July Phoenicids (PHE#176) and psi-Phoenicids (PPH#769)

By Paul Roggemans, Denis Vida, Damir Šegon, Milan Kalina, James M. Scott, Jeff Wood

Abstract: The July Phoenicids and psi-Phoenicids have radiants that overlap in Sun-centered ecliptic coordinates, and the orbits for the available modern solutions in the IAU-MDC Working List of Meteor Showers are very similar. We recommend merging the solutions under a single entry in the Working List.

 

1 Introduction

The July Phoenicids (PHE#176) were first recognized in 1957 by Weiss (1960a) and observed in 1958 data (Weiss, 1960b) using the Adelaide radar observations. Detections during five sessions between 1953 and 1958 led Weiss to conclude this shower may be classed as permanent. The shower was added to the IAU-MDC Working List of Meteor Showers (Jopek and Kaňuchová, 2017) by Jenniskens (2006) based on Cook (1973). This shower has never been detected by optical (visual, photographic or video) techniques and no activity from this source has been detected from Global Meteor Network low-light camera data. A new solution for this shower has been obtained by Jenniskens (2023) based upon SAAMER radar observations for 2017 to 2019.

 

 

The psi-Phoenicids (PPH#769) were discovered and reported by Pokorný et al. (2017) using the data from 2012 to 2015 of the Southern Argentina Agile MEteor Radar (SAAMER) but it was not recognized as a solution for the July Phoenicids. This shower was confirmed by Greaves (2026a) using 2020 to 2023 SAAMER data and identifying 899 radar orbits as psi-Phoenicids. This solution has been reported to the IAU-MDC. The psi-Phoenicids were reassessed by Greaves (2026b) against the newly released PANSY radar meteor orbit dataset (Vierinen et al., 2026) using D-criteria. A total of 156 orbits fitted the criteria and provided further independent confirmation of this shower and this solution has also been reported to the IAU-MDC.

2  Overlapping radiants

During a routine check-up, the RadiantMap tool for λ_ʘ = 112° in 2026 in Sun-centered geocentric ecliptic coordinates shows the PHE radiant and the PPH radiant overlapping each other (Figure 1). Some neighboring shower radiants show distinct activity, for instance the zeta-Phoenicids (ZPH#768), the Fornacids (FOR#1066) and the eta-Sculptorids (ESC#1067) but no clear activity can be seen at the position of the PHE and PPH radiants.

Comparing the available solutions in Table 1 for both shower entries it appears that the psi-Phoenicids are identical to the July Phoenicids. The first solution taken from Cook (1973) is misleading. Cook based his data on two papers by Weiss (1960a, 1960b) where only radiant positions, radiant drift and hourly rates were derived. Cook (1973) does not state the source of the adopted velocity; his range of orbital elements corresponds to the Weiss radiant combined with an assumed speed of about 44–50 km/s. The original publication by Cook mentions a range for the orbital elements with semi-major axis between 2.5 A.U. and ∞, eccentricity between 0.62 and 1.00, perihelion distance 0.96 to 0.97 A.U., inclination between 82° and 87°, argument of perihelion between 24° and 31° and an ascending node at 289.6°. The MDC lists an arbitrary end-member of Cook’s range which does not match its own v_g so that the MDC entry is internally inconsistent. Recomputing the orbit with the currently known geocentric velocity shows that the Weiss radiant is the psi-Phoenicid radiant: the Southworth and Hawkins (1963) D_SH and Drummond (1981) D_D values are in good agreement (* in Table 1). The modern solutions agree closely with each other (D_SH = 0.007–0.055). The Jenniskens (2023) solution for PHE#176 and the Pokorný et al. (2017) solution for PPH#769 are within all six limits of the maximum-sigma duplicate test of Jopek et al. (2024): the differences are 1.7° in λ_g – λ_ʘ, 0.7° in β_g, 0.6 km/s in v_g, 4.4° in ω, 0.3° in Ω and 0.0° in i (limits 5°, 3°, 2.5 km/s, 9°, 7.5° and 5°). Both Greaves (2026a; 2026b) solutions are also within all six limits.

Table 1 – The solutions listed in the IAU-MDC Working List of Meteor Showers for the July Phoenicids and the psi-Phoenicids. The solution for Cook (1973) recomputed with v_g = 38.2 km/s (*) has been added. The D_SH and D_D values are given for each solution with Cook, 1973 (*) as reference orbit.

	PHE#176 Cook, 1973	PHE#176 Cook, 1973(*)	PHE#176 Jenniskens, 2023	PPH#769 Pokorný et al. 2017	PPH#769 Greaves 2026a	PPH#769 Greaves 2026b
λʘ (°)	110.30	110.30	110.7	111	111.4	110.6
λʘb (°)	101.70	101.70	101.0	98	–	107.4
λʘe (°)	116.70	116.70	119.0	120	–	114.9
αg (°)	31.58	31.58	29.1	30.1	29.9	29.8
δg (°)	–47.78	–47.78	–48.3	–46.9	–47.2	–47.0
Δαg (°)	0.94	0.94	0.88	0.84	–	–
Δδg (°)	0.38	0.38	0.58	0.59	–	–
vg (km/s)	47	38.2 (*)	38.2	37.6	37.3	37.7
λg (°)	2.83	2.83	0.3	2.32	1.84	2.02
λg – λʘ (°)	252.53	252.53	249.6	251.32	250.44	251.41
βg (°)	–55.03	–55.03	–54.4	–53.73	–53.89	–53.65
a (AU)	∞	1.36	1.34	1.26	1.26	1.26
q (AU)	0.97	0.927	0.897	0.890	0.888	0.891
e	1.0	0.320	0.339	0.291	0.295	0.293
i (°)	87.00	74.9	74.8	74.8	74.48	75.0
ω (°)	23.89	50.3	58.9	63.3	63.65	62.8
Ω (°)	290.30	290.3	290.7	291	291.06	290.6
Π (°)	314.19	340.6	349.6	354.3	354.71	353.4
TJ	–	4.07	4.32	4.39	4.38	4.37
DSH (*)	–	–	0.062	0.085	0.087	0.081
DD (*)	–	–	0.037	0.056	0.052	0.053
N	n.a.	n.a.	6887	673	899	156

 

Without lookup tables and with data that do not match the values in the cited reference, the solution by Cook (1973) does not fulfill the current requirements to be listed in the Working List of Meteor Showers (Hajduková et al., 2023). The solutions by Jenniskens (2023), Pokorný et al. (2017) and Greaves (2026a) are all based upon SAAMER data. Greaves (2026b) based upon PANSY data is the only truly independent confirmation. Note that the inset in Figure 1 is the 2022 MDC submission by Jenniskens but the actual publication in Jenniskens (2023) is different and has been included in Table 1. Also, in Jenniskens (2023) the semi-major axis a = 1.34 AU does not equal q/(1–e) (1.357 AU) and T_J = 4.32 does not follow from its own a, e and i, which give 4.13.

 

 

3   Conclusion

The psi-Phoenicids (PPH#769) are another solution for the July Phoenicids (PHE#176). Therefore, it is recommended to keep the PHE#176 designation, remove the Cook solution (or flag it as radiant-only), and move the PPH#769 solutions under #176 (Jenniskens et al., 2020). The solution cited for Cook (1973) agrees with the original observations published by Weiss (1960a; 1960b) for the radiant position and the activity period, but the listed geocentric velocity has never been measured and is an estimate. The orbital elements listed in the MDC are an arbitrary end-member of the range given by Cook (1973) and do not match the listed geocentric velocity. No activity from this source has been detected from Global Meteor Network low-light camera data (Vida et al., 2020a; 2020b; 2021).

 

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