24,500 LY

After trying some galaxies using LRGB under nearly full Moon conditions and failing miserably, I decided to try something I was pretty sure would work, globular clusters. Hence, M5. After taking a luminance sub I realized the sky background was still way too bright, so I used R, G, & B filters without any L. I felt like I cheated in several ways on this image. I used 2’ subs rather than the usual 3’ I have been using for most LRGB imaging lately, and cheating came in the form of using 3’ darks rather than taking the time to get proper 2’ ones. I can see I need to shoot some new flats as well because I’ve got some new dust donuts the flats are not removing. Thanks to the nearby full Moon, there were strong gradients in the stacked image I had to take out in software. I understand this cluster is believed to be very old, just a couple of billion years younger than the universe itself. That’s a sobering thought!

Date: 7 May 2020
Subject: M5
Scope: AT8IN+High Point Scientific Coma Corrector
Filters: ZWO 31 mm diameter unmounted R, G, B
Mount: EQ-6 (EQMOD 2.000j)+PEC
Guiding: Orion Thin Off-axis Guider + ASI120MM-mini +PHD 2.6.7 (Win 10 ASCOM)
Camera: ASI1600MM-Cool, -20 °C, Gain 139 Offset 21
Acquisition: Sequence Generator Pro 3.1.0.457
Exposure: 30x180 R, 30x180 G, 30x180 B
Stacking: Deep Sky Stacker 4.2.3 (64-bit) dark+flat+bias, κ-σ stacking with κ = 1.5
Processing: StarTools 1.6.392 beta: Combined R, G, & B in StarTools. Software binned 2x2, cropped, gradient wiped (95%), developed, HDR (reveal core), slight deconvolution, color, untrack denoised (grain equalization). A little bit of levels, some clone stamp work to remove dust donuts. AstroFrame.