Hi all, In the early morning of May 20 I obtained a 9-minute long sequence of photometric data on Kosmos 2553 (2022-011A). This is the infamous much debated satellite in a weird orbit (~2000 km altitude, 67-degree inclined) with a 4-day closely repeating groundtrack, that according to some US sources is connected to a 'nuclear space weapon' program, although the orbit seems more consistent with an imaging role. In April, news reports appeared that it had started tumbling, reportedly already in late 2024. I can confirm Kosdmos 2553 is irregular in brightness now, while a year ago, when I observed it in May 2024, it was still steady (I didn't observe it for a full year). It is now showing a regular flash pattern with flashes 2.22 seconds apart, and an alternation between one bright flash and (2.22 seconds later) a fainter flash, then 2.22 seonds later a brighter flash again, then a fainter flash, and so on. Imagery of the pass and diagrams with the photometric data can be found in this blogpost: https://sattrackcam.blogspot.com/2025/05/the-tumbling-behaviour-of-mysterious.html - Marco ----- Dr Marco Langbroek - SatTrackCam Leiden, the Netherlands. e-mail: sattrackcam_at_langbroek.org Cospar 4353 (Leiden): 52.15412 N, 4.49081 E (WGS84), +0 m ASL Cospar 4355 (Cronesteyn): 52.13878 N, 4.49937 E (WGS84), -2 m ASL Station (b)log: http://sattrackcam.blogspot.com Twitter: _at_Marco_Langbroek ----- _______________________________________________ Seesat-l mailing list https://lists.seesatmail.org/mailman/listinfo/seesat-lReceived on Fri May 23 2025 - 10:23:01 UTC
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