Archive for December, 2013

V1369 fading again

December 30, 2013

I made a visual estimate of magnitude 4.4 of the nova overnight. Subsequent observations show that it has dropped further since.

Here is the updated light curve:

V1369CenDec302013

The observation under the cross-hairs is my last (magnitude 4.4) observation and the others in purple (click image to enlarge) are the estimates I’ve submitted to AAVSO so far. 

Sebastian Otero’s latest forum reply asks whether the current fading will be the nova’s last one and suggests possibly not, given its erratic behaviour so far.

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V1369 light curve update

December 28, 2013

I just made an estimate of V1369 Cen (at about 2am on Dec 29) at magnitude 4.3. It may actually be closer to 4.2 but I could not convince myself of that with respect to nearby magnitude 4.0 and 4.3 comparison stars. Visual and Johnson V observations are shown below (via VStar), with my estimate in the cross-hairs and a polynomial fit (in red) to make the outline of the light curve more obvious.

V1369CenDec292013

Regarding the polynomial fit, bear in mind of course George E.P. Box’s maxim that:

Essentially, all models are wrong, but some are useful.

So far, 628 observations have been submitted to AAVSO. Of these, 214 are visual observations.

What a fascinating, meandering, unpredictable progression. I’ll try to monitor this nova as much as possible over the next week, while still on holidays.

Estimates of V1369 Cen and light curve update

December 21, 2013

Once the weather had improved, I was able to make two estimates of V1369 Cen, in the early hours of December 12th and 14th, and submit them to AAVSO.

In the week following these observations, work was all-consuming (in a positive way) and I needed to get plenty of sleep. The weather is uncooperative in Adelaide again at the moment. Being on leave for a couple of weeks makes it less of a problem getting up at an early hour when the weather does improve again.

The nova continues to be interesting as shown by the current light curve.

NovaCenDec21

This AAVSO article provides a great summary of the evolution of the nova so far.

I continue to watch this object with interest.

V1369 Centauri naked eye glimpses this morning

December 8, 2013

Gaps in the clouds from my suburban location at around 4:54 am today again provided glimpses of the nova, still visible to the naked eye. I was only able to briefly see two stars for comparison purposes but not both at the same time: v Cen (4.33 with a small variability of 0.01) and beta Musca (3.5). It was certainly closer to v Cen than beta Musca, perhaps around magnitude 4.0 or 4.1 but again, this observation is very uncertain and not good enough to submit to the AAVSO International Database.

Reports from others indicate that V1369 Cen continues to fade.

V1369 Cen light curve and cloud, cloud, cloud (did I mention cloud?)

December 7, 2013

Not even a glimpse this morning at 4:15 am and for the next hour.

“Partly cloudy” was a slight exaggeration and the forecast currently doesn’t look good for most of the coming week.

adelaide_forecast_dec7

Of course, that part of the sky was clear by the time I emerged after an unusually long saturday morning sleep in.

Reports from others suggest that the nova may have peaked. Here’s the light curve so far, consisting of 55 (non fainter-than) observations.

V1369CenDec72013

It shouldn’t be too surprising that there are fewer observations for this nova in the same period of time as there were for V0339 Del which was:

  • Visible in the evening sky rather than the early morning.
  • Not as bright (around a magnitude less at peak).
  • Visible in northerly latitudes.

Despite the forecast, I’ll try again tomorrow morning. A fellow ASSA member told me that the southern sky was clear around 30 minutes before I was observing yesterday morning. The weather pays no heed to the likes of us.

Brief glimpses of Nova Cen 2013 (now V1369 Cen) through cloud

December 5, 2013

AAVSO visual observer Michael Linnolt had this to say on an AAVSO forum a short time ago:

Even here in the southernmost tip of Hawaii (19N) This nova rises too late in morning twilight to be readily visible. I suppose from the summit of Mauna Kea, with the perfect horizon and clarity above the clouds, it may be possible, but I’m not going to drive all the way up there just for this (2.5 hrs by road and 14000ft high!)

That drive to Mauna Kea would be a bit much. At least all I have to do is step out into my backyard. ;)

But then there are clouds to contend with…

Adelaide_South_Dec_6_dawn

That doesn’t look so bad now does it? Hmm…

I caught brief, tantalising glimpses of V1369 Cen near dawn (around 5:05 am Adelaide time and for 20 minutes or so thereafter) through thinning cloud with 7×50 binoculars.

It was, of course, clear soon after sunrise…

Adelaide_South_Dec_6_after_sunrise

The nova seemed brighter than yesterday morning but I cannot quantify that since I couldn’t see more than one comparison star and the nova for long enough to be able to make an estimate. I briefly spotted bet Mus and the nova within a few seconds of each other and the nova was certainly less than beta Mus (<3.045). So, all I can declare is that V1369 Cen was brighter than my Dec 4 observation (which was >4.33) and fainter than magnitude 3.045. 

Jonathon Powles and another observer in Canberra estimated V1369 Cen at around magnitude 3.5 this morning.

I spent time last night looking for additional sufficiently bright comparison stars and talking with Sebastian Otero about this since we seem to have run out of them! VSP has some limits in that regard.

nova_cen_2013_comp_stars1

The screenshot above shows some of the comparison stars as circled (from Sky Safari on an iPad).

The forecast for tomorrow is less dismal, so I’ll try again then.

First glimpse of Nova Centauri 2013!

December 4, 2013

I had my first glimpse of Nova Centauri 2013 (PNV J13544700-5909080) at 5:14 am local (Adelaide) time today, near dawn, as the sky was starting to turn blue.

All I can really say from that hurried observation, given the finder chart I was using, is that it was brighter than the magnitude 4.33 comparison star (JD 2456631.28102, >4.33). I used  7×50 binoculars.

What an awesome sight!

Tomorrow morning I need to be better prepared by:

  1. being outside about 45 mins earlier;
  2. using additional comparison stars from the AAVSO alert notice.

Nova candidate in Centaurus brightens overnight

December 3, 2013

Further to my post last night, the transient near Beta Centauri (PNV J13544700-5909080) has brightened to 4.6 overnight. Paul Camilleri (NSW) observed the nova candidate at magnitude 5 and soon after, Andrew Pearce (WA) reported a magnitude of 4.7, closely followed by 4.6.

In addition to Malcolm Locke’s, Rob Kaufman (NSW) has also obtained a spectrum (also showing the H-α and H-β emission lines) and others will no doubt follow.

This blog post shows a nice before and after animation of the region of sky around the nova. Note that the object was discovered by John Seach, Chatsworth Island, NSW, as per the CBAT announcement.

2013 12 02.692

Possible new nova in Centaurus. Discovered by John Seach, Chatsworth Island, NSW Australia. Instrument DSLR with 50 mm f/1.0 lens. Visible on 6 images, limiting magnitude 11. Nothing visible on image taken with same instrument on November 26.69 UT 2013 limiting magnitude 11. Nothing visible on variable star index, DSS2-red, or minor planet checker.

See the CBAT page for some additional follow-up.

The AAVSO International Database still has only 4 visual observations of the object but Arne Henden has said that APASS observations are in the works.

I can’t convey to you how frustrating it is to have to wait for decent weather to be able to make observations of this object!

Updates:

  • Sebastian Otero’s latest observation puts the nova at magnitude 4.3!
  • As mentioned in the AAVSO forum thread, Steven Graham’s webcam in NZ may show that the outburst occurred on December 2.

Possible Nova near Beta Centauri

December 3, 2013

A possible nova has been discovered near Beta Centauri, one of the two stars that “point to” the Southern Cross.

Initial estimates put it at around magnitude 5.3. As Sebastian Otero says, we will have to wait and see whether it has been caught near its peak or is still brightening.

Here is an AAVSO thread about the object. One of the posts to the thread (by Sebastian Otero) includes a finder chart with comparison stars.

Right now, I’m biding my time, waiting for the object to rise higher so I can catch my first glimpse of it from my suburban Adelaide site. That’s assuming a sufficient gap in the clouds. The forecast for the next couple of days is not fantastic. The story was not dissimilar around the time of peak brightness of V0339 Delphini.

What’s interesting is that while there are currently only two observations submitted to the AAVSO International Database, amateurs are already taking spectra. For example, see Malcolm Locke’s initial spectrum. Amateur spectroscopy is certainly on the rise, especially for bright objects with interesting spectral features, e.g. H-α and H-β emission lines (see the two peaks in Malcolm’s spectrum).

First V0339 Delphini, now this! I can hardly contain myself! 🙂

Update: It’s just after midnight and the clouds are thickening, so off to get some sleep.