Overview
A collection of 100,000 stars, packed together 100 times more densely than the stars in our Sun’s stellar neighbourhood.
Background
After my epic 100-hour Pinwheel Galaxy project, I was keen for something a bit more manageable! M13 was well-positioned in the sky, and being a globular cluster its lack of faint nebulosity means it holds up well with shorter integration times. I collected about 11 hours, and then used PixInsight‘s SubframeSelector tool to whittle this down to the best eight.
Mid-to-long focal length telescopes with decent aperture are really useful for resolving the individual stars in globulars. Below is a comparison of a previous attempt I made at imaging M13 using my Askar FRA400, compared to this latest version made with my Askar 130PHQ. It’s not really a fair test, as the FRA400 is an extreme crop, and also I processed it before I had NoiseXTerminator and BlurXTerminator, but I still think it’s interesting to compare the two side-by-side. Note that the FRA400 has 16 hours of data compared to the 130PHQ’s eight, which I think makes the latest version all the more impressive.
Imaging details
| Date | 22 June to 8 July 2023 to (2 weeks) |
| Location | Bristol, UK (Bortle 8) |
| Telescope | Askar 130PHQ Flatfield Astrograph |
| Camera | ZWO ASI 2600MC-PRO |
| Mount | Sky-Watcher EQ6-R PRO |
| Guide | William Optics 50mm Guidescope with 1.25″ RotoLock; ZWO ASI 120MM Mini |
| Control | ASIAIR Plus |
| Software | PixInsight, Lightroom |
| Filters | – No filter 240 x 120 seconds (8 hours) |
| Total exposure time | 8 hours |
| Image credit | Lee Pullen |
Processing
The processing was fairly straight-forward too, especially compared to the tricky faint targets I usually go for. BlurXTerminator was useful, and I set it to increase the star halos to 0.4, making the individual stars glow, which I think is a nice effect.
See below for a full processing video.
Source data
Previous version
I first imaged M13 back in March 2022, using my wide-field Askar FRA400 telescope.
* March to April 2022
* Bristol, UK (Bortle 8)
* Telescope: Askar FRA400 f/5.6 Quintuplet APO Astrograph
* Camera: ZWO ASI 2600MC-PRO
* Filter: none
* Mount: Orion Sirius EQ-G
* Guide: William Optics 32mm; ZWO ASI 120MM Mini
* Control: ASIAIR Plus, ZWO EAF
* Software: PixInsight, Lightroom
* 480 x 120 seconds
Total integration time: 16 hours
By Lee Pullen
Seestar S50
Seestar S50 image to be added later…
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