Venus and Jupiter Put on an Early Morning Show

[Editor's note: I notice that lots of people are still finding this now a few years old post. If you are trying to find out what those bright stars in the eastern evening sky (Sirius and Jupiter) and eastern Morning sky (Venus) are (Jan/Feb 2014), go to the front page of this blog at transientsky.wordpress.com for the latest posts.]

I see there have been lots of searches recently about the 2 bright ‘stars’ in the early morning eastern sky.

The show is being put on by the planets Venus (the brighter and lower one) and Jupiter. Also in line with the two is the Pleiades open star cluster (above the 2 planets) and Aldebaran , the brightest star in Taurus (below the two planets). The two planets will spend the next few weeks close together. On the morning of July 15 a thin crescent Moon will add even more to the show.

So for all of you early risers out there who have been watching these two, congratulations. As for the rest of us (myself included), set your clocks for an hour before sunrise, find a clear view of the eastern horizon and enjoy the show.

Image

A chart of Venus and Jupiter an hour or so before sunrise on the morning of 2012 June 30. Credit: Carl Hergenrother/Stellarium.

Nova Oph 2012 Fades Rapidly

After spending the past 3 months since discovery bouncing back and forth between V magnitude 10.5 and 12.5, Nova Oph 2012 has finally begun to fade. And what a fade! In just the past 24 hours the nova has faded by over 2 magnitudes. Over the past 48 hours the fade has exceeded 3 magnitudes.

Only a few days ago I posted (see post here) that Nova Oph 2012 was likely to be a ‘P’ or ‘plateau’ type of nova based on the shape of its lightcurve near maximum. Namely the nova spent months near maximum brightness. Well there is another type of nova described by Strope, Schaefer and Henden (2010) called the ‘D’ or ‘dip’ type. D-types experience a large sharp drop in brightness due to the formation of a dust shell around the nova which absorbs the light of the nova. As a result, less light gets through the dust and it appear fainter to us. Over time the dust clears and the nova starts to brighten again. Is Nova Oph 2012 a ‘D’ type. I’m certainly not a nova expert but for now we’ll just have to watch what other tricks this nova has up its sleeves.

Lightcurve of Nova Oph 2012. Plot includes visual and CCD V magnitude measurements. Observations overplotted with a cross were made by Carl Hergenrother. All observations are from the AAVSO. Plot created with the AAVSO Variable Star Plotter (VSP).

Novae Update

There are now 4 (and possibly 5) novae in the Sagittarius/Ophiuchus/Scorpius region that have erupted in the past few months. Three of the 5 are still bright enough for small telescope observers.

I have been routinely observing all 5 with the Sierra Stars Observatory 0.61-m telescope. Continuing the post, 3 Relatively Bright Novae in Sagittarius/Ophiuchus, from last month, here is the latest on the novae.

Nova Sagittarii 2012 = PNV J17452791-2305213

Nova Sag 2012 has rapidly faded from its peak magnitude of V ~ 8.8. Recent CCD observations place it at V ~ 15.2 and much too faint for most visual observers. This nova is typical of most novae with a sharp peak in brightness and rapid fading. Novae are classified based on the shape of their lightcurve and the rate at which they fade. This nova faded by 2 magnitudes (t_2) in about 3 days, by 3 magnitudes (t_3) in about 6.5 days and 6 magnitudes (t_6) by about 40 days. According to the Strope, Schaefer, Henden (2010) classification scheme, Nova Sag 2012 appears to be either a S(6) or O(6) type nova. S types display smooth declines in brightness while O types show oscillations in the lightcurve. You can see hints of rapid oscillations of up to 1 magnitude during the month of May. The ’6′ in each classification is the length of time for the nova to drop 3 magnitudes in brightness. In this case, the nova dropped 3 magnitudes from magnitude 8.8 to 11.8 in 6-7 days.

 

Nova Ophiuchi 2012 No 2 = PNV J17395600-2447420

Similar to Nov Sag 2012, Nova Oph 2012 No 2 also faded rapidly from a peak of ~11 to ~15.2. Assuming the earliest observations represent it maximum brightness, it faded 2 magnitudes (t_2) in 7 days and 3 magnitudes in (t_3) in 15 days. Its smooth decline makes it a S(15) nova. There was a slight brightening starting on June 14 that lasted till June 20. This could be what’s called a ‘cusp’ which is typical of the C or cusp type of nova. Usually these cusps are larger and longer lasting so the S(15) classification still seems the best for this nova.

The brightness graph below shows observations taken in 3 wavelengths, V for visual or yellow, B for blue and R for red. It is apparent that the nova is red since it is brightest in the R filter. Part of this is that much of the nova’s light is due to Hydrogen-α emission which is located at a wavelength covered by the R filter.

 

Nova Ophiuchi 2012 = PNV J17260708-2551454

In contrast to the 2 novae above, Nova Oph 2012 is a much slower nova. For starters the nova was first seen ~3 months ago and it still hasn’t faded by 3 magnitudes. Also it has shown numerous oscillations of almost 2 magnitudes. Currently around magnitude 12.8, the nova did appear to start fading but that fading is in question since the nova has actually brightened a little over the past week. There is a type of nova called ‘Flat’ or F types due to their long flat maximas. Nova Oph 2012 may be of this type. Only time (and more observations) will tell.

 

Nova Scorpii 2012

Now on to the first of the more recently discovered novae. Nova Scorpii 2012 may go down as an historic nova. The Microlensing Observations in Astrophysics (MOA) collaboration were observing the region of the sky around Nova Sco 2012 as part of their program to detect and study microlensing events (the brightening of foreground stars by lower mass objects passing between the star and Earth). An otherwise unassuming 19th magnitude (in the I band) star started a slow rise in brightness between May 14 and 16. The rate of brightening started to increase on May 24. Soon a 1.6-hr oscillation (due to the rotation period of the nova double star system?) was observed superimposed on the brightening trend. Suddenly on June 1 to 2 the object jumped 6 magnitude in brightness. Spectroscopic observations confirm the object as a slow “Fe-II” nova. Never before have the earliest days of a classical nova outburst been observed.

The nova peaked around V magnitude 9.9-10.0 on June 20. Since then it has faded to V magnitude 10.8. It is located a few degrees north of the bright open star cluster M7 at R.A. = 17h50m53s.90, Decl. = -32d37’20″.5 (equinox 2000.0).

PNV J17522579-2126215

The newest “nova” is still a ? since there hasn’t been any published spectroscopic observations confirming its nature. It was discovered by K. Itagaki with an independent discovery by Y. Sakurai (both of Japan) on June 26. I was able to observe it last night with the Sierra Stars 0.61-m at V = 9.8. The “nova” is located a few degrees to the NW of M8 at R.A. = 17h52m25s.79 Decl. = -21d26’21″.5 (J2000.0).

Meteor Activity Outlook for June 23-29, 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.

June is another slow month for meteor activity. There are no major showers active in June and only the Antihelion source can be counted on for continuous activity. Even the Antihelion radiant is located so far south this time of year that rates rarely exceed one per hour as seen from the mid-northern hemisphere (45 N) . Sporadic rates have reached their nadir and are now slowly rising as seen from the northern hemisphere. Sporadic rates seen from the mid-southern hemisphere (45 S) see a slow decline this month and a more moderate decline in July.

During this period the moon reaches its first quarter phase on Tuesday the 26th. At this time the moon will be located ninety degrees west of the sun and will set between midnight and 0100 for observers located in mid-northern latitudes. This weekend the waxing crescent moon will set during the late evening hours and will be long gone by the time the more active morning hours arrive. 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 ten as seen from mid-northern latitudes and fourteen 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. 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 June 23/24. These positions do not change greatly day to day so the listed coordinates may be used during this entire period.

The following radiant is expected to be active this week:

A few June Bootids (JBO) may be seen during the evening hours this week radiating from a position near 14:56 (224) +48. This area of the sky lies in northern Bootes, seven degrees north of the fourth magnitude star Beta Bootis. This radiant is best placed as soon as it becomes dark. Hourly rates at this time are expected be less than one for those located in the northern hemisphere and near zero for observers south of the equator. With an entry velocity of 18 km/sec., the average June Bootid meteor would be of very slow speed.

Studies by Sirko Molau and Juergen Rendtel of the IMO’s video data has revealed an active radiant located in Ophiuchus this time of year. The f-Ophiuchids (FOP) are only active from June 27th through July 1, with maximum activity occurring on June 29th. The radiant position at maximum is located at 17:46 (266) +09. This area of the sky lies in northern Ophiuchus, four degrees southeast of the second magnitude star Ras Alhague (Alpha Ophiuchi). This radiant is best placed near 0100 local daylight time (LDT), when it lies on the meridian and is located highest in the sky. Rates at this time are expected to be less than one no matter your location. With an entry velocity of 21 km/sec., the average f-Ophiuchid meteor would be of slow speed.

The large Antihelion (ANT) radiant is currently located at 19:00 (285) -22. This position lies in central Sagittarius, near the group of third and fourth magnitude stars known as  Xi, Omicron and Pi Sagittarii. Due to the large size of this radiant, Antihelion activity may also appear from eastern Scorpius, southeastern Ophiuchus, Serpens Cauda, Corona Australis, southern Aquila, 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 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.

Another active radiant in Pisces has been found by Sirko Molau and Juergen Rendtel using the IMO’s video data. The Delta Piscids (DPI) are only active from June 20th through the 24th with maximum activity occurring on the 23th. The radiant position at maximum is located at 00:44 (011) +06. This area of the sky lies in south-central Pisces, just southwest of the fourth magnitude star Delta Piscium. This radiant is best placed just before dawn when the radiant lies highest in a dark sky. Rates, even at maximum activity, are expected to be less than one per hour no matter your location. With an entry velocity of 71 km/sec., the average delta Piscid meteor would be swift.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately seven 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 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.

June Bootids (JBO) – 14:56 (224) +48   Velocity 18km/sec
Northern Hemisphere – <1 per hr   Southern Hemisphere – <1 per hour

f-Ophiuchids (FOP) – 17:46 (266) +09   Velocity 21km/sec
Northern Hemisphere – <1 per hr   Southern Hemisphere – <1 per hour

Antihelions (ANT) – 19:00 (285) -22   Velocity 30km/sec
Northern Hemisphere – 2 per hr Southern Hemisphere – 3 per hour

Delta Piscids (DPI) – 00:44 (011) +06 Velocity 71km/sec
Northern Hemisphere – <1 per hr Southern Hemisphere – <1 per hour

Clear Skies!
Robert Lunsford
American Meteor Society

 

Meteor Activity Outlook for June 9-15, 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.

June is another slow month for meteor activity. There are no major showers active in June and only the Antihelion source can be counted on for continuous activity. Even the Antihelion radiant is located so far south this time of year that rates rarely exceed one per hour as seen from the mid-northern hemisphere (45 N) . Sporadic rates have reached their nadir and are now slowly rising as seen from the northern hemisphere. Sporadic rates seen from the mid-southern hemisphere (45 S) see a slow decline this month and a more moderate decline in July.

During this period the moon reaches its last quarter phase on Monday the 11th. At this time the moon will be located ninety degrees west of the sun and will rise near 0100 local daylight time (LDT) as seen from mid-northern latitudes. This weekend the moon will pose a problem to meteor observers but this can be overcome if you observe during the evening hours before the moon rises or face in the opposite direction if the moon lies above the horizon. Transparent skies would help immensely as moonlight would be less scattered throughout the sky. As the week progresses the waning crescent moon will become less of a problem with each passing 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 five 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. Morning rates during this period 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 June 9/10. These positions do not change greatly day to day so the listed coordinates may be used during this entire period.

The following radiant is expected to be active this week:

The large Antihelion (ANT) radiant is currently located at 18:12 (273) -23. This position lies in western Sagittarius, three degrees southwest of the fourth magnitude star Mu Sagittarii. Due to the large size of this radiant, Antihelion activity may also appear from eastern Scorpius, southeastern Ophiuchus, 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 near one per hour as seen from the northern hemisphere and two as seen from south of the equator. With an entry velocity of 30 km/sec., the average Antihelion meteor would be of slow 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 one 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 two 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.

Antihelions (ANT) – 18:12 (273) -23   Velocity 30km/sec
Northern Hemisphere – 1 per hr   Southern Hemisphere – 2 per hour

Clear Skies!
Robert Lunsford
American Meteor Society

 

A Picture From Yesterday’s Venus Transit

It’s been a pretty amazing run of celestial eclipse events the past few weeks here in Tucson. Last month, we witnessed a partial solar eclipse. Sunday morning brought a partial lunar eclipse and yesterday was a rare Venus transit.

I watched the Venus transit with a SolarScope that projected the image of the Sun onto a white background. The picture below shows what the transit looked like. Venus is the round and dark spot near the lower left edge of the Sun. A few sunspots (and dirt on the screen) can be seen closer to the center of the Sun’s image.

Though I didn’t think to take any images of the Sun during last month’s eclipse, my wife, Alyse, did snap this great photo of hundreds of crescent Suns on our back wall. Each crescent was caused by the Sun shining through our trees. The gaps between leaves acted like pinhole cameras, each making its own pinhole projection image of the Sun.

In the Transient Sky – June 2012

The big event this month (at least for folks around the northern Pacific basin) is the annular solar eclipse on May 20. As for planets, Venus, Mars and Saturn are easy to see in the evening.

June 2012 Highlights
* Transit of Venus on June 5
* Partial Lunar Eclipse on June 3 
* Venus rockets out into the morning sky
* Mars fades but still is high in the evening sky
* Saturn is easily seen in eastern evening sky
* Mercury starts 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>.

Partial Lunar Eclipse

The Moon follows up last month’s annular eclipse with a partial eclipse on the morning of June 4th. The eclipse can be seen  North and South America, Australia, eastern parts of Asia and all across the Pacific Ocean. Only 37% of the Moon will enter the umbra so it will be far from a total eclipse. Here in the US, the Moon enters the dark umbra at 10:00 UT (6:00 am EDT, 5:00 am CDT, 4:00 am MDT, 3:00 am PDT). Maximum eclipse occurs an hour and three minutes later. For more information on when and where this event can be seen go to Science News @ NASA Science.

Venus Transit of the Sun

On June 5th, Venus will pass in front of the Sun for the first time since 2004 and the last time till 2117. For more info please visit the Transit of Venus website.

Planets

Evening Planets

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 June, it fades from +0.5 to +1.0. The red planet will spend the month moving eastwards from the constellation of Leo into Virgo. The Moon visits on the evening of the 25th and 26th.

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 with the bright 1st magnitude Spica. Both can be seen to the South at the end of twilight. Saturn will fade from magnitude +0.5 to +0.7. The Moon visits on the mornings of the 27th.

Morning Planets

Mercury – This month Mercury starts a rather good apparition for northern observers in the evening. It reaches its highest point above the horizon on June 22.

Jupiter – A month past conjunction with the Sun, Jupiter can be seen slowly rising out of morning twilight. During the later half of the month Jupiter and Venus make a nice pair once again (similar to their showing this Spring in the evening) against the backdrop of the Pleiades and Hyades clusters of Taurus. The Moon is located near Jupiter on the morning of the 17th.

Venus  – After its spectacular transit of the Sun on the 5th Venus enters the morning sky. Not quite reaching as high as Jupiter, the brightest planet will be easy to see just before the start of morning twilight by the end of the month. The Moon pays it a visit on the morning of the 18th.

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. Background rates start to tic upwards in June.

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

None this month

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 may be brighter than 10th magnitude this month. And even then it will only be brighter than 10th magnitude for the last day or two of the month. Next month the comet will be much brighter though it will also be located closer to the Sun.

This comet 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. During June it will only be visible from the Southern Hemisphere. Northerners will get their chance towards the end of July. At the start of June, it will be located 1.19 AU from the Sun and 1.17 AU from Earth. Though rapidly brightening it will still only be a faint magnitude 14. By the end of the month the comet will have brightened to magnitude 10 or a little brighter. It will close out the month at a distance of 0.55 AU from the Sun and 0.95 AU from Earth.

Don Machholz first spotted 96P back on May 12, 1986 at magnitude 9.7. Though the comet can get very bright (up to magnitude -2) it is always located too close to the Sun for observation when that bright. By the time the comet has moved far enough from the Sun for easy observations it will have faded to 8th or 9th magnitude. It currently takes ~5.3 years to orbit the Sun.

Date            RA        DEC    Delta   r   Elong    V
2012 Jun 01   01h 59m  -31d 44'  1.168 1.190   66   14.2
2012 Jun 10   02h 58m  -26d 41'  1.031 1.015   59   13.1
2012 Jun 20   04h 12m  -17d 24'  0.942 0.798   48   11.7
2012 Jun 30   05h 27m  -04d 13'  0.949 0.549   32    9.8

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
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