3 Relatively Bright Novae in Sagittarius/Ophiuchus

Hello Everyone!

First a quick update. A few months back I moved to a new home here in Tucson. During the move I had to take down my meteor camera set-up. Though it took me longer than it should to find the time to set the cameras back up again, I finally did get around to it. BUT… all four of my cameras (the 3 PC164Cs and the single Watec 902H2) now have issues. One of the PC164Cs is completely dead (no signal, nasty electrical burning smell). The other three cameras produce a very noisy (and suspiciously similar) signal. I was hoping it was related to my cables/connectors but my all-sky Sentinel system works fine. Hopefully I won’t have to buy a new camera. In the meantime, my video meteor watching remains on hold.

In the meantime I’ve been remotely observing a number of recently discovered novae. The most recent nova is Nova Ophiuchi 2012 No. 2 (originally designated as PNV J17395600-2447420). This nova was first spotted by John Seach of Chatsworth Island in New South Wales, Australia on May 19.484 UT at magnitude 10.5. Seach was hunting for novae with a DSLR camera and 50mm f/1.o lens. Spectroscopic observations reported on CBET 3124 classify the nova as a Fe II-type.

I have been observing the Nova Oph 2012 No 2 remotely with the Sierra Stars 0.61-m on an almost nightly basis. After peaking around V magnitude 10.5, the nova has now faded to V ~ 13.4. In the red (R-band) it is nearly 2 magnitudes brighter. Part of the reason for the extreme red color is that the nova is located behind a dust-rich area of the galaxy. Dust can redden any starlight that passes through it. The difference between the nova’s brightness in the V and R bands also appears to be increasing. This is probably due to actual changes in the light of the nova rather than intervening dust.

Nova Sagittarii 2012 (originally designated as PNV J17452791-2305213) was picked up by Russian astronomers, Stanislav Korotkiy and Kirill Sokolovsky, on Apr. 21.011 UT at magnitude 9.6. They used a 135-mm f/2 telephoto lens and ST-8300M CCD camera. In the over one month since maximum, the nova has faded from V ~ 8.9 to V ~ 14.5.

While the two novae above are behaving like ‘normal’ nova with rapid and gradual fading, the first nova of 2012 to be found in Ophiuchus is acting much differently. Nova Ophiuchi 2012 No. 1 (originally PNV J17260708-2551454) was yet another John Seach find. He originally reported the nova on Mar. 23.39 UT at magnitude 9.2. Since that time the nova has widely varied in brightness from as bright as V ~ 10.5 to as faint as V ~ 12.5. Even over the course of hours V-band photometry shows brightness changes of many tenths of a magnitude.

As the two novae above show, most novae fade rather rapidly. Nova Oph 2012 No. 1 hasn’t faded much in two months. It will be very interesting to see how its lightcurve develops. Will it finally start fading? Brighten again to a brighter maximum? Will its brightness jitters continue? Stay tuned…

In case your wondering, the PNV J########-####### style designation is a preliminary designation given to suspected novae and supernovae by the Central Bureau of Astronomical Telegrams. The PNV stands for possible nova. PSN would mean possible supernova. The numbers after the J is the Right Ascension and Declination of the suspect. So PNV J17260708-2551454 means ‘a possible nova at Right Ascension of 17h 26m 07.08s and Declination of -25° 51′ 45.4″.

Lightcurves for all three novae were produced on the AAVSO website.

Meteor Activity Outlook for May 12-18, 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.

May is a fairly slow month for meteor activity. The Eta Aquariids are very active the first two weeks of the month then fade as the month progresses. The only other showers active this month are the weak Nu Cygnids, the Eta Lyrids,  and the Antihelion radiant. These will add only 1-2 meteors per hour to the total count. 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) are strong and remain so the entire month.

During this period the moon reaches its last quarter phase on Saturday the 12th. At this time the moon will be located ninety degrees west of the sun and will rise near 0100 local daylight time (LDT). As the week progresses the waning crescent moon will rise later in the morning, increasing the window of opportunity to view in totally dark conditions. 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 nine as seen from mid-northern latitudes and fifteen 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 slightly due to moonlight during this period.

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 May 12/13. 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:

The large Antihelion (ANT) radiant is currently located at 16:16 (244) -21. This position lies in northwestern Scorpius, six degrees northwest of the bright first magnitude orange star Antares (Alpha  Scorpii). Due to the large size of this radiant, Antihelion activity may also appear from western Ophiuchus, Libra, northern Lupus, as well as Scorpius. 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.

The last of the Eta Lyrids (ELY) are visible this weekend from a radiant located at 19:23 (292) +43. This position lies in extreme eastern Lyra, four degrees southwest of the third magnitude star Delta Cygni. This shower is active from May 6 through the 14th and peaked on May 11. Rates at maximum activity are near two per hour as seen from the northern hemisphere. Unfortunately the Eta Lyrid radiant does not rise very high in the northern sky as seen from the southern hemisphere so rates seen from below the equator are minimal. Activity from this shower is best seen during the last hour before dawn when the radiant is situated highest in a dark sky. With an entry velocity of 43 km/sec., the average Eta Lyrid meteor would be of medium speed.

The Eta Aquariids (ETA) are particles from Halleys Comet, produced in Earth-crossing orbits many centuries ago. We pass closest to these orbits from May 5 through the 9th. During this period the Eta Aquariids are at their best, capable of producing ZHRs of sixty. The actual visible rates are most often less than half this figure due to the low altitude of the radiant at dawn. Observed hourly rates at maximum normally vary from zero at 60 degrees north latitude to 30 near the equator and back down to near zero again in Antarctica, where the radiant elevation is again very low. Hourly rates this weekend will most likely be less than five per hour. Rates will slowly decrease as the week progresses as we move further from the May 7 maximum. The radiant is currently located at 22:52 (343) +01. This area of the sky is located on the Aquarius/Pisces border, three degrees east of the fourth magnitude star Eta Aquarii. The best time to view this activity is during the hour before the start of morning twilight, when the radiant lies highest in a dark sky. With the moon now in the morning eastern sky, it would be best to face either due north or due south, just enough to keep the moon out of your field of view. With an entry velocity of 67 kilometers per second, a majority of these meteors will appear to move swiftly with a high percentage of the bright meteors leaving persistent trains. Surprisingly, this shower produces very few fireballs.

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 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.

Antihelion (ANT) – 16:16 (244) -21   Velocity 30km/sec
Northern Hemisphere – 1 per hr Southern Hemisphere – 2 per hour

Eta Lyrids (ELY) – 19:23 (292) +43   Velocity 43km/sec
Northern Hemisphere – 1 per hr Southern Hemisphere – <1 per hour

Eta Aquariids (ETA) – 22:52 (343) +01   Velocity 67km/sec
Northern Hemisphere – 3 per hr Southern Hemisphere – 5 per hour

Clear Skies!
Robert Lunsford
American Meteor Society

 

In the Transient Sky – May 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.

May 2012 Highlights
* Annular Solar Eclipse for western North America, the north Pacific basin and far eastern Asia
* Venus dominates the evening sky
* Mars fades but still is high in the evening sky
* Saturn is easily seen in eastern evening sky
* Comet C/2009 P1 (Garradd) is a nice binocular object 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>.

Annular Solar Eclipse

The big event this month is an annular eclipse of the Sun on May 20. For more information on when and where this event can be seen go to Science News @ NASA Science.

Planets

Evening Planets

Venus  – Venus reaches its maximum brilliance at magnitude -4.7 right at the start of the month. At the start of the month Venus is riding high in the West and sets up to 3.5 hours after the Sun. But Venus is now on a bee-line towards the Sun. By mid-month it sets 2.5 hours after the Sun and by the end of the month it will be so close to the Sun that it sets within 40 minutes of the Sun. All during the month, Venus will slightly fade but in a telescope it will appear to become bigger in apparent diameter while also becoming more crescent. All of this leads up to a rare Venus transit on June 5 when Venus will appear to pass in front of the disk of the Sun. The Moon makes a nice pair with Venus on May 22.

Mars - Mars is the bright reddish “star” nearly overhead early in the evening. 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 May, it fades from +0.0 to +0.5. The red planet will spend the month moving eastwards below the constellation of Leo. The 1st Quarter Moon visits on the 28th.

Saturn - Saturn reached opposition on April 15 at a distance of 8.75 AU (813 million miles or 1.3 million km) from Earth. Opposition meant Saturn was directly opposite the Sun in the sky. This month it can be seen in the east at the start of evening making a nice but distant pair with bright 1st magnitude Spica. Being past opposition it will fade from magnitude +0.3 to +0.5. The nearly Full Moon visits on the mornings of the 3rd and 4th.

Morning Planets

Mercury – If you live in the Southern Hemisphere, Mercury is still in the middle of a nice morning apparition at the start of the month. By mid-month it will be too low for easy observation.  If, like me, you live north of the equator, this month’s display will be a hard one to observe. At the every end of the month, Mercury starts a better apparition for northern observers in the evening. Though still very low, It will be within ~2° of Venus although both will be only 8° from the Sun at the time.

Jupiter – With conjunction on May 13th, this planet will be located to close to the Sun to be easily seen this month.

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 will remain low in May.

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 May mornings, 6 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

Eta Aquariids (ETA)

The Eta Aquarids are a major shower, especially for southern hemisphere observers, when they peak on May 5. For northern observers, the shower will only be observable for an hour or two before dawn. Since the radiant doesn’t get very high for NH observers, rates can be low. The radiant is located near the “jar” of Aquarius.

The ETA were produced by Comet Halley which also gives us the Orionids in October. Models suggest that the ETA were released by Comet Halley no later than 837 AD. The Orionids are easy to see because the particles are hitting the Earth from the anti-solar direction. This means the meteor shower can be seen in the middle of the night. The ETA are produced by meteoroids moving outbound from the Sun, as a result the radiant is located relatively close to the Sun. This means that the ETA radiant is only visible for an hour or so before twilight. Unfortunately the Moon is full just a day after the expected peak of the ETAs on May 5 making this a difficult shower to observe this year.

The shower spans from April 19 to May 28 with a peak around May 5 with a maximum ZHR of ~60.

Additional information on these showers and other minor showers not included here can be found at the following sites: Robert Lunsford’s Meteor Activity Outlook and the International Meteor Organization’s 2012 Meteor Shower Calendar.

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 8.0 to 8.9 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
May  1   08h 50m  +38°01'   2.190  2.311    84    8.0
May 10   08h 50m  +33°56'   2.420  2.395    77    8.3
May 20   08h 52m  +30°07'   2.677  2.489    68    8.6
May 30   08h 56m  +26°51'   2.929  2.584    60    8.9

Small Telescope Comets (V = 8.0 – 10.0)

None

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