In the Transient Sky – August 2012

August 2012 Highlights
* Perseid meteor shower peaks on the morning of August 12
* Moon occults Venus on August 13
* Moon located between Venus and Jupiter during the peak of the Perseids
* Mars, Saturn and Spica form a tight group mid-month (Moon joins on the 21st)
* Mercury is visible in the morning after mid-month

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

Mars and Saturn - Mars and Saturn are visible in the WSW sky during early evening hours. The two are joined by the bright 1st magnitude star Spica. The three are similar in brightness with the brightest being Saturn at magnitude +0.8 followed by Spica at magnitude +1.0 and Mars at +1.1 to 1.2. Saturn moves slowly relative to the stars and will be within 5° of Spica all month. Mars is moving much faster. At the start of the month Mars is ~7° of Saturn and Spica. On the 13th and 14th Mars passes in between Saturn and Spica. The three will form a nice line only ~5° long on those evenings. The Moon joins to make a quartet on the evening of the 21st.

Morning Planets

Jupiter - The largest planet rises around 1-2 am at the start of the month and around 11 to midnight at the end of the month. At magnitude -2.2 to -2.3 it is much brighter than the evening planets. Jupiter is currently moving slowly through the constellation of Taurus. The Moon is nearby on the mornings of August 11 and 12 (the night before and the night of the Perseid peak).

Venus – Venus rises about 3.5 hours before the Sun this month. In fact, on August 15 it is at Greatest Elongation from the Sun. In a telescope the planet will appear half-illuminated. The Moon is close by on the mornings of August 13th and 14th. The Moon passes so close to Venus that it actually passes in front of the planet for all of Mexico and the United States and all but the extreme NE corner of Canada. The event can also be seen from Japan, the Koreas, NE China and eastern Siberia. In the United States, the occultation is visible during the late afternoon on August 13. The Moon and Venus will be very low in the sky for eastern observers. The view is easier towards the western half of the country.

Mercury – The innermost planet is too close to the Sun for easy observation at the beginning of the month. By 2nd week of August it is rapidly climbing out of the dawn twilight. Use the Moon to spot Mercury on the morning of the 15th (Mercury to the lower left of the Moon) and 16th (Mercury above a very thin crescent Moon).

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 at an annual peak 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 June mornings, 7 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

Perseids (PER)

The Perseids are one of the 2 annual showers worth getting up early for. This year the peak will occur on the morning of August 12. The Moon will be up at that time though it shouldn’t hamper meteor watching too much.

From the International Meteor Organization’s 2012 Meteor Calendar:

Recent IMO observations found the timing of the mean or “traditional” broad maximum varied between λ⊙ ∼ 139.8° to 140.3°, equivalent to 2012 August 12, 07h to 19h30m UT. No additional peaks are anticipated this year, but this does not guarantee what will occur!

Although the Moon is a waning crescent, three days after last quarter on August 12, it will rise from mid-northern locations around local midnight to one a.m. Its brightness and relative proximity to the Perseid radiant should be considered more of a nuisance than a deterrent, even so. Such mid-northern latitudes are the more favored for Perseid observing, as from here, the shower’s radiant is usefully observable from 22h—23h local time onwards, gaining altitude throughout the night. The near-nodal part of the “traditional” maximum interval would be best-viewed from eastern Asia east to far western North America (with increasing moonlight for places further east in this zone), assuming it happens as expected. All forms of observing can be carried out on the shower, though unfortunately, it cannot be usefully observed from most of the southern hemisphere.

The best time to look will be after about 1-2 am on the night of August 11/12. Meteors will appear to radiate from the constellation of Perseus in the northeast sky.

Over the past five years, the Perseids have peaked with zenithal hourly rates (ZHR) of 58 (in 2011), 91 (in 2010), 173 (in 2009), 116 (in 2008) and 93 (in 2007). These are the rates that would be seen under perfectly dark skies, with no Moon and with the radiant overhead. In reality these conditions are never really met especially if you live anywhere near a city. Still observed rates of 20-40 meteors per hour are possible even under suburban skies.

The Perseids were produced by Comet 109P/Swift-Tuttle which orbits the Sun once ever ~135 years. This comet was discovered by American astronomers Lewis Swift (Marathon, New York) and Horace Tuttle (Cambridge, Massachusetts) in July of 1861. During that return the comet reached a bright 2nd magnitude and developed a tail up to 30° long. The comet returned late in 1992 and brightened up to 4th-5th magnitude. Based on our updated knowledge of Swift-Tuttle’s orbit it is now known that the comet was also seen in 1737 and likely seen in 188 AD and 69 BC.

Back in 1992, Tim Spahr and I used the Catalina schmidt to take a photographic image of Comet Swift-Tuttle (seen below).

Comet Swift-Tuttle observed with the University of Arizona Catalina Schmidt in 1992. This is a scan of a photographic image taken by Tim Spahr and Carl Hergenrother. Credit: Carl Hergenrother/Tim Spahr.

The best time to look will be after about 1-2 am on the night of August 12/13. Meteors will appear to radiate from the constellation of Perseus in the northeast sky.

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)

None this month

Small Telescope Comets (V = 8.0 – 10.0)

None this month

Meteor Activity Outlook for July 28-August 3, 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 season finally gets going in July for the northern hemisphere. The first half of the month will be much like June. After the 15th though, both sporadic and shower rates increase significantly. For observers in the southern hemisphere, sporadic rates will be falling but the overall activity will increase with the arrival of the Delta Aquariids.

During this period the moon reaches its full phase on Wednesday August 1st. At this time the moon will be located opposite the sun and will be above the horizon all night long.This weekend the waxing gibbous moon will set during the late morning hours, allowing a short window of opportunity to view activity under dark skies. The estimated total hourly meteor rates for evening observers this week is near four no matter your location. For morning observers the estimated total hourly rates should be near twenty six from the mid-northern hemisphere and twenty eight 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. Evening rates are reduced 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 July 28/29. These positions do not change greatly day to day so the listed coordinates may be used during this entire period.

The following radiants are expected to be active this week:

A new source found by the IMO video cameras to be active this time of year are the July Zeta Draconids (ZED). This radiant has been found to be active from July 19-29 with maximum activity activity occurring on the 19th. The last of these meteors may be seen this weekend from a radiant located at 18:06 (271) +62, which is situated in southern Draco, eight degrees southeast of the third magnitude star Al dhibain (Zeta Draconis). Due to a low amount of data the mean position of activity shifts quite a bit night to night so consider this a wide radiant until better parameters can be obtained. Current rates would most likely be less than one per hour no matter your location. The radiant is best placed near 2200 (10pm) LDT when it lie highest above the horizon. With an entry velocity of 23 km/sec., the average July Zeta Draconid meteor would be slow.

Another new source found by the IMO video cameras to be active this time of year is the July Gamma Draconids (GDR). This radiant has been found to be active from July 24-31, with maximum activity occurring on the 28th. Unfortunately the bright, waxing gibbous moon is above the horizon when this source is best placed in the sky. Therefore rates would most likely be less than one per hour no matter your location. The radiant is currently located at 18:42 (281) +51, which is locate six degrees east of the second magnitude star Eltanin (Gamma Draconis). The radiant is best placed near 2300 (11pm) LDT when it lie highest above the horizon. With an entry velocity of 27 km/sec., the average July Gamma Draconid meteor would be slow.

The Alpha Capricornids (CAP) are active from a wide radiant located at 20:18 (305) -11. This position lies in northwestern Capricornus, only one degree north of the third magnitude double star Alpha Capricornii. The radiant is best placed near 0100 local daylight time (LDT), when it lies on the meridian and is highest in the sky. Maximum activity is expected on the 29th so current rates should be near two per hour under dark skies. Don’t confuse these meteors with the antihelion meteors, which have a radiant just to the east. Both radiants need to be in your field of view to properly sort these meteors. With an entry velocity of 25 km/sec., most activity from this radiant would be slow, a bit slower than the antihelions. This radiant is well seen except for far northern latitudes where it remains twilight all night long and the radiant does not rise as high into their sky.

The large Antihelion (ANT) radiant is currently located at 21:12 (318) -14. This position lies on the Capricornus/Aquarius border, two degrees northwest of the fourth magnitude star Iota Capricorni. Due to the large size of this radiant, Antihelion activity may also appear from southern Aquila, Microscopium, eastern Sagittarius, Aquarius, and Piscis Austrinus as well as Capricornus. 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 are expected to be near one per hour as seen from the northern hemisphere and two per hour 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 Delta Aquariids (SDA) reach maximum activity on the 29th from a radiant located at 22:42 (340) -16. This position is located in southwestern Aquarius, three degrees west of the third magnitude Delta Aquarii. Hourly rates will depend on your latitude and time of night. Unfortunately the moon will be above the horizon when the radiant culminates near 0300 LDT. During the last hour of darkness rates should range from fifteen shower members as seen from the southern hemisphere to less than five as seen from high northern latitudes. With an entry velocity of 42 km/sec., most activity from this radiant would be of average velocities.

The Piscids Austrinids (PAU) are a minor shower not well seen from the northern hemisphere. This radiant is active from July 15 through August 10. Maximum activity occurs on July 28 when the zenith hourly rate (ZHR) may reach five. These rates are only seen from the southern hemisphere where the radiant passes overhead. From mid-northern latitudes, rates of one per hour at maximum are usually seen. The radiant is currently located at 22:48 (342) -29. This position lies in eastern Piscis Austrinus, three degrees southwest of the bright first magnitude star Fomalhaut (Alpha Piscis Austrinus). The radiant is best placed near 0300 LDT, when it lies highest in the sky. With an entry velocity of 35km/sec., most
activity from this radiant would be of average velocities.

The Perseids (PER) are active from a radiant located at 01:46 (027) +54. This position lies on the Cassiopeia/Perseus border, five degrees east of the fourth magnitude star Theta Cassiopeiae. The radiant is best placed during the last hour before the start of morning twilight when it lies highest in a dark sky. Since the maximum is not until August 12th, current rates would be only three to four per hour at best, as seen from the northern hemisphere. Activity from this source is not visible south of 40 degrees south latitude. With an entry velocity of 61 km/sec., most activity from this radiant would be swift.

Another new source found by the IMO video cameras to be active this time of year are the Alpha Triangulids (ATR). This radiant has recently been found to be active later than previously published, with the activity period ranging from July 25 through August 21 with maximum activity occurring on July 27. Current rates would be near one per hour as seen from the northern hemisphere and less than one from the southern hemisphere. The radiant is currently located at 02:02 (031) +40, which is actually situated in eastern Andromeda, three degrees south of the famous second magnitude star double star Almach (Gamma Andromedae). The radiant is best placed during the last hour before dawn, when it lies highest in a dark sky. With an entry velocity of 67 km/sec., the average Alpha Triangulid meteor would be swift.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately twelve 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 seven per hour as seen from rural observing sites and one per hour during the evening hours. Locations between these two extremes would see activity between the listed figures. Evening rates are reduced due to moonlight.

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

July Zeta Draconids (ZED) – 18:06 (271) +62   Velocity 23km/sec
Northern Hemisphere – <1 per hr   Southern Hemisphere – <1 per hour

July Gamma Draconids (GDR) – 18:42 (281) +51   Velocity 27km/sec
Northern Hemisphere – <1 per hr   Southern Hemisphere – <1 per hour

Alpha Capricornids (CAP) – 20:18 (305) -11   Velocity 25km/sec
Northern Hemisphere – 2 per hr   Southern Hemisphere – 2 per hour

Antihelions (ANT) – 21:12 (318) -14   Velocity 30km/sec
Northern Hemisphere – 1 per hr   Southern Hemisphere – 2 per hour

Delta Aquariids (SDA) – 22:42 (340) -16   Velocity 42km/sec
Northern Hemisphere – 5 per hr   Southern Hemisphere – 12 per hour

Piscids Austrinids (PAU) – 22:48 (342) -29   Velocity 35km/sec
Northern Hemisphere – 1 per hr   Southern Hemisphere – 3 per hour

Perseids (PER) – 01:46 (027) +54   Velocity 61km/sec
Northern Hemisphere – 4 per hr   Southern Hemisphere – 2 per hour

Alpha Triangulids (ATR) – 02:02 (031) +40   Velocity 67km/sec
Northern Hemisphere – 1 per hr   Southern Hemisphere – <1 per hour

Clear Skies!
Robert Lunsford
American Meteor Society

 

The Moon, Saturn, Mars and Spica Team Up This Evening

Only a week or so ago, the Moon made a beautiful grouping with 2 planets (Venus and Jupiter) and a bright star (Aldebaran) in the early morning sky. Tonight (evening of July 24) the Moon will team up with a different collection of planets (Mars and Saturn) and a bright star (Spica).

Once it is dark enough to see some stars this evening, look to the SW. The chart below shows the relative positions of the objects. The bright star to the lower left of Saturn and upper left of the Moon is Spica. A B-type or blue giant, Spica is the 15th brightest star in the sky. It is located 260 light years away and produces as much light as 1500 Suns with a mass of 10 Suns.

View of the Moon-Mars-Saturn-Spica grouping in the SW sky during the evening of July 24. Credit: Carl Hergenrother (chart made with Stellarium)

 

Meteor Activity Outlook for July 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 season finally gets going in July for the northern hemisphere. The first half of the month will be much like June. After the 15th though, both sporadic and shower rates increase significantly. For observers in the southern hemisphere, sporadic rates will be falling but the overall activity will increase with the arrival of the Delta Aquariids.

During this period the moon reaches its first quarter phase on Wednesday the 25th. At this time the moon will be located ninety degrees east of the sun and set near midnight local daylight time (LDT). This weekend the waxing crescent moon will set during the late evening hours and will not hamper observing efforts during the more active morning hours. The estimated total hourly meteor rates for evening observers this week is near four no matter your location. For morning observers the estimated total hourly rates should be near sixteen from the mid-northern hemisphere and fourteen 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 July 21/22. These positions do not change greatly day to day so the listed coordinates may be used during this entire period.

The following radiants are expected to be active this week:

A new source found by the IMO video cameras to be active this time of year are the July Zeta Draconids (ZED). This radiant has been found to be active from July 19-29. Maximum activity activity occurs on the 19th from a position of  17:23 (263) +61, which is situated in southern Draco, five degrees southeast of the third magnitude star Al dhibain (Zeta Draconis). Due to a low amount of data the mean position of activity shifts quite a bit night to night so consider this a wide radiant until better parameters can be obtained. Current rates would most likely be less than one per hour no matter your location. The radiant is best placed near 2200 (10pm) LDT when it lie highest above the horizon. With an entry velocity of 23 km/sec., the average July Zeta Draconid meteor would be slow.

The Alpha Capricornids (CAP) are active from a wide radiant located at 20:04 (301) -12. This position lies near the Sagittarius, Aquila, Capricornus border, three degrees west of the third magnitude double star Alpha Capricornii. The radiant is best placed near 0100 local daylight time (LDT), when it lies on the meridian and is highest in the sky. Current rates should be near one per hour no matter your location. Don’t confuse these meteors with the antihelion meteors, which have a radiant just to the east. Both radiants need to be in your field of view to properly sort these meteors. With an entry velocity of 25 km/sec., most activity from this radiant would be slow, a bit slower than the antihelions. This radiant is well seen except for far northern latitudes where it remains twilight all night long and the radiant does not rise as high into their sky.

The large Antihelion (ANT) radiant is currently located at 20:48 (312) -17. This position lies in central Capricornus, four degrees west of the fourth magnitude star Dorsum (Theta Capricorni). Due to the large size of this radiant, Antihelion activity may also appear from southern Aquila, Microscopium, eastern Sagittarius, northwestern Aquarius,  and western Piscis Austrinus as well as Capricornus. 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 are near their lowest of the year with one 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 Delta Aquariids (SDA) will begin this weekend from a radiant located at 22:18 (334) -18. This position is located in southwestern Aquarius, eight degrees southwest of the third magnitude Delta Aquarii. Maximum activity is expected on July 29th. Hourly rates will depend on your latitude. Those viewing from the southern tropics will see the best rates of near 1-2 per hour. Rates seen from mid-northern latitudes will range from 0-1 per hour, depending on the haziness of your skies. The radiant rises near 2200 (10pm) LDT for observers located in the mid northern latitudes, but is best placed near 0300 LDT, when it lies highest in the sky. With an entry velocity of 42 km/sec., most activity from this radiant would be of average velocities.

The Piscids Austrinids (PAU) are a minor shower not well seen from the northern hemisphere. This radiant is active from July 15 through August 10. Maximum activity occurs on July 28 when the zenith hourly rate (ZHR) may reach five. These rates are only seen from the southern hemisphere where the radiant passes overhead. From mid-northern latitudes, rates of one per hour at maximum are usually seen. The radiant is currently located at 22:23 (336) -32. This position lies in central Piscis Austrinus, eight degrees southwest of the bright first magnitude star Fomalhaut (Alpha Piscis Austrinus). The radiant is best placed near 0300 LDT, when it lies highest in the sky. With an entry velocity of 35km/sec., most activity from this radiant would be of average velocities.

The July Pegasids (JPE) are active with low rates during most of July with maximum activity occurring on the 10th. The radiant is currently located at 23:52 (358) +14. This area of the sky lies in southeastern Pegasus, four degrees west of the third magnitude star Algenib (Gamma Pegasi). This radiant is best placed during the last dark hour before dawn, when it lies highest above the horizon in a dark sky. Rates at this time should be less than one per hour no matter your location. With an entry velocity of 68 km/sec., the average July Pegasid meteor would be of swift speed.

The Perseids (PER) are active from a radiant located at 01:04 (016) +52. This position lies in southern Cassiopeia, six degrees southeast of the second magnitude star Shedar (Alpha Cassiopeiae). The radiant is best placed during the last hour before the start of morning twilight when it lies highest in a dark sky. Since the maximum is not until August 12th, current rates would be only two to three per hour at best, as seen from the northern hemisphere. Activity from this source is not visible south of 40 degrees south latitude. With an entry velocity of 61 km/sec., most activity from this radiant would be swift.

Another new source found by the IMO video cameras to be active this time of year is the Phi Piscids (PPS). This radiant has been found to be active from June 14 through July 30 with maximum activity occurring on July 1st. Current rates would most likely be less than one per hour no matter your location. The radiant is currently located at 01:56 (029) +36, which is situated on the Andromeda/Triangulum border, three degrees northwest of the third magnitude star Beta Triangulum. The radiant rises near midnight LDT but does not reach a sufficient altitude above the horizon until three hours later. Activity would best seen during the last dark hour of the morning when the radiant is located highest in a dark sky. With an entry velocity of 71 km/sec., the average Pi Piscid meteor would be swift.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately ten sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near three 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.

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

July Zeta Draconids (ZED) – 17:23 (263) +61   Velocity 23km/sec
Northern Hemisphere – <1 per hr   Southern Hemisphere – <1 per hour

Alpha Capricornids (CAP) – 20:04 (301) -12   Velocity 25km/sec
Northern Hemisphere – 1 per hr   Southern Hemisphere – 1 per hour

Antihelions (ANT) – 20:48 (312) -17   Velocity 30km/sec
Northern Hemisphere – 1 per hr   Southern Hemisphere – 1 per hour

Delta Aquariids (SDA) – 22:18 (334) -18   Velocity 42km/sec
Northern Hemisphere – 1 per hr   Southern Hemisphere – 2 per hour

July Pegasids (JPE) – 23:52 (358) +14   Velocity 68km/sec
Northern Hemisphere – <1 per hr   Southern Hemisphere – <1 per hour

Perseids (PER) – 01:04 (016) +52   Velocity 61km/sec
Northern Hemisphere – 3 per hr   Southern Hemisphere – 1 per hour

Phi Piscids (PPS) – 01:56 (029) +36   Velocity 71km/sec
Northern Hemisphere – <1 per hr   Southern Hemisphere – <1 per hour

Clear Skies!
Robert Lunsford
American Meteor Society

 

Meteor Activity Outlook for July 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 season finally gets going in July for the northern hemisphere. The first half of the month will be much like June. After the 15th though, both sporadic and shower rates increase significantly. For observers in the southern hemisphere, sporadic rates will be falling but the overall activity will increase with the arrival of the Delta Aquariids.

During this period the moon reaches its new phase on Wednesday the 18th. At this time the moon will be located near the sun and will be invisible at night. This will be the best time of the month to try and view meteor activity as the bright moon will spoil the showers that peak near months end. This weekend the waning crescent moon will rise during the late morning hours and will not hamper observing efforts. The estimated total hourly meteor rates for evening observers this week is near four no matter your location. For morning observers the estimated total hourly rates should be near fourteen 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.

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 July 14/15. These positions do not change greatly day to day so the listed coordinates may be used during this entire period.

The following radiants are expected to be active this week:

The Alpha Capricornids (CAP) are active from a wide radiant located at 19:56 (297) -14. This position lies in northeastern Sagittarius, seven degrees west of the third magnitude double star Alpha Capricornii. The radiant is best placed near 0100 local daylight time (LDT), when it lies on the meridian and is highest in the sky. Current rates should be less than one per hour as seen from the northern hemisphere and near one per hour from the southern. Don’t confuse these meteors with the antihelion meteors, which have a radiant just to the east. Both radiants need to be in your field of view to properly sort these meteors. With an entry velocity of 25 km/sec., most activity from this radiant would be slow, a bit slower than the antihelions. This radiant is well seen except for far northern latitudes where it remains twilight all night long and the radiant does not rise as high into their sky.

The large Antihelion (ANT) radiant is currently located at 20:20 (305) -18. This position lies in western Capricornus, three degrees south of the third magnitude star Dabih (Beta Capricorni). Due to the large size of this radiant, Antihelion activity may also appear from southern Aquila, Microscopium, eastern Sagittarius, northwestern Aquarius, western Piscis Austrinus, and Scutum as well as Capricornus. 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 are near their lowest of the year with less than one per hour as seen from the northern hemisphere and one per hour 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 Sigma Capricornids (SCA) are a new source of activity to look for this time of year. Actually this radiant has been listed before many years ago but had become lost in the many radiants active in this area of the sky this time of year. With over one million meteors available for analysis, the International Meteor Organization’s video section, led by Sirko Molau, has been able to isolate activity from this radiant. The radiant has been found to be active from June 19 through July 24 with maximum activity occurring on June 27. In early July it is still one of the most active radiants in the sky. Unfortunately that is not saying much as the strongest radiant only produces two meteors per hour this time of year. This radiant is now located at 21:12 (318) -03. This area of the sky is actually in western Aquarius, four degrees northwest of the third magnitude star Sadalsuud (Beta Aquarii). This radiant is best positioned for view on the meridian near 0300 LDT. With an entry velocity of 42 km/sec., the average Sigma Capricornid meteor would be of medium speed. Meteors from this source should be easy to distinguish from the slower Antihelion meteors as the two sources are separated by nearly twenty degrees. One must have both radiants within your field of view to properly distinguish between the two sources.

Another radiant returning to the list of active radiants are the July Pegasids (JPE). This source is active with low rates during most of July with maximum activity occurring on the 10th. The radiant is currently located at 23:28 (352) +12. This area of the sky lies in northern Pegasus, five degrees east of the third magnitude star Scheat (Beta Pegasi). This radiant is best placed during the last dark hour before dawn, when it lies highest above the horizon in a dark sky. Rates at this time should be near one per hour no matter your location. With an entry velocity of 68 km/sec., the average July Pegasid meteor would be of swift speed.

The Perseids (PER) are now active from a radiant located at 00:25 (006) +50. This position lies in southern Cassiopeia, seven degrees southwest of the second magnitude star Shedar (Alpha Cassiopeiae). The radiant is best placed during the last hour before the start of morning twilight when it lies highest in a dark sky. Since the maximum is not until August 12th, current rates would be only one to two per hour at best, as seen from the northern hemisphere. Activity from this source is not visible south of 40 degrees south latitude. With an entry velocity of 61 km/sec., most activity from this radiant would be swift.

Another new source found by the IMO video cameras to be active this time of year is the Phi Piscids (PPS). This radiant has been found to be active from June 14 through July 30 with maximum activity occurring on July 1st. During late June and early July this radiant is often the most active source of meteors in the sky with 1-2 shower members per hour during the early morning hours. The radiant is currently located at 01:30 (023) +31, which is situated on the Pisces/Triangulum border, four degrees northwest of the third magnitude star Ras al Muthallah (Alpha Triangulum). This position also happens to be very close to the large spiral galaxy M33. The radiant rises near midnight LDT but does not reach a sufficient altitude above the horizon until three hours later. Activity would best seen during the last dark hour of the morning when the radiant is located highest in a dark sky. With an entry velocity of 71 km/sec., the average Pi Piscid meteor would be swift.

Studies by Sirko Molau and Juergen Rendtel of the IMO’s video data has revealed an active radiant located in Andromeda this time of year. The c-Andromedids (CAN) are active from July 4-16, with maximum activity occurring on the 12th. The radiant position is currently located at 02:22 (035) +50. This area of the sky lies in extreme northeastern Andromeda, eight degrees north of the famous second magnitude double star Almach (Gamma Andromedae). This radiant is best placed during the last dark hour before dawn, when it lies highest above the horizon in a dark sky. Rates at this time should be less than one no matter your location. With an entry velocity of 59 km/sec., the average c-Andromedid meteor would be of swift speed.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately nine sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near three per hour. As seen from the mid-southern hemisphere (45S), morning rates would also be near nine 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 table below presents a condensed version of the expected activity this week. Rates and positions are exact for Saturday night/Sunday morning .

Alpha Capricornids (CAP) – 19:56 (297) -14   Velocity 25km/sec
Northern Hemisphere – <1 per hr   Southern Hemisphere – 1 per hour

Antihelions (ANT) – 20:20 (305) -18   Velocity 30km/sec
Northern Hemisphere – <1 per hr   Southern Hemisphere – 1 per hour

Sigma Capricornids (SCA) – 21:12 (318) -03   Velocity 42km/sec
Northern Hemisphere – 1 per hr   Southern Hemisphere – 1 per hour

July Pegasids (JPE) – 23:28 (352) +12   Velocity 68km/sec
Northern Hemisphere – 1 per hr   Southern Hemisphere – 1 per hour

Perseids (PER) – 00:25 (006) +50   Velocity 61km/sec
Northern Hemisphere – 2 per hr   Southern Hemisphere – <1 per hour

Phi Piscids (PPS) -01:30 (023) +31   Velocity 71km/sec
Northern Hemisphere – 2 per hr Southern Hemisphere – 1 per hour

c-Andromedids (CAN) – 02:22 (035) +50   Velocity 59km/sec
Northern Hemisphere – <1 per hr Southern Hemisphere – <1 per hour

Clear Skies!
Robert Lunsford
American Meteor Society

Comet 96P/Machholz Visible in SOHO Images

Updated (at 3 pm Tucson time on July 17).

Every ~5.3 years, comet 96P/Machholz makes a close and personal swing around the Sun. At a distance of 0.12 AU, comet Machholz comes within 11 million miles (18 million km). That is 8 times closer to the Sun than the Earth and even 2.5 times closer than the innermost planet Mercury.

Though the comet can become very bright at perihelion, its close proximity to the Sun makes it all but impossible to observe at that time. Luckily we have a number of spacecraft observing the Sun which can also be used to observe the comet. One such spacecraft, the joint ESA/NASA Solar and Heliospheric Observatory (SOHO) is currently picking up the comet. The image below is the latest image from the LASCO instruments on the spacecraft. [Update:  96P has now moved out of the SOHO LASCO field-of-view. As of 10 am (Tucson time) on the 13th, the comet is visible to the lower right of the Sun. A short tail is also visible trailing away from the Sun. As of 10 am (Tucson time) on the 14th, the comet is visible just to the upper right of the center obscuration. As of 10 am (Tucson time) on the 15th, the comet is visible halfway between the center and the top of the image. As of 8 am (Tucson time) on the 16th, 96P is visible near the edge of the field at the 11 o'clock position.  Since the comet is about as close to the Sun as it gets, it is also visible in the higher resolution LASCO C2 field. A real-time C2 image is located below under the C3 image. In the C2 image the comet can be seen near the upper right corner though it will move out of the field in a few hours. The comet is no longer visible in the C2 field.] Additional SOHO images can be found here.

Perihelion occurred on July 14.78 UT (or roughly 11:40 am Tucson time on the 14th, that’s 11:40 am PDT, 12:40 pm MDT, 1:40 pm CDT, 2:40 pm EDT). By the end of July, the comet will be visible in the evening sky as a faint and difficult 9-10th magnitude object for telescope observers.

A Bright Nova in Sagattarius

Yet another nova has been spotted in the Sagittarius. This makes the 4th nova detected in that constellation this year.

This one is a bit brighter than the others making it an easy target for small telescope users. Even small binocular observers under dark skies will be able to spot it.

Nova Sgr 2012 No. 4 (also known as PNV J18202726-2744263) is around magnitude 8.0 give or take a few tenths of a magnitude. It is very possible that the nova has already begun its decline phase and may be a bit fainter (~8.5). The nova is located at

RA = 18h 20m 27s.26   Decl = -27° 44′ 26″.3  (2000.0).

More info on the nova and how to produce finder charts can be found on the AAVSO Special Notice #289.

Meteor Activity Outlook for July 7-13, 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 season finally gets going in July for the northern hemisphere. The first half of the month will be much like June. After the 15th though, both sporadic and shower rates increase significantly. For observers in the southern hemisphere, sporadic rates will be falling but the overall activity will increase with the arrival of the Delta Aquariids.

During this period the moon reaches its last quarter phase on Wednesday the 11th. At this time the moon will be located ninety degrees east of the sun and will rise near midnight local daylight time (LDT) for observers located in mid-northern latitudes. This weekend the waning gibbous moon will rise during the late evening hours and will severely hamper efforts to view meteor activity the remainder of the night. The moonlight situation improves with each passing night it will not be until late in the week when dark skies are available during the early morning hours. The estimated total hourly meteor 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 ten as seen from mid-northern latitudes and twelve 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 reduced 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 July 7/8. These positions do not change greatly day to day so the listed coordinates may be used during this entire period.

The following radiants are expected to be active this week:

The large Antihelion (ANT) radiant is currently located at 19:52 (298) -19. This position lies in a blank area of eastern Sagittarius between the third magnitude stars Pi Sagittarii and Dabih (Beta Capricorni). Due to the large size of this radiant, Antihelion activity may also appear from Serpens Cauda, Corona Australis, southern Aquila, Microscopium, western Capricornus, and Scutum as well as Sagittarius. 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 less than one per hour as seen from the northern hemisphere and one per hour 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 Sigma Capricornids (SCA) are a new source of activity to look for this time of year. Actually this radiant has been listed before many years ago but had become lost in the many radiants active in this area of the sky this time of year. With over one million meteors available for analysis, the International Meteor Organization’s video section, led by Sirko Molau, has been able to isolate activity from this radiant. The radiant has been found to be active from June 19 through July 24 with maximum activity occurring on June 27. In early July it is still one of the most active radiants in the sky. Unfortunately that is not saying much as the strongest radiant only produces two meteors per hour this time of year. This radiant is now located at 21:02 (316) -04. This area of the sky is actually in western Aquarius, five degrees northwest of the third magnitude star Sadalsuud (Beta Aquarii). This radiant is best positioned for view on the meridian near 0300 LDT.  With an entry velocity of 42 km/sec., the average Sigma Capricornid meteor would be of medium speed. Meteors from this source should be easy to distinguish from the slower Antihelion meteors as the two sources are separated by nearly twenty degrees. One must have both radiants within your field of view to properly distinguish between the two sources.

Another radiant returning to the list of active radiants are the July Pegasids (JPE). This source is active with low rates during most of July with maximum activity occurring on the 10th. The radiant is currently located at 23:08 (345) +11. This area of the sky lies in southern Pegasus, six degrees south of the second magnitude star Markab (Alpha Pegasi). This radiant is best placed during the last dark hour before dawn, when it lies highest above the horizon in a dark sky. Rates at this time should be near one per hour no matter your location. With an entry velocity of 68 km/sec., the average July Pegasid meteor would be of swift speed.

Another new source found by the IMO video cameras to be active this time of year is the Phi Piscids (PPS).  This radiant has been found to be active from June 14 through July 30 with maximum activity occurring on July 1st. During late June and early July this radiant is often the most active source of meteors in the sky with 1-2 shower members per hour during the early morning hours. The radiant is currently located at 01:15 (019) +29, which is situated in extreme northeastern Pisces. The nearest bright star is Mirach (Beta Andromedae), which lies seven degrees to the north. The radiant rises near midnight LDT but does not reach a sufficient altitude above the horizon until three hours later. Activity would best seen during the last dark hour of the morning when the radiant is located highest in a dark sky. With an entry velocity of 71 km/sec., the average Phi Piscid meteor would be swift.

Studies by Sirko Molau and Juergen Rendtel of the IMO’s video data has revealed an active radiant located in Andromeda this time of year. The c-Andromedids (CAN) are active from July 4-16, with maximum activity occurring on the 12th. The radiant position is currently located at 01:58 (029) +47. This area of the sky lies in northeastern Andromeda, five degrees north of the famous second magnitude double star Almach (Gamma Andromedae). This radiant is best placed during the last dark hour before dawn, when it lies highest above the horizon in a dark sky. Rates at this time should be less than one no matter your location. With an entry velocity of 59 km/sec., the average c-Andromedid meteor would be of swift speed.

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 seven 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 reduced 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 unless the
showers are of short duration. In that case the position on the night of maximum
activity is listed.

Antihelions (ANT) – 19:52 (298) -19  Velocity 30km/sec
Northern Hemisphere – <1 per hr   Southern Hemisphere – 1 per hour

Sigma Capricornids (SCA) – 21:02 (316) -04    Velocity 42km/sec
Northern Hemisphere – 1 per hr   Southern Hemisphere – 1 per hour

July Pegasids (JPE) – 23:08 (345) +11   Velocity 68km/sec
Northern Hemisphere – 1 per hr   Southern Hemisphere – 1 per hour

Phi Piscids (PPS) – 01:15 (019) +29   Velocity 71km/sec
Northern Hemisphere – 2 per hr   Southern Hemisphere – 1 per hour

c-Andromedids (CAN) – 01:58 (029) +47   Velocity 59km/sec
Northern Hemisphere – <1 per hr   Southern Hemisphere – <1 per hour

Clear Skies!
Robert Lunsford
American Meteor Society

 

In the Transient Sky – June 2012

July 2012 Highlights
* Venus and Jupiter share the early morning sky
* The Moon, Venus, Jupiter and Aldebaran are within 5° of each other on the morning of the 15th
* Mars and Saturn slowly fade in the evening sky
* Mercury continues a nice apparition in the evening sky

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

Mercury – This month Mercury finishes off a rather good evening apparition for northern observers. On the 1st Mercury is located a few degrees above the WNW horizon an hour after sunset. It will quickly drop (as well as slowly fade) out of sight by the 2nd week of July.

Mars - Mars is the brightish reddish “star” to the SW early in the evening. Mars reached opposition (the point opposite the Sun on the sky) in early March. In July, it fades from magnitude +0.9 to +1.1. The red planet will spend the month moving eastwards through western Virgo. The Moon visits on the evenings of the 23rd and 24th.

Saturn - Saturn reached opposition on April 15 at a distance of 8.75 AU (813 million miles or 1.3 million km) from Earth. This month it continues making a nice but distant pair (~5°) with the bright 1st magnitude Spica. Both can be seen to the South at the end of twilight. Saturn will fade from magnitude +0.7 to +0.8. The Moon visits on the mornings of the 24th and 25th. Mars is quickly closing in on Saturn and Spica and will make a nice trio of similarly bright “star” in mid-August.

Morning Planets

Jupiter and Venus – Last March, these two put on a nice display in the evening sky. After parting for a few month, they are back together, this time in the early morning sky. On the 1st, the two are located within ~5° of each other. Jupiter is further from the horizon at magnitude -2.0. Venus is much brighter at magnitude -4.6 and further down. About 3° below Venus is the brightest star in Taurus, 1st magnitude Aldebaran. Both planets will shift down relative to the stars with Venus passing within 1° of Aldebaran on the morning of the 9th. On the morning of the 15th the Moon will join the two planets and Aldebaran. All 4 will be located within an area 7° across. Definitely wake up early to see this.

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 really takes off 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 June mornings, 7 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

Southern Delta Aquariids

This shower will be spoiled by the nearly Full Moon this year. Luckily the even better Perseids in August won’t be bothered by the Moon.

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)

None

Small Telescope Comets (V = 8.0 – 10.0)

Comet 96P/Machholz

Comet 96P/Machholz is the only comet that will be brighter than 10th magnitude this month. And even it will be a difficult object as it will be located very close to the Sun.

This comet was discovered the old fashioned way, by an astronomer looking through a telescope. No cameras, whether photographic or digital, were used. Don Machholz first spotted 96P on 1986 May 12 from Loma Prieta peak in California. It currently takes ~5.3 years to orbit the Sun.

It has one of the smallest perihelion distances of any short-period comet at 0.12 AU. For this go-around, the comet will reach perihelion on July 14. Though the comet will be very bright at perihelion, estimates range from magnitude +2 to -2, it will be located within a few degrees of the Sun at that time making it invisible to everyone except for a few Sun-watching spacecraft. With difficulty, observers with telescopes in the Southern hemisphere will be able to watch the comet rapidly brighten but also rapidly approach the Sun for the first few days of July. Those of us in the Northern hemisphere have a chance of spying the quickly fading comet during the last few nights of July.

Date            RA        DEC    Delta   r   Elong    V
2012 Jul 01   05h 35m  -02d 44'  0.955 0.521   31    9.5
2012 Jul 11   06h 51m  +14d 14'  1.092 0.211   11    5.1
2012 Jul 21   09h 01m  +30d 30'  1.003 0.291   17    6.6
2012 Jul 31   11h 10m  +27d 03'  0.894 0.587   35   10.0

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

Meteor Activity Outlook for June 30-July 6, 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 season finally gets going in July for the northern hemisphere. The first half of the month will be much like June. After the 15th though, both sporadic and shower rates increase significantly. For observers in the southern hemisphere, sporadic rates will be falling but the overall activity will increase with the arrival of the Delta Aquariids.

During this period the moon reaches its full phase on Tuesday July 3rd. At this time the moon will be located opposite of the sun and will rise as the sun sets and will set as the sun rises. This weekend the waxing gibbous moon will set near the start of morning twilight. One may get in an hour of decent viewing just before dawn but this disappears on Monday as the moon will remain above the horizon the entire night. The estimated total hourly meteor rates for evening observers this week is near two for observers in the northern hemisphere and three for those south of the equator. For morning observers the estimated total hourly rates should be near four as seen from mid-northern latitudes and eight 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. Rates are 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 June 30/July 1. These positions do not change greatly day to day so the listed coordinates may be used during this entire period.

The list below presents a condensed version of the expected activity this week. Details of each radiant will be posted again next week when moonlight is not as bad.

June Bootids (JBO)  15:02 (226) +47   Velocity – 18km/sec
Northern Hemisphere – <1 per hour   Southern Hemisphere – <1 per hour

f-Ophiuchids (FOP)  18:16 (274) +07   Velocity – 21km/sec
Northern Hemisphere – <1 per hour   Southern Hemisphere – <1 per hour

Antihelion (ANT) 19:28 (292) -21   Velocity – 30km/sec
Northern Hemisphere – 1 per hour   Southern Hemisphere – 2 per hour

c-Andromedids (CAN)  01:36 (024) +45   Velocity – 59km/sec
Northern Hemisphere – <1 per hour   Southern Hemisphere – <1 per hour

Clear Skies!

Robert Lunsford
American Meteor Society

 

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