If you're following me you've seen pictures of amazing nebulas and galaxies from space.
How can I take this dark portion of the sky and get a nebula out of it? From the ground? From light-polluted Vancouver?!
Physics to the rescue! /1
In #Astrophotography, cameras & randomness of light sources in space filtering through the atmosphere produce noise.
But! The photons of space are there! So we do something called "Stacking".
Here is one 90-second exposure of the Iris Nebula. EW! barely looks like anything. /2
However, here is 5 x 90s images stacked together. as the noise is random, and the signal coming from space is constant, as we add more images, we start being able to separate the signal from the noise.
See how there is more nebula visible now? /3
We're at 10 x 90s images.
The random noise keeps averaging out on top of itself (decreasing the noise), whereas the signal is constant!
Noise down, signal same = increasing the signal-to-noise ratio!
Now we start seeing details within and outside the nebula. /4
13 x 90s images.
When we started, the noise was much higher, but with each 90 second image added, the noise decreases. At this point, it's precisely half what it was before.
You'll note the light parts are getting *very smooth*. The noise is weak compared to strong signal. /5
20 x 90s images (30 minutes)
The gains start becoming smaller, so the time invested needs to increase. Our signal to noise ratio inches higher and higher. (2.5x better now!)
Despite the minor minimal gains, we are starting to see more "space dust" outside the nebula! /6
40 x 90s images (60 minutes)
We've gone from 2.5x better to 3.3x better, and we're getting even more detail of the dust clouds surrounding the Iris Nebula. /7
And here we are at 240 images!
Of course it is not processed yet so it still looks noisy, but now we have tons of definition within the nebula, as well as more than a few surrounding dust clouds. /8
Side by side, you can see what a difference stacking makes. By the time I'm at 6 hours, woah! huge difference. /9
So future/present astrophotographers! check out some videos/tutorials on stacking! It's a great way to get that exposure time up while keeping thermal noise low (for uncooled cameras), and it is essential for deep space photography. /10
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Talking to kids when they're struggling🧵
For parents (or anyone who cares for kids!)
It can be really scary to notice something in your kid & be worried suicidality/self-harm.
How do you approach kids?
I've had this conversation >10000 times so I have some tips!
Be CALM
/1
CALM is a memory-trick to remember the key concepts of communicating to a struggling kid but also to remind you to be in control of your own emotions. If you are prepared, you will defeat your initial instinct, which will be to FREAK THE BLEEP OUT!
/2
First, COOPERATE!
You & your kid are a team, and you have a common goal: their present & future wellbeing. Don't set yourself up as the security guard, jailor, punisher, or antagonist. Don't push. Don't pull. Be alongside them, tell them you're willing to walk with them.
A recent study looking at >2M Americans presenting to ERs with MH concern shows the difficulty of "predicting suicide" - we can't predict suicide to help guide important clinical decisions.
The problem: Sensitivity vs PPV
/1
They used machine learning EMR-coded variables (outpatient visits, medications, previous appointments, age, etc etc) - you can see the entire dictionary used to "predict" here (word doc):
They had 2,069,170 ER visits and 899 suicides within 90 days.
After running the model and letting machine learning do its thing, the best fit had the following predictive properties at the 95% percentile cutoff of risk:
Debunking Antivaxxer Tropes:
"Antivaxxer is a slur" 🧵
Many many many accuse me of using a "slur" when I say "antivaxxer". It is a twitter shorthand for sure, but it is not a "slur", and I use it without regret or remorse.
/1
I certainly believe that if one is an "anti-vaxxer", they are not using science, reason, or reality to understand vaccines.
& I note a distrubing trend in antivax and some concerning other beliefs.
That being said, when I say antivax, I only mean "antivaccine belief holder"
/2
Check out my "antivax misinfo" threads. Someday take a look at the "hidden replies" & note that the antivax profiles are quite.. well.. recognizable.
Note: Do not assume every "Antivaxxer" is, I just notice the trend. As do many of my colleagues here space fighting misinfo.
Debunking Antivaxxer Myths
"🇪🇺 Vaxxed Countries have higher mortality"
No, they don't.
This is COMPLEX:
a) countries had different PRE-VACCINE infection (offers more dangerous protection than vax but indeed protection). Obv, vaccination NOT correlated with pre-vax death.
/1
b) The FIRST VACCINATION SERIES against OG COVID was phenomenally effective at preventing infection, transmission, illness, hospitalization, and death (VE >80-90% in all).
This is clearly evident by one of the most striking correlations you'll see!
COVID deaths vs Vax:
/2
And because COVID was the primary driver of excess mortality in 2021, excess ALL CAUSE mortality was almost identical to COVID MORTALITY.
He presents data to scare people into believing that vaccines have caused harm, & he continuously is on the bandwagon that C19 vaccines cause cancer. This is contrary to the damage.
Here, he's using a report using 1998-2019 data.
/1
In fact, there was such a DROP in incidence (assumed to be due to lack of access to health care) in 2020, that they had to amputate the model at 1998-2019 so that it wouldn't project a decrease! (a reasonable thing to do!)
/2
In their report, they clearly show that their trending is based off of models that ONLY end at 2019. ZERO PERCENT of this report is suggesting, implying, or reporting that vaccines have led to an increase in cancers.
He will have a huge platform & can say what ever he wants as long as there is right wing grift.
He is a licensed professional being held standard.
/1
It is against his license to publicly suggest to die by suicide.
It is against his license to publicly & intentionally call physicians 'criminals,' people "not beautiful" or "appalling self-righteous moralizing things."
His license prohibits misgender people intentionally.
/2
The standards of his college are publicly available; including social media. By being licensed, he represents his college and the profession, and that college/profession gets to have a say in how they are represented.