this image (after subtracion of dark exposures to remove pixel artifacts), July 10, 2000]
Figure 5. Zoom factor 1.8, covering a region of sky 27 x 18 'arc. The greater sensitivity of the system used to take this image shows that whereas most of the ring nebula is green the outer edges are red. North is up. [2002.04.21, Meade LX200 10-inch SCT, f/6.3, SBIG ST-8E CCD, True Technologies CFW; exposure times are 60, 60 and 120 seconds for R, G and B filters; Santa Barbara, CA residence]
Figure 6. Same image scale. This black-and-white image shows details within the ring, as well as a two central stars. North is up. [2001.08.09, average of 5 10-second exposures with Pictor 416XTE at prime focus of Meade LX-200 10-inch Schmidt-Cassegrain, f/6.3, HA-50 visible CCD interference filter, Maximum entropy enhanced using MaxImDL].
Figure 7. Zoom factor of 2, detailing portion of above image. The faintest stars in this image are magnitude 16.8 (in the original 17.3 can be seen). The 14th magnitude central star causes the surrounding gas shell to glow consisting largely of 501 nm green light emitted by twice-ionized oxygen atoms.
Stay tuned for an upcoming color version.
____________________ Advanced Amateur Images of Ring Nebula _______________________________
Figure 7. For comparison, here's an advanced amateur's M57 image. Jack Newton used a 25-inch f/5 telescope and a Meade Pictor 208XT CCD imager. From Meade's General Catalog. Note that with a larger telescope you can achieve better resolution (but I'm not through trying to improve).
To see what a regular digital camera can do when applied to an astrophotography task, click here.
For more zoom sequences of the sky, click on AstroPhotos (try the Whirlpool Galaxy).
____________________________________________________________________
This site opened: June 25, 2000. Last Update: May 27, 2002