M15 Globular Cluster

Date: 8 August 2004

Telescope: Celestron 11 SCT with stabilized mirror on Gemini G-41 mount

Guiding: ST-4 Autoguider with Celestron C80, 80mm F11 refractor on side-by-side plate.

Camera: Genesis KAF-1602E with Astronomik FR-4 filterwheel with 34mm LRGB filters, Meade 0.63x reducer in Ted Argos adapter.

Location: Tai Mei Tuk, Hong Kong

Exposure: Luminance filter:  unbinned     12 x 4mins

                Red filter:         2x2 binned      5 x 2mins

                Green filter:      2x2 binned      5 x 2mins

                Blue filter:         2x2 binned    10 x 4mins

Software: Image acquisition by Astroart, calibration and auto-alignment also in Astroart, sigma-combined by Sigma, color combine and DDP in MaximDL, blooming removal (by rubber stamp) and final brightness adjustment in Photoshop.

Comment: The reducer in Ted Argos adapter was set to the same length as the Celestron 55mm SCT-T adapter, there was coma at corners.