Galaxies from U.A.O.

NGC 253 : four 120-s exposures (clear filter) summed, log-scaled and sharpened.

Comparison of Woomera (right) and A.U.O. images of NGC 253. The A.U.O. image has been cropped and scaled to match the extent of the Woomera image. Total exposure times were similar, but note that (i) Woomera has very dark skies (ii) image scale for the Meade is about 3.9"/pixel and for the C14, around 2"/pixel.

Centaurus A : 28-29/5/2003, 480-seconds total exposure.

Centaurus A : as above. The ellipse-fitting routine in IRIS was used to model the light from the galaxy, which was then subtracted from the original image. Doing this emphasises the dust lanes in this galaxy, and allows one to see stars, etc., which are otherwise lost in the image. The left part of the image is the original; the right side shows the result of subtracting the fit, and both images have had their intensities scaled similarly. Please note there is about a 2% variation in the sky brightness in these images from May 2003 due to a slight imperfection in the flat-field images used. Some residual artefacts of the processing are visible as elliptical intensity variations around Cen A.

M83 : 28-29/5/2003, 480-seconds total expsoure time. A classic spiral galaxy. Image on the left has been log-scaled. That on the right shows the faint parts of the image as negative, with the bright parts as positive.

NGC 6822 (Barnard's Galaxy) : 29-30/5/2003, 12 minutes total exposure. This is a dwarf memeber of the Local Group of galaxies, at about 1.7 Mly distance.

M65 : 11-12/6/2003, three auto-guided 5-minute exposures, giving 15 minutes total integration time. Taken with a waxing gibbous Moon nearby, and with some light, high cloud present. Left-hand side is a median-sum of the original images; right-hand side is a simple addition, showing the effect of a few hot pixels. The visibility of these is greatly reduced when median-filtering of multiple images is used (the left-hand image also has had MaxIm DL's Digital Development routine applied).

M31 : 7-8/9/2003, two 60-second exposures, clear filter, median-combined. M31 was only at about 14º elevation at the time of the exposures, with a waxing moon in the sky.