M15 is a globular cluster, discovered by Jean-Dominique Maraldi in 1746 and included in Messier's list in 1764. It is estimated to be 12,000 million years old and is 33,000 light years away in Pegasus. Its diameter is about 18 arc-minutes which corresponds to about 180 light years.
This is my first attempt to image a globular cluster.
Date and Time: 28th August 2005 21:50 UT
Camera: Modified Toucam 840K
Telescope: LX200 with 0.33 focal reducer (focal length 800 mm)
Capture: K3CCDTools. High gamma, exposures 1, 2.5, 5, 10, 15 sec, 32% gain
Processing: K3CCDTools. Individual exposures aligned and stacked then the 5 resulting frames stacked together.
Unsharp mask in Photoshop factor 150, radius 5
Focus Magic 3,100.
13 years later! Another attempt to image M15. This time with an 8-inch Ritchey-Chrétien, guided with an ETX125. I had to offset the cluster in order to find a suitable guide star in the longer focal-length ETX.
Date and Time: 7th October 2018 00:06 to 00:26 UT
Camera: DMK 21AF04 (monochrome)
Telescope: 8-inch Revelation Ritchey-Chrétien
Guided: ETX125, Loadstar X2 and PHD2
Capture: ICCapture. Exposures 3.4, 6.8, 13.7, 23.1 sec, gain 939
Number of Frames: 38, 36, 13, 16, respectively
Processing: Registax 5: All frames at each exposure aligned and stacked and enhanced wavelets 1,2 = 10
The 4 resulting frames stacked in Registax 5.
PhotoImpact: Focus Magic 3,100 and 3 at angle 315, brightness -20
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