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Table 4
Comparison of Comet C/1908 R1 tail observations and auroral sightings between September and December 1908.
| Date of event | Comet observations | Auroral observations |
|---|---|---|
| 5–6 September | Guillaume (1908a) cites a lack of tail, even though the tail had been long and visible since its discovery on 1 September | A bright aurora with a nearly full moon was observed on 4 September (Barnard 1910). |
| 14–15 September | Eddington (1909) describes a bright condensed coma, though a detached V-shaped portion of the tail is seen 20′ from the head, moving at a rate of 2′/h. | Barnard (1910) cites large aurora after midnight on 12 September. They were seen as far south as Pittsburgh, Pennsylvania, and were remarkably bright (WashingtonPost1908). John A. Brashear suggests that these are linked to the immense sunspot he observed on the sun (Brashear 1908). Cameron (1909) describes the most violent magnetic storm of 1908 to have come shortly after 10 September. |
| 30 September-1 October | The comet was seen to have become incredibly bright (Wilson 1908), with a more disturbed tail (Eddington 1909) following. By the morning of 1 Octobert (before 11:24 GMT), the comet was said to have entirely lost its tail (Bigourdan 1908; Van Biesbroeck 1908; Holetschek 1909) and the brightness of the coma was greatly diminished. Eddington (1909) and Flammarion (1908) describe a bright detached mass at 1° from the nucleus. This event can be seen in Fig. 6. | Newspaper articles from Pennsylvania and California confirm that the auroras were also observed on the nights of 28 September through 1 October Sidgreaves (1908). An auroral glow was visible until 5 October (Barnard 1910). |
| 15–16 October | Here, the tail is not lost, but rather broken. A dislocation or mass (Flammarion 1908) occurs at ~25′ (Eddington 1909; Flammarion 1908; Guillaume 1908a) and produces its own tail that ‘looks like a chimney’. This was observed in real time between the hours of 7h03 and 10h25 GMT. The next day, the tail is described as being more faint. | Despite this being the date of one of the most dramatic events in C/1908 R1’s tail, Cameron (1909) say this is also the only sun-spotless day in Stonyhurst’s records of the entirety of 1908. The closest auroral sighting is on 12 October (Barnard 1910), which was described as very active. |
| 29–30 October | The tail is described as incredibly faint (Guillaume 1908b) and hard to detect (Holetschek 1909) but can be traced to 8° (Eddington 1909). A condensation in the middle of the tail is followed by a deformation that dissipates at 17–18° (Guillaume 1908b; Flammarion 1908). | Barnard (1910) describes a very bright arch, almost like daylight, though the brightest aurora in a long time this was not a specially active one. |
| 13–14 November | The tail was described as bright, and a second head is observed detaching from the tail at approximately 15′ from the nucleus (Guillaume 1908b). | Cameron (1909) describes a period of higher solar activity on 8–14 November. This culminates on the night of 16 November with well-defined auroral arches (Corrigan 1909), also observed by Barnard (1910), who notes a bright aurora the following night as well on 17 November. |
| 28–29 November | The tail was barely visible (Holetschek 1909). | Barnard (1910) notes an auroral glow low in the north for a short time. |
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