Late April Meteors

April 22 marked the peak of the Lyrid meteor shower. The Lyrids are considered a major shower though, in reality, they are the weakest of the major showers. You might even be able to call them the strongest minor shower.

The Lyrids were produced by comet C/1861 G1 (Thatcher), a comet seen only in 1861. It is a high inclination (~80º) long-period comet with a period of ~400 years. The shower is also prone to outbursts though none was predicted for or reported this year. On the April 22 UT, a total of 21 Lyrids were observed. The star chart below shows the radiant of the Lyrids halfway between Lyra and the keystone of Hercules.

2014Apr22_Lyrids

.

Obs  Date(UT)      Time    TOT SPO ANT SLE PPU LYR ETA
SAL  2014-04-30   09h 13m   16  12  1   -   -   -   3
SAL  2014-04-29   09h 23m   13  11  2   -   -   -   0
SAL  2014-04-28   09h 09m   12  10  1   -   0   -   1
SAL  2014-04-27   09h 01m   16  13  2   -   0   -   1
SAL  2014-04-26   08h 03m   6   4   0   2   0   -   0
SAL  2014-04-25   09h 07m   12  10  2   0   0   0   0
SAL  2014-04-24   08h 15m   11  8   1   0   0   2   0
SAL  2014-04-23   07h 39m   15  8   1   2   0   4   0
SAL  2014-04-22   09h 08m   30  8   1   0   0   21  0
SAL  2014-04-21   09h 12m   14  9   1   1   0   3   0
SAL  2014-04-20   07h 54m   15  13  0   1   0   1   0
SAL  2014-04-19   06h 19m   5   4   0   0   0   1   0
SAL  2014-04-18   00h 00m    "Clouds All Night"
SAL  2014-04-17   08h 23m   11  7   2   1   0   1   -
SAL  2014-04-16   09h 49m   17  13  3   1   0   0   -

SAL - SALSA3 camera in Tucson (Carl Hergenrother)
VIS - Visual observations from Tucson (Carl Hergenrother)
Time - 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 - AntihelionsZSE - Zeta Serpentids
SLE - Sigma Leonids
PPU - Pi Puppids
LYR - Lyrids
ETA - Eta Aquariids

Meteor Activity Outlook for April 20-26, 2013

The following is a slightly edited version of Bob Lunsford’s excellent weekly summary of meteor activity. The original version can be found at the American Meteor Society’s site.

Meteor activity picks up a bit during April as the Lyrids become active during the month. They are active from the 18th through the 25th, with a pronounced maximum on the 22nd. Sporadic rates during April are steady as seen from both hemispheres with southern observers enjoying twice the activity that can be seen from the mid-northern hemisphere.

During this period the moon reaches its full phase on Thursday April 25th. At this time the moon is located opposite the sun and will lie above the horizon all night long. This weekend the waxing gibbous moon will set during the late morning hours and allow a very short period of dark skies for meteor observing. The estimated total hourly meteor rates for evening observers this week is near three as seen from the northern hemisphere and four as seen from south of the equator. For morning observers the estimated total hourly rates should be near seventeen no matter your location. The actual rates will also depend on factors such as personal light and motion perception, local weather conditions, alertness and experience in watching meteor activity. Evening rates are reduced during this period due to the bright moon.

The radiant (the area of the sky where meteors appear to shoot from) positions and rates listed below are exact for Saturday night/Sunday morning April 20/21. These positions do not change greatly day to day so the listed coordinates may be used during this entire period.

The following showers are expected to be active this week:

Activity from the Pi Puppids (PPU) may be seen from the southern hemisphere from a radiant located at 07:16 (109) -45. This area of the sky is located central Puppis, just southwest of the third magnitude star Sigma Puppis. This area of the sky is best seen as soon as it becomes dark during the early evening hours. No matter your location, rates are expected to be low. Observers located in the tropical northern hemisphere may also see some activity but at latitudes north of 30 degrees north, the odds are against seeing any activity at all. At 18km/sec. the Pi Puppids would produce meteors of very slow velocity.

The Sigma Leonids B (SLE) is the second of two branches of this shower. This shower was first noticed by Terentjeva (1990) in her analysis of 554 fireball orbits. This particular branch is active from April 18-26, with maximum activity occurring on the evening of the 19th. The radiant is currently located near 13:32 (203) +03. This position actually lies in central Virgo (not Leo), three degrees north of the third magnitude star Heze (Zeta Virginis). The radiant is best placed near 0100 when it lies highest above the horizon. This shower can be seen equally well from both hemispheres and may be partially responsible for the April fireballs. At 20km/sec. this shower would produce meteors of slow velocity.

The center of the large Anthelion (ANT) radiant is currently located at 14:44 (221) -16. This position lies in western Libra, just west of the third magnitude double star known as Zubenelgenubi (Alpha 2 Librae). These meteors may be seen all night long but the radiant is best placed near 0200 LDT when it lies on the meridian and is highest in the sky. Rates at this time should be near two per hour no matter your location. With an entry velocity of 30 km/sec., the average Anthelion meteor would be of slow velocity.

Activity from the Lyrid (LYR) shower reaches maximum activity on the morning of April 22th with the radiant located at 18:08 (272) +33. This area of the sky is actually located in eastern Hercules, two degrees southwest of the faint star known as Kappa Lyrae. This position also lies six degrees southwest of the brilliant zero magnitude star Vega (Alpha Lyrae). The radiant is best placed just before the break of dawn when the radiant lies highest in the sky. While Lyrid meteors can be seen in both hemispheres, the north is favored as the radiant lies much higher in the sky. Hourly rates at maximum are expected to be 10-15 shower members during the short time between moon set and dawn, when the sky is totally dark. South of the equator rates would most likely be near 5 Lyrids per hour. At 48km/sec. the Lyrids would produce meteors of medium-swift velocity.

Studies of the IMO video database by Sirko Molau and Juergen Rendtel has revealed a weak radiant active in the constellation of Cygnus this time of year. The Nu Cygnids (NCY) are active from April 2 through May 4 with maximum activity occurring on April 18. The current radiant position lies at 20:40 (310) +43. This position lies in central Cygnus, two degrees south of the bright first magnitude star known as Deneb (Alpha Cygni). Rates are expected to be near one shower member per hour during the last couple of hours before dawn. While well placed for the northern hemisphere, this radiant is poorly seen from the southern hemisphere. At 42km/sec. the Nu Cygnids would produce meteors of average velocity.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately five sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near one per hour. As seen from the mid-southern hemisphere (45S), morning rates would be near ten per hour as seen from rural observing sites and two per hour during the evening hours. Locations between these two extremes would see activity between the listed figures. Evening rates are reduced due to bright moonlight.

The list below presents a condensed version of the expected activity this week.
Rates and positions are exact for Saturday night/Sunday morning .

Pi Puppids (PPU) – 07:16 (109) -45   Velocity – 18km/sec.
Northern Hemisphere – <1 per hr.   Southern Hemisphere – <1 per hr

Sigma Leonids B (SLE) – 13:32 (203) +03   Velocity – 20km/sec.
Northern Hemisphere – 2 per hr.   Southern Hemisphere – 2 per hr

Anthelions (ANT) – 14:44 (221) -16   Velocity – 30km/sec.
Northern Hemisphere – 2 per hr.   Southern Hemisphere – 2 per hr

Lyrids (LYR) – 18:08 (272) +33   Velocity – 48km/sec.
Northern Hemisphere – 10 per hr.   Southern Hemisphere – 5 per hr

Nu Cygnids (NCY) – 20:40 (310) +43   Velocity – 42km/sec.
Northern Hemisphere – <1 per hr.   Southern Hemisphere – <1 per hr

Clear Skies!
Robert Lunsford
American Meteor Society

Meteor Activity Outlook for April 13-19, 2013

The following is a slightly edited version of Bob Lunsford’s excellent weekly summary of meteor activity. The original version can be found at the American Meteor Society’s site.

Meteor activity picks up a bit during April as the Lyrids become active during the month. They are active from the 18th through the 25th, with a pronounced maximum on the 22nd. Sporadic rates during April are steady as seen from both hemispheres with southern observers enjoying twice the activity that can be seen from the mid-northern hemisphere.

During this period the moon reaches its first quarter phase on Wednesday April 17th. At this time the moon is located ninety degrees east of the sun and sets near 0100 local daylight time (LDT). This weekend the waxing crescent moon will set during the late evening hours and will not cause any problems for meteor observing. The estimated total hourly meteor rates for evening observers this week is near three as seen from the northern hemisphere and four as seen from south of the equator. For morning observers the estimated total hourly rates should be near ten from the mid-northern hemisphere and fifteen from the mid-southern hemisphere. The actual rates will also depend on factors such as personal light and motion perception, local weather conditions, alertness and experience in watching meteor activity.

The radiant (the area of the sky where meteors appear to shoot from) positions and rates listed below are exact for Saturday night/Sunday morning April 13/14. These positions do not change greatly day to day so the listed coordinates may be used during this entire period.

The following showers are expected to be active this week:

Activity from the Pi Puppids (PPU) begins this week from a radiant located at 07:04 (106) -44. This area of the sky is located central Puppis, five degrees southwest of the third magnitude star Sigma Puppis. This area of the sky is best seen as soon as it becomes dark during the early evening hours. No matter your location, rates will be low, far less than one per hour this early in the activity curve. Observers located in the southern hemisphere have a much better view of this activity as the radiant lies higher in their evening sky. At 18km/sec. the Pi Puppids would produce meteors of very slow velocity.

The Sigma Leonids A (SLE) is the first of two branches of this shower. This shower was first noticed by Terentjeva (1990) in her analysis of 554 fireball orbits. This particular branch is active from April 8-16, with maximum activity occurring on the evening of the 10th. The radiant is currently located near 13:20 (200) +04. This position actually lies in central Virgo (not Leo), five degrees east of the third magnitude star Auva (Delta Virginis). The radiant is best placed near 0100 when it lies highest above the horizon. This shower is currently the strongest in the sky, producing an average of two shower members per hour while the radiant is high in the sky. This shower can be seen equally well from both hemispheres and may be partially responsible for the April fireballs. At 22km/sec. this shower would produce meteors of slow velocity.

The second branch (B) of the Sigma Leonids (SLE) becomes active on April 18th and lasts until the 26th. Maximum activity is not until April 20th. On the 18th, the position of this radiant lies at 13:28 (202) +07, which also places it central Virgo, seven degrees northeast of the third magnitude star Auva (Delta Virginis). The radiant is best placed near 0100 when it lies highest above the horizon. At 20km/sec. this shower would produce meteors of slow velocity.

The large Anthelion (ANT) radiant is currently located at 14:28 (217) -15. This position lies in western Libra, five degrees west  of the third magnitude double star known as Zubenelgenubi (Alpha 2 Librae). These meteors may be seen all night long but the radiant is best placed near 0200 LDT when it lies on the meridian and is highest in the sky. Rates at this time should be near two per hour no matter your location. With an entry velocity of 30 km/sec., the average Anthelion meteor would be of slow velocity.

Activity from the Lyrid (LYR) shower is first detectable on April 18th and the shower reaches maximum activity four nights later. On the 18th the radiant is located at 18:00 (270) +35. This area of the sky is actually located in eastern Hercules, two degrees southeast of the faint star known as Theta Herculis. This position also lies eight degrees southwest of the brilliant zero magnitude star Vega (Alpha Lyrae). The radiant is best placed just before the break of dawn when the radiant lies highest in the sky. While Lyrid meteors can be seen in both hemispheres, the north is favored as the radiant lies much higher in the sky. Rates this early in the activity curve would be low, less than one per hour no matter your location. At 48km/sec. the Lyrids would produce meteors of medium-swift velocity.

Juergen Rendtel and Sirko Molau have discovered an previously unknown radiant active this time of year on the Lyra-Cygnus border. IMO shower #59 is active from April 13-19 with maximum activity occurring on the 16th. The position at maximum activity lies at 19:27 (292) +37, which places it on the Lyra-Cygnus border, only three degrees southeast of the twin fourth magnitude stars Eta and Theta Lyrae. Rates, even at maximum activity, is expected to be less that one per hour no matter your location. With an entry velocity of 45 km/sec., the average meteor from this shower would be of medium velocity.

Studies of the IMO video database by Sirko Molau and Juergen Rendtel has revealed a weak radiant active in the constellation of Cygnus this time of year. The Nu Cygnids (NCY) are active from April 2 through May 4 with maximum activity occurring on April 18. The current radiant position lies at 20:28 (307) +38. This position lies in central Cygnus, two degrees south of the second magnitude star known as Sadr (Gamma Cygni).  At maximum, rates are expected to be near one shower member per hour during the last couple of hours before dawn. While well placed for the northern hemisphere, this radiant is poorly seen from the southern hemisphere. At 42km/sec. the Nu Cygnids would produce meteors of average velocity.

The last of the Delta Aquiliids (DAL) can be seen this weekend. This weak shower is active from April 5 through through the 13th, with maximum activity occurring on the morning of 11th. This stream was first noticed by Peter Jenniskens and is mentioned in his book Meteor Showers and their Parent Comets. It has been recently verified in the IMO video database producing low activity during the period mentioned above. The radiant is currently located near 20:48 (312) +14. This position actually lies in central Delphinus, two degrees south of fourth magnitude double star Gamma Delphini. The radiant is best placed in a dark sky just before dawn. Rates are expected to be less than one per hour and is seen equally well from both hemispheres. At 66km/sec. this shower would produce meteors of swift velocity.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately five sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near two per hour. As seen from the mid-southern hemisphere (45S), morning rates would be near ten per hour as seen from rural observing sites and three per hour during the evening hours. Locations between these two extremes would see activity between the listed figures.

The list below presents a condensed version of the expected activity this week.
Rates and positions are exact for Saturday night/Sunday morning .

Pi Puppids (PPU) – 07:04 (106) -44   Velocity – 18km/sec.
Northern Hemisphere – <1 per hr.   Southern Hemisphere – <1 per hr

Sigma Leonids A (SLE) – 13:20 (200) +04   Velocity – 22km/sec.
Northern Hemisphere – 2 per hr. Southern Hemisphere – 2 per hr

Sigma Leonids B (SLE) – 13:28 (202) +07   Velocity – 20km/sec.
Northern Hemisphere – 2 per hr.   Southern Hemisphere – 2 per hr

Anthelions (ANT) – 14:28 (217) -15   Velocity – 30km/sec.
Northern Hemisphere – 2 per hr.   Southern Hemisphere – 2 per hr

Lyrids (LYR) – 18:00 (270) +35   Velocity – 48km/sec.
Northern Hemisphere – <1 per hr.   Southern Hemisphere – <1 per hr

IMO #59 – 19:27 (292) +37   Velocity – 45km/sec.
Northern Hemisphere – <1 per hr.   Southern Hemisphere – <1 per hr

Nu Cygnids (NCY) – 20:28 (307) +38   Velocity – 42km/sec.
Northern Hemisphere – <1 per hr. Southern Hemisphere – <1 per hr

Delta Aquiliids (DAL) – 20:48 (312) +14   Velocity – 66km/sec.
Northern Hemisphere – <1 per hr. Southern Hemisphere – <1 per hr

Clear Skies!
Robert Lunsford
American Meteor Society

In the Transient Sky – April 2013

April 2013 Highlights
* Comet C/2011 L4 (PANSTARRS) will be visible in the morning sky fading from magnitude 4 to 7
* Comet C/2012 F6 (Lemmon) will be a 5th-6th magnitude object for SH observers
* Saturn at opposition on the 28th
* Jupiter continues to dominate the early evening sky
* Mercury finishes a great morning apparition for southern observers (not so good for northerners)
Note: If anyone has pictures or observations of these objects/events and want to share them with my readers, send them to the Transient Sky at <transientsky1@yahoo.com>.

Planets

Evening Planets

Venus – Venus was in superior conjunction last month. This month the planet is still too close to the Sun for most observers. A lucky few may be able to pick it out against the bright glow of evening twilight by the end of the month.

Jupiter – The King of the Planets dominates the early evening sky being high in the western sky at the end of evening twilight. On the 1st Jupiter sets around 11:30 pm and by 10 pm at the end of the month. It spends the month a few degrees  northeast of the stars of the Hyades cluster in Taurus as it fades from magnitude -2.1 to -2.0.  The Moon pays Jupiter a visit on the evening of the 14th.

Saturn – Saturn reaches opposition this month on the 28th. On that data the ringed planet will be observable all night long. It will also be at its brightest for the year on that night at magnitude +0.1. The Moon passes close to Saturn on the morning of the 25th.

Morning Planets

Mercury – Mercury starts the month in the midst of a good morning apparition for Southern Hemisphere observers. The view is much worse for northern observers. Mercury slowly moves back towards the Sun as the month progresses.

Mars – Both planets are too close to the Sun for easy observation this month. They will be back this summer, Venus in the evening sky and Mars in the morning sky.

Meteors

The year is usually split in 2 with January through June having low rates with few major showers while July through December have high rates with many major showers. Meteor activity is near its annual minimum this month.

Sporadic Meteors

Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During April mornings, 5 or so Sporadic meteors can be observed per hour from a dark moonless sky. The rate is near an annual minimum this month.

Major Meteor Showers

Lyrids [LYR]

This year’s Lyrid meteor shower is seriously hampered by a nearly Full Moon on the night of its peak (April 22nd). The Moon will greatly reduce the usual number of 10-15 meteors per hour.

Minor Meteor Showers

Minor showers produce so few meteors that they are hard to notice above the background of regular meteors. Info on many minor showers are provided on a weekly basis by Robert Lunsford’s Meteor Activity Outlook.

Additional information on these showers and other minor showers not included here can be found at the International Meteor Organization’s 2012 Meteor Shower Calendar.

Comets

Naked Eye Comets (V < 6.0)

C/2011 L4 (PANSTARRS)

Comet PANSTARRS peaked around magnitude 1.5 when it reached perihelion at 0.30 AU from the Sun on March 10. The comet has rapidly faded as it moves away from the Earth and Sun. Observations over the past few days place is around magnitude 4.0 to 5.0.

In March it was an evening object though it spent all month hugging the western horizon and was only visible in twilight. In April the comet can still be seen in the evening with difficulty but it has become much easier to see in the morning. PANSTARRS starts the month in Andromeda only a few degrees from the Andromeda galaxy. As the month progresses it will continue moving north across Andromeda and Cassiopeia.

The comet will fade by ~1 magnitude per week but should remain a good sight in small telescopes and binoculars all month long.

Finder charts can be found at Chasing Comets.

Ephemeris for C/2011 L4 (PANSTARRS)
Date            RA        DEC    Delta   r   Elong    V
2013 Apr 01   00m 31m  +36d 33'  1.275 0.684   32    4.4
2013 Apr 11   00h 27m  +48d 13'  1.358 0.899   41    5.5
2013 Apr 21   00h 21m  +58d 12'  1.442 1.102   50    6.3
2013 May 01   00h 11m  +67d 12'  1.528 1.295   57    7.0

RA = Right Ascension, DEC = Declination, Delta = distance from Earth in AU
r = distance from the Sun in AU, Elong = elongation from Sun in degrees
V = Visual magnitude

C/2012 F6 (Lemmon)

Everyone was expecting C/2011 L4 (PANSTARRS) and C/2012 S1 (ISON) to be the two naked eye comets of 2013. No one was expecting C/2012 F6 (Lemmon) to be vying for the status of naked eye comet when it was discovered by Alex Gibbs of the Mount Lemmon survey back on March 23, 2012. At that time the comet was a faint 20th-21st magnitude and 5.0 AU from the Sun. It also appeared to be an intrinsically faint comet. So faint in fact that I though it had a good chance of disintegrating near perihelion. Instead the comet brightened at a rapid rate.

This surprise comet brightened to magnitude 4.5 to 5.0 as it reached perihelion on March 24, 2013 at a distance of 0.73 AU from the Sun. Unfortunately there have been very few brightness estimates made over the past few weeks. Not only is the comet not visible for those north of the Equator but the comet is also located only ~24 degrees from the Sun.

Lemmon should fade now that it is moving away from the Sun and Earth and may be as faint as magnitude 6-7 by month’s end. Even though it is moving nearly due north through Cetus and Pisces this month it will still not be visible to northern observers till May.

Finder charts can be found at Chasing Comets.

Ephemeris for C/2012 F6 (Lemmon)
Date            RA        DEC    Delta   r   Elong    V
2013 Apr 01   00h 11m  -17d 50'  1.547 0.746   24    4.9
2013 Apr 11   00h 12m  -08d 40'  1.622 0.810   24    5.3
2013 Apr 21   00h 14m  +00d 06'  1.671 0.910   28    5.8
2013 May 01   00h 17m  +08d 32'  1.701 1.031   34    6.4
RA = Right Ascension, DEC = Declination, Delta = distance from Earth in AU
r = distance from the Sun in AU, Elong = elongation from Sun in degrees
V = Visual magnitude

Binocular Comets (V = 6.0 – 8.0)

None

Small Telescope Comets (V = 8.0 – 10.0)

None

Meteor Activity Outlook for April 21-27, 2012

The following is a slightly edited version of Bob Lunsford’s excellent weekly summary of meteor activity. The original version can be found at the American Meteor Society’s site.

Meteor activity picks up a bit during April as two major showers are active during the month. The first of these, the Lyrids, are active from the 16th through the 25th, with a pronounced maximum on the 22nd. The Eta Aquariids start appearing near the 28th and reach maximum activity during the first week in May. Sporadic rates are low but steady as seen from the mid-northern hemisphere (45 N). Sporadic rates seen from the mid-southern hemisphere (45 S) rise this month toward a maximum in July.

During this period the moon reaches its new phase on Saturday the 21st. At this time the moon will be near the sun and will not be visible at night. This will be the best time of the month in which to view meteor activity.  As the week progresses the waxing crescent moon will enter the evening sky but will not be bright enough to interfere with observing. In addition the moon will set during the evening hours allowing the more active morning to be free from any interfering moonlight.  The estimated total hourly rates for evening observers this week is near three for observers in the northern hemisphere and four for those south of the equator. For morning observers the estimated total hourly rates should be near twenty-three as seen from mid-northern latitudes and nineteen from mid-southern latitudes. The actual rates will also depend on factors such as personal light and motion perception, local weather conditions, alertness and experience in watching meteor activity.

The radiant (the area of the sky where meteors appear to shoot from) positions and rates listed below are exact for Saturday night/Sunday morning April 21/22. These positions do not change greatly day to day so the listed coordinates may be used during this entire period.

The following showers are expected to be active this week:

Activity from the Pi Puppids (PPU) continues this week from a radiant located at 07:16 (109) -45. This area of the sky is located central Puppis, two degrees southwest of the third magnitude star Sigma Puppis. This area of the sky is best seen as soon as it becomes dark during the early evening hours. Maximum activity is predicted to occur on Sunday evening the 22nd (23rd UT). Despite this, rates less than one per hour are expected, no matter your location. Observers located in the southern hemisphere have a much better view of this activity as the radiant lies higher in the sky. At 18km/sec. the Pi Puppids would produce meteors of very slow velocity.

The weak shower known as the Sigma Leonids (SLE) is active from a radiant located at 13:40 (205) +04, which actually lies in northern Virgo, four degrees northeast of the third magnitude star Zeta Virginis. One might feel this shower was named for the wrong constellation, but the case is more likely that visual observations, made before the advent of video methods, placed the radiant incorrectly further westward in Leo. This radiant is best placed near 0300 local daylight time (LDT), when it lies on the meridian and is located highest in the sky. Rates at this time would be less than one per hour no matter your location. With an entry velocity of 20 km/sec., the average Sigma Leonid meteor would be of very slow velocity.

There is also another radiant active in Virgo this time of year. Video data from The IMO shows that the h Virginids (HVR) are active from April 22-25 with maximum activity occurring on the 22nd. On the evening of the 21st (22nd UT), the radiant is located at 14:16 (214) -11. This position lies on the Virgo/Libra border, two degrees southeast of the fourth magnitude star Kappa Virginis. The radiant is best placed near 0200 LDT, when it lies on the meridian and is highest above the horizon. At 24km/sec. the h Virginids would produce more slow meteors. Expected rates would also be less than one per hour no matter the date or your location.

The large Antihelion (ANT) radiant is currently located at 14:56 (224) -16. This position lies in western Libra, only one degree southeast of the third magnitude star Zubenelgenubi (Alpha Librae). Due to the large size of this radiant, Antihelion activity may also appear from extreme eastern Hydra, eastern Virgo, northwestern Scorpius, as well as Libra. This radiant is best placed near 0200 LDT, when it lies on the meridian and is located highest in the sky. Rates at this time should be near two per hour as seen from the northern hemisphere and three as seen from south of the equator. With an entry velocity of 30 km/sec., the average Antihelion meteor would be of slow velocity.

The Lyrid (LYR) shower is expected to reach maximum activity on the night of April 21/22 with rates up to 15 shower members per hour. The radiant is located at 18:08 (272) +33. This area of the sky is actually located in extreme eastern Hercules, eight degrees southwest of the brilliant blue-white star Vega (Alpha Lyrae). The radiant is best placed just before the break of dawn when the radiant lies highest in the sky. While Lyrid meteors can be seen in both hemispheres, the north is favored as the radiant lies much higher in the sky. Rates will fall rapidly after maximum and little activity will be seen the remainder of the week. At 48km/sec. the Lyrids would produce meteors of medium-swift velocity. It should be noted that the Lyrids can occasionally produce bright meteors of fireball class magnitude.

Studies of the IMO video database by Sirko Molau and Juergen Rendtel has revealed a weak radiant active in the constellation of Cygnus this time of year. The Nu Cygnids (NCY) are active from April 18 through May 7 with maximum activity occurring on April 19. The current radiant position lies at 20:44 (311) +42. This position lies in central Cygnus, two degrees south of the first magnitude star Deneb (Alpha Cygni). The radiant is best placed during the last dark hour before dawn, when it lies highest above the horizon in a dark sky. Due to the northern declination of the radiant, this activity is not well seen from the southern hemisphere. No matter your location, rates are expected to be less than one per hour. At 42km/sec. the Nu Cygnids would produce meteors of average velocity.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately five sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near two per hour. As seen from the mid-southern hemisphere (45S), morning rates would be near ten per hour as seen from rural observing sites and three per hour during the evening hours. Locations between these two extremes would see activity between the listed figures.

The list below presents a condensed version of the expected activity this week.
Rates and positions are exact for Saturday night/Sunday morning.

Pi Puppids (PPU) – 07:16 (109) -45   Velocity 18km/sec
Northern Hemisphere – <1 per hr Southern Hemisphere – <1 per hour

Sigma Leonids (SLE) – 13:40 (205) +04   Velocity 20km/sec
Northern Hemisphere – <1 per hr   Southern Hemisphere – <1 per hour

h Virginids (HVR) – 14:16 (214) -11   Velocity 24km/sec
Northern Hemisphere – <1 per hr   Southern Hemisphere – <1 per hour

Antihelion (ANT) – 14:56 (224) -16   Velocity 30km/sec
Northern Hemisphere – 2 per hr   Southern Hemisphere – 3 per hour

Lyrids (LYR) – 18:08 (272) +33   Velocity 48km/sec
Northern Hemisphere – 15 per hr   Southern Hemisphere – 5 per hour

Nu Cygnids (NCY) – 20:44 (311) +42   Velocity 42km/sec
Northern Hemisphere – <1 per hr   Southern Hemisphere – <1 per hour

Clear Skies!
Robert Lunsford
American Meteor Society

 

Meteor Activity Outlook for April 14-20, 2012

The following is a slightly edited version of Bob Lunsford’s excellent weekly summary of meteor activity. The original version can be found at the American Meteor Society’s site.

Meteor activity picks up a bit during April as two major showers are active during the month. The first of these, the Lyrids, are active from the 16th through the 25th, with a pronounced maximum on the 22nd. The Eta Aquariids start appearing near the 28th and reach maximum activity during the first week in May. Sporadic rates are low but steady as seen from the mid-northern hemisphere (45 N). Sporadic rates seen from the mid-southern hemisphere (45 S) rise this month toward a maximum in July.

During this period the moon wanes from its last quarter phase to nearly new. This weekend the waning crescent moon will rise during the early morning hours, disturbing the nearby sky but allowing dark views in the opposite direction. The moon wanes and rises later which each passing night, providing more favorable circumstances as time goes on. The estimated total hourly rates for evening observers this week is near three for observers in the northern hemisphere and four for those south of the equator. For morning observers the estimated total hourly rates should be near seven as seen from mid-northern latitudes and eleven from mid-southern latitudes. The actual rates will also depend on factors such as personal light and motion perception, local weather conditions, alertness and experience in watching meteor activity. Morning rates are slightly reduced during this period due to moonlight.

The radiant (the area of the sky where meteors appear to shoot from) positions and rates listed below are exact for Saturday night/Sunday morning April 14/15. These positions do not change greatly day to day so the listed coordinates may be used during this entire period.

The following showers are expected to be active this week:

Activity from the Pi Puppids (PPU) begins this weekend from a radiant located at 07:04 (106) -44. This area of the sky is located central Puppis, five degrees southwest of the third magnitude star Sigma Puppis. This area of the sky is best seen as soon as it becomes dark during the early evening hours.  No matter your location, rates will be low, far less than one per hour this early in the activity curve. Observers located in the southern hemisphere have a much better view of this activity as the radiant lies higher in the sky. At 18km/sec. the Pi Puppids would produce meteors of very slow velocity.

The weak shower known as the Sigma Leonids (SLE) becomes active on the 18th and peaks on the 20th. The radiant is located at 13:32 (203) +05, which actually lies in northern Virgo near the faint star Sigma Virginis. One might feel this shower was named for the wrong “Sigma” star, but the case is more likely that visual observations, made before the advent of video methods, placed the radiant incorrectly further westward in Leo. This radiant is best placed near 0300 local daylight time (LDT), when it lies on the meridian and is located highest in the sky. Rates at this time would be less than one per hour no matter your location. With an entry velocity of 20 km/sec., the average Sigma Leonid meteor would be of very slow velocity.

The large Antihelion (ANT) radiant is currently located at 14:32 (218) -15. This position lies in eastern Libra, five degrees west of the third magnitude star Zubenelgenubi (Alpha Librae). Due to the large size of this radiant, Antihelion activity may also appear from extreme eastern Hydra, eastern Virgo, as well as Libra. This radiant is best placed near 0200 LDT, when it lies on the meridian and is located highest in the sky. Rates at this time should be near two per hour no matter your location. With an entry velocity of 30 km/sec., the average Antihelion meteor would be of slow velocity.

Activity from the Lyrid (LYR) shower is first detectable on April 16th and the shower reaches maximum activity 6 nights later. The radiant is currently located at 17:52 (268) +36. This area of the sky is actually located in eastern Hercules, close to the faint star known as Theta Herculis. The radiant is best placed just before the break of dawn when the radiant lies highest in the sky. While Lyrid meteors can be seen in both hemispheres, the north is favored as the radiant lies much higher in the sky. Rates this early in the activity curve would be low, less than one per hour no matter your location. At 48km/sec. the Lyrids would produce meteors of medium-swift velocity.

Studies of the IMO video database by Sirko Molau and Juergen Rendtel has revealed a weak radiant active in the constellation of Cygnus this time of year. The Nu Cygnids (NCY) are active from April 18 through May 7 with maximum activity occurring on April 19. The current radiant position lies at 20:20 (305) +39. This position lies in central Cygnus, two degrees southwest of the second magnitude star Sadr (Gamma Cygni). The radiant is best placed during the last dark hour before dawn, when it lies highest above the horizon in a dark sky. Due to the northern declination of the radiant, this activity is not well seen from the southern hemisphere. No matter your location, rates at this time are expected to be less than one per hour. At 42km/sec. the Nu Cygnids would produce meteors of average velocity.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately four sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near two per hour. As seen from the mid-southern hemisphere (45S), morning rates would be near eight per hour as seen from rural observing sites and three per hour during the evening hours. Locations between these two extremes would see activity between the listed figures. Morning rates are slightly reduced during this period due to moonlight.

The list below presents a condensed version of the expected activity this week.
Rates and positions are exact for Saturday night/Sunday morning.

Pi Puppids (PPU) – 07:04 (106) -44  Velocity 18km/sec
Northern Hemisphere – <1 per hr Southern Hemisphere – <1 per hour

Sigma Leonids (SLE) – 13:32 (203) +05  Velocity 20km/sec
Northern Hemisphere – <1 per hr Southern Hemisphere – <1 per hour

Antihelion (ANT) – 14:32 (218) -15  Velocity 30km/sec
Northern Hemisphere – 2 per hr Southern Hemisphere – 2 per hour

Lyrids (LYR) – 17:52 (268) +36  Velocity 48km/sec
Northern Hemisphere – <1 per hr Southern Hemisphere – <1 per hour

Nu Cygnids (NCY) – 20:20 (305) +39  Velocity 42km/sec
Northern Hemisphere – <1 per hr Southern Hemisphere – <1 per hour

Clear Skies!
Robert Lunsford
American Meteor Society

 

In the Transient Sky – April 2012

Though not quite as spectacular as March, 4 planets are visible in the evening this month (Venus, Jupiter, Mars and Saturn).

April 2012 Highlights
* Venus dominates the evening sky
* Jupiter sinks lower into the evening twilight
* Mars fades but rides higher in the evening sky
* Saturn reaches opposition on the 15th
* Comet C/2009 P1 (Garradd) is a nice binocular object in the evening sky
* Mercury is the midst of a relatively poor morning apparition for northern observers and a great apparition for southern observers  

Note: If anyone has pictures or observations of these objects/events and want to share them with my readers, send them to the Transient Sky at <transientsky1@yahoo.com>.

Planets

Evening Planets

Jupiter – The King of the Planets continues to slowly sink into the twilight glow this month. For most of us this will be the last time to spot Jupiter in the evening sky till next year. At magnitude -2.1 to -2.0, it is still the second brightest “star” in the sky after Venus. A very thin and difficult to see Moon will pair up with Jupiter on the evening of March 22.

Venus  – Other than the Moon Venus is the brightest object in the sky. The brilliant beacon is visible high up in the southwest after sunset. Venus starts the month at its highest in the twilight sky and ends the month at its brightest (magnitude -4.7). The real showstopper occurs at the end of the apparition in June when Venus will transit the disk of the Sun. This will be the last Venus transit till 2117. The Moon and Venus make a gorgeous pair on the evening of the 24th.

Mars - Mars is the bright reddish “star” high in the East after evening twilight. Mars reached opposition the point opposite the Sun on the sky) in early March. Since Mars was near its aphelion when we passed it on our inside track, this opposition is almost as faint as can be at a magnitude of -1.2. In April, it fades from -0.7 to -0.1. The red planet will spend the month in the constellation of Leo.

Saturn - Saturn reaches opposition on April 15 at a distance of 8.75 AU (813 million miles or 1.3 million km) from Earth. Opposition means Saturn is directly opposite the Sun in the sky. As a result, it rises around sunset and is highest in the sky at midnight. The Full Moon visits on the mornings of the 7th and 8th.

Morning Planets

Mercury – If you live in the Southern Hemisphere, Mercury will put on a nice display in the morning sky reaching its highest around April 19th. If, like me, you live north of the equator, this month’s display will be a hard one to observe.

Meteors

The year is usually split in 2 with January through June having low rates with few major showers while July through December have high rates with many major showers. March marks the lowest rates of the year.

Sporadic Meteors

Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During January mornings, 10 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

Lyrids (LYR)

April brings the first major meteor shower since the Quadrantids of early January. The Lyrids were produced by Comet Thatcher, a comet on a ~400 years orbit that has only been observed once back in 1861. The Lyrids meteors, on the other hand, can be seen every year.

The radiant is located between the constellations of Lyra and Hercules. Though the radiant rises during the evening, the best time to see Lyrids is after 11 pm when the radiant is high in the sky. The shower is active from April 16 to 25 with a peak on the morning of April 22. The shower only shows good levels of activity on the night of the peak. Even then, this is the most minor of the major showers with a peak rate of ~15-25 meteors per hour.

Though there are no predictions on enhanced activity, the Lyrids have been known to put on grand displays. The 1st great display goes back almost 25oo years while the last happened in 1982. But you never know, this year the Lyrids could put on a good show.

Minor Meteor Showers

Minor showers produce so few meteors that they are hard to notice above the background of regular meteors. Info on many minor showers are provided on a weekly basis by Robert Lunsford’s Meteor Activity Outlook.

Additional information on these showers and other minor showers not included here can be found at the International Meteor Organization’s 2012 Meteor Shower Calendar.

Comets

Naked Eye Comets (V < 6.0)

None this month.

Binocular Comets (V = 6.0 – 8.0)

C/2009 P1 (Garradd)

First seen way back on August 13, 2009 by Gordon Garradd who was observing for the Siding Spring Survey, a NASA-funded survey observing from Australia. At the time of discovery it was located at a distance 8.7 AU from the Sun, nearly the distance of Saturn. Perihelion occurred 2 days before Christmas 2011 at 1.55 AU from the Sun. Though the comet does not get very close to the Sun, it is an intrinsically bright comet and could have been a real sight had it come closer to the Sun and Earth.

The comet is in full retreat from the Earth and Sun as it heads outward on its long journey back to the cold depths of the outer Solar System.  Comet Garradd is slowly moving south through the constellation of Cancer in the evening sky.  Since the comet is moving away from us and the Sun it should continue to fade from around magnitude 7.0 to 7.9 as the month progresses. The comet does appear to be fading rather slowly and may be brighter than predicted here as the month progresses.

Date       RA       DEC     Delta    r    Elong   Mag
Apr  1   09h 34m  +58°01'   1.517  2.047   107    7.0
Apr 10   09h 08m  +50°53'   1.693  2.124   101    7.3
Apr 20   08h 55m  +44°06'   1.919  2.212    93    7.6
Apr 30   08h 50m  +38°31'   2.165  2.302    85    7.9

Small Telescope Comets (V = 8.0 – 10.0)

None

Follow

Get every new post delivered to your Inbox.

Join 106 other followers