M13 Questar LRGB
The M13 globular cluster in Hercules is a summer favorite. With 300,000 stars some 25,000 light years away, it has an apparent magnitude of 5.8 placing it in a sweet spot for urban backyard astronomers -- we'll never make it out with the naked eye but it shows well in a small telescope, and it makes a beautiful target for beginning and intermediate astrophotographers. In this instance I'm exploring the capabilities of a monochrome CMOS camera and basic RGB filter set; the longest single exposure used to build this image was 2 seconds.
Tech stuff: Questar 3.5" telescope with PG III mount, unguided. QHY163 mono camera at native Questar focal length 1570 mm, binned 2X. L 300 X 0.4 sec; R 300 X 0.4 sec; G 292 X 0.4 sec; B 63 X 2.0 sec; total integration time 8 minutes. Acquired and stacked live with Sharpcap Pro and processed with PixInsight. Imaged from my yard 10 miles north of New York City.
M13 Questar LRGB
The M13 globular cluster in Hercules is a summer favorite. With 300,000 stars some 25,000 light years away, it has an apparent magnitude of 5.8 placing it in a sweet spot for urban backyard astronomers -- we'll never make it out with the naked eye but it shows well in a small telescope, and it makes a beautiful target for beginning and intermediate astrophotographers. In this instance I'm exploring the capabilities of a monochrome CMOS camera and basic RGB filter set; the longest single exposure used to build this image was 2 seconds.
Tech stuff: Questar 3.5" telescope with PG III mount, unguided. QHY163 mono camera at native Questar focal length 1570 mm, binned 2X. L 300 X 0.4 sec; R 300 X 0.4 sec; G 292 X 0.4 sec; B 63 X 2.0 sec; total integration time 8 minutes. Acquired and stacked live with Sharpcap Pro and processed with PixInsight. Imaged from my yard 10 miles north of New York City.