All:

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I don’t recall seeing anything about this, but looking at an event in OW for C/2021 P4 (Atlas) on 04 March 2022, there appears to be an error in the orbital elements for this comet.? What caught my eye first was that the comet’s magnitude in OW is listed as 4.8, but digging a bit more revealed that the orbit semi-major axis listed in OW is 1.08045 AU, which would give the comet an orbital period of just over one year.? Checking against the published orbital elements, it looks like the perihelion distance was inadvertently used for the semi-major axis value.? (Also, OW has the comet’s mean anomaly listed as “0.”)? The effect of all this is that OW thinks the comet’s going to be occulting a star in Virgo on 04 March, when it will actually be in the vicinity of the Cassiopeia/Andromeda border.

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So, hopefully Carlos Perelló (who maintains the COMETOCC feed) is on this listserve, and can take a look at this error.

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Chris Anderson, Coordinator (he/him/his)

Centennial Observatory

Herrett Center for Arts & Science

College of Southern Idaho

Twin Falls, Idaho, USA

(208) 732-6663

canderson@...

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