Infrequently posting #astrophotographer due to clouds. Fireworks. More at https://teapaw.org/t.co/biXlXzGS0a
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ALT Comet C/2025 R2 (SWAN) (bottom right) and Dark Horse nebula (centre top)
ALT Annotated version of: Comet C/2025 R2 (SWAN) (bottom right) and Dark Horse nebula (centre top)
ALT Two comets and Mars (bottom right). Although they look like they're traveling in the same direction, their motion in front of the stars are different - the fainter comet is heading down and to the left in this image but the brighter one is heading 'tail-first' upwards to the right. Comets' tails pretty much always point away from the sun, whichever way the comet is going. This image is the second attempt as I failed to bring a power supply the evening before, when the comets were closer together at about 1.0deg separation. Here they are 1.75deg apart - which just fit into the camera frame (Canon 6D MK1 on SW 750PDS with 0.9x coma corrector). Comets were low in the sky - and due to incompetence I failed to get too many subs and there were serious shortcomings with the flats. Other pics including from the same night but with other optics will be easier to process - I fell down a rabbit hole with this one.. Palm Beach, New South Wales.
ALT Same image but comets and Mars labelled
ALT Two comets and Mars in one photo. 09.00UT (7pm local time) on 18th September 2025, Sydney Australia. Upper, fainter comet is moving towards lower left and the lower, brighter one is moving almost straight up. At this time they were 4.5 degrees apart. Comet ATLAS is inbound towards the sun whereas SWAN is on its way out from its closest approach and will pass closest to Earth on October 21st. It will miss us by a distance equivalent to a quarter of the distance from Earth to the sun. At the time of imaging, SWAN was 117 million km from Earth and ATLAS was 165 million km distant. Mars was at 347 million km.
ALT Two comets and Mars in one photo. 09.00UT (7pm local time) on 18th September 2025, Sydney Australia. Upper, fainter comet is moving towards lower left and the lower, brighter one is moving almost straight up. At this time they were 4.5 degrees apart. Annotated version of the same photo: Comet ATLAS is inbound towards the sun whereas SWAN is on its way out from its closest approach and will pass closest to Earth on October 21st. It will miss us by a distance equivalent to a quarter of the distance from Earth to the sun. At the time of imaging, SWAN was 117 million km from Earth and ATLAS was 165 million km distant. Mars was at 347 million km.
