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M 109, NGC 3992, Spiral Galaxy
in Ursa Major
M109, NGC 3992, in Ursa Major, is approximately 46 million ly distant. Its light is equivalent to about 19 billion suns but because of its distance, it is quite dim and a very long exposure — over 6 hours total — was needed. Its size — about 100,000 ly — is in the same range as our Milky Way galaxy. The shape is that of a barred spiral galaxy, so-called because of the distinct bar across the diameter from the nucleus to the beginning of the spiral arms. it was originally discovered by Mechain around 1781-2. The apparent size is 7.6 x 4.3 arcmin, which puts it in the range of the 2858 mm focal length f/9 Ritchey-Chretien telescope used for the image. North is up in this image.
| Date | 2003-03-07 |
| Scope |
RCOS Ritchey-Chretien scope at f/9 with ST-10XME CCD camera at -15 °C on the A-P 1200 GTO mount. Guided with internal guide chip. SBIG CFW-8 filter wheel. |
| Exposure |
18 - 5 min exposures R, G, B at 2x2 binning and 22 - 5 min exposures through the clear filter for the luminance image at 1x1 binning. Total 380 minutes. |
| Processing |
Raw frames calibrated in MaxIm 3.09. Master L, R, G, and B frames were then created in MaxIm. A gradient was removed from the red master by means of Wodaski's Gradient Removal plug-in. DDP processing was carried out on each of the master frames. The RGB color combine was then carried out in MaxIm with a weighting of 1.2, 1.0, and 1.2, for RGB, respectively. The luminance image was then registered with the RGB image in RegiStar. The images were imported into Photoshop and combined with the L image as Luminosity at 100% opacity. The RGB and luminosity layers were then separately adjusted with Levels and Curves before flattening and converting to a jpg file. |