08_MercApp_1.jpg Canon 60Da 70-200mm @ 70mm f/6.3 ISO 640 1/3sbr/ [This is quot;Two or more pictures showing movement...quot;]br/ 2019 February. Edmonton, Alberta. I had always wanted to do a composite like those one sees on quot;Astronomy Picture of the Dayquot;, but winter weather in Canada makes this impossible. And then we got a ridiculously long streak of good evening skies right as Mercury reached its greatest elongation in February 2019. A decent amount of planning was required, because I did not want to simply shoot at say 30mm for a wide enough angle. At the end of it, I wanted to have the resolution to make a nice print of it. This meant I could image at 70mm and each couple of days add more horizon to the north, to merge later. Because the background sky will brighten significantly in two weeks if I shoot at the same local time, I target the imaging for a solar depression of -9.2 degrees, when Mercury is nicely visible with the unaided eye. Planetarium software in ephemeris mode gives me the drifting local time for this for the time period of choice. br/ I still took many shots before and after for quot;contingencyquot; purposes when clouds were nearby. In fact one of the fainter dots on the left side of the arc is due to a cloud, and I had to fudge the position slightly because it was completely obscured at the appointed time, but visible 10 minutes later.br/ The composite was much trickier and more time consuming to create than I had first thought. Simply take each image and use lighten in layer mode - except that each was slightly rotated and the colour of the sky different due to conditions aloft and to the west beyond the horizon, affecting the shadowing of the atmosphere locally. Also, I found I had to double the size of Mercury's image otherwise it got lost in too few pixels.