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Sunday, March 29, 2015

 

Nova Sagittarii 2015 No. 2 Rebrightens (a bit)

Nova Sagittarii 2015 No. 2 in the lid of the teapot of Sagittarius. This is a stack of 10x15 second exposures, ASA 400, 3x Zoom with my Canon IXUS, taken on 21 March at 5:10 am, click to embiggen24 March, stack of 8 images, same conditions a the 21st.28 March, stack of  10 images, same conditions a the 21st.

 Light curve of  Nova Sagittarii 2015 No. 2. It has faded then rebrightened, and may be fading again


Following Nova Sagittarii 2015 No. 2 has been a bit frustration as there have only been a few days without cloud. Up the top is a series of 3 images from the 21st, 24th and 28.


Animation centred on the nova (couldn't align the  stars properly sorry) showing brightness variation.

On the 21st it was just visible to the uniaded eye with averted vision, and quite clear in binoculars, on the 24th it was no longer unaided eye visible, in binoculars it was obvious, but no longer outstanding. On the 28th it was again just visible to the unaided eye with averted vision, and again brighter in binoculars.

This nova is well worth extended follow up, and may bounce around in brightness like Nova Cent 2013 and  Nova Delphinus 2013.


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Saturday, March 28, 2015

 

Aurora Watch (28-30 March)

Still another Aurora Watch issued by the Australian IPS for the 28th (yes tonight) to the 30th due to increased solar wind speed from a Coronal Hole. The 29th seems the most likely time (although that might be in the early morning of the 29th). Geomagnetic activity is rate at only "unsettled to active" rather than storm levels but sub storms may occur, and aurora, if they occur, are likely to be seen only in Tasmania (possibly Victoria if there is a substorm).

Aurora can occur at any time after nightfall (although around midnight or just after seems to be common). 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 too.

The waxing Moon will interfere a bit in the early evening, but late evening/morning should be okay.


The all sky aurora camera in Southern Tasmania at Cressy may be helpful),
<http://www.ips.gov.au/Geophysical/4/2>http://www.ips.gov.au/Geophysical/4/2
SUBJ: IPS AURORA WATCH
ISSUED AT 2233 UT ON 27 Mar 2015 BY IPS RADIO AND SPACE SERVICES
FROM THE AUSTRALIAN SPACE FORECAST CENTRE

A high speed solar wind stream is expected to impact the Earth
sometime within the next 24-48 hours and should remain effective for
several days after arrival. The high speed stream is caused by a solar
feature that has persisted on the Sun for several months and on
previous rotations has produced geomagnetic activity sufficient to
produce Aurora potentially viewable from Tasmania. An alert will be
issued should favourable conditions for producing Aurora be observed.

2B. MAGNETIC FORECAST
Date Ap Conditions
28 Mar 12 Unsettled
29 Mar 20 Active
30 Mar 15 Unsettled to Active

Further monitoring at
http://www.ips.gov.au

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Thursday, March 26, 2015

 

Total Lunar Eclipse, April 4, 2015

Eastern horizon as seen from Sydney on  4 April at 9:15 pm AEDST. The eclipse is just about to begin. Click to embiggenEastern horizon as seen from Adelaide on  4 April at 8:45 pm ACDST . The eclipse is just starting. Click to embiggenEastern horizon as seen from Perth on  4 April at 6:15 pm AWST. The eclipse is about to start. Click to embiggen
Above the North-Eastern horizon as seen from Sydney on  4 April at 10:54 pm AEDST. The total eclipse has just begun . Click to embiggenNorth-Eastern horizon as seen from Adelaide on  4 April at 10:24 pm ACDST. The total eclipse has just begun . Click to embiggenEastern horizon as seen from Perth on  4 April at 8:00 pm AWST. The total eclipse is just about midway. Click to embiggen

On the evening of 4 April there there be a total eclipse of the Moon, the only Lunar eclipse seen from Australia, and the last we will see until 2018. The 4 April eclipse starts after twilight has ended in the eastern and central states. In Western Australia the partial phase occurs shortly after sunset, and totality starts when the sky is fully dark. Totality is short, only 12 minutes long for this eclipse. See timings table below.

You don't need special filters or fancy equipment to watch the lunar eclipse, you just need your eyes and somewhere comfortable to sit and watch. Binoculars or a telescope are a plus, but not necessary.
A guide to taking photos of the eclipse is here.

On the East coast, the eclipse starts after when the sky is quite dark at 8:15 pm AEST (9:15 pm AEDST) and Totality is at 9:54 pm AEST (10:54 pm AEDST), so the Moon will appear to be a burnished copper disk in a dark sky full of stars. As totality fades you will see the stars extinguish.

In the central states the eclipse starts just after Astronomical twilight at 7:45 pm ACST (8:45 pm ACDST) and Totality begins at 9:24 pm ACST (10:24 pm ACDST). Central states will also see the eclipsed Moon in all its coppery glory and the stars fade as the Moon returns.

In WA, the eclipse starts in the just after sunset, but totality will occur when the sky is fully dark. The eclipse starts at 6:15 pm AWST and Totality begins at 7:54 pm AWST.

The eclipse occurs reasonably high in the sky and is good viewing from almost anywhere. It finishes a bit late for the kids though.

New Zealand sees the eclipse late in the evening and the early morning of the following day.

See here for a map and contact timings in UT for sites outside Australia.

City Moonrise Eclipse Start Totality Start Maximum Eclipse Totality End Eclipse End
Adelaide (ACDST) 7:00 pm 8:45 pm 10:24 pm 10:30 pm 10:36 pm 00:15 am
Alice Springs (ACST) 6:25  pm 7:45 pm 9:24 pm 9:33 pm 9:36 pm 10:15 pm
Auckland (NZT) 6:00 pm 10:15 pm 11:53 pm 12:00 am 12:06 am 01:44 am
Brisbane (AEST) 5:34 pm 8:15 pm 9:54 pm 10:00 pm 10:06 pm 11:45 pm
Cairns (AEST) 6:06 pm 8:15 pm 9:54 pm 10:00 pm 10:06 pm 11:45 pm
Canberra (AEDST) 7:47 pm 9:15 pm 10:54 pm 11:00 pm 11:06  pm 00:45  am
Christchurch (NZT) 6:06 pm 10:15 pm 11:53 pm 12:00 am 12:06 am 01:44 am
Darwin (ACST) 6:42 pm 7:45 pm 9:24 pm 9:33 pm 9:36 pm 10:15 pm
Hobart (AEDST) 6:51 pm 9:15 pm 10:54 pm 11:00 pm 11:06 pm 00:45  am
Melbourne (AEDST) 7:02 pm 9:15 pm 10:54 pm 11:00 pm 11:06 pm 00:45  am
Perth (AWST) 6:05 pm 6:15 pm 7:54 pm 8:00 pm 8:06 pm 9:45 pm
Rockhampton (AEST) 5:46 pm 8:15 pm 9:54 pm 10:00 pm 10:06 pm 11:45 pm
Sydney (AEDST) 6:39 pm 9:15 pm 10:54 pm 11:00 pm 11:06 pm 00:45  am
Townsville (AEST) 6:03 pm 8:15 pm 9:54 pm 10:00 pm 10:06 pm 11:45 pm

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Wednesday, March 25, 2015

 

The Sky This Week - Thursday March 26 to Thursday April 2

The First Quarter Moon is Friday March 27. Venus is prominent in the twilight evening sky. Mars is lost in the twilight. Jupiter is the brightest object in the evening sky once Venus has set. Jupiter is visited by the Moon on the 30th. Saturn is in the head of the Scorpion and now visible in the evening. Mercury is lost to view.

The New Moon is Friday March 20. The Moon is at apogee, when it is furthest from the Earth, on April 1st.

Evening sky on Saturday March 28 looking west as seen from Adelaide at 20:00 (8:00 pm) ACDST in South Australia.  Mars is low in the twilight, with Venus above it heading towards the Pleiades. Similar views will be seen elsewhere at the equivalent local time (click to embiggen).

Venus is easy to see low above the western horizon in the twilight. At civil twilight, half an hour after sunset, it is around one and a half hand-spans above the horizon. On the 22nd the thin crescent Moon is below Venus, and then on the 23rd it is above Venus.

Mars  is low in the western twilight sky and is effectively lost to view.

Evening sky on Monday March 30 looking north as seen from Adelaide at 22:00 ACDST showing Jupiter.  The inset shows Jupiter's Moons at this time. Jupiter is the brightest object above the northern horizon. (click to embiggen).

 Jupiter  is now easily seen  in the evening sky. It is the brightest object above the north-eastern horizon when twilight ends, and continues into the northern sky as the night goes on. It is between the bright star Regulus in the sickle of Leo (this forms the head of the constellation of the  Lion) and Pollux in Cancer. It is also not far from the rather nice Beehive cluster in Cancer, and looks very good in binoculars.

Jupiter was  at opposition, when it is biggest and brightest in our sky, on 7 February, but it will be an excellent object for may weeks to come.  Jupiter is visible all night and is high enough for decent telescopic observation from around 10 pm. Jupiter's Moons will be putting on a good display in both binoculars and small telescopes.

On the 30th, The Moon is close to Jupiter. On April 1st from around 10:00 pm, Io's shadow traverses Jupiter's disk.

Evening sky on Saturday March 28 looking east as seen from Adelaide at 23:00 ACDST .  Saturn is now visible above the horizon. (click to embiggen).

Saturn climbs still higher in the morning sky. It is now easily visible before midnight  near the head of the constellation of the Scorpion not far from the bright red star Antares. The sight of the distinctive constellation of the Scorpion curled above the horizon, with bright Saturn in its head, is very nice indeed.

Saturn is  readily visible from around 23:00, but is still best after midnight.

Mercury is lost in the twilight.
 
There are lots of interesting things in the sky to view with a telescope. Especially with Jupiter just past opposition and Saturn rising. 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 AEDST. For further details and more information on what's up in the sky, see Southern Skywatch.

Cloud cover predictions can be found at SkippySky.

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Tuesday, March 24, 2015

 

Nova Sagittarii 2015 No. 2 Still Bright

Nova Sagittarii 2015 No. 2 in the lid of the teapot of Sagittarius. This is a stack of 10x15 second exposures, ASA 400, 3x Zoom with my Canon IXUS, taken on 21 March at 5:10 am, click to embiggenChart of the same area showing the reference stars. click to embiggen and compare with the actual image.

PNV J18365700-2855420, is now Nova Sagittarii 2015 No. 2 (because there was an earlier nova in Sagittarius). It is a classic nova based on its spectrum.


Light curve of  Nova Sagittarii 2015 No. 2.

There were reports of it being magnitude 4.4, which makes it one of the brightest nova since nova Centauri 2013. It looks like it is fading now, but still above the unaided eye threshold. It is possible it may flare up again like nova Centauri 2013 and nova Delphinus 2013.

Nova Sagittarii 2015 No. 2 taken with iTelescope T12 on 19 March, single 60 second exposure. click to embiggen. compare with my earlier shot.

Cloud and timing have been my foe for this nova, I caught it once on the 21st at 5:00am, when it was just visible to the averted eye. Lack of decent reference stars at the time suggested it was around magnitude 5. Then on the 22nd I was able to see it only in twilight with binoculars, but it was very distinctive, altering the shape of the teapot asterism.

While it is still bright it is worth getting up in the morning for a look. Observing charts are here.

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Sunday, March 22, 2015

 

Aurora Watch and Geomagnetic Alert (22-23 March)

After 2 nights of aurora (with some activity seen by die-hard observers on the 19th) we have yet another Aurora Watch issued by the Australian IPS for the  22nd (yes tonight) and the 23rd due to increased solar wind speed from a Coronal Hole. Geomagnetic activity is rate at only "unsettled to active" rather than storm levels, and aurora, if they occur, are likely to be seen only in Tasmania.

Aurora can occur at any time after nightfall (although around midnight or just after seems to be common). 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 too. In the last display proton arcs were seen to the west of the main display.

The all sky aurora camera in Southern Tasmania at Cressy may be helpful),
http://www.ips.gov.au/Geophysical/4/2
SUBJ: IPS AURORA WATCH
ISSUED AT 2305 UT ON 21 Mar 2015 BY IPS RADIO AND SPACE SERVICES
FROM THE AUSTRALIAN SPACE FORECAST CENTRE

Geomagnetic activity could result in auroras visible from Tasmania
during local nighttime hours 22-23 Mar. Aurora alerts will follow
should favourable space weather activity eventuate.

Due to elevated solar wind speed and increased IMF magnitude,
there is the possibility of minor storm periods 22-23 Mar if
IMF Bz turns southward.

INCREASED GEOMAGNETIC ACTIVITY EXPECTED
DUE TO CORONAL HOLE HIGH SPEED WIND STREAM
FROM 22-23 MARCH 2015
 GEOMAGNETIC ACTIVITY FORECAST
22 Mar:  Unsettled to Active
23 Mar:  Unsettled to Active

http://www.ips.gov.au

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Friday, March 20, 2015

 

Viewing Today's Solar Eclipse (20 March 2015)

The total Solar Eclipse of 20 March in the Northern Hemisphere is a long one, due to the perigee full Moon. Unfortunately the track of totality largely misses land. It is effectively only visible in the Fareo Islands and Svalbard Islands. A lot of the Northern Hemisphere sees a decent partial eclipse though.

While we in the Southen Hemisphere don't see any of this, there are a couple of live webcasts of the eclipse to help us enjoy it vicariously.

SLOOH observatory webcast (starts 8:30 UT, 19:30 AEDST, 19:00 ACDST, 18:30 AEST and 16:30 AWST) http://live.slooh.com/stadium/live/the-total-solar-eclipse-of-2015

Space.com webcast (starts same time as SLOOH) http://www.space.com/19195-night-sky-planets-asteroids-webcasts.html

Virtual telescope webcast (starts 8:00 UT) http://www.virtualtelescope.eu/



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