References
Chereau, F., Wolf, A., Zotti, G (2001) Stellarium [Online]. Available at https://www.stellarium.org (Accessed June 2019).
Jackson G. R., Owsley, C., and, McGwin Jr, G. (1999). ‘Aging and dark adaptation’,.Vision Research,. vol. 39, no. 23, pp. 3975–82. [Online]. DOI:10.1016/s0042-6989(99)00092-9. PMID 10748929 (Accessed 13 April 2018).
Kalloniatis, M. and Luu, C. (2018). ‘Webvision – Light and Dark Adaptation
’, Webvision [Online]. Available at //webvision.med.utah.edu/book/part-viii-gabac-receptors/light-and-dark-adaptation/ (Accessed 1 March 2019).
MacRobert, A. (2006). ‘The Stellar Magnitude System’, Sky and Telescope [Online]. Available at 2006 http://www.skyandtelescope.com/astronomy-resources/the-stellar-magnitude-system/ (Accessed Mar 13 April 2018).
Frommert, H. and Kronberg, C. (2006) ) ‘Timeline of Charles Messier’, seds.org [Online]. Available athttp://www.messier.seds.org/xtra/history/timeline.html (Accessed 12 March 2019).
Frommert, H. and Kronberg, C. (2006) ‘Charles Messier’s Comets’, seds.org [Online]. Available at
http://www.messier.seds.org/xtra/history/m-comets.html.Accessed 12 March 2019).
Frommert, H. and Kronberg, C. (2006) ‘List of The Messier Objects Catalog’, seds.org [Online]. Available at http://www.messier.seds.org/. (Accessed 12 March 2019).
Frommert, H. and Kronberg, C. (2006) ‘Twelve Months Tour of the Messier Catalog’, seds.org [Online]. Available at http://www.messier.seds.org/xtra/12months/12months.html (Accessed 12 March 2019).
Bonnell, J. and Nemiroff, R. (2018) ‘Astronomy Picture of the Day Index – Messier Objects’, www.nasa.gov [Online]. Available at https://apod.nasa.gov/apod/messier.html (Accessed 12 March 2019).
Garner, R. (2019) ‘Hubble’s Messier Catalog’, www.nasa.gov [Online]. Available at https://www.nasa.gov/content/goddard/hubble-s-messier-catalog (Accessed 12 March 2019).