Quadrantids

Best Night: January 3-4, with between 45 and 200 faint meteors per hour
Total Duration of Activity: December 28 to January 7

How to Observe

      The Quadrantids emanate from the constellation of Boötes, but they get their name from a now defunct constellation called Quadrans Muralis. The radiant never reaches a high altitude for most northern hemisphere observers and southern hemisphere observers will probably see no activity. The location of the radiant in astronomical terms is RA=229 degrees (15 hours 20 minutes), DEC=+49 degrees, but the chart below will also help you find it.

History

      The first observation of the Quadrantids seems to have occurred on the morning of January 2, 1825, when Antonio Brucalassi (Italy) remarked that "the atmosphere was traversed by a multitude of the luminous bodies known by the name of falling stars." Other observations were made on January 2, 1835, by Louis Francois Wartmann (Switzerland), and on January 2, 1838, by M. Reynier (Switzerland).
      First mention that early January activity might be annual came in 1839, when Adolphe Quetelet (Brussels Observatory) and Edward C. Herrick (Connecticut) independently made the suggestion. The meteor shower became known as the Quadrantids because of its emanation from a now obsolete constellation called Quadrans Muralis (the Mural Quadrant) located on some 19th-century star atlases near the point of meeting between Hercules, Boötes and Draco.
      Details of the characteristics of this shower are not available from the time of its discovery, although the lack of published observations during the 1840s and 1850s probably indicates minor activity. The first major useful observation of this shower came in January 1863, when Stillman Masterman, of the United States, determined the first accurate radiant point as RA=238 deg, DECL=+46 deg 26 min. The following year, Professor Alexander Stewart Herschel of England was met with the unusually high rate of 60 meteors per hour at a time when the radiant was at an average height of only 19 degrees! According to J. P. M. Prentice, the ZHR was 131. Although Herschel's high hourly rate did not become an annual event, it did help to stimulate interest in the shower in the years that followed.
      Observations of this meteor shower since 1864 have revealed the earliest activity to be present on December 28, while the stream last appears on January 7. However, the shower is particularly noteworthy for a very sharp rise to maximum activity during January 3 and 4. Keith B. Hindley (England), using observations of the British Astronomical Association (BAA) made during the period 1965 to 1971, noted rates were higher than half the maximum rate for only 16 hours. A study of BAA, British Meteor Society (BMS) and American Meteor Society (AMS) observations by the Author reveals that rates tend to drop below ten per hour just one day before and after the peak of shower activity. Furthermore, the rise and decline of the shower activity before and after January 3 and 4 tends to be more gradual and this apparently confirms the frequently held suspicion that this stream is made up of both a diffuse and a compact component. Additional support of this theory was gathered by Hindley in 1971. Using an IBM 360/65 computer at the University of Liverpool, telescopic observations of the Quadrantids were examined. The computer revealed a normal radiant diameter of 8 degrees, which contracts to less than a degree at the time of maximum.
      Investigating 122 observations of this shower made between 1864 and 1953, Prentice concluded that the normal ZHR of the Quadrantids was 45. However, this is far from being a consistent figure, as he pointed out that very strong returns occurred in 1909 (ZHR=202) and 1922 (ZHR=79), while very weak returns were noted in 1901 (ZHR=17), 1927 (ZHR=20) and 1940 (ZHR=21). One figure Prentice did find more consistent was that of Earth's heliocentric longitude at maximum. This was determined as 282.9 deg, but it should be stressed that this represents only visual observations. During 1947 to 1951, radio-echo observations were conducted at Jodrell Bank and the average time of maximum occurred when Earth was at a heliocentric longitude of 282.5 deg. This difference between the times of the maximum of visual and radio-echo meteors illustrates the dispersion due to the Poynting-Robertson effect. According to Hindley, the dispersion factor amounts to 68 minutes of time per magnitude, thus allowing the radar maximum to occur 6.3 hours before the visual maximum.
      Interestingly, the hourly rate has continued to fluctuate in more recent times, though the range has been less prominent than in the past. During the period of 1965 to 1971, observers of the British Astronomical Association detected maximum hourly rates as low as 65 and as high as 190. In 1975 the Nippon Meteor Society observed a maximum hourly rate of 101.2.
      The Quadrantids have not been consistently studied by visual observers. Cold weather prevalent in northern latitudes has frequently been cited as the main reason behind this. Another factor has been the very sharp maximum the shower displays, which frequently causes even the most diligent of observers to miss the activity only because they are in the wrong longitude. A final factor is related to the general faintness of this shower's meteors, thus requiring exceptional observing conditions for the main activity of the shower to be noted.
      Some of the best observational data has been obtained by Norman McLeod III (Florida). He took all of his Quadrantid observations for the period of 1960 to 1976 and determined an average magnitude of 2.81 (based on 142 meteors). Similar average magnitudes have been obtained by other observers. Another interesting statistic is the percentage of meteors seen exhibiting trains. Robert M. Dole (Maine) found that 5.0 percent showed trains in 1933. The British Astronomical Association found that 5.7 percent showed trains in 1971. Robert Lunsford (California) obtained percentages of 7.4 and 2.4 in 1984 and 1985.
      Examination of the photographic and radio-echo data by the Author reveals the average Quadrantid radiant to be at RA=229.5 deg, DECL=49.4 deg, but it should be pointed out that this is strictly an average. As mentioned earlier the shower does not possess a sharply defined radiant. In 1953, George E. D. Alcock and J. P. M. Prentice pointed out that "it has always been difficult to determine the radiant of the Quadrantid shower". To correct this, they carried out a program in 1952 to obtain duplicate observations of radiants. On January 3, they established the existence of 13 active radiants, thus demonstrating the complexity of the region.
      Other studies have shown that the region is even more complex, since the same radiants are not necessarily active from year to year. The earliest mention of this was in 1918, when W. F. Denning and Mrs. Fiammetta Wilson noted their surprise to find the main radiant in January 1918 to be about eight degrees north of the normal radiant. They stated that a more northern radiant had been suspected in January 1916 and 1917, "but the data at the time were regarded as insufficient." Independent confirmations of the 1918 radiant came from several observers in England and it was noted that a weak shower actually did occur from the normal radiant as well. This apparent change in active radiants from year to year is probably a by-product of the perturbations experienced by the stream every 11.86 years from Jupiter.
      The planet Jupiter frequently appears in literature concerning the Quadrantids. In addition to the radiant changes mentioned, it has been linked to the initial appearance of the shower in the early 19th century and to the occasional irregularity in hourly rates. Also considered a result of perturbations is the slow retrogression of the ascending node, an occurrence which attracted four studies between 1958 and 1972. The subsequent calculated rates of the nodal retrogression were 0.31 degrees/century, 0.41 degrees/century, 0.54 degrees/century, and 0.6 degrees per century.
      One of the first studies of the long-term gravitational effects of Jupiter on the stream was conducted by S. E. Hamid and M. N. Youssef in 1963. They took six doubly photographed meteors from 1954 and applied the secular perturbations of Jupiter during the last 5000 years. They noted that both the present inclination of 72 degrees and the perihelion distance of about 1 AU were at their lowest values of 13 degrees and 0.1 AU, respectively, 1500 years ago. About 4000 years ago, these values were very similar to what they are today, with the inclination being 76 degrees and the perihelion distance being about 1 AU. As a study of why the meteor stream is composed of at least two branches, the authors examined the change in the stream's distance from Jupiter over the last 5000 years. Prior to today's distance of only 0.3 AU, the stream was found to have been farthest from Jupiter 1500 years ago and only 0.2 AU away about 4000 years ago. The authors speculated that the stream's parent comet was captured by Jupiter about 4000 years ago and shortly thereafter it developed meteors along its path. "Because an appreciable number of these meteors, which now form the Quadrantids, did not suffer another close approach to Jupiter, the shower is observed to be compact."
      Later in 1963, as a by-product of this study, Hamid and Whipple suggested a possible common origin for the Quadrantids and the Delta Aquarids, as 1300-1400 years ago the orbital planes and perihelion distances were very similar. "Also," they added, "the physical characteristics of the meteoroids belonging to the two streams appear to be similar, as judged by their light curves."
      In 1979, Iwan P. Williams, Carl D. Murray and David W. Hughes essentially repeated the Hamid-Youssef study, but they used a stream model and ten "test" meteoroids scattered about the orbit. Their study basically confirmed the earlier study back to 1500 years ago, but found the inclination and perihelion distance to closely reflect today's values only 3000 years ago. The study also indicated that, "casual observations of the original meteoroids at any time in the interval 200-1000 yr before the present would not have revealed them to be members of the same stream. 1690 and 1300 yr ago they started off with similar orbits; these then separated, only coming together again in the last 200-150 yr." The authors added that the parent comet probably underwent two major disruptions-one 1300 years ago and the other 1690 years ago.
      The future of the Quadrantid stream was also examined in the 1979 study. The authors noted that the inclination would remain near 72 degrees and that the perihelion distance eventually will exceed 1 AU. Therefore, the authors predict Earth will no longer encounter the stream by the year 2400.
      During 1985 Ken Fox looked at the Quadrantid orbit 1000 years in the past, as well as 1000 years in the future. Nothing different was really noted about the orbit in the past that was different from the previous studies, although he did note that maximum occurred at the beginning of August from a radiant of RA=341.1 deg, DECL=-12.8 deg. Fox revealed Earth would no longer pass through the Quadrantid orbit 1000 years from now.

Orbit

      The photographic meteor orbit was based on 25 meteor orbits collected from papers written by Fred L. Whipple in 1954, Richard E. McCrosky and Annette Posen in 1961, P. B. Babadzhanov and E. N. Kramer in 1967, and Gale A. Harvey and Edward F. Tedesco in 1977. The radio-echo orbit was determined by Zdenek Sekanina from data collected by the Harvard Radio Project of 1961-1965.

	Photographic	Radio-echo
Argument of Perihelion () [J2000]	170.7 deg.	168.1 deg.
Ascending Node () [J2000]	283.3 deg.	283.0 deg.
Inclination (i) [J2000]	71.4 deg.	70.3 deg.
Perihelion Distance (q)	0.975 AU	0.974 AU
Eccentricity (e)	0.614	0.682
Semimajor axis (a)	2.526 AU	3.064 AU

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