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Vera C. Rubin Observatory first images

rubinobservatory.org

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Re: Vera C. Rubin Observatory first images

#101

Post by SiempreViernes »

o11c wrote: post #83
jcims wrote: post #42

Earlier quoted context omitted.

What's going on directly above with what looks to be 3-4 galaxies interacting?

It says that NGC 4410 is (gravitationally) interacting galaxies. After clicking through the link, it calls it RSCG 55 instead and explains more. I don't understand the naming scheme.

The naming scheme is based on the principle "tens of thousand of people have done this over thousands of years, and they all named things themselves". Its not uncommon for objects to have ~20 separate names[1], with some having over a hundred [2].

In this particular case, RSCG 55 means a group of galaxies[3], of which NGC 4410 is one member. Apparently RSCG is the "Redshift Survey Compact Groups" (https://cds.unistra.fr/cgi-bin/Dic-Simbad?RSCG) so 55 is just an index number.

That's also the case for the 4410 after NGC; in that case stands for "New General Catalog". In contrast the Sloan Digital Sky Survey gave NGC 4410 the name SDSS J122628.29+090111.4 where the numbers indicates its position in the sky.

The "index number" and the "position of the sky" are the two most popular naming strategies.

[1] NGC 4410 has 37, but the NGC objects are among the more popular https://simbad.u-strasbg.fr/simbad/sim-id?Ident=+NGC+4410&Nb... [2] https://simbad.u-strasbg.fr/simbad/sim-id?Ident=M87&submit=s... [3] https://simbad.u-strasbg.fr/simbad/sim-id?Ident=RSCG+55&NbId...

Re: Vera C. Rubin Observatory first images

#102

Post by andruby »

myrmidon wrote: post #98
bjt wrote: post #43

Earlier quoted context omitted.

If it has the potential to wipe out our entire species, but there's something we could do to prevent it (which I'm not sure about w/r/to asteroids), then it's worth looking out for the black swan event. Doing some extremely rough math along these lines to double check myself: * Gemini says that a dinosaur-extincting asteroid hits Earth about once every 100 million years. So in any given year that's 0.000001%. * Econo…

These numbers are not what I expected at all. So you could actually make an argument that to a country like the US, full 100% reliable asteroid protection is only worth like $50M/year (even if an impact means full extinction)? So if upkeep for a detection/deflection system costs more than that we'd be "better off" just risking it?! Thats insane. I would have expected this number to be much higher than $50M/year.

The economists calculated the value of 1 life. The calculation might be different if it extinguishes the whole of humanity (and thousands of other species). In a way, it also presents all future human lives. Should we include those?

Re: Vera C. Rubin Observatory first images

#103

Post by spacecadet »

Tepix wrote: post #95
dekhn wrote: post #68

Earlier quoted context omitted.

I've worked on quite a few large-scale scientific collaborations like this (and also worked on/talked to the lead scientists of LSST) and typically, the end groups that do science aren't the ones handling the massive infrastructure. That typically goes to well-funded sites with great infrastructure who then provide straightforward ways for the smaller science groups to operate on the bits of data they care about. Her…

If you’re dealing with a fairly constant amount of data every day for years, using the cloud will be way more expensive than necessary.

The whole thread comes off as an AWS sales pitch...

Re: Vera C. Rubin Observatory first images

#106

Post by 0x0203 »

Why do the brighter objects have the four way cross artifact? My (apparently incorrect) understanding was that those types of artifacts were a result of support structures holding reflecting mirrors on a telescope. But this camera just has a "standard" glass lense with nothing obstructing the light path to the sensor.

Re: Vera C. Rubin Observatory first images

#107

Post by aragilar »

spacecadet wrote: post #105
phsilva wrote: post #2

https://skyviewer.app/

We got DOGE instead of using $100k of tax dollars making this into a super nice public mobile app...

While it would be cool to make a mobile app for this, having used both the tech stack behind this site (it's open source, and really great), and written a mobile app with a similar tech stack, $100k will get you one, but it's going to be a pain to debug all the various niggles around various devices, so you'll need at least double that to make a robust one (and then the question is, do you just go native and reimplement that tech stack).

Re: Vera C. Rubin Observatory first images

#108

Post by aragilar »

IAmBroom wrote: post #14
NitpickLawyer wrote: post #5

Earlier quoted context omitted.

Those are diffraction spikes, caused by how the light interacts with the support structure holding the secondary mirror. Each telescope has different patterns, hubble, jwst, etc. I think they only happen for stars, and not for galaxies (an easy way to know which is which), but I might be wrong on that (there's a possibility for faint stars not to have them IIRC).

No, they happen for absolutely every externally-generated pixel of light (that is, not for shot noise, or firelflies that happen to fly between the mirrors). Where objects subtend more than one pixel, each pixel will generate it's own diffraction patterns, and the superposition of all are present in the final image. Of course, each diffraction pattern is offset from the next, so they mostly just broaden (smear out),…

It depends on the science you're doing as even these small effects add up, there's a project within the LSST science team (which a college is working on) to reduce this scattered light (search for "low surface brightness"), where there's a whole lot of work around modelling and understanding what effect the telescope system on the idealised single point that is a star.

There are projects (dragonfly and huntsman are the ones I know of) which avoid using mirrors and instead use lenses (which have their own issues) to reduce this scattered light.

Re: Vera C. Rubin Observatory first images

#109

Post by frontfor »

0x0203 wrote: post #106

Why do the brighter objects have the four way cross artifact? My (apparently incorrect) understanding was that those types of artifacts were a result of support structures holding reflecting mirrors on a telescope. But this camera just has a "standard" glass lense with nothing obstructing the light path to the sensor.

It’s a reflecting telescope, not a camera with a glass lens.

Re: Vera C. Rubin Observatory first images

#110

Post by aragilar »

dekhn wrote: post #8

I really like the Rubin because I think a lot of people focus too much on "deep" seeing (IE, looking at individual or several objects with very high magnification only once). The Rubin does much more "wide" seeing and this actually produces a ton of useful data- basically, enough data to collect reliable statistics about things. This helps refine cosmological models in ways that smaller individual observations cannot…

My feeling is the "deep" vs "wide" thing is a circumstance of which groups you interact with (and also which facilities you have access to, and even to some extent the culture of your science community). Rubin is an example of what you can do when you build something massive specifically for a single purpose, and as more of these kind of facilities come online (SDSS and Gaia have been around for a while, but DESI, 4MOST and other similar facilities are coming, and let's not forget radio), it's what we get out of the whole suite supporting each other that gets the best science.
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