How to Discover a Galaxy with a Telephoto Lens | Hacker News Reader

How to Discover a Galaxy with a Telephoto Lens

nautil.us

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Ultimately the reason these small telescopes are so useful for finding these faint, diffuse galaxies is because the surface brightness of an object is independent of the collecting area. Larger optical telescopes have much better resolution, so the amount of light detected from a diffuse galaxy is fairly similar per pixel to a little telescope like Dragonfly. But a little telescope costs probably about three orders of magnitude less than a big telescope and you can afford to hammer a particular target night after night, whereas you'd be lucky to have an hour of time on a large telescope.

There are a number of other great small-telescope projects in different areas of astronomy. The one closest to my heart is ASAS-SN (pronounced "Assassin") since it was the idea of the professor across the hall from me when I was at Ohio State and an officemate of mine was the one who spent much of his graduate career building it. The idea was to get a little telescope (like Dragonfly it's pretty much just a telephoto lens with a detector attached) and then have it look at ~1/3 of the sky every night. That way if a supernova goes off in a nearby galaxy (or there is some other transient) it's discovered within a few days. Just this month they published a paper on the discovery of the brightest supernova ever observed [1]. They currently discover more supernovae than all other groups combined (including amateur astronomers, who are a formidable force!).

There's another small-telescope project built to search for exoplanets called KELT (the Kilodegree Extremely Little Telescope). Since transiting planets are generally detected around bright stars (at least in apparent magnitude), telescope size is not so important for their discovery. In fact, having too big a telescope can be an issue because the host star is so bright that it saturates the detector. So far they've discovered (I think) somewhere around a dozen planets, though my favorite is Kelt-4Ab because it's in a triple star system (and also because I'm on the paper) [2].

[1]: https://en.wikipedia.org/wiki/ASASSN-15lh

[2]: http://arxiv.org/abs/1510.00015

But a little telescope costs probably about three orders of magnitude less than a big telescope and you can afford to hammer a particular target night after night, whereas you'd be lucky to have an hour of time on a large telescope.

Precisely why PCs/workstations revolutionized research/individual analyst computing.

Make no mistake, in prime focus photography the brightness of extended objects does not depend on the size of the scope, but the size of the generated image is still proportional to the size of the instrument.

Has anybody put together a project to build a "distributed observatory" to coordinate the efforts of a great number of amateur astronomers, each with a small telescope?

> Has anybody put together a project to build a "distributed observatory" to coordinate the efforts of a great number of amateur astronomers, each with a small telescope?

For the purposes of looking for faint objects, not that I'm aware of. But there is an effort called the "Center for Backyard Astrophysics"[0] that is a loose network of (mostly amateur) observatories to do long time series brightness measurements of variable stars. I was involved in taking some data with/for them ~10 years ago while an undergrad[e.g., 1] and it was a fun experience.

[0] http://cbastro.org/

[1] http://spiff.rit.edu/richmond/ritobs/sep18_2005/sep18_2005.h...

Yes, for example: Project PANOPTES[0] which aims to use many citizen scientists' participation to discover transiting planets. Check it out!

[0] http://panoptes.github.io/

>The idea was to get a little telescope (like Dragonfly it's pretty much just a telephoto lens with a detector attached) and then have it look at ~1/3 of the sky every night.<

That part--"every night"--is so important to the science (and art) of astronomy...dogged determination (read as regular viewing) has led to countless insights and discoveries...

One of my goals is to incorporate an R-Pi 2 (minimum) into my viewing...program it to look for changes when I can't spend time at the telescope on the deck outside my house...

I'm strictly an amateur at astronomy, but my interest was piqued, in 1994 when I spent a summer volunteering at a youth camp which included, as evening programming, a once-a-week visit by an astronomy club from a semi-major metropolitan area...

That year, as most amateur astronomers will likely remember, the year the comet Levy-Shoemaker broke apart and impacted Jupiter...we were able to watch this maginificent event as it unfolded ...it was something to see...

Images here: http://www2.jpl.nasa.gov/sl9/top20.html

The kids at camp were more interested in looking at the moon for a while then heading off to the Tradin' Post for evening snacks, but the astronomy club members always stayed until around 1:00pm, and let me share some peeks...wonderful...

I had an idea a while ago for a "telescope as a service" platform. The idea was to build relatively small telescopes and put them in ideal places (maybe partner with existing observatories). They would be fully controllable via api and from a web interface. I was thinking it would be a good educational resource for educators, you could connect and use a telescope right in your classroom during the day, on the other side of the world where it is dark. Researches could buy time and program them to observe the sky as well since as you said, even small telescopes can be useful for some types of astronomy.

IMO teachers would be very receptive to an opportunity to do just that...if you're thinking of dev for a subscription service my advice would be to keep it affordable--education budgets are much smaller than they should be...

My inclination would be to make it a non-profit.

Have some experience with non-profits...

Some options for seed money:

Partnering--combine your request(s) for funding with other providers, or beneficiaries (schools).."collaborating" is big just now...

Grants--arduous route with a steep learning curve in terms of writing effective proposals...

Benefactor-- local moneyed enthusiast who wouldn't mind making the news with a bit of altruism...

Solo--funding it yourself then selling it...

Good luck!

Such networks already exist, e.g. http://www.faulkes-telescope.com/ or http://www.schoolsobservatory.org.uk/

If you'd like to try out radio astronomy you can use SALSA: http://vale.oso.chalmers.se/salsa/welcome

You get access to a 2.3 m radio telescope for free, you just need to book a time slot.

The paper by Dragonfly designers:

http://arxiv.org/abs/1401.5473

It's not "just" the off-the shelf lenses and cameras, although the lenses are really the crucial part and they are very cleverly used, achieving up to then never achieved low light scattering. At the time it used only 8 lenses, the telescope had weight of more than 100 kg.

Here's the robotic mount they used then:

http://www.bisque.com/sc/pages/ParamountMEII.aspx

The paper with the first results from the Dragonfly:

http://iopscience.iop.org/article/10.1088/2041-8205/782/2/L2...

Thanks for those links. The paper by the designers is so much better than the incredibly dumbed down fluff in the article.

As I read the article I kept thinking things like "what Canon lens?", and "what are the details of the coating?". The paper has a wealth of technical information on all of this.

The paper mentions "science grade CCD sensors" - are these really better than some of the new ultra low light CMOS cameras from Sony and Canon?

My understanding is that "science grade CCD sensors" have thermal controls to ensure the thermal noise is constant.

More than likely. Most "science" grade CCD sensors, at least in the Astronomy world, are in fact shaved down to make them even more sensitive.

The sensors used are Kodak KAF8300, which are a stand-alone sensor that you hook up to a laptop. They are designed specifically for astronomy, and perform better in some ways than typical consumer cameras. DSLRs that are marketed as tuned for astrophotography often have better sensitivity to certain key wavelengths than their standard counterparts (especially hydrogen-alpha at 656nm), but are missing other benefits of 'science-grade sensors'.

"Astronomical CCD cameras are a whole different world from DSLR cameras. These are cameras designed exclusively for AP, and most offer active cooling. The nature of a CCD vs a CMOS sensor in a DSLR results in a camera that is higher sensitivity, but also higher noise. Many Astro CCD cameras have mono sensors (no bayer color layer) which means they are used with filter wheels with different colored filters to capture a natural color image. They can also be used with various narrow-band filters to capture light outside the visible spectrum."

from http://soggyastronomer.com/the-best-dslr-cameras-for-astroph...

Nice. Did a bit of reading on this, looks like high as possible quantum efficiency (across a broad spectrum) is what is desired.

You are right, most DSLR cameras lose about half of the QE to the rgb filters.

Footnote 20 is wonderful.

They were also frustrated with how cumbersome astronomy had become: Modern astronomical projects are typically large-scale affairs, requiring a small fortune, a mountain of paperwork, and plenty of patience. “You have to envision ways to get $10 million and put a team together, and even then, you only know if things will come to fruition a decade later,” says Abraham, a professor at the University of Toronto.

Sounds like big company software development.

Taking two expensive hobbies(photo + astro) and combining them!

Also my jaw dropped a bit when I saw all those white telephotos packed together, that's a lot of glass!

Only one hobby. These folks are professional astronomers.

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