M3

M3 is a globular cluster containing 500,000 stars. It formed around 11.4 billion years ago, making it more than twice as old as planet Earth.


Version 2, reprocessed December 2022

From the Reprocessing Bonanza 2022. This version uses exactly the same data as version 1, but with better processing tools and skills. I find globular clusters tricky because it’s all too easy to blow out the cores. I fell into this trap with my first processing attempt, but was more careful this time. I want to tackle a globular with my new Askar 130PHQ telescope, and really try to do the core justice.

An extreme crop of version 1 on the left; 2 on the right.

Version 1, April 2021

City light pollution makes imaging broadband deep sky objects tricky, but M3 is relatively bright so I thought I’d have a go. The result isn’t bad, although I think I messed up the processing a bit because there’s not enough definition in the cluster’s core. I’ll re-edit sometime and try to avoid clipping any highlights.

* March and April 2021
* Bristol, UK (Bortle 8)
* Telescope: Askar FRA400 f/5.6 Quintuplet APO Astrograph
* Camera: ZWO ASI 2600MC-PRO
* Mount: Orion Sirius EQ-G
* Guide: William Optics 32mm; ZWO ASI 120MM Mini
* Software: PixInsight, Photoshop, Lightroom
* 300 x 120 seconds

Total integration time: 10 hours

By Lee Pullen

Example source data

This is what a single 120-second subframe looks like, debayered and with a simple stretch.
This is the integration of 300 x 120 seconds (10 hours) just with a simple stretch, before any proper editing.

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