Lyrids Revisited – Apr 19/20/21/22

Bob Lunsford trekked out to the Mojave Desert to view last week’s Lyrid peak. From his notes:

“I made a 3 night camping trip to the Mojave Desert to view Lyrid activity. It was clear the first night but I lost the last two hours on the second night due to clouds. The third night was totally clear. The video camera ran between 1 and 5am PDT each morning. The dark skies allowed many more meteors than would have been captured from the San Diego area.”

Obs  Date (UT)   TotTime TOT SPO ANT LYR
MJD  2009-04-20  04h 00m  57  45  4   8
MJD  2009-04-21  02h 00m  23  11  5   7
MJD  2009-04-22  04h 00m  69  34  6   29

TUS – Camera in Tucson operated by Carl Hergenrother
MJD – Camera in the Mojave Desert operated by Bob Lunsford
SDG – Camera in San Diego operated by Bob Lunsford
TotTime – Total amount of time each camera looked for meteors
TOT – Total number of meteors detected
SPO – Sporadics (meteors not affiliated with any particular meteor shower)
ANT – Antihelions
LYR – Lyrids

Apr 27/28/29/30 Meteors

Rates are starting to pick up a bit. Most of the month has seen meteor numbers in the single digits so it’s nice to see a few double digit night.

Many of the meteors from the past few nights have been bright and long-lasting. A few even showed evidence of fragmenting as small pieces were visible breaking off and falling behind the main body of the meteor.

The Eta Aquarids are still producing a very low rate of activity. This should change as we get closer to its May 5th maximum.

Obs  Date (UT)   TotTime TOT SPO ANT ETA
TUS  2009-04-30  08h 50m  12  9   2   1
TUS  2009-04-29  08h 50m  11  10  1   0
TUS  2009-04-28  06h 56m  7   5   1   1

TUS – Camera in Tucson operated by Carl Hergenrother
SDG – Camera in San Diego operated by Bob Lunsford
TotTime – Total amount of time each camera looked for meteors
TOT – Total number of meteors detected
SPO – Sporadics (meteors not affiliated with any particular meteor shower)
ANT – Antihelions
ETA - Eta Aquarids

Tonight: Moon-Pleiades-Mercury Conjunction

This evening is your best chance to see the innermost planet Mercury. Since Mercury is located ~2/3rds of the way closer to the Sun than the Earth, it never travels very far from the Sun in our sky.

The Moon will also located just above Mercury this evening, April 26. Observers will need a clear view of the western horizon to see the event. This is because they will be located low in the sky. The image below shows what the scene will look like from North America. Note that the Pleiades open star cluster will be located between Mercury and the Moon. It will be a great sight via your eye or binoculars. In a telescope, Mercury will appear as a fat crescent with ~36% of its disk illuminated.

mercury_moon_apr26

Map of the Moon-Mercury-Pleiades conjunction on the evening of April 26. Map made with Stellarium.

Apr 22/23/24 Meteors

After peaking on Wednesday morning, the activity level of the Lyrids falls as rapidly as it rose. Now we look forward to the gradual rise of the Eta Aquarids.

Obs  Date (UT)   TotTime TOT SPO ANT PPU LYR ETA
TUS  2009-04-24  07h 42m  9   6   2   0   1   0
TUS  2009-04-23  09h 10m  14  7   1   0   6   0

TUS – Camera in Tucson operated by Carl Hergenrother
SDG – Camera in San Diego operated by Bob Lunsford
TotTime – Total amount of time each camera looked for meteors
TOT – Total number of meteors detected
SPO – Sporadics (meteors not affiliated with any particular meteor shower)
ANT – Antihelions
PPU – Pi Puppids
LYR – Lyrids
ETA - Eta Aquarids

Apr 21/22 Meteors – The Peak of the Lyrids and a Cloud Occultation

Yesterday morning the sky showed a double feature, the Lyrid meteor shower and a lunar occultation of Venus. I was outside to see and hopefully get some pictures of both.

I’ve never seen a lunar occultation, or a planet or asteroid occultation for that matter. And I still haven’t seen one. All I saw were the clouds that occulted the Moon and Venus. About 15 minutes before Venus was set to disappear, the clouds rolled in. At least I got to see the awesome sight of a very close Venus and Moon as they rose over the horizon.

Bob Lunsford, on the other hand, got some great video of the disappearance and reappearance of Venus. I’ll try and post those videos in the next day or two.

Luckily it was clear enough to observe the Lyrids. I began my watch at 3 am. Right off the bat I observed a bright Lyrid. A minute later I saw an even brighter one. Within 15 minutes I counted 5 Lyrids and 1 Sporadic. So I’m think “this is pretty good, the Lyrids must be real active this year”. Then things ground to a halt. It was another 22 minutes till I spotted another meteor (a Sporadic) and 50! minutes till the next Lyrid rocketed into view.

Lulls in the action are common when watching meteor showers. Unfortunately, they make me question myself. Why am I out here? Am I too tired to see the meteors? Or am I just missing them? Luckily the meteors do come back and the last half hour of my observing saw 7 meteors. Whether the apparent non-random distribution of meteors is a statistical fluke or the result of clumpiness in the meteor stream is not know.

So after observing for 65 minutes (the same clouds that blocked my view of the occultation put an end to my Lyrid observing) I counted 14 meteors (7 LYR, 6 SPO and 1 ETA). Based on my observations and those of others (like my good friend Salvador Aguirre of Hermosillo), the IMO Live ZHR plot shows a peak Lyrid rate of 16 meteors per hour. This is typical for the Lyrids.

Though I only observed for an hour, my camera was running all night. It picked up 27 meteors, of which 13 were definitely Lyrids. A few of the 14 Sporadics were probably also Lyrids but not ID’d as such my the MetRec program. Last year my camera saw 16 Lyrids during with a bright Moon out so the Lyrids may have been more active last year. 27 meteors is the best single night for my camera system since the Quadrantid peak (107 meteors) on Jan 2/3.

Obs  Date (UT)   TotTime TOT SPO ANT PPU LYR ETA
TUS  2009-04-22  08h 42m  27  14  0   0   13  0

TUS – Camera in Tucson operated by Carl Hergenrother
SDG – Camera in San Diego operated by Bob Lunsford
TotTime – Total amount of time each camera looked for meteors
TOT – Total number of meteors detected
SPO – Sporadics (meteors not affiliated with any particular meteor shower)
ANT – Antihelions
PPU – Pi Puppids
LYR – Lyrids
ETA - Eta Aquarids

Apr 20/21 Meteors

Last night was the night before the peak of the Lyrids. The past 4 nights have seen a nice increase in the number of detected Lyrids from 1 to 2 to 3 to 5. Remember that even though only 5 Lyrids all night seems like a low number, your eye will see many more than my camera. My system can only detect meteor down to magnitude 2. Most people, even those who live in the suburbs or small cities can see fainter than this. Even from my home within Tucson proper, I can see 4th magnitude stars. Each increase in magnitude results in 2.1 times as many Lyrids (what meteor scientists call the population index). So if I were to have been sitting outside all night watching the Lyrids, I would have seen over 20 Lyrids. With tonight’s peak, hopefully many more will be seen.

Obs  Date (UT)   TotTime TOT SPO ANT PPU LYR ETA
TUS  2009-04-21  09h 40m  9   4   0   0   5   0

TUS – Camera in Tucson operated by Carl Hergenrother
SDG – Camera in San Diego operated by Bob Lunsford
TotTime – Total amount of time each camera looked for meteors
TOT – Total number of meteors detected
SPO – Sporadics (meteors not affiliated with any particular meteor shower)
ANT – Antihelions
PPU – Pi Puppids
LYR – Lyrids
ETA - Eta Aquarids

Apr 19/20 Meteors

Lyrid rates continue to crawl higher. If we use last year as a guide, tonight will see a few more Lyrids before the majority of the activity kicks in on Wednesday morning. According to the Live ZHR chart at the IMO, visual observers are seeing 2-4 Lyrids per hour from dark sites.

Obs  Date (UT)   TotTime TOT SPO ANT PPU LYR ETA
TUS  2009-04-20  07h 45m  9   5   1   0   3   0

TUS – Camera in Tucson operated by Carl Hergenrother
SDG – Camera in San Diego operated by Bob Lunsford
TotTime – Total amount of time each camera looked for meteors
TOT – Total number of meteors detected
SPO – Sporadics (meteors not affiliated with any particular meteor shower)
ANT – Antihelions
PPU – Pi Puppids
LYR – Lyrids
ETA - Eta Aquarids

Two Reasons to Wake Up Early Wednesday Morning

Reason #1 …

On the morning of April 22, the Moon will occult (or pass in front) of Venus for observers in most of North America. This event happens in daylight for most people. Only observers roughly west of the Rockies will see it in a dark sky. The below map from the International Occultation Timing Association (IOTA) shows where the occultation will be visible. Times for the beginning and end of the occultation can be found at IOTA’s site. A map showing time of disappearance and reappearance can be found at Science@NASA.

0422venus1

Venus and the Moon will rise around ~4 am local time in the east. It will help if you have a clear eastern horizon since all of the action will occur close to the horizon. [Added Apr 21: This morning I was up at ~5 am similar to the time when the occultation will start this morning. In Tucson at 5 am, twilight has already started. Still the sky is dark enough that the Moon and Venus are obvious. I didn't appreciate how low Venus is though. It was just barely visible between the trees. You may have to find a clear view of the eastern horizon to see the show.]

The following diagram gives a good representation of what the occultation will look like right before the Moon passes in front of Venus on the morning of April 22. Note that Mars will be located nearby as well. For those with binoculars or a telescope, Venus will appear as a thin crescent similar to, but much smaller than, the Moon.

venus_moon_mars_april22

The Moon, Venus and Mars just before the start of the occultation of Venus on the morning of April 22. Sky map produced with Stellarium.

Even if you can’t see the occultation, the close proximity of the Moon and Venus will appear awe inspiring. For those who want a nice challenge, try spotting Venus in broad daylight near the Moon. Venus is more than bright enough to be seen in a clear daylight sky assuming you know exactly where to look. Luckily the nearby Moon can help guide you.

Reason #2 …

The first few months of the year usually bring few meteors. After the excitement of early January’s Quadrantids there are no major showers for the next 3 months. This month the drought ends as the Lyrids, and in 2 weeks the Eta Aquarids, bring some much welcomed meteor “rain”.

The Lyrids are usually classified as a major shower though they are just barely so. They can be considered the weakest of the major showers or the strongest of the minor ones. They are produced by Comet Thatcher, a comet on a ~400 years orbit that has only been observed in 1861. The Lyrids, on the other hand, can be seen every year.

Comet Thatcher was discovered by American Professor A. E. Thatcher on April 5, 1861, only a week before start of hostilities in the US Civil War. Thatcher discovered the comet from New York City. Back in those days, light pollution was not a problem and the sky was dark even in the middle of major cities. One wonders if NYC will ever be the host any more comet discoveries. A short piece in the New York Times published on Feb. 28, 1870 contains a private letter sent from Sir John Herschel to Professor A. E. Thatcher. The letter was published nearly a decade after the discovery but shows the excitement in having a local scientist being personally congratulated by one of the world’s eminent astronomers of the time.

Thatcher first detected the comet as a 7thmagnitude object with no tail in the constellation of Draco. The comet brightened to magnitude 2 or 3 a month later as it passed closest to Earth at 0.34 AU on May 5. At the time the comet was an easy naked eye object with a 1 degree long tail. Perihelion occurred on June 3rd at a distance of 0.92 AU from the Sun. The parent of the Lyrids was last seen on Sept. 7, 1861. [Ref: Cometography, Volume II and Comets - A Descriptive Catalog, both by Gary Kronk]

The Lyrid meteors have been known for thousands of years. The earliest definite observation of the Lyrids goes back to 687 BC China. Many additional metoer displays in 11th and 12th centuries have been linked to the Lyrids. One of the best displays occured in 1803 when an observer noted 167 Lyrids in only 15 minutes. The last great Lyrid outburst happened in 1982 when 3-5 Lyrids per minute were seen. The next Lyrid outbursts are predicted for 2040 and 2041. Regardless, our understanding of meteor stream dynamics is still poor and a major outburst could happen in any year making yearly observations important.

This year the Lyrids are predicted to peak at 11 hour UT on the morning of April 22. The timing is great for the Americas which should see rates of ~15-25 meteors per hour. (These rates are only valid for observers under dark rural skies and when the radiant is nearly overhead.) Rates should be above ~10 per hour for a 24 hour period centered on the peak. A live plot of visual Lyrid rates from the International Meteor Organization can be found here.

Like most meteor showers, the Lyrids are best observed early in the morning a few hours before dawn. If you don’t want to get up that early, meteors can be seen, in diminished numbers, anytime after ~11 pm. The radiant is located between the constellations of Lyra and Hercules just to the west of the bright star Vega.

lyrids_map

The sky at ~4:00 am on the morning of April 22 (valid for North America). The radiant of the Lyrids is overhead and denoted by the yellow starburst pattern. Star chart created with Stellarium.

When you see a Lyrid, what are you actually seeing? You regular run-of-the-mill Lyrid is a small piece of dust that was ejected from the nucleus of Comet Thatcher many hundreds to thousands of years ago. The reason why the meteor “burns” up in the atmosphere is due to the friction caused by its rapid velocity. The Lyrids strike the Earth’s atmosphere at 49 km/s or 30 miles/second.

Apr 18/19 Meteors

Meteor rates are still low but the 2 detected Lyrids are a sign of things to come. As we approach the Lyrid peak on Wednesday morning, the number of Lyrids should rapidly increase. Last year, the Tucson camera detected 34 Lyrids with 26 happening on the nights of April 20/21 and 21/22.

Last night also saw the beginning of activity for the Eta Aquarids. These meteors from Comet Halley will peak on May 5/6 though this shower is more of a southern Hemisphere event.

Obs  Date (UT)   TotTime TOT SPO ANT PPU LYR ETA
TUS  2009-04-19  09h 17m  8   6   0   0   2   0

TUS – Camera in Tucson operated by Carl Hergenrother
SDG – Camera in San Diego operated by Bob Lunsford
TotTime – Total amount of time each camera looked for meteors
TOT – Total number of meteors detected
SPO – Sporadics (meteors not affiliated with any particular meteor shower)
ANT – Antihelions
PPU – Pi Puppids
LYR – Lyrids
ETA - Eta Aquarids

Apr 16/17/18 Meteors

Finally got a decent showing last night. I have to go back nearly 3 weeks to find the last night with 9 or more meteors. Last night also saw the 1st Lyrid of the year for my camera system. Hopefully there will be many more over the next few nights.

Obs  Date (UT)   TotTime TOT SPO ANT PPU LYR
TUS  2009-04-18  09h 06m  9   6   2   0   1
TUS  2009-04-17  06h 49m  5   4   1   0   0

TUS – Camera in Tucson operated by Carl Hergenrother
SDG – Camera in San Diego operated by Bob Lunsford
TotTime – Total amount of time each camera looked for meteors
TOT – Total number of meteors detected
SPO – Sporadics (meteors not affiliated with any particular meteor shower)
ANT – Antihelions
PPU – Pi Puppids
LYR – Lyrids

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