In Greaves (2012) a September shower in Orion was suggested.  This is now formally catalogued as the September π Orionids, code POR shower number 430.

In retrospect the existence of this shower’s radiant roughly 90 degrees West of the Solar position and slightly below the Ecliptic during its peak activity in tandem with its highly inclined retrograde orbit and consequent high geocentric velocity places it amongst the region of the mid-September realm of the Southern Apex.  Consequently, the shower is either a false detection delineated by unrecognized Apex meteors or at best barely distinguishable from said, thus just as unproven.  Accordingly, there is no real evidence for the shower 430 POR existing as a discrete shower.

Ironically, and possibly somewhat prophetically, at the time of submission the author’s suggested code of POR and the name π4 Orionids for this shower was suggested to the then relevant naming committee which then modified it to the current name and changed the code to SPO.  The referee of the paper, the well-known and experienced (late) Wayne T Halley, very correctly took umbrage to this, and in an important contribution pointed out that SPO had long been utilized as the abbreviation for sporadic meteors, at least amongst amateurs.  Accordingly, based on his advice, the abbreviation was changed from SPO to the current one.  The ironic aspect being that in the end the orbits used to define this “shower” were in fact likely sporadic ones, and therefore are SPO!


Greaves J. (2012). “Four Meteor Showers from the SonotaCo Network Japan”. WGN, Journal of the International Meteor Organization, 40, 16–23.