Sign in

Bruce Macintosh

@bmacastro.bsky.social
1.8K followers 558 following 555 posts

Astronomer working on imaging extrasolar planets, instrumentation, and science policy. Spare time: hiking with a golden retriever, and not playing enough boardgames. Director, University of California Observatories, but opinions are my own. He/him

PostsRepliesMedia
Bruce Macintosh @bmacastro.bsky.social · 1h
Talisman! Talisman! Talisman!
010
Bruce Macintosh @bmacastro.bsky.social · 1h
Yes! There's all sorts of interesting earlier phases before I got involved, like the experiments at LLNL when they sent a 1 kW laser for their first experiments. Supposedly you could see the beam from Oakland.
000
Bruce Macintosh @bmacastro.bsky.social · 3h
One last thing: my absolute favorite figure from the paper isn't the "hey, we made a star look small" picture, but this: a temporal power spectrum of the wavefront error with and without AO, laser and natural. If you know what those words mean we can be friends.
Graphs showing the power spectrum of the wavefront; y axis (log scale) is how much wavefront error there is, x axis (log scale from 0.01 to 100 Hz) is how fast the turbulence is moving. Upper panel compares the uncorrected atmosphere with correction on a bright natural guide star, lower panel compares uncorrected atmosphere with correction from a laser guide star, which did about as well.
040
Bruce Macintosh @bmacastro.bsky.social · 02/10/2026
In the
100
Bruce Macintosh @bmacastro.bsky.social · 02/10/2026
The paper from that night is here. Lots of nights working at Lick, looking for airplanes and mountain lions, but it all paid off. www.science.org/doi/10.1126/... - -
science.org
Image Improvement from a Sodium-Layer Laser Guide Star Adaptive Optics System
A sodium-layer laser guide star beacon with high-order adaptive optics at Lick Observatory (Mount Hamilton, California) produced a factor of 2.4 intensity increase and a factor of 2 decrease in full w...
150
Bruce Macintosh @bmacastro.bsky.social · 02/10/2026
Making it all work at Lick Observatory taught us a huge amount about how to do science with laser guide star AO. That paid off immensely when Keck got their LGS; from almost day 1 it did science, and (as we all know) made amazing discoveries.
110
Bruce Macintosh @bmacastro.bsky.social · 02/10/2026
It turns out there's a lot of subtle differences between laser guide star light and starlight. But on September 30 / October 1 1996 we made it all work and made images and history.
220
Bruce Macintosh @bmacastro.bsky.social · 02/10/2026
It turned out the laser was tuned to an argon line (long story) at 588 nm; so we retuned and then saw light the next night, which was amazing. One other problem: after that, it took about a year to reach the point where turning AO system on didn't actively make images worse.
140
Bruce Macintosh @bmacastro.bsky.social · 02/10/2026
Problem: no-one had brought a good enough spectrograph. My second contribution was pointing out that we were literally on top of a room-sized ultra-high-res spectrograph that was part of the telescope and if we wanted to see the laser spectrum maybe we could use that.
110
Bruce Macintosh @bmacastro.bsky.social · 02/10/2026
The first time we fired the laser, the beam went up...but no fluorescence and no guide star light back down. After a night of head scratching, people wanted to check the laser spectrum.
110
Bruce Macintosh @bmacastro.bsky.social · 02/10/2026
I got to work on this as a postdoc fresh out of grad school - helping people like Claire Max and Scot Olivier prove a technology that has since transformed astronomy. My main contributions were (1) saying "hey, let's not try this in January, because it's going to rain and the seeing is terrible"
130
Bruce Macintosh @bmacastro.bsky.social · 02/10/2026
The laser is tuned to the 589 nm sodium transition. It turns out there's a layer of sodium atoms 90-100 km above the earth; these fluoresce, making an artificial guide star wherever you want it. That serves as a reference to measure atmospheric turbulence and let you sharpen images to space-quality
120
Bruce Macintosh @bmacastro.bsky.social · 02/10/2026
Nice historical note: this is the 30th anniversary of the first time astronomers reached the diffraction limit with a sodium laser guide star. www.ucobservatories.org/pioneering-t...
ucobservatories.org
Pioneering the Stars: Celebrating 30 Years of Sodium Laser Guide Star Adaptive Optics at Lick Observatory
Thirty years ago, in September and October 1996, an extraordinary breakthrough took place atop Mount Hamilton that forever changed ground-based astronomy. On the 3-meter Shane Telescope at Lick Observ...
1314
Bruce Macintosh @bmacastro.bsky.social · 02/10/2026
This is one of my thoughts. More large systematic programs, with public data, and (important!) funding both for program planning and for data analysis that is awarded by an independent process. Are we really better off with six groups taking exoplanet spectra in slightly different ways?
100
Bruce Macintosh @bmacastro.bsky.social · 02/10/2026
It actually feels like the sort of problem we shouldn't try to solve alone - economists and sociologists of science and game-theory specialists and other fields might help a lot.
010
Bruce Macintosh @bmacastro.bsky.social · 02/10/2026
I have a short list of suspects, but am genuinely curious; feel free to message me...
120
Bruce Macintosh @bmacastro.bsky.social · 02/10/2026
I really want to meet the 15-proposal-person though!
330
Bruce Macintosh @bmacastro.bsky.social · 01/10/2026
Absolutely agree! To be clear it's a part of the whole state-of-the-field issue.
160
Bruce Macintosh @bmacastro.bsky.social · 01/10/2026
The 1970s model of peer-reviewed-GO-proposals for ground based telescopes doesn't scale here. I'm not sure what to replace it with, but we should be having the conversation.
3240
Bruce Macintosh @bmacastro.bsky.social · 01/10/2026
So much work making proposals. So much work reviewing proposals as if we could meaningfully distinguish between the 9th and 11th percentile. And then next year so many brilliant people who are going to be disappointed.
1293
Bruce Macintosh @bmacastro.bsky.social · 01/10/2026
This graph represents probably more than a hundred thousand hours of work by our community. Every year when I look at it I think our current proposal model is broken.
610723
Bruce Macintosh @bmacastro.bsky.social · 24/09/2026
Yay PRIMA! Brilliant mission concept.
040
Bruce Macintosh @bmacastro.bsky.social · 23/09/2026
It looks like a lovely place, but an extensive outdoor collaboration area is certainly an interesting lifestyle choice in Canada. I’m picturing you all determinedly huddled around the chalkboard in January as the blizzard sweeps through.
111
Bruce Macintosh @bmacastro.bsky.social · 22/09/2026
Beta pic b is really young, if that matters, and probably somewhat degenrate in its core.
201
Bruce Macintosh @bmacastro.bsky.social · 18/09/2026
Both the GPI2 and Roman collaborations are absolutely great, full of brilliant people who are also reasonable human beings to work with and learn from and teach things to. Also I'm nice too! So come work with us! aas.org/jobregister/...
aas.org
Postdoctoral Scholar in Adaptive Optics & Coronagraphy | American Astronomical Society
The Department of Astronomy and Astrophysics at the University of California, Santa Cruz, and University of California Observatories has an opportunity for a postdoctoral researcher working on analyzi...
010
Bruce Macintosh @bmacastro.bsky.social · 18/09/2026
The other project I work on is the Gemini Planet Imager, aka GPI; now being upgraded to GPI2. That's a coronagraph (plus other stuff) that works on the big ground-based Gemini telescopes in Chile and/or Hawaii. A hypothetical postdoc could also work on GPI2.
100
Bruce Macintosh @bmacastro.bsky.social · 18/09/2026
At least according to models, it could see Earths. So it'd be a good idea to test those models with the telescope we have now!
100
Bruce Macintosh @bmacastro.bsky.social · 18/09/2026
The "even better coronagraph" will go on NASA's next flagship mission, the Habitable Worlds Observatory. (HWO is allowed an official NASA acronym.) It would be about ten to a hundred times more sensitive than Roman, which would allow it not just to see Jupiters orbiting other stars, but Earths.
100
Bruce Macintosh @bmacastro.bsky.social · 18/09/2026
Since I've already seen a lot of extrasolar planets (ten depending on how you count), my main goal is (a) seeing who was right in various arguments/discussions about performance, because I'm petty, and (b) in using Roman to figure out how to build an even better coronagraph
100
Bruce Macintosh @bmacastro.bsky.social · 18/09/2026
Now that it's up there, a big team of which I am a small part will start making it work, test it out, measure how well it's operating, and (fingers crossed) see some giant Jupiter-like planets orbiting some nearby stars.
100
Bruce Macintosh @bmacastro.bsky.social · 18/09/2026
I worked on the Roman coronagraph (you're allowed to just say "Roman") for a decade and got to see it launch last month, which was amazing. www.linkedin.com/feed/update/...
linkedin.com
16 years ago the Astro2010 commitee glued five different mission concepts together to make a combined dark energy / microlensing / IR survey 1.3m telescope called WFIRST. It was supposed to be fast… |...
16 years ago the Astro2010 commitee glued five different mission concepts together to make a combined dark energy / microlensing / IR survey 1.3m telescope called WFIRST. It was supposed to be fast an...
100
Bruce Macintosh @bmacastro.bsky.social · 18/09/2026
The Nancy Grace Roman Space Telescope (officially it does not have an acronym) is carrying the most advanced planet-coronagraph ever flown in space, about a hundred times better than predecessors.
100
Bruce Macintosh @bmacastro.bsky.social · 18/09/2026
The main new coronagraph is on the Roman telescope. No actual people in togas are involved; that's short for the Nancy Grace Roman Space Telescope, named after the woman who made the Hubble Space Telescope happen.
100
Bruce Macintosh @bmacastro.bsky.social · 18/09/2026
I'm looking for someone to work with me on seeing how well some new coronagraphs work, comparing that to computer models, and figuring out what science we can do with them.
100
Bruce Macintosh @bmacastro.bsky.social · 18/09/2026
Another case of seeing something faint next to something bright is looking for a planet orbiting a nearby star. We use similar masks, and still call them coronagraphs, because attempts to make "planetograph" catch on were unsuccessful.
110
Bruce Macintosh @bmacastro.bsky.social · 18/09/2026
(Also, nose grease was involved, but that's another story.)
100
Bruce Macintosh @bmacastro.bsky.social · 18/09/2026
"Coronagraphs" were originally special telescopes designed to look at the sun. Generally, looking at the sun with a telescope is an extremely bad idea, but these included masks to block the sun and let astronomers see the very faint corona around it. ui.adsabs.harvard.edu/scan/manifes...
ui.adsabs.harvard.edu
100
Bruce Macintosh @bmacastro.bsky.social · 18/09/2026
In 300 characters (including the preview) one has to be cryptic and rely on acronyms. But I can translate! It's hard to see something faint next to something bright.
100
Reposted by Bruce Macintosh
Michael Busch @michael-w-busch.bsky.social · 18/09/2026
Today on the #arXiv : Miles et al. 2026 describe the weather on the brown dwarf WISE 0855: arxiv.org/abs/2609.20664 . Patchy water clouds along with carbon monoxide, methane, ammonia, and phosphine. When a star is as cold as ice...
arxiv.org
Water Cloud and Chemical Modulations in the Coldest Brown Dwarf
We present high signal-to-noise, medium resolution (R ~ 1000), time-series JWST/NIRSpec spectra of WISE 0855 (265K), the coldest known brown dwarf. Medium resolution, time-series spectroscopy gives us...
1163
Bruce Macintosh @bmacastro.bsky.social · 18/09/2026
Postdoc opportunity! I'm looking for a postdoc to work with me on coronagraph performance and modeling and science. The primary project is understanding Roman with an eye to HWO; secondary project could be a side order of GPI2. aas.org/jobregister/...
aas.org
Postdoctoral Scholar in Adaptive Optics & Coronagraphy | American Astronomical Society
The Department of Astronomy and Astrophysics at the University of California, Santa Cruz, and University of California Observatories has an opportunity for a postdoctoral researcher working on analyzi...
093
Bruce Macintosh @bmacastro.bsky.social · 17/09/2026
...am I have to going to do my Kepler-22b rant again?
010
Bruce Macintosh @bmacastro.bsky.social · 16/09/2026
On a good day I can understand interferometery for a pair of telescopes because it's basically the two-slit experiment, and once I understand something for N=2 I can leave it to other people to generalize.
260
Bruce Macintosh @bmacastro.bsky.social · 15/09/2026
Science! Very cool. I’m realizing at my new job I have t really been paying attention to dark stuff like this and hadn’t heard of DE neutron stars. Interesting! Can I ask naive questions? Is the idea that they’d form from massive star core collapse and catch some DE in the process?
110
Bruce Macintosh @bmacastro.bsky.social · 09/09/2026
Does the proposal actually include funding to get the PI (you) a sword? Because it pretty much has to.
110
Bruce Macintosh @bmacastro.bsky.social · 09/09/2026
Mark and I are pretty friendly about this and I think basically agree. Definitely a looking-at-the-elephant situation.
110
Bruce Macintosh @bmacastro.bsky.social · 09/09/2026
And my favorite series spot was DS9 for a very long time, but it might just barely have been pipped out.
static.klipy.com
Star Trek Lower Decks: Come On Guys!
ALT: Star Trek Lower Decks: Come On Guys!
140
Bruce Macintosh @bmacastro.bsky.social · 09/09/2026
Of all the big franchises, Star Trek remains by far my favorite - formative exposure as a 6-year-old to just having watched TWOK on the big screen with my kid. Optimistic, with a belief that the future really can be better, and that good people can solve problems with science and diplomacy.
191
Bruce Macintosh @bmacastro.bsky.social · 08/09/2026
Whereas the original sin of planetary science is thinking that the handful of things we happen to see in our back yard must be the most important and fundamental exemplars of the entire universe.
130
Bruce Macintosh @bmacastro.bsky.social · 08/09/2026
All astrophysics is exoplanets if you‘re creative enough.
1100
Bruce Macintosh @bmacastro.bsky.social · 04/09/2026
Very nice!
110