Messier 71

A Globular Cluster in Saggita

Sagitta is the third smallest of the eighty-eight constellations, with just eighty square degrees of sky – and M71 is its only notable deep sky object. While it is listed as one of the closest globular clusters which orbit the Milky Way at a mere 13,000 light years, it is not one of the brightest. It checks in at only magnitude +8 and appears relatively small.

It certainly is small and its apparent diameter of only 3.3 arc-minutes indicates a true diameter of only about 12 light years, very small for a globular cluster.

Image details:

Exposure: 30 minutes.
Field of view: 48 x 48 arcmin
Date: 2021-08-14.

Constellation of Sagitta
Image source: Wikimedia Commons

Astro-News

I thought I would mention some news from the guest speaker we had at MAS last Monday night, Dr Emil Lenc. He is a radio astronomer here in Sydney with the Australian National Science Agency (CSIRO), where he is a Senior Research Scientist. He has the skill and good fortune to be working on the spanking new ASKAP radio telescope 36 dish array located in Western Australia, as it transitions from the commissioning phase into full science operations.

ASKAP has the capacity to simultaneously cover large areas of the sky using wide field cameras in a wide field dish array.

Five (or more?) of the ASAP dishes. Image: ASKAP

After giving us an insiders perspective of the ASKAP Telescope operations, Emil recounted two exciting new classes of object which the ASKAP science team has recently discovered.

Did you read that correctly? Not two new ‘objects‘ discovered; but two new ‘classes of object‘ – and right now no-one knows what they are!

Odd Radio Circles

So far at least five ORCs have been discovered. These are huge circular objects, about 1 arc-minute in diameter and have been detected only in the radio spectrum. Some of them have galaxies located in the centre (so they may be quite remote) but a robust theory of how these mysterious new objects were formed has not yet been proposed.

Here is an article from a popular science website.

You can read a scientific paper about the ORC discovery here. or if you are really interested you can watch this YouTube video from the paper’s lead author, Prof. Ray Norris (WSU). (it’s a 41 minute video which I have set to begin at 2 minutes. Just watch to about 11 minutes).🙂

Intra-day variables

In another fantastic discovery for ASKAP, they conducted multiple ten-hour observations across a 30° field, searching for new radio variables on timescales of hours. They anticipated they might observe something new but didn’t really know what to expect. The speculation paid off. They found multiple rapid scintillators or intra-day variables (IDV).

Then they found more.

They discovered six unusual linear scintillating arrangements on the radio sky with angular widths ∼1 arcmin and length ∼2°. Two of them are extreme intra-hour variables with timescales as short as tens of minutes.

Again, there is no explanation** for the objects, other than that it appears that they are distant background radio signals caused to scintillate by an otherwise invisible foreground filament of gas or dust.

** No, it is not @#$%^&* aliens!

The science paper is here.

nova.astrometry.net

Thanks for reading 🙃

Cosmic Focus Observatory

34° S

Above us only sky….

Telescope:SkyWatcher Esprit 120 mm apochromatic 3-element refractor; 840 mm f/l @ f/7.
Optics:Field flattener; ZWO duo narrowband Ha + [OIII] filter.
Mount:SkyWatcher EQ6-R Pro mount.
Imaging camera:ZWO ASI 071 MC cooled.

Images © Roger Powell
I’m one of the founder members of Macarthur Astronomical Society and current webmaster.
🙃

29 Comments

  1. I have a short list of globular clusters to view when more clear nights come. Interesting finds you reported on. I’ll watch that video this morning. I enjoyed some good views of Saturn and Jupiter recently.

    Liked by 2 people

    1. I hope you get some more viewing opportunities before your summer ends.

      Are you affected by the fires at all? This winter has been unusually clear of smoke here in Sydney. We normally get a lot of particle haze from official hazard reduction burns in preparation for the fire season but so far nothing.

      The rest of that video, if you have the inclination to watch it, is a discussion on some of the surprising astronomical expertise of indigenous aAustralians before the British invasion. Eye opening.

      Like

      1. I was out last evening under ok skies. Some smoke haze limited what I could see. I had a list of globular clusters to try and got 4 of the 8. I couldn’t see any at 7th mag or higher.

        Liked by 1 person

        1. Smoke haze can be a killer for deep sky observing but it’s always better to keep trying. I’m glad you have accepted the challenge.

          Yes, I was pleasantly surprised about the latter part of the video. I have been bored by some of the talks we’ve had about aboriginal astronomy. I care nothing about their interpretations of the shapes of the constellations etc. (and ditto for Greek, Chinese or any of the other versions). I don’t care whether Orion is called a hunter or a hedgehog.

          However, my ears pricked up when I heard about the Aboriginals – the original occupants of this great country – using scientific methods, which I had never heard attributed to them before. It was an interesting surprise.

          Liked by 1 person

    1. Hi Mark, one of the targets I’ve set for myself is imaging fifty Messiers and fifty Caldwell objects. The big problem with that is the number of globs in both lists. It gets a bit monotonous…..

      Sorry to hear about all the smoke, those fires seem pretty bad.

      Like

  2. New stuff closer to home too, like a new carnivorous plant.

    … and. you know, it could be aliens … really BIG aliens. But then, it’s a big universe.

    Seriously, wouldn’t it be nice if these exciting bits of news could be enjoyed without the burden of messy world affairs intruding in the background?

    And, yes, I must admit I much prefer exploring interesting shapes in expansive galactic images and colorful nebulas to photos of open clusters.

    Liked by 1 person

    1. After following world news by day, getting out under the stars at night is the only thing that is keeping me sane and calm and it’s therapeutic to keep up with scientific news too.

      Australia did so well in eliminating the covid until June this year – but was not proactive enough in getting enough vaccines ordered. Now the unstoppable delta has begun ravaging us, particularly here in Sydney and not enough people have vaccinated yet.

      My Bride and I have already stayed home for eighteen months, neither wanting to catch it nor to participate in spreading it to others. That was our choice. Now, for the last eight weeks the entire population has had been in lock-down again too.

      We won’t win this war until everyone is vaccinated, so our fate lies in the hands of the vaccine hesitators and the anti-vaxxers….😣


      I try to vary my astro-targets, bearing in mind the limitations of my gear but the two types of objects that tantalise and mosly elude me are the smaller objects, such as galaxies and planetary nebulae.

      I am hoping to broaden my optical options soon.


      It’s never aliens. 😐

      Liked by 2 people

  3. Very interesting on the ORCs. One day, they won’t be “odd” but well-defined. Until then, as is partially alluded in the video, here is material for another sci-fi story on wormholes.

    Looking forward to hearing more about them, like how large they truly are and how far they really are. If they are in other galaxies then they must be at least a few billion years old. Could they be older? Remnants from the Universe’s creation? Or something far less grand? That will be the fun stuff to find out.

    Liked by 1 person

    1. That’s good feedback and I’m glad the new discoveries interested you. The first ORC discovery was 2019, so you can find more information about them by web search.

      There is much less info about the second new class of objects, IDVs, because the discoveries are even more recent.

      Wormholes are an interesting theoretical concept but as we have no evidence for them I personally don’t find them very exciting. My guess is they will remain in the realm of fiction.

      However, as you can see, these new telescopes are finding lots of new stuff and who knows what discoveries await us?

      Next up will be the James Webb Infra-red Telescope, due to launch in November. Now I do sense a feeling of excitement as that date gets closer!

      Liked by 1 person

        1. Your assumption is correct. I am not a movie fan and that includes science fiction. I just don’t watch it.

          If you were to ask me “why is that so?”, I would respond that, in my opinion, much of it is poor science and much of it is also poor fiction. However, I acknowledge that I am very much in a minority in this regard. 🙃

          I do admit that my much younger self did get some considerable pleasure from science fiction books.

          Liked by 1 person

          1. The suspension of belief (or the acceptance of belief) is a part of all fiction, not just Science Fiction.

            My favorite series (Firefly) got a fair amount of things right, and some major things wrong . . . but you wouldn’t have a story without taking some liberties.

            Police procedurals, mysteries, romance, you name it, if looked at with a critical eye, are all flawed, sometimes deeply so.

            Fantasy gets away from it (somewhat) by posturing a system that does not obey the laws of our world/universe, but there, too, you can find inconsistencies.

            Meaning, no matter the system, there has to be some governing and consistent way that it works, but that greatly limits what is the most important function of fiction; to stir the imagination. So, sometimes realism is sacrifice to the altar of entertainment.

            But, even then, one doesn’t know the long-term effects of stirring the imagination.

            There are many examples of science fiction spurring the development of a real-world counterpart (even if not exactly the same) while adhering to our physics laws. Same for social movements and personal development.

            One final observation … well, two.

            1) Much of my objection to fiction is only in the areas with which I have some familiarity. If I’m not familiar with something, it’s much easier to “accept” particulars of a movie or book without having them grate on me. Even so, if the story and characters are engaging, I’m willing to overlook almost anything, whether I know it to be crap or not.

            2) I think education being what it is, I worry about some of the liberties that books and movies take in the telling of the story (and not just as it relates to science). That’s because when someone doesn’t have the underlying understanding of the world around them, they can be made to believe anything. I could point to the Bible, but Romance stories, for instance, paint a very distorted view of relationships, and that probably does a lot more harm than someone believing we can go faster than the speed of light. . . but still not as harmful as the Koran or the Torah or the Bible or (insert favorite sacred book here).

            Liked by 2 people

            1. No influence at all. My interest in astronomy has its roots in my primary school years and pre-dates any of the science fiction which I began reading in my late teens.

              I’ve generally drawn a distinction between fiction in books as opposed to tv/movies. With books, your mind is encouraged to imagine strange realities, to paint your own picture. On a tv screen I always thought the attempts to portray the unusual story line were a let down. I suppose an example of this is that apart from daleks, “aliens” always look like costumed humans.

              You mentioned sacred books. Don’t get me started but….well that is a second example. Read the book and many might believe the wizardry as non-fictional reality but you only have to watch a biblical movie to come to the harsh reality that the bible is pure science fiction!

              I do read some fiction from time to time – but there always needs to be a close resemblance to reality, else my eyes start rolling.

              Like

          2. Nothing to apologize for or explain – certainly an understandable perspective.

            I think there is a great play and reverberation between real science fiction and real science. A great example of this is when Stephen Hawking had a cameo on an episode of Star Trek: The Next Generation, he visited the engine room set, looked at the warp core engine, and said, “I’m working on that.”

            I also think what can be a turn off is that “sci-fi” pretends to be real science fiction all too often, and too often both are intermingled. Speaking still of Star Trek, the latter shows were very guilty of this. When it becomes about space marines fighting alien bugs, it’s no longer engaging from a science perspective, just pulp entertainment.

            Liked by 1 person

            1. I respect that but I think science fiction manipulates people’s opinions about reality. Generalising, the fantasy that they like becomes confused with the actual truth which they don’t care to understand. Sometimes I might be guilty of that myself.

              An example is when I mention that I have scepticism about the very common conception that the galaxy is teeming with advanced civilisations. The derisive responses I get seem to have been moulded by the events portrayed in Star Wars, Star Trek and Doctor Who. The only honest truth is that despite our searches, we haven’t discovered any evidence yet..

              If I try explaining to someone how bogglingly distant the nearest stars are and how long it would take to even get to the closest star, I get regaled with various proposed methods of unproven high speed propulsion that we will soon develop; or teleporting; or cryogenic travel; or other stuff they’ve watched in science fiction movies. In fiction, it’s easy to travel at warp speed and beam me down. They’ve seen it so it will happen. I remain sceptical about inter-stellar travel.

              But each to there own….

              🙃

              Liked by 1 person

              1. I completely agree with your first paragraph, how fiction manipulates, and dare I say, alters, opinions and perception of reality. Frankly, I’ve felt this can be applied to the past year and a half as, I believe, most people’s understanding of microbiology comes from the TV show The Walking Dead and other zombie horror derivatives. I have thought about developing this notion into a full blog post, but I hesitate to tackle the pandemic directly.

                I do feel fiction and real science can work off of each other, as I alluded before. I get this perception, I think, from my father. He was a big Star Trek fan yet also was chemist, mathematician, and computer scientist. In hindsight I clearly see a balance, because my enjoyments of the Star Treks, Star Wars, and Doctor Whos were tempered by my curiosity sparked by Carl Sagan’s Cosmos, The Mechanical Universe, and Jack Horkheimer’s stargazer shorts, among others. And neither of us ever had a desire to dress up as a Klingon. 🙂

                I’ve had my own experiences trying to explain cosmic distances and such. I like to say, though I’m not sure how many get this, that you need to think of Star Wars’s galaxy far, far away as if it were drawn like a Tolkien map of Middle Earth. Planets are akin to towns and villages, solar systems like bigger regions such as The Shire and Mordor. Everything really is that close to each other in fiction space to the point that it better labeled space fantasy instead of science fiction.

                Like

                1. The words “science fiction” never sat well with me. I think you are right that “space fantasy” is a much more genuine description.

                  You mention Carl Sagan’s Cosmos. This was THE best tv series “that is, or ever was or ever will be”.

                  🙃

                  Liked by 1 person

                    1. I don’t know what Firefly is 🤣 but I do know Vangelis and I would vehemently contend that the “Theme from “Cosmos” and “Alpha” are far better. 🦉

                      Like

                    2. I think if I was voting for the best tv series of all time I would put Cosmos first, followed by “Time Team” and “The Meteorite Men”. For a bit of fun and variety I would include the “Muppett Show” because it was very cleverly put together.

                      Like

                    3. Sorry, I misspoke and meant “Heaven and Hell” (not Fire and Hell – I was remembering the album cover as I wrote) which is the theme from Cosmos.

                      And yes, I like Alpha as well.

                      . . . still, as far as series go, Firefly better than Cosmos. Meaning, I’ve rewatched Firefly uncounted times . . . Cosmos? Once, and I didn’t get through it the second time.

                      Like

                    4. Not heard of Time Team and the Meteorite Men was good for a few episodes before losing me.

                      The Muppet Show was OK, mostly because of the old farts on the balcony.

                      Like

                    1. Everything Sagan said was true. I recall him saying in Cosmos: <“If you want to know more about the greenhouse effect, have a look at Venus” (or words to that effect).

                      Liked by 1 person

  4. Beautiful! And that’s fascinating about the ORCs.

    I honestly feel like “aliens” is too simple an answer to jump to for the majority of unexplained astronomical phenomena. The universe is so full of wonders and expected possibilities. It doesn’t need an ET behind things to be amazing.

    Liked by 1 person

  5. An asteroid originating from elsewhere in the galaxy shot through the Solar System in 2017 at very high speed. Many, including one astronomer immediately started yelling “aliens!”.

    The problem is that people so often jump to the preconceived conclusion that it is aliens, without ever considering all the other options.

    Like

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