About image
M71 is a controversial object in the Sagitta constellation: globular or open cluster? 

Until 1970 it was considered a particularly concentrated open cluster but various clues suggest that we could be faced with a poorly concentrated globular cluster and in fact today this seems to be the prevailing opinion of astronomers. 

M71 is located at a distance of about 12,000 light years from Earth and has a real extension of only 27 light years, very few for a globular cluster; its apparent diameter is 7.2’.

Technical data
Optic          GSO RC12 Truss - Aperture 304mm, focal lenght 2432mm, f/8
Mount        10Micron GM2000 HPSII
Camera         Moravian G3-16200 with external filter wheel 7 positions
Filters         Astrodon Gen2 E-Serie Tru-Balance 50mm unmounted RGB
Guiding system    OAG Moravian M68 with guide camera Moravian G1-0301
Exposure details  R 12x300" bin2 -20C
                                    G 15x300" bin2 -20C
                                    B 10x300" bin2 -20C
Total integration  3h5'
Acquisition      Voyager, PHD2
Processing      Pixinsight 1.8, Photoshop CS5
SQM-L       20.9    
Location       Promiod (Aosta Valley, Italy), own remote observatory
Date          29 August/1 September 2021

© Roberto Marinoni 2019 - All rights reserved