Please click the above image for a high res version
Object data: NGC 2903 is an interesting barred spiral galaxy in the constellation of Leo, about 30 million light years distant. It is interesting partly because it is relatively bright and close yet was not discovered by Charles Messier, hence it does not have an 'M' number. But this is not surprising since Charles Messier could hardly have discovered every bright 'fuzzy object' in the northern skies with his relatively primitive equipment - as it is his 110 discoveries are an amazing achievement. In fact this galaxy was discovered by William Herschel in 1784 during one of his major sky surveys.
Date: 12/03/10, 15/03/10, 02/04/11
Location: Southern France
Conditions: Good but periods of poor seeing, transparency=8, seeing=7
Optics: RCOS 12.5" Ritchey-Chretien with custom field flattener working at f/9.5
Mount: AP 900 GTO on Portable Pier
Camera: SBIG ST-11K, SBIG LRGBC filter set, -30°C
Guiding: Integral ST-11K autoguider
Exposure: LRGB Seq: 14x 20 minutes; 3x 20 : 13 : 20 minutes (binned 2x2).
Processing: Image acquisition, calibration, combining, and DDP were done using Maxim DL, registration of Luminance and RGB images was done using Registar, and final processing was done in Photoshop CS4.
Notes: For no apparent reason this proved a tough one for me - I had been trying to image NGC 2903 for a few years but was never able to obtain a satisfactory set of Luminance and RGB images. Finally eight usable Luminance images were acquired on 12/03/10 and a further six on 02/04/11, whereas the nine RGB images were acquired on 15/03/10. Like the images of M101 and M51 all image sequences were taken without having to flip the mount - a tremendous advantage of Astro-Physics mounts - see more on this capability in this new article.