U Sco update

June 8, 2022

Within a day, the nova reached a peak magnitude of 7.8, then dropped two magnitudes, becoming around 5 times dimmer in actual brightness (magnitude is logarithmic).

The AAVSO Alert Notice details the decline of the last outburst over a few months and flares with an amplitude of around half a magnitude that began several days after the peak, for which the mechanism is unknown.

Outburst of the Recurrent Nova U Sco

June 8, 2022

In late September 2021, I wrote about the recurrent nova U Scorpii: Waiting for U Sco and Waiting for U Sco: nearby gamma ray transient detected.

The last image I took of the region around U Sco in September showed no sign of it, but within the last day it has undergone an outburst, and appears to have quickly peaked, as per previous events (the last being in January 2010) before declining again. The nova reached a visual magnitude of 7.8 on June 7 2022 up from its usual magnitude 18 or thereabouts, a difference in brightness of around 25 times (each magnitude being a factor of 2.512 brighter than the whole number magnitude on either side of it). As I write, U Sco has declined to around magnitude 8.4.

The light curves show the current and 2010 outburst, and a close up of the current outburst. It’s interesting note that there appears to have been some evidence of an increase in magnitude in the few months leading up to the outburst.

I took a DSLR image of the region around the nova tonight. U Sco is marked with a red arrow.

While I don’t have images that are suitable for DSLR photometry from tonight (the sky was less than ideal), nor did I have the chance to make a visual (binocular or telescope) observation, from the image I estimate the nova’s magnitude to be around 8.4 (magnitude 8.3 and 8.6 comparison stars are marked with green arrows), which is consistent with the current photometry in the AAVSO International Database.

The following images show the U Sco region tonight (June 2022) and late last September for comparison, in different sky conditions and positions on the sky. The second image has been rotated to match the current event’s sky rotation. Flicking up and down between the images will help reveal the nova, aided by the arrowed image above if necessary.

June 2022 outburst (5 seconds, ISO 800, f2.0, Canon 1100D)
U Sco region in late September 2021 (3 seconds, ISO 800, f2.0, Canon 1100D)

For more information about recurrent novae, I gave a talk in early September 2021 to ASSA about another recurrent nova RS Oph. See also this AAVSO forum page regarding the current outburst.

EDIT: Here is the AAVSO alert notice: https://www.aavso.org/aavso-alert-notice-779

Facebook Immortals?

May 14, 2022

I try to remember to light a candle each year on my mother’s and father’s birthday. Today (May 14), it was for Dad, and he would have been 91.

On August 17th this year, it will be 20 years since Mum died (four days before her 74th birthday). On January 7th this year, it was 2 years since Dad died.

So, you can imagine my mild surprise when Facebook notified me that it was Dad’s birthday and invited me to post on his timeline. Apparently Facebook time stretches beyond this life…

I’ve noticed this phenomenon a number of times now. Of course, given concerns about “what social media knows about us” and “how it controls what we think” (to which I’m not entirely unsympathetic, but about which I have not yet succumbed to total paranoia), I suppose it’s comforting to know that Facebook hasn’t yet figured out whether or not an account owner is still alive. Seems like a not-too-crazy-hard application of traditional symbol systems AI to search death records etc and put two and two together though.

At some point in time, the living Facebook population may outnumber the non-living. Perhaps just in time for Facebook Metaverse v2.0: reanimation? That may be taking AI too far though. 😉

Still, I thought I’d take Facebook up on the invitation to post on Dad’s apparently eternal timeline. Given his particular sense of humour, and that he was a Uniting Church minister, I’m pretty sure he would have found it funny.

Where do pandemics come from?

March 19, 2022

If you actually want to create pandemics, then build factory farms.

Bird Flu: A Virus of our Own Hatching, Dr Michael Gregor (2006)

While it is true that many infectious diseases that have wreaked havoc on humans have come from animals, it is not entirely the case that ending the consumption of animals would put an end to such diseases. Limiting contact with animals, even assuming they are not being consumed by humans, would be necessary to lessen the chances that viruses and other pathogens transfer between species and infect humans.

Fact check: Is COVID-19 caused by human consumption of animals?

Large scale meat production increases the pandemic risk. Here are some videos that look at various aspects of the origin of pandemics.

A great video about the history and causes of pandemics

Once in awhile I’m not misanthropic…

March 13, 2022

In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves.

(Carl Sagan, Pale Blue Dot)

I find it increasingly easy to be misanthropic now.

Climate action malaise.

Zoonotic diseases (e.g. COVID-19, Japanese Encephalitis Virus).

Rampant speciesism.

Russia’s invasion of Ukraine and who knows what country next.

All unnecessary. All preventable.

I find myself speaking about homo sapiens in the third person more and more, despite (obviously) being a deeply flawed member of that species.

Despite a willingness to be conciliatory, to be a glass half full kind of guy, to encourage open, honest conversation, some days, I find it really really hard to have any hope that our species will mature quickly enough to significantly mitigate the coming climate catastrophe or to avoid decades more unnecessary suffering and death of the members of many species, but especially those that members of species homo sapiens use and abuse.

Every so often though, my spirits are buoyed and hope seems possible. That happened recently, when I watched this video.

Having said that, I do tire of the us and them phrasing of the title of videos like this (“meat eater” vs “vegan”). The content is positive and respectful though.

But there will need to be many more such intellectually honest, respectful conversations, before my view of the future is likely to be significantly perturbed.

Earthling Ed and Eric have the quintessential open conversation

Making sense of variable star observations

February 23, 2022

I recently gave a talk via ASSA@Home about making the connection between variable star observations (from the AAVSO International Database and Kepler mission) with the processes in the star systems themselves.

I gave examples of pulsating variables (Chi Cyg, RS Pup, RR Lyr, T Umi), an Algol type eclipsing binary (ASAS J035812+1629.7), the enigmatic luminous blue variable eta Car, and the recurrent nova RS Oph, showed videos linking light curves with stellar processes, inspected time series observations, created phase plots and carried out analyses such as period search and time-frequency analysis using VStar.

While not as polished and more ad hoc and exploratory than last year’s RS Oph recurrent nova eruption talk for ASSA, it was fun and seemed to be appreciated, despite less than best audio and video at times. It’s also not easy watching yourself give a talk. 🙂

A brief critique of the documentary 2040

February 20, 2022

The documentary 2040 (or visual diary as it has been referred to) does a good job of putting a positive outlook on the future by emphasising solutions, things that can be done to mitigate climate change, including but not limited to local solar electricity networks, kelp farms as a future protein source, and a move away from private car ownership toward more efficient transport systems.

I’m a father too, so I understand the film maker’s desire to put his young child (daughter in this case) at the centre of the story, imagining a better world for her early adult years and beyond.

2040 – official trailer

But, as uplifting and inspiring as 2040 is, it doesn’t go nearly far enough in my view.

What bothers me about the film is how anthropocentric it is. In what follows, I give examples of how its vision falls short. I may be accused by some of being overly critical of what is an otherwise heart-felt, genuine labour of love, but so be it.

There is a section in which a farmer is interviewed and there is talk of farming practices to improve the health of the soil, which is great. But the true costs of animal agriculture in terms of emissions (comparable to the whole transport sector) and animal welfare are not really addressed.

Near the end of the film, there is a self-congratulatory comment about how much less meat people will eat by 2040. We are already seeing a trend towards eating less meat and towards other protein alternatives.

Primary-school aged children were interviewed throughout. Their insights sometimes bordered on the profound and were often more wise than the adult utterances. The kid who talked about planting a seed and getting meat was on the money, if the rise of the lab grown meat industry is anything to go by, as was the girl who liked bacon but wasn’t sure she should eat it because of its source. These are the sorts of comments that get an uncomfortable “isn’t that cute” laugh from the audience, the members of whom may more-or-less dismiss the seriousness of the points being made.

There is a rushed and insipid comment by the film maker about the existence of some nice meat alternatives as supplements (not potential replacements), but no meaningful concession to the need for a totally plant based diet, just that we should be heading toward eating more plants: a no brainer since that’s what the latest Australian Dietary Guidelines have been telling us for almost a decade anyway!

At one point the future daughter asks her off-screen father “what were you thinking” regarding our generation’s shipping of fish long distance, as opposed to “what were you thinking” by engaging in the act of industrial scale fishing at all, with its attendant destruction of the ocean environment, species population decimation and untold suffering.

The film ends with a jubilant young generation having a party, but it’s a little too soon for much celebration it would seem to me, when there is no sign that any serious attempt to tackle speciesism (arguably, a barometer of our maturity as a species) has been made, and we are in 2040 likely still too narcissistic to think much beyond the end of our collective noses.

In short, 2040 is evolutionary, not revolutionary, and to be fair, that’s consistent with the film maker’s focus on what we can do in future derived from what approaches exist today.

But I think we should want to do even better than what is proposed by 2040, if we are not only going to mitigate the worst of effects of climate change for Australia and the world in general, but also to be able to look our future selves in the mirror and consider homo sapiens worthy of a place as anything like competent stewards of this planet.

Comet 2001/A1 Leonard

January 4, 2022
Dec 26, Canon 1100D, 100mm lens, piggybacked on Meade LX-90, ISO 200, f4, 90 secs

Comet Leonard has been putting on a show for us in the southern hemisphere since mid to late December 2021 and I’ve taken images with my modest equipment, a Canon 1100D with 100mm lens, and exposures of either a few seconds on a tripod or >= 30 second exposures with the camera piggybacked on my 20 year old (hard to believe) 8″ Schmidt-Cassegrain Meade LX-90.

These are all from my fairly light-polluted suburban home site, at least low in the western sky, so it’s a battle between gain (ISO), exposure time, f-stop.

Dec 25, Canon 1100D, 100mm lens, ISO 800, f2, 7 secs; a short satellite trail is evident at right

The following shows the comet’s movement with respect to reference stars over 6 days.

Comet’s path with respect to background stars (arrowed) from Dec 25 to Dec 30

I’ve been posting images to Facebook, Instagram, and Twitter mostly.

Michael Mattiazo’s Southern Comets page has some amazingly detailed images of the comet (look for Leonard in the left-hand side panel) taken with much better equipment and under darker skies.

Having just passed perihelion and with Luna encroaching on the night sky darkness, the days of good views of Comet Leonard are numbered. It’s been nice to have this over the holidays though.

I find that from time to time, I need events like this to reinvigorate my enthusiasm.

Bearing Witness

October 11, 2021

I wrote a post about Jehovah’s Witnesses in 2017, “Mr & Mrs JW: I have some questions…” If words are not enough to convince you of the problems with this organisation, you should watch the September 2021 Australian Broadcasting Corporation Four Corners episode: Bearing Witness.

source: ABC Four Corners

Waiting for U Sco: nearby gamma ray transient detected

September 29, 2021
The Fermi Gamma-ray Space Telescope (source: NASA)

Two days ago I wrote Waiting for U Sco. Today, here are a few excerpts from ATel #14941 (The Astronomer’s Telegram):

The Large Area Telescope (LAT), one of two instruments on the Fermi Gamma-ray Space Telescope, has detected a new transient gamma-ray source, Fermi J1623-1752.

A possible counterpart to the LAT transient is the recurrent nova U Scorpii with position offset by 0.18 deg from the LAT position, thus just outside the 95% confidence error circle, but within the 99% confidence error circle. U Sco has a known recurrence interval of 10.3 years (Schaefer 2010, ApJS, 187, 275) prior to its outburst in January 2010, thus a new outburst from U Sco could be anticipated. The last observation of U Sco in the AAVSO lightcurve database was on 2021 Sep 19.

Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. In consideration of the ongoing activity of this source, we encourage multi-wavelength observations, particularly optical follow-up of U Sco.

ATel #14941

I read about this in a post by Alexandre Amorim (Brazil) in the AAVSO novae forum. Robert Fidrich (Hungary) soon followed up with an iTelescope observation to say that there was no eruption visible.

Given that U Sco almost certainly had an outburst in its “seasonal gap” (unobservable due to position on the sky), probably in 2017, what this current gamma ray event means seems pretty uncertain.

I’ll continue imaging the U Sco region until it’s too low tonight (in between the clouds) and, consistent with my last post, whenever I can thereafter.