November 21, 2024

Archives for December 29, 2021

NGC 188 – Open Cluster in Cepheus

NGC 188 – Open Cluster in Cepheus

Telescope: Light Switch 8 @ f/6.2 (Optec 0.62x focal reducer), altaz mode

Camera: Full Spectrum Modified Canon 600D, interval timer

Filter: GSO IR Blocking Filter

Guide scope: None

Exposure: 40x10sec, ISO 1600, saved as RAW

Darks: Internal (Long Exposure Noise Reduction On)

Flats: 32×1/10sec, Tee shirt flats taken at dusk

Average Light Pollution: Red zone, Bortle 8, fair transparency

Lensed Sky Quality Meter: 18.4

Stacking: Mean with a 1-sigma clip.

White Balance: Nebulosity Automatic

Software: Deep Sky Stacker, Nebulosity, Photoshop

Located less than 5 degrees from the north celestial pole NGC 188 is one of the most northern objects in the New General Catalog. It is also one of the oldest open clusters known with an estimated age on the order of 5 billion years. Open clusters usually slowly disperse as they interact with other stars in the surrounding galaxy. NGC 188, however, lies above the galactic plane where it is fairly isolated. Composed almost entirely of 12 and 13th magnitude yellow giants, I find this cluster to be quite delicate, requiring very good transparency to be visible in an 8” telescope. Under these conditions it blossoms into a rich field of tiny pinpoints of light on the edge of visibility and it is quite beautiful. In a larger telescope it becomes easier to see, but remains quite faint and subtle.

NGC 188 is currently well placed above Polaris in the evening sky.