Archive for the ‘Astronomy, Science’ Category

Nova TCP J18102829-2729590 still on the rise

October 24, 2016


Nova TCP J18102829-2729590 in Sagittarius is still on the rise although not at the same rate as a day or so ago. Early days though: these things are unpredictable.

The official AAVSO alert notice was posted overnight:

I have ongoing alignment problems with my LX-90 8″ scope (16 years old) and they caused me enough grief last night that I couldn’t make a visual estimate before the nova was below my fence line. I’ll try again in the next day or two.

Nova in Sagittarius

October 23, 2016

Not far from one of my favourite Cepheid variables (W Sagittarii), a nova in Sagittarius was discovered 3 days ago (TCP J18102829-2729590) by Koichi Itagaki of Japan. It has risen from magnitude 11 to 8 in that time.

The plot below shows the 10 visual and Johnson V observations submitted so far to the AAVSO International Database:


Two thirds of the visual observations are from Andrew Pearce in Western Australia. My single observation so far, made tonight, is under the cross hairs at upper right, with Andrew close on my heels. It’s always reassuring when two observations made close in time (less than an hour in this case) by different observers agree, within the limits of precision of the chosen method (visual estimation: approximately one tenth of a magnitude).

Many of my visual estimates of variable stars are made with 7×50 binoculars. Tonight I used my Meade LX-90 8″ telescope (magnification of 82x) because the nova is still too faint for my binoculars. There’s a beautiful asterism near the nova that makes the field hard to miss and makes for an enjoyable observation.


Last night I took images of the nova with the intention of carrying out wide field DSLR photometry, however there’s a star quite close to the nova. When combined with the amount of defocus normally used for DSLR photometry, separating the light from the two stars becomes impractical. So, I haven’t submitted an observation (untransformed) from that imaging run.

I’ll follow this object visually with interest for as long as the weather and my equipment allow.

Nova Lupi 2016 update

October 5, 2016

The nova in Lupus (ASASSN-16kt) continues to decline, having peaked at a visual magnitude of 5.6, declining to 6.5 in less than a day.

The plot shows my two binocular observations before the weather in Adelaide went loopy (as opposed to Lupi), the last under cross-hairs at magnitude of 7.2. It’s now down to around magnitude 9.0.


The sky is clear tonight, and may be okay for a couple more days, so I might attempt some tri-colour DSLR observations. Tonight’s out due to an ASSA meeting. Typical!🙂

ASASSN-16kt update

September 28, 2016

I made a second observation of the nova in Lupus last night (Sep 27). It had faded from a visual magnitude of 6.7 on Monday to 7.2 (both in purple below). Observations since then show a further brightness decline.


I was pleased to see my first observation counted among those submitted by Elizabeth Waagen (AAVSO) for inclusion in “telegram 4322” from the the Central Bureau for Astronomical Telegrams in Harvard (my first). See the AAVSO alert from Elizabeth for more details.

There was no chance of another observation tonight after the storm here in Adelaide today; no power so no light pollution but no clear sky either. I’d say another day or two will go by before I can observe it again.

Nova in Lupus!

September 26, 2016

ASASSN-16kt was discovered in the constellation of Lupus on September 24 by the All-Sky Automated Survey for SuperNovae with data from a 14″ telescope in Chile.

The discovery magnitude was 9.1 with nothing greater than magnitude 17.5 previously known at that location.

I made a visual estimate of the nova at magnitude 6.7 tonight (September 26) from suburban Adelaide with 7×50 binoculars. At the time of writing, only 8 observations by 6 observers had been submitted to the AAVSO International Database including three Australian amateurs: Terry Bohlsen, Rod Stubbings and myself (highlighted at right), two Argentinians (Gustavo Ballan and the near-omniscient Sebastian Otero) and one Brazillian (Alexandre Amorim).


Other than photometry (visual or image based), amateurs are increasingly taking the spectra of bright novae, and ASASSN-16kt is no exception, with Terry Bohlsen (New South Wales) taking an early spectrum soon after discovery.

These Stellarium screenshots show the location of the nova in Lupus as the south-west sky appeared at around 8pm tonight from Adelaide (wide and narrow field):

Lupus constellation borders.png


The AAVSO finder chart (7.5 degrees) is shown below in a similar orientation:


I was interested to see a request from a researcher, Laura Chomiuk, for high-speed photometry of the nova to:

…to test a recent theoretical prediction of Ken Shen’s: that novae should show fast periodic oscillations in their optical light curves, if gravity waves help expel the envelope.

Time will tell whether the nova has peaked short of naked eye visibility. I hope to make another observation tomorrow night but the forecast does not look favourable for at least a couple of days thereafter.

At least this nova waited for the cloud-dominated winter we’ve just had to pass by.

Another Gravitational Wave detection

June 16, 2016

Another gravitational wave detection by LIGO has been announced!


The June 15 announcement page points out that while the signal was weaker than the first detection due to the black hole masses being smaller (14 and 8 solar masses vs 36 and 29):

…when these lighter black holes merged, their signal shifted into higher frequencies bringing it into LIGO’s sensitive band earlier in the merger than we observed in the September event. This allowed us to observe more orbits than the first detection–some 27 orbits over about one second (this compares with just two tenths of a second of observation in the first detection). Combined, these two factors (smaller masses and more observed orbits) were the keys to enabling LIGO to detect a weaker signal. They also allowed us to make more precise comparisons with General Relativity. Spoiler: the signal agrees, again, perfectly with Einstein’s theory.

The news release continues:

Our next observing interval – Observing Run #2, or “O2” – will start in the Fall of 2016. With improved sensitivity, we expect to see more black hole coalescences, and possibly detect gravitational waves from other sources, like binary neutron-star mergers. We are also looking forward to the Virgo detector joining us later in the O2 run. Virgo will be enormously helpful in locating sources on the sky, collapsing that ring down to a patch, but also helping us understand the sources of gravitational waves.

Gravitational Wave astronomy does seem to have arrived!


LIGO Gravitational Wave detection: the work of many…

February 13, 2016
I think it’s worth noting that 3 of the authors of the LIGO Gravitational Wave detection paper are listed as deceased (two in 2015 and 1 in 2012) and humbling to realise that, especially in a field like cosmology or particle physics, a scientist could spend his or her working life on something like this and never see the sought-after result.
It also emphasises that Science is usually not about a single person working in isolation, but about the work of many people collaborating and competing over a long period of time.
An ABC post about David Blair’s work on this for 40 years further underscores the point.
Congratulations to the hundreds (from the author list alone!) of scientists, engineers, and support people who contributed in some way to the first direct detection of gravitational values 100 years after their prediction from general relativity by Einstein.

DSLR photometry of BL Tel

August 28, 2015



Today I submitted an August 22 DSLR observation of the long period eclipsing variable BL Tel to the AAVSO international database.

My observation (9.124  (0.031) V), is shown under the cross-hairs in the images: Visual and Johnson V together and V alone.



Minimum should be happening around about now (~Aug 27).

I have images from Aug 25 that I’ll process this weekend. The conditions were less than ideal, but I managed to get some data before the clouds became a persistent problem.

I hope to take some more images this weekend.

Thanks to Peter Williams for prompting me to consider making observations of BL Tel which is nicely positioned high in the evening night sky now.

Another Nova Sgr 2015 No. 2 update

March 30, 2015

I’ve made 10 observations of the nova since March 19, mostly visual, 3 DSLR, one of which has yet to be processed.

The (rather noisy) light curve is starting to show the kind of early oscillations that seem to be common in novae and certainly the last two bright novae I’ve seen. The red fit “line” helps to make this more obvious.


The cross-hairs are over my most recent observation early this morning.

Nova Sgr 2015 No. 2 update

March 25, 2015

I made visual and DSLR photometric observations of the nova on March 21 and 22. The image below shows the nova before sunrise on March 22.


The light curve shows my most recent submission under the cross hairs.



It appears that the nova has peaked but these objects are unpredictable so we may see some fluctuations yet. The local weather has made observations difficult for the last 3 days.