By Thomas Weiland
Abstract: A summary report is presented for the visual observations during the Lyrid activity from April 19–20 to 23–24 under exceptional favorable weather circumstances.
Rarely does it occur that April presents five clear and moonless nights in a row, especially around the time when the Lyrid maximum is due. This was the case in 2020! Combined with exceptionally dry air and the effects of diminished human activity in the course of the Corona lockdown one got magnificent skies, even near major towns.
All the observations (April 19–20 to 23–24) were carried out from Atzelsdorf, Austria (16°33’11” E, 48°30’30” N, 220 m a. s. l.), some 30 km away from the capital Vienna. Limiting magnitudes were slightly varying between lm = 6.20 and 6.30 before the onset of dawn (mean 6.28), and the effective observing time added up to Teff = 17.72 hours, during which 210 meteors (78 Lyrids, 17 Antihelion and 115 sporadic meteors) were logged (Table 1).
2. 2020 April 19–20
As expected, at the beginning of the campaign (April 19–20) observed Lyrid rates stayed on a rather low level (1–3/h), the brightest member reaching only magnitude 0 (Table 1). Based on an average population index of r = 2.79 ± 0.37 for all Lyrids recorded (78 LYR; Table 1 and Figure 2), corresponding ZHRs were fluctuating between 1 ± 1 and 5 ± 3 (Figure 3). For comparison, the mean population index for the sporadic background (excluding ANT) was found to be r = 2.86 ± 0.32 (115 SPO; Table 1), in good agreement with values found in the literature for the current season (Rendtel and Arlt, 2014).
3. 2020 April 20–21
During the following night (April 20–21) Lyrid rates saw only a modest increase (2–4/h), reflected by slightly raised ZHRs between 3 ± 2 and 6 ± 3. Remarkably, observed Lyrids were fainter than on April 19–20, within the +2 to +5 magnitude range. To compensate for this, a yellow, star-like SPO of magnitude –3 showed up at 23h08m10s ± 5s UT, travelling on a > 40° path and leaving a short train behind.
4. 2020 April 21–22
As for the peak night (April 21–22), hopes were high that Lyrid activity would match the excellent conditions to a similar extent, though the predicted maximum time, April 22, 06h40m UT (Rendtel, 2019) did not favor my location in Central Europe.
Observations started at 21h30m UT, at a time when the Lyrid radiant had already a useful elevation of hRad = 29.87°, but first rates remained rather low (2/h; ZHR 5 ± 3). Once more, sporadic meteors stole the show with an impressive yellow-blue, star-like member of magnitude –4 at 22h25m35s ± 5s UT, moving on a 40° path across the northern sky.
After 22h30m UT, Lyrid activity showed signs of going up, resulting in modest rates during the next two hours (6–7/h; corresponding ZHRs 11 ± 5 and 11 ± 4 respectively), though the majority of meteors was rather faint (of magnitude +4 and +5). Again, to my pleasure, a fine SPO of magnitude –4 appeared at 23h45m40s ± 5s UT, slowly travelling on a 25° path almost parallel to the northeastern horizon. Its bulbous, drop-like head sported a distinctive orange/red color, focusing in a thread-like train.
A further increase of Lyrid rates to 12/h between 00h30m and 01h30m UT yielded the highest ZHR of this night (17 ± 5), but with the exception of 3 LYR of magnitude –1, 0 and –2 most of the meteors were still in the +3 to +5 range. That seemed all the more striking since a sharp descent during the last observing hour to 2/h (ZHR 3 ± 2) could be observed. My hopes for an impressive Lyrid maximum (as in 2012) were gone!
5. 2020 April 22–23
With that in mind, I did not expect too much for the forthcoming night (April 22–23). Nevertheless, appropriate to my 25th anniversary of active meteor observing (I started on 1995, April 22–23), I felt I had a wish open.
Table 1 – Magnitude distribution of Lyrids and sporadic meteors logged from 2020 April 19–20 to 23–24.
|SPO excl. ANT||–6||–5||–4||–3||–2||–1||0||+1||+2||+3||+4||+5||+6||Tot.|
Already a few minutes after the start of my observations, at 22h15m UT, a flash lit up the sky in the west, but I could not detect any meteor. Apart from that, with 5 Lyrids logged during the first hour (ZHR 10 ± 4), the brightest one of magnitude –1, and 9 sporadics as well, overall meteor activity looked more promising than the night before.
Shortly after the beginning of the second interval (23h15m–00h15m UT), remarkable things commenced. The kick-off made a beautiful orange ANT of magnitude 0 at 23h20m05s ± 5s UT, which slowly travelled some 10° from northeastern Virgo to southeastern Bootes showing a drop-like head with a short train, followed by another one of magnitude +3 a few minutes later. At 23h25m15s ± 5s UT a yellow –4 LYR flashed up near the horizon at the border of Crater and Hydra; it could photographically be traced over a distance of 250 km to the west (http://www.astromethyst.at/meteore.html).
The absolute highlight of the night and even the entire session came at 23h29m45s ± 5s UT – a white/blue/green ANT of magnitude –3, showing up in northwestern Libra and culminating with two flashes of –5 and –6 in southeastern Virgo; it left three glowing fragments and a train behind (see Figure 1). Both pictures give an impression of the changing perspective from the two locations lying some 125 km apart, the latter resembling the appearance from my observation point (path length > 10°).
On top of that, less than 3 minutes later, at 23h32m25s ± 5s UT, another ANT of magnitude –2 and blue/green color took its course from northwestern Scorpius to southeastern Ophiuchus; once more it showed a drop-like head with a short train. Finally, a star-like ANT of magnitude +3 appeared shortly before the end of the interval.
Five Antihelion meteors within one hour – I do not recall ever seeing more of them at my location, not even in winter, when their radiant is culminating high in the sky!
As for the Lyrids, their rates remained fairly constant for the rest of night (5–7/h; corresponding ZHRs 7 ± 3 to 11 ± 4).
Forty-five seconds before official observations ended (02h14m15s ± 5s UT) my “anniversary night” delivered a worthy final – a yellow-blue SPO of magnitude –4, travelling on a 25° long path from the Ursa Major / Bootes border to southwestern Bootes. Great!
6. 2020 April 23–24
Despite top level sky quality, observed Lyrid rates during the last night (April 23–24) were more or less comparable to those at the beginning of the campaign (1–4/h; corresponding ZHRs 1 ± 1 to 7 ± 3); this applies for the Antihelion and sporadic meteors, too.
In 2020 both lunar and meteorological circumstances were top notch for observing the Lyrids. Nonetheless, they delivered only a modest return for Central European observers, mainly because the maximum occurred after sunrise on April 22, as predicted (ZHR 18 ± 3 around 08h UT, according to www.imo.net).
Apart from that, most of the Lyrids observed in 2020 were rather faint, with nearly two-thirds (62.82 %) belonging to the +4 and +5 magnitude class respectively; only 1 LYR (1.28 %) was classified as a fireball (magnitude –4). The relatively high population index of r = 2.79 reflects that as well. 50 % of the Lyrids ≥ 0mag showed a yellow color; additionally, white and orange tints were observed. Nearly 18 % of the Lyrids left a (short) train, less than in previous years.
However, the sporadic, in particular the Antihelion meteors can be called the undisputed “stars” of the entire observing session. Four members of magnitude –4 up to –6 within less than 20 hours of observing time seem to be a lone record of usually “low-tide” April nights!
Rendtel J. (2019). 2020 Meteor Shower Calendar. International Meteor Organization.
Rendtel J. and Arlt R. (2014). Handbook for Meteor Observers. International Meteor Organization, Potsdam.