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Thursday, April 27, 2017

 

The Moon Occults Regulus (4 May 2017)

The northern horizon as seen from Adelaide at 18:17 ACDST Thursday 4 May, the bright star Regulus is close to the Moon an hour before it is occulted. Similar views will be seen elsewhere in Australia at the equivalent local time, see the table below. Click to embiggen.The Moon and Regulus at 19:24 ACST  Thursday 4 May just before the Moon covers Regulus.Click to embiggen.

On the early evening of Thursday 4 May the bright star Regulus is occulted by the Moon as seen from the most of Australia. This is the second of two occultations of Regulus, the brightest star in the constellation of Leo the lion, this year. The previous one was in February, and images can de seen here.

The Moon is a very obvious signpost for where to look and Regulus will be the brightest object near the Moon. Start watching about half an hour before the occultation (see table of times below) to get set up and become familiar with the sky. Although this event is easily seen with the unaided eye, given the brightness of the Moon the occultation is best seen  in a small telescope or binoculars.

Regulus will appear to "wink out" as it goes behind the dark limb of the Moon, at just past first quarter, the dark edge of the Moon will be sufficiently dark for the disappearance to be dramatic, although seeing the edge will be difficult. Reappearance on the bright limb will be harder to see as you have to be looking just at the right moment.

Reappearance as seen from Hobart at 21:19 AEST.Reappearance as seen from Brisbane at 21:36 AEST. Note the difference in location where Regulus reappears.

The occultation occurs in the early evening, a good time to get the kids involved (although maybe a littel close to dinner time), the Moon will be reasonably high above the northern horizon. The Moon is easily visible and a ready signpost to Regulus.

If using a telescope, it is advisable to set up and practise on the Moon a day or so before the event, so you are familiar with your telescope set-up. Set up at least half an hour ahead of time so that you can be sure everything is working well and you can watch the entire event comfortably (trying to focus your telescope moments before the occultation will cause a lot of unnecessary stress).

Regulus will be clearly visible with the unaided eye, binoculars or in a telescope near the Moon before the occultation. Here's some images from the occultation of Regulus back in February, so you know what to expect.However, the first quarter Moon will not be as bright as the nearly full Moon, so photography will be easier.

PlaceDisappears Bright Limb Reappears Dark Limb
Adelaide ACST19:2420:39
Brisbane AEST20:1421:36
Canberra AEST20:1121:31
Darwin ACST18:3320:05
Hobart AEST20:1921:19
Melbourne AEST20:0921:21
Perth AWST-18:01
Sydney AEST20:1421:35

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Wednesday, April 26, 2017

 

A good Week for ISS passes, including seeing the ISS shoot through Orions Belt (27 April - 2 May)

The ISS passes almost over η Orion, as seen from Melbourne on the evening of Sunday 30 April at 19:28 AEST. Simulated in Stellarium (the ISS will actually be a bright dot), click to embiggen.The ISS  passes almost over Alnitak, as seen from Adelaide on the evening of Saturday 29 April at 18:56 ACST. Simulated in Stellarium (the ISS will actually be a bright dot), click to embiggen.The ISS passes Betelguese and Sirius, as seen from Perth on the evening of Saturday 29 April at 18:07 AWST. Simulated in Stellarium (the ISS will actually be a bright dot), click to embiggen.
All sky chart showing local times from Heavens Above for Sunday 30 April for Melbourne.All sky chart showing local  times from Heavens Above for Saturday 29 April for Adelaide.All sky chart showing local times from Heavens Above for Saturday 29 April for Perth.

Starting tomorrow night there are a series of bright evening passes of the International Space Station lasting around five days. Some are low to the horizon, but for many places in Australia this series has the ISS gliding either close to Jupiter, the crescent Moon or a series of bright stars (except Darwin, which only gets one bright evening pass on the 27th).

The most spectacular is between the 29th and the 2nd, when the ISS passes through the iconic constellation of Orion with the crescent Moon nearby. From some places the ISS will pass through the belt of Orion, and may pass in front of some of the belts stars.

Most of the major cites see the ISS pass through Orion at the following days and times:
Adelaide 29th April 18:56 ACST (belt pass),
Brisbane 29th April 17:52 AEST (belt pass)
Sydney 1st May 17:44 AEDST (close to Rigel)
Melbourne 29th April 19:28 AEST (belt pass)
Perth 30th April 18:07 AWST (Close to Betelguese)
Hobart 2 May  18:28 AEST (Belt Pass)

When and what you will see is VERY location dependent, so you need to use either Heavens Above or CalSky to get site specific predictions for your location, a small difference in location can mean the difference between the ISS passing over a belt star or missing it completely.
 
Start looking several minutes before the pass is going to start to get yourself oriented and your eyes dark adapted. Be patient, there may be slight differences in the time of the ISS appearing due to orbit changes not picked up by the predictions. Use the most recent prediction for your site.

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The Sky This Week - Thursday April 27 to Thursday May 4

The First Quarter Moon is Wednesday May 3. The Moon occults the bright star Regulus on the 4th. Mars is low in the twilight and is visited by the crescent Moon on the 28th. Jupiter and the bright star Spica are close in the late evening skies. Saturn is low in the evening sky. Venus climbs higher in the morning sky.

The First Quarter Moon is Wednesday May 3. The Moon occults the bright star Regulus on the 4th.

Evening sky on Friday April 28 looking west as seen from Adelaide at 18:17 ACST (45 minutes after sunset). Mars is low above the horizon, forming a tirangle with Aldebaran and the crescent Moon.

 Similar views will be seen throughout Australia at the equivalent local time (that is 45 minutes after local sunset, click to embiggen).

Mercury is lost in twilight.

Mars is in the western evening skies in Taurus It is is low in the dusk sky, but is the brightest object above the western horizon low in the late twilight below Aldebaran. Over the week Mars passes between the Pleiades cluster and the Hyades cluster, you will need a clear, unobscured level horizon to see this though. On the 28th the tin crescent Moon form a triangle with Aldebaran and Mars.

Evening sky on Saturday April 29 looking east as seen from Adelaide at 19:09 ACST (90 minutes after sunset).  Jupiter is above the horizon between the bright star Spica and the relatively bright star Porrima. The inset shows the telescopic view of Jupiter at 19:09 ACST Europa is occulted later in the evening.

Similar views will be seen elsewhere in Australia at the equivalent local time. that is 90 minutes after local sunset, click to embiggen).

Jupiter is rising at dusk and is now reasonably high above the horizon in the early evening this week. It is in between the bright star Spica, the brightest star in the constellation of Virgo, and the relatively bright star Porrima.

Opposition, when Jupiter is biggest and brightest as seen from Earth, was on the 8th. Jupiter is rising as the sun sets and is visible all night long. Jupiter is a good telescopic target from around 8 pm on, and the dance of its Moons is visible even in binoculars. The following Jupiter events are in AEST.


Thu 27 Apr 18:22 GRS: Crosses Central Meridian
Fri 28 Apr 3:30 Eur: Transit Begins               T
Fri 28 Apr 4:18 GRS: Crosses Central Meridian
Fri 28 Apr 4:25 Eur: Shadow Transit Begins        ST
Sat 29 Apr 0:09 GRS: Crosses Central Meridian
Sat 29 Apr 4:52 Io : Disappears into Occultation
Sat 29 Apr 18:48 Gan: Shadow Transit Ends
Sat 29 Apr 20:00 GRS: Crosses Central Meridian
Sat 29 Apr 22:21 Eur: Disappears into Occultation
Sun 30 Apr 1:46 Eur: Reappears from Eclipse
Sun 30 Apr 2:09 Io : Transit Begins               T
Sun 30 Apr 2:39 Io : Shadow Transit Begins        ST
Sun 30 Apr 4:20 Io : Transit Ends                 S
Sun 30 Apr 4:51 Io : Shadow Transit Ends
Sun 30 Apr 23:19 Io : Disappears into Occultation
Mon 1 May 1:47 GRS: Crosses Central Meridian
Mon 1 May 2:02 Io : Reappears from Eclipse
Mon 1 May 17:43 Eur: Shadow Transit Begins        ST
Mon 1 May 19:02 Eur: Transit Ends                 S
Mon 1 May 20:10 Eur: Shadow Transit Ends
Mon 1 May 20:36 Io : Transit Begins               T
Mon 1 May 21:08 Io : Shadow Transit Begins        ST
Mon 1 May 21:38 GRS: Crosses Central Meridian
Mon 1 May 22:46 Io : Transit Ends                 S
Mon 1 May 23:19 Io : Shadow Transit Ends
Tue 2 May 17:45 Io : Disappears into Occultation
Tue 2 May 20:31 Io : Reappears from Eclipse
Wed 3 May 3:25 GRS: Crosses Central Meridian
Wed 3 May 4:20 Gan: Disappears into Occultation
Wed 3 May 17:48 Io : Shadow Transit Ends
Wed 3 May 23:16 GRS: Crosses Central Meridian
Thu 4 May 19:08 GRS: Crosses Central Meridian

 
Evening  sky on Saturday April 29 looking east as seen from Adelaide at 22:00 ACST.  Saturn is reasonably high above the horizon.

The inset shows the telescopic view of Saturn at this time. Similar views will be seen elsewhere in Australia at the equivalent local time. (click to embiggen).

 Saturn is now visible in the evening skies this week. Saturn is a good telescopic target from 11 pm on. It continues to climb into the evening skies as the week progresses. It is within binocular distance of the Triffid and Lagoon nebula and makes a very nice sight in binoculars.

The constellation of Scorpio is a good guide to locating Saturn. The distinctive curl of Scorpio is easy to see above the north-eastern horizon, locate the bright red star, Antares, and the look below that towards the horizon, the next bright object is Saturn.

Morning sky on Saturday April 29 looking east as seen from Adelaide at 5:25  ACST (90 minutes before sunrise). The inset shows the telescopic view of Venus at this time.

 Similar views will be seen throughout Australia at the equivalent local time (that is 90 minutes before sunrise, click to embiggen).

Venus  climbs higher in the morning sky and is visible in telescopes as a crescent.



The northern horizon as seen from Adelaide at 18:17 ACDST on Thursday May 4, the bright star Regulus is close to the Moon an hour before it is occulted. The inset shows the Moon and Regulus at 19:24 ACST, just as Regulus is occulted. Similar views will be seen elsewhere in Australia at the equivalent local time. Click to embiggen.

Viewing hints and exact times for other cities are here.

On the early evening of Thursday 4 April the bright star Regulus is occulted by the Moon as seen from the most of Australia. This is the second of two occultations of Regulus, the brightest star in the constellation of Leo the lion, this year. The Moon is a very obvious signpost for where to look and Regulus will be the brightest object near the Moon.

There are lots of interesting things in the sky to view with a telescope. If you don't have a telescope, now is a good time to visit one of your local astronomical societies open nights or the local planetariums.

Printable PDF maps of the Eastern sky at 10 pm AEST, Western sky at 10 pm AEST. For further details and more information on what's up in the sky, see Southern Skywatch.

Cloud cover predictions can be found at SkippySky.
Here is the near-real time satellite view of the clouds (day and night) http://satview.bom.gov.au/

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Sunday, April 23, 2017

 

Geomagnetic warning and Aurora Watch (23-24 April)

The SWS has issued a geomagnetic warning and an aurora watch for 23-24 April due to a high speed stream from a recurrent coronal hole and the arrival of a coronal mass ejection (this caused strong aroral conditions yesterday, which was clouded out for mots of Australia). A G2 storm is predicted to start anywhere between 4pm to 7 pm, with G1 (minor) storm conditions thereafter.

If these geomagnetic events occur and  result in aurora they could be seen from Tasmania and Southern Victoria, weather permitting (the weather is rubbish). 

Currently Hobart Kindex is 5 and Velocity: 689 km/sec Bz: -2.0 nT Density = 8.0 p/cc  (so promising). The Moon is rising late in the morning, so evening skies will have little Moon interference, but cloud cover is predicted for Tasmanian and most of Southern Victoria.  However, the last occurrence saw nice displays through gaps in the cloud. Be patient, as the activity may rise and fall as the magnetic polarity of the wind may fluctuate significantly.

Dark sky sites have the best chance of seeing anything, and always allow around 5 minutes for your eyes to become dark adapted.

As always look to the south for shifting red/green glows, beams have been reported consistently over the last few aurora, as well as bright proton arcs and "picket fences".

If you are up early on the morning of the 24th look for the crescent Moon near Venus.

Here is the near-real time satellite view of the clouds http://satview.bom.gov.au/
Cloud cover predictions can be found at SkippySky.  

The all sky aurora camera in Northern Tasmania at Cressy is being upgraded and is not yet online.

SUBJ: SWS GEOMAGNETIC DISTURBANCE WARNING 17/21 ISSUED AT 2323UT/21 APRIL 2017 BY THE AUSTRALIAN SPACE FORECAST CENTRE.
On 22 April the geomagnetic activity will remain elevated due to a CME arrival.
A recurrent coronal hole is expected to be geoeffective on 23-24 April.
INCREASED GEOMAGNETIC ACTIVITY EXPECTED DUE TO CORONAL HOLE HIGH SPEED WIND STREAM FROM 22-24 APRIL 2017
_____________________________________________________________

GEOMAGNETIC ACTIVITY FORECAST
22 Apr: Active
23 Apr: Active to Minor Storm
24 Apr: Minor Storm
==============================================================
SUBJ: SWS AURORA WATCH
ISSUED AT 0010 UT ON 23 Apr 2017 by Space Weather Services
FROM THE AUSTRALIAN SPACE FORECAST CENTRE

The Earth is currently under the influence of very high solar wind
speeds from a combined effect of the 18 April CME and high speed
streams from a recurrent,negative polarity coronal hole. As a
result,the geomagnetic conditions at earth could reach minor storm
levels today with isolated chance of major storms. Auroras may be
visible tonight (23 April) in Tasmania and possibly from the coastline
of Victoria. Aurora alerts will follow should favourable space weather
activity eventuate.

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Thursday, April 20, 2017

 

Aurora happening NOW (20 April)

Aurora are being reported now in Tasmania from Taranna and Doges Ferry. Cloud is still an issue though. Hobart Kindex is currently 4 with Velocity: 591 km/sec Bz: 0.0 nT Density = 12.0 p/cc  a bit ordinary, but further G1 storms are predicted for tonight/tomorrow morning and it is likely that the aurora will die down and flare up again during the night and early morning. (see also NOAA)

Dark sky sites have the best chance of seeing anything, and always allow around 5 minutes for your eyes to become dark adapted.As always look to the south for shifting red/green glows, beams have been reported consistently over the last few aurora, as well as bright proton arcs and "picket fences".

Here is the near-real time satellite view of the clouds http://satview.bom.gov.au/
Cloud cover predictions can be found at SkippySky.  

The all sky aurora camera in Northern Tasmania at Cressy is being upgraded and is not yet online.

SUBJ: SWS GEOMAGNETIC DISTURBANCE WARNING 17/19
ISSUED AT 2345UT/18 APRIL 2017
BY THE AUSTRALIAN SPACE FORECAST CENTRE.

Recurrent positive polarity coronal hole is expected to be geoeffective.

INCREASED GEOMAGNETIC ACTIVITY EXPECTED
DUE TO CORONAL HOLE HIGH SPEED WIND STREAM
FROM 19-20 APRIL 2017
_____________________________________________________________

GEOMAGNETIC ACTIVITY FORECAST
19 Apr:  Active
20 Apr:  Unsettled to Active

==============================================================
SUBJ: SWS AURORA WATCH
ISSUED AT 0315 UT ON 20 Apr 2017 by Space Weather Services
FROM THE AUSTRALIAN SPACE FORECAST CENTRE

The Earth is now under influence of the High Speed Stream from a
recurrent coronal hole. The geomagnetic activity has reached Minor
Storm level. This may result in increased chances of auroral activity.
Auroras may be visible on the local night of 20-21 April in Tasmania
and possibly near the coastline of Victoria.

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Asteroid 2014 JO25 recedes from view (20 April, 2017)

Asteroid 2014 JO25 ziping along with the scope tracking on the asteroid (the asteroid is the dot near the edge). 20 x 60 second luminance exposures with iTelescope T11 stacked and aligned in ImageJ. Imaging starts at 9:05 UT (3:05 am local time 20th) Click to embiggen.Animation of the same 20 x 60 frames (click to embiggen for animated asteroidal goodness)

As Asteroid 2014 JO25 recedes from earth I was able to get some more images and animations. By the time I took the above images with iTelescope T11 in New Mexico, it had moved far enough away that I could track on the asteroid. Still moving at a fair clip and the stars are trailed.

Asteroid 2014 JO25 zips along receding from Earth with added satellite trails (the asteroid is the dotted line through the centre). 20 x 60 second luminance exposures with iTelescope T14 stacked and aligned in ImageJ. Imaging starts at 3:05 UT (9:05 pm local time 19th) Click to embiggen.Animation of the same 20 x 60 frames (click to embiggen for animated asteroidal goodness)

Earlier in the UT day from T14, also New Mexico. Asteroid is moving too fast to track.

Asteroid 2014 JO25 near galaxy NGC 4710. 7 x 120 second luminance exposures with iTelescope T13 (Siding Spring Observaory) stacked and aligned in ImageJ. Imaging starts at 11:00 UT (9:05 pm local time 20th) Click to embiggen and see more galaxies.Animation of the same 20 x 60 frames (click to embiggen for animated asteroidal goodness). Cloud comes over in the last frames.

Finally an image from telescope T13 at Siding Spring Observatory in Australia, choosing to track on the galaxies rather than the asteroid for a prettier composition. Clouds have ruined any chance of me seeing the asteroid with my own instruments.

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Wednesday, April 19, 2017

 

Capturing asteroid 2014 JO25 (19 April 2017)

Asteroid 2014 JO25 zips past the magnitude 13.1 galaxy NGC 6248 while bracketed by satellite trails (the asteroid is the dotted line through the centre). 10 x 120 second luminance exposures with iTelescope T14 stacked and aligned in ImageJ. Imaging starts at 10:00 UT (4:00 am local time) Click to embiggen and see more galaxies.Animation of the same 10 x 120 frames (click to embiggen for animated asteroidal goodness)

Asteroid 2014 JO25 is, as I type, making its closest approach to Earth (12:24 UT 19 April). Zipping past at 4.6 Earth-Moon distances at closest approach, this asteroid was moving at a speedy 92.2 arc seconds per minute whin I was  trying to image it, making imaging a tad challenging. However, using the remote telescopes of iTelescope in Mayhill New Mexico I succeeded (with a bit of bad luck with some cloud early on). With the wide-field T14 instrument I caught the asteroid zipping through a field of galaxies, looking rather nice.

Asteroid 2014 JO25 also at 10:00 UT taken with iTelescope T5, moving so fast the tracker is just barely coping (hint the asteroid is the only thing that is not a streak).

Australia gets its chance tomorrow, when  the asteroid zips through Virgo. It won't be as bright as at closest approach, but still within reach of modest amateur scopes.

This is the closest approach of asteroid 2015 JO25 for around 400 years, and it wont come this close again for another 500 years. 

The asteroid turn out to be a very interesting object, images from the Arecibo radio telescope show that the asteroid is a contact binary, and about twice the size we though it was, one of the two lobes is around 620 meters in diameter, see here and here of radio telescope "images" and animations from the Goldstone and Arecibo radio telescopes.

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Tuesday, April 18, 2017

 

The Sky This Week - Thursday April 20 to Thursday April 27

The New Moon is Wednesday April 26. Mars is low in the twilight. Jupiter and the bright star Spica are close in the late evening skies. Saturn is low in the late evening sky. Venus climbs higher in the morning sky and is close to the crescent Moon on the 24th. Lyrid meteor shower morning 23rd.

The New Moon is Wednesday April 26.

Evening sky on Saturday April 22 looking west as seen from Adelaide at 18:24 ACST (45 minutes after sunset). Mars is low above the horizon, between Aldebaran and close to the Pleiades.

 Similar views will be seen throughout Australia at the equivalent local time (that is 450 minutes after local sunset, click to embiggen).

Mercury is lost in twilight.

Mars is in the western evening skies in Taurus It is is low in the dusk sky, but is the brightest object above the western horizon low in the late twilight below Aldebaran. Over the week Mars passes between the Pleiades cluster and the Hyades cluster, you will need a clear, unobscured level horizon to see this though.

Evening sky on Saturday April 22 looking east as seen from Adelaide at 19:08 ACST (90 minutes after sunset).  Jupiter is above the horizon between the bright star Spica and the relatively bright star Porrima. The inset shows the telescopic view of Jupiter at 22:40 ACST on the same night with Europa appearing from occultation.

Similar views will be seen elsewhere in Australia at the equivalent local time. that is 90 minutes after local sunset, click to embiggen).

Jupiter is rising at dusk and is now reasonably high above the horizon in the early evening this week. It is in between the bright star Spica, the brightest star in the constellation of Virgo, and the relatively bright star Porrima.

Opposition, when Jupiter is biggest and brightest as seen from Earth, was on the 8th. Jupiter is rising as the sun sets and is visible all night long. Jupiter is a good telescopic target from around 8 pm on, and the dance of its Moons is visible even in binoculars. The following Jupiter events are in AEST.


Fri 21 Apr 1:13 Eur: Transit Begins               T
Fri 21 Apr 1:49 Eur: Shadow Transit Begins        ST
Fri 21 Apr 3:32 GRS: Crosses Central Meridian
Fri 21 Apr 3:36 Eur: Transit Ends                 S
Fri 21 Apr 4:16 Eur: Shadow Transit Ends
Fri 21 Apr 23:23 GRS: Crosses Central Meridian
Sat 22 Apr 3:08 Io : Disappears into Occultation
Sat 22 Apr 5:39 Io : Reappears from Eclipse
Sat 22 Apr 19:15 GRS: Crosses Central Meridian
Sat 22 Apr 20:06 Eur: Disappears into Occultation
Sat 22 Apr 23:12 Eur: Reappears from Eclipse
Sun 23 Apr 0:25 Io : Transit Begins               T
Sun 23 Apr 0:45 Io : Shadow Transit Begins        ST
Sun 23 Apr 2:35 Io : Transit Ends                 S
Sun 23 Apr 2:57 Io : Shadow Transit Ends
Sun 23 Apr 5:10 GRS: Crosses Central Meridian
Sun 23 Apr 21:34 Io : Disappears into Occultation
Mon 24 Apr 0:08 Io : Reappears from Eclipse
Mon 24 Apr 1:01 GRS: Crosses Central Meridian
Mon 24 Apr 18:51 Io : Transit Begins               T
Mon 24 Apr 19:14 Io : Shadow Transit Begins        ST
Mon 24 Apr 20:53 GRS: Crosses Central Meridian
Mon 24 Apr 21:01 Io : Transit Ends                 S
Mon 24 Apr 21:25 Io : Shadow Transit Ends
Tue 25 Apr 18:36 Io : Reappears from Eclipse
Wed 26 Apr 1:01 Gan: Disappears into Occultation
Wed 26 Apr 2:40 GRS: Crosses Central Meridian
Wed 26 Apr 4:59 Gan: Reappears from Eclipse
Wed 26 Apr 22:31 GRS: Crosses Central Meridian
Thu 27 Apr 18:22 GRS: Crosses Central Meridian
 
Evening  sky on Saturday April 22 looking east as seen from Adelaide at 23:00 ACST.  Saturn is reasonably high above the horizon.

The inset shows the telescopic view of Saturn at this time. Similar views will be seen elsewhere in Australia at the equivalent local time. (click to embiggen).

 Saturn is now visible in the late evening skies this week. Saturn is only a good telescopic target from midnight on. It continues to climb into the evening skies as the week progresses. It is within binocular distance of the Triffid and Lagoon nebula and makes a very nice sight in binoculars.

The constellation of Scorpio is a good guide to locating Saturn. The distinctive curl of Scorpio is easy to see above the north-eastern horizon, locate the bright red star, Antares, and the look below that towards the horizon, the next bright object is Saturn.

Morning sky on Monday April 24 looking east as seen from Adelaide at 5:20  ACST (90 minutes before sunrise). The inset shows the telescopic view of Venus at this time.

 Similar views will be seen throughout Australia at the equivalent local time (that is 90 minutes before sunrise, click to embiggen).

Venus  climbs higher in the morning sky and is visible in telescopes as a crescent. On the monring of Monday 24th the crescent Moon is near crescent Venus.

The morning sky looking north as seen from Adelaide at 4:40 am AEST on April 23. The Lyrid radiant is marked with a yellow starburst. Similar views will be seen elsewhere at an equivalent local time. The radiant will be higher in northern Australia, and lower in southern Australia (click to embiggen). 






The Lyrids, the debris of comet C/1861 G1 (Thatcher) are a weak but reliable shower that occurs every year between April 16- April 25, the best time to view the Lyrids in Australia is from 4 am local on the 23rd. 

The predicted ZHR this year is 18 meteors per hour. This means that under ideal conditions, you will see a meteor on average about once every three minutes. In Australia, the rate is even less, around 4-5 meteors an hour in Northern Australia (around one every 10 minutes). For southern Australia, the rate is even lower. If you are dedicated and don't mind waiting a long time between meteors, look north, the meteors will appear near the bright star Vega (the only obvious bright star near the horizon)


There are lots of interesting things in the sky to view with a telescope. If you don't have a telescope, now is a good time to visit one of your local astronomical societies open nights or the local planetariums.

Printable PDF maps of the Eastern sky at 10 pm AEST, Western sky at 10 pm AEST. For further details and more information on what's up in the sky, see Southern Skywatch.

Cloud cover predictions can be found at SkippySky.
Here is the near-real time satellite view of the clouds (day and night) http://satview.bom.gov.au/

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Monday, April 17, 2017

 

Seeing Asteroid 2014 J025 from Australia (20 April 2017)

Asteroid 2014 JO25 as seen from Adelaide facing north-east at 21:10 ACST 20 April (2 hours after astronomical twilight). Similar views will be seen elsewhere in Australia at the equivalent local time (2 hours after local astronomical twilight), click to embiggen.

Asteroid 2014 JO25 will come close to Earth on 12:24 UT 19 April (19 April 22:24 AEST) at distance of 0.012 AU (around 4.6 Earth-Moon distances). At an estimated diameter of around 650m it is about the size of the Chelyabinsk impactor.

However, it will not be visible from Australia at closest approach (when it will be around magnitude 10.5). We only see the asteroid the following night (20th) when it has faded to magnitude 11.1. This is still within the range of most amateur scopes, but out of the range of all but the most powerful astronomical binoculars under dark skies.

Black and white printable spotters chart for asteroid 2014 JO25 as seen from Adelaide at 19:10 ACST 20 April (astronomical twilight) showing the track of the asteroid. Similar views will be seen elsewhere in Australia at the equivalent local time ( local astronomical twilight), click to embiggen.  The crosses mark the position of the asteroid every 3 hours. The large circle  is the field of view of 10x50 binoculars, the small that of  a 24 mm eyepiece on a 4" Newtonian. Various guide stars are marked for use with the larger scale maps. Click to embiggen and print.

Asteroid 2014 JO25 moves from Coma Bernicies through Virgo on the evening of the 20th and through the 21st and 22nd as well.

Black and white printable chart for asteroid 2014 JO25 showing the track of the asteroid at modest magnification. Similar views will be seen elsewhere in Australia at the equivalent local time ( local astronomical twilight), click to embiggen.

The crosses mark the position of the asteroid every 30 minutes. The large circle  is the field of view of 10x50 binoculars, the small that of  a 24 mm eyepiece on a 4" Newtonian. use the guide stars (see map above) to orient yourself. Click to embiggen and print.

It is not moving as fast as at closest approach, but still fast enough (84 -60 arc seconds/minute aover the course of the night), to visibly move over the space of 10-15 minutes.While there is still some paralax difference btween poistions plotted in a standard planaterium program and a proper topocentric ephemeris the difference is around 4 minutes of arc (mauch smaller than at closest approach and small enough that the charts here as a useful guide for all sites in Australia).

Black and white printable chart for asteroid 2014 JO25 showing the track of the asteroid at telescope magnification. Similar views will be seen elsewhere in Australia at the equivalent local time ( local astronomical twilight), click to embiggen.

The crosses mark the position of the asteroid every 30 minutes. The circle  is the field of view of a 24 mm eyepiece on a 4" Newtonian. Stars down to magnitude 13 are shown use the guide stars (see map above) to orient yourself. Click to embiggen and print.

While theoretically visible from astronomical twilight on the 20th, it will be better to wait until after 20:00 (8pm) as the asteroid will be higer in the sky above the murk of the horizon. The asteroid will be difficult to spot, as it will be too  dim to see in finderscopes, but there are several useful guide stars.

If you draw an imaginary line between Arcturus and Regulus, then drop a line perpendicular to this line from Spica, the asteroid will  be almost at the intersection of these lines, within a binocular field of alpha Coma Cernicies and epsilon Virginis, just down from rho Virginis.Within that area, using the charts above, you can star hop to the location of the asteroid. While faint, you should be able to see it slowly move over a period of several minutes.

For topocentric ephemerides go to http://www.minorplanetcenter.net/iau/MPEph/MPEph.html
type 2014 JO25 in the input box and enter you latitude and longitude (the times give are all UT, so you will need to convert to your local time). Ephemeris start date: is 20170420, and choose 50 output, ephemeris interval 30 minutes.  Here is the ephemeris for Siding Spring Observatory (not to differnt from the ephemeris for Adelaide).

     K14J25O       [H=18.1]
Date       UT      R.A. (J2000) Decl.    Delta     r     El.    Ph.   V      Sky Motion        Object    Sun   Moon                Uncertainty info
            h m s                                                            "/min    P.A.    Azi. Alt.  Alt.  Phase Dist. Alt.    3-sig/" P.A.
... Suppressed ...
2017 04 20 080000 12 54 10.5 +18 47 38   0.020   1.021  146.4  32.9  11.0   83.76    199.6    247  +02   -06   0.41   122  -41        10 063.7 / Map / Offsets
2017 04 20 083000 12 53 12.3 +18 08 47   0.020   1.022  146.9  32.5  11.0   81.18    199.6    243  +08   -12   0.41   122  -43        10 064.1 / Map / Offsets
2017 04 20 090000 12 52 15.8 +17 31 08   0.020   1.022  147.3  32.0  11.1   78.71    199.7    239  +14   -18   0.41   123  -43        10 064.6 / Map / Offsets
2017 04 20 093000 12 51 21.1 +16 54 39   0.021   1.022  147.8  31.6  11.1   76.33    199.7    234  +20   -25   0.41   123  -43        10 065.0 / Map / Offsets
2017 04 20 100000 12 50 28.2 +16 19 16   0.021   1.023  148.1  31.2  11.1   74.05    199.7    229  +26   -31   0.40   124  -41         9 065.5 / Map / Offsets
2017 04 20 103000 12 49 36.8 +15 44 57   0.021   1.023  148.5  30.9  11.1   71.84    199.8    223  +31   -38   0.40   124  -39         9 065.9 / Map / Offsets
2017 04 20 110000 12 48 47.1 +15 11 39   0.022   1.023  148.9  30.5  11.1   69.71    199.8    216  +36   -44   0.40   124  -36         9 066.4 / Map / Offsets
2017 04 20 113000 12 47 59.0 +14 39 20   0.022   1.024  149.2  30.2  11.2   67.66    199.8    208  +40   -50   0.40   125  -32         9 066.8 / Map / Offsets
2017 04 20 120000 12 47 12.4 +14 07 58   0.022   1.024  149.5  29.8  11.2   65.68    199.8    199  +43   -56   0.40   125  -28         8 067.3 / Map / Offsets
2017 04 20 123000 12 46 27.3 +13 37 31   0.023   1.024  149.8  29.5  11.2   63.76    199.8    189  +45   -61   0.39   125  -23         8 067.8 / Map / Offsets
2017 04 20 130000 12 45 43.7 +13 07 57   0.023   1.025  150.1  29.2  11.2   61.90    199.7    178  +46   -66   0.39   126  -18         8 068.2 / Map / Offsets
2017 04 20 133000 12 45 01.6 +12 39 14   0.023   1.025  150.4  28.9  11.3   60.10    199.6    167  +45   -69   0.39   126  -12         8 068.7 / Map / Offsets
2017 04 20 140000 12 44 20.9 +12 11 20   0.024   1.026  150.7  28.7  11.3   58.36    199.5    157  +44   -71   0.39   126  -07         8 069.1 / Map / Offsets
2017 04 20 143000 12 43 41.7 +11 44 14   0.024   1.026  150.9  28.4  11.3   56.68    199.4    147  +41   -69   0.38   127  -01         8 069.6 / Map / Offsets
2017 04 20 150000 12 43 03.8 +11 17 53   0.024   1.026  151.2  28.2  11.3   55.04    199.3    139  +38   -66   0.38   127  +05         7 070.0 / Map / Offsets
2017 04 20 153000 12 42 27.4 +10 52 17   0.025   1.027  151.4  28.0  11.4   53.46    199.2    131  +33   -62   0.38   127  +11         7 070.5 / Map / Offsets
2017 04 20 160000 12 41 52.3 +10 27 23   0.025   1.027  151.6  27.7  11.4   51.93    199.0    124  +28   -56   0.38   128  +17         7 070.9 / Map / Offsets
2017 04 20 163000 12 41 18.5 +10 03 10   0.026   1.027  151.8  27.5  11.4   50.44    198.8    119  +23   -51   0.38   128  +23         7 071.3 / Map / Offsets
2017 04 20 170000 12 40 46.1 +09 39 38   0.026   1.028  152.0  27.3  11.4   49.01    198.7    113  +17   -45   0.37   128  +30         7 071.8 / Map / Offsets
2017 04 20 173000 12 40 14.9 +09 16 44   0.026   1.028  152.2  27.1  11.5   47.62    198.5    108  +11   -38   0.37   129  +36         7 072.2 / Map / Offsets
2017 04 20 180000 12 39 44.9 +08 54 27   0.027   1.029  152.4  27.0  11.5   46.28    198.3    104  +05   -32   0.37   129  +42         6 072.7 / Map / Offsets
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