Phi Sagittariids

Observing

This stream possesses a duration extending from June 1 to July 15. It reaches a fairly weak maximum on June 18 (λ=86.6°) from an average radiant of RA=278°, DECL=-25° and then attains a ZHR of about 5. A recent name attached to this stream was “Scorpiids-Sagittariids.”

History

In his 1948 book Meteorströme, C. Hoffmeister investigated numerous visual radiants collected during 1908 to 1938, and identified what he called the “Scorpius-Sagittarius-System.” It has earlier been shown that the Theta Ophiuchids are apparently the main core of this vast system, but the present stream actually represents one of the weaker of the consistent radiants to become active from that system.

The first definite observation of this shower was made by W. F. Denning (England) on June 21, 1917, although this observer claimed to have seen meteors from this area of the sky during June 18 to 28, 1887. Denning also showed that several meteors and fireballs had been observed from an average radiant of RA=282°, DECL=-24° during the period of 1902 and 1917.

Phi Sagittariids Radiants

These observations by Murray Geddes were obtained from the June-July, 1932, issue of Popular Astronomy.

The earliest study of this stream was made by Hoffmeister, who, using observations made during the period of 1920-1937, determined the radiant as RA=279.8 deg, DECL=-22.8 deg when the shower reached maximum at a solar longitude 86.6 deg. Interestingly, Hoffmeister succeeded in detecting this shower on four nights during June 11-15, 1937.

Surprisingly, this stream has not shown any significant orbital dispersion in radar surveys conducted during the 1960’s. C. S. Nilsson’s radar survey conducted at Adelaide during 1960-1961, revealed 3 meteors originating from an average radiant of RA=275.2°, DECL=-24.5°, during June 15-18. During the 1961-1965 Radio Meteor Project conducted at Havana, Illinois, and directed by Z. Sekanina, 17 meteors were detected during the period of June 1 to July 2, from an average radiant of RA=277.8°, DECL=-25.3° (the stream was referred to as the Scorpiids-Sagittariids). Sekanina’s second Radio Meteor Project conducted during 1968-1969, again revealed this stream. On this occasion, 31 meteors were detected during the period of June 2 to July 15, from an average radiant of RA=282.2°, DECL=-25.2°. Finally, during 1968-1969, G. Gartrell and W. G. Elford conducted a radar survey at Adelaide Observatory. Based on 6 meteors, the radiant was seen during June 10-13, 1969, at an average position of RA=271°, DECL=-24°.

Orbit

The following four orbits, acquired from radar surveys conducted during the 1960’s, show a remarkable consistency for an ecliptic stream, although a large variation is present concerning the semimajor axis.