Capturing luminous contrast and crisp clarity, Yves Tremblay won Photo of the Week with a two-tile mosaic of IC 1805, the Heart Nebula in Cassiopeia, in RGB and narrow band.
He said the capture was done over two nights: October 4 and 8, 2019, in his observatory located in Vaudreuil, Quebec (a red light pollution zone).
“I captured 14 x 10min bin 2 in Ha and O3 and 12 x 2min in RGB bin 1 for each of the tiles,” he said in an email. “All captured with my small SV80ED refractor with TRF-2008 (0.8x) for FL = 440mm and a ZWO1600M camera on an EQ8 mount. Captured with SGPro.”
He also said all of his processing done with PixInsight.
“First, I would like to say that it is really a charm to make mosaics with SGPro using the ‘Framing & Mosaic Wizard’ tool!” he wrote. “The real challenge is in the processing!”
He said the assembly of each tile in pre-processing was quite a job, especially as the mosaic has five layers.
He also said he found it quite difficult to balance the layers, background intensity and then colours’ intensity.
“It is also quite difficult to balance the layers to produce a pleasing colour image, especially when the difference in intensity between the Ha and the O3 is important, as is almost always the case in narrow band imaging,” he said.
He also noted the resulting image covers about 2.5 degrees by 3.5 degrees of the sky, and is a composition of RGB + Ha + O3 for luminance, RHa for red, GO3 and BO3 for green and blue respectively.