This is one that’s featured in previous images of mine but this time it’s in close up courtesy of GRAS-6, an RCOS 16? Ritchey-Chrétien Cassegrain with a focal length of over 3.5 metres. With a full moon in the sky I used an Ha filter on the camera and binned the pixels 2×2 to reduce the sub-frame exposure length to a manageable 5 minutes. This image is a stack of 6 exposures.
Set against the bright emission nebula IC434, the Horsehead is a cloud of cold, dark gas in the constellation of Orion.
