Double rainbow

August 31, 2015

My wife Karen was in the front yard early this morning and called out to come have at look at this nicely defined (and double) rainbow:

As she remarked, the spectrum of colours was really obvious in parts.

Nice start to the day, followed by a quick ride and dash to the bus.

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.

Primitive cultures

April 29, 2015

In Star Trek: The Voyage Home, Captain Kirk amusingly refers to late 20th century America as a primitive and paranoid culture. The same could be said for many countries then and now, some more than others of course, especially in recent times.

Like many (but not all, that’s for sure) in Australia, I’m saddened and disturbed by today’s executions. In comments about the event I’ve seen people conflate two distinct issues:

  1. The Law
  2. Morality

The (flawed) legal machine that eventually led to the firing squad has nothing to say about morality. There’s no ethical content to be found in The Law. Ethics must come first to inform The Law.

In my view, the death penalty is the sign of a primitive culture or at least some aspects of that culture.

Back in the Star Trek universe, a rare culture might be thought ready to join the club (Federation), but many are thought to be too primitive in one sense or another at a particular point in time.

At the moment, I think of the country in question as being like one of those primitive cultures: not yet ready to join the club due to an inability to see the moral harm of the death penalty and an unwillingness to engage in rational conversation about it. I’m sure there are many individuals in that country who do see the problem which is why it’s important to distinguish a country’s citizens from those who purport to run it.

If we didn’t worship the almighty dollar so much and had the strength of our convictions, we might consider imposing economic sanctions, declaring the country unfit to join the club suggesting: “perhaps one day when you have grown up and apologised for your barbarism, we will consider trading with you again”.

Of course, sanctions are not without harmful effects, at least on ordinary people.

There’s no simple response, but there must be one, and it must be clear.

April 4th 2015 Total Lunar Eclipse from Adelaide

April 5, 2015

We were mostly clouded out here in suburban Klemzig. I took images during small breaks in the cloud. This one was taken at 22:11 ACDT, 16 minutes before the start of totality.


Canon 1100D, ISO 800 for 3 seconds at prime focus of Meade LX-90 8″ SCT

Unfortunately totality was completely clouded out here. There are plenty of better images by others, e.g. by Jarrod Koh and Paul Haese.

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.

Nova Sgr 2015: first observation

March 19, 2015

The conditions at 6am today were not ideal: lots of intermittent cloud, or more accurately, intermittent gaps.

I estimated the nova to be at magnitude 4.9. It was substantially brighter than the 53 comparison star and may even have been brighter than the 47 comparison star (AAVSO chart ID 14582KC).


I marked the observation as “uncertain” (comment code Z on WebObs) and added the comment:

7×50 binoculars;AT LEAST mag 4.9;may have actually been brighter than 47 comp;intermittent cloud

Tomorrow morning, whether permitting, a brighter comparison star may be needed assuming this thing keeps brightening. Getting up early enough to make a DSLR observation would be nice too.



Nova Sgr 2015

March 18, 2015

There’s a bright nova in Sagittarius (PNV J18365700-2855420 where PNV = possible nova candidate, its discovery designation).

Like the last bright southern nova (Nova Cen 2013), this one was also discovered by John Seach in NSW.

The nova was discovered on March 15 so it’s early days yet. There are 35 observations in the AAVSO International Database.


I tried to get out to observe it this morning but it was cloudy. When the weather clears I’ll make visual and time-permitting, DSLR observations.

My first DSLR photometry observation

February 3, 2015

After more than 5 months of gearing up to do DSLR photometry and two AAVSO CHOICE courses later, I submitted my first DSLR photometry observation yesterday: R Car, magnitude 5.054 with an error of 0.025.

First Submission

With a visual observation, the best I could have said that it was magnitude 5.1 with an error of a tenth of a magnitude. With DSLR photometry I can get down to a hundredth of a magnitude. A CCD could do better (a thousandth) but for ten times the cost, or more.

Yet another step in the evolution of my hobby. Thanks to Mark Blackford for sharing his considerable experience.




More C/2014 Q2 Lovejoy images

January 6, 2015

I took some more images of the comet on December 28, this time from my suburban backyard in Klemzig, again with a Canon 1100D piggybacked on my Meade LX-90.

Both images shown below were stacked and saturation-reduced with IRIS, and cropped with The GIMP. They are quite noisy since no bias or dark frame subtraction was carried out, nor were any flat frames applied; I still don’t have a light box. Effects due to vignetting and dust donuts were obvious on the processed image, likewise for hot pixels, but less so in the cropped portion.


C/2014 Q2 Lovejoy, 10 stacked 5 second images, ISO 1600, f2.0


C/2014 Q2 Lovejoy, 10 stacked 20 second images, ISO 1600, f3.2

I intend to take some more images when the lunar phase is more favourable in a week or so.


Get every new post delivered to your Inbox.

Join 82 other followers