Altina

Object data: M101 (NGC 5457, Pinwheel Galaxy) is a large magnitude 8 galaxy located in Ursa Major. Photographically it is quite spectacular, however it has low surface brightness, making it difficult to observe in small instruments. It was discovered by P. Mechain in 1781 and catalogued by Messier in March the same year. Its distance is estimated at about 24 million light years. The diameter is approximately 90,000 light years and the total mass is estimated to be the eqivalent of 16 billion suns - about 10% of the mass of the Milky Way.

Date: 18/4/99, 12/5/99, 13/5/99, 19/5/99
Location: UK, Southern France
Conditions: Mixed, but mostly very poor. Most of the exposures were interrupted by cloud. During one of the exposures a thunderstorm was in full swing 20 miles away.
Optics: LX200 10" with GEG working at f/11.2
Mount: AP 900 GTO on Portable Pier
Autoguiding: SBIG ST-4 tracking off-axis guide star with GEG.
Camera: Nikon F2 with N2 gas purge into the film transport chamber.
Film: Kodak Ektapress Multispeed PJM-2 - gas hypersensitised.
Filtration: None
Exposure: 3x 2 hours, 1x 90 minutes.

Enhancement: Four negatives were scanned using a Polaroid Sprintscan 35 Plus and digitally stacked in Picture Window, then further enhanced in Photoshop.

Notes: This photo has been assembled from a collection of mediocre exposures taken in adverse weather conditions during April and May. All exposures except one were interrupted by cloud and poor transparency. During one of the exposures there was even a thunderstorm in full swing about 20 miles away causing bright lightning flashes to illuminate the sky every few seconds. In fact this was the only exposure that was fairly reasonable - perhaps the lightning helped by 'pre-flashing' the film :-)

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