June 8th: AAVSONet: An Interview with Dr. Arne Henden


Date: June 8, 2010

Title: AAVSONet: An Interview with Dr. Arne Henden


Podcaster: Slacker Astronomy

Description: Mike Simonsen from Slacker Astronomy interviews Arne Henden, the Director of the AAVSO, about AAVSONet, a new global, automated research telescope network created and operated by the AAVSO.

Bio: Slacker Astronomy is a light-hearted podcast that wanders the astronomical road-less-traveled. Visit us at http://www.slackerastronomy.org/.

Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by Kylie Sturgess and the Token Skeptic podcast, a weekly show about superstition, science and why we believe – at www.tokenskeptic.org.


Michael Koppelman: Welcome back! It’s us again, the slackers from Slacker Astronomy here with a podcast for the 365 Days of Astronomy podcast. I’m here with Doug Welch.

Doug Welch: Surprise!! It’s the same year [laughter] and we’re back.

Michael: And Mike Simonson.

Mike Simonson: It’s summertime. I’d rather be slackin’ [laughter]. What are we doin’ dude?

Doug: Sounds like southern time in the northern hemisphere.

Michael: We have to keep telling ourselves that.

Doug: You forget the global reach of Slacker Astronomy.

Michael: The multi-hemisphere of global00.42 reach. Anyway, we’re back again. We have another great short Slacker astronomy-style episode for you today.

Once again Mike Simonson is out there scurrying around interviewing people.

Mike: [Laughter] Scurrying, you make me sound like some sort of rat or something.

Michael: You do have a bit of a scurry toward a thing if you ask me. Today we’re talking about telescopes – automated telescopes taking pictures every clear night of the sky.

It’s called AAVSONet. We’re talking to Dr. Arne Henden of the AAVSO. Mike, what is AAVSONet in one sentence?

Mike: It is a network of robotic telescopes that the AAVSO is developing.

Michael: Doug, do you have maybe two sentences of why that’s cool?

Doug: Well, it’s a very cool thing for people who want to be studying certain stars and their membership in AAVSO allows them to really schedule these observations at no additional cost.

They’re actually beautifully calibrated on really world-class photometry. Arne is one of the best photometrists in the world and so you know your data is going to be really first rate.
Michael: So as Doug just said AAVSONet is something AAVSO members get to use. It is telescopes you can sort of use and get data from; it is free and sort of included.

The guy we’re going to talk to is sort of the brains behind the whole outfit in terms of how they take pictures and how that data eventually makes it to you. Let’s give it a listen.

This is Mike Simonson talking to Dr. Arne Hendon about AAVSONet.

Mike: We’re back again. I’m at the headquarters of the AAVSO. This time I’m talking with Arne Hendon, the director of the AAVSO. We’re going to talk about robotic telescopes. AAVSO now has robotic telescopes.

In fact we have a whole network called AAVSONet. Why don’t you tell us about the telescopes and equipment and where they’re located and some of the sketch details.

Dr. Arne Hendon: AAVSONet was born with a conversation that I had at a Society for Astronomical Sciences meeting in 2005, not long after I became director of the AAVSO. John Gross had a robotic telescope in southern Arizona at Sonoita. He and Walt Cooney and Dirk Terrell were running the telescope.

They wanted to ask the AAVSO to join them as a partner because, first of all these things are efficient. They had extra time sitting available on the telescope and they also thought that my expertise in photometry and so on would be valuable in getting the telescope up and running, making it even better. That was the basis for the network.

We saw that it was fairly easy to do with modern telescopes and commercial software. We then expanded and started bringing in other telescopes into the network. Most of them currently are in the southwestern United States but we are expanding beyond that.

Mike: So you have how many telescopes running right now?

Arne: Right now there are five telescopes that are up and running as of the time that we’re speaking. We have about another five or so that will be coming up in the next year.

Mike: Some of these telescopes are being used for a specific task like APASS. Others are available for AAVSO members to do their own projects. Why don’t we start with APASS first.

Tell us what APASS is – what it stands for – and then we’ll talk about the other telescopes.

Arne: APASS stands for the AAVSO photometric all-sky survey. It is a project that I’ve wanted to do for many decades. If you go back and look at my career in addition to research scientist, I’ve been doing calibration of star fields for many researchers because I’ve gained the experience and ability to do this.

I went back and looked and realized that I was calibrating about ten square degrees per year with a relatively large telescope but small field of view. It was taking me about one hundred nights per year to do this.

If you then extrapolate that to the entire sky, I would have to be at it for 4,000 years. I figured that I [laughter] wasn’t going to be around that long and actually I was getting kind of tired of this and the logical idea to well “can you do this to the entire sky with some sort of a sophisticated system”?

Certainly groups like Pan-STARRS and SkyMapper and SDSS and so on have done it with hundred million dollar class telescopes. But with the telescopes in CCD cameras that were available only a few years ago, we found that we could do a reasonable survey with something far less expensive.

Mike: So this is a photometric survey where you’re actually measuring the brightnesses and colors of stars to a high degree of precision. That’s what you mean when you say calibrating the field.

Arne: That’s right.

Mike: So you’re calibrating the whole sky.

Arne: That’s right.

Mike: You can’t do it all at once so the first part is to do what, the northern sky and then are you going to have another set of telescopes in the south?

Arne: The intent is to take this telescope that we’re currently running in the north – located in New Mexico – and has been operational for a couple three months now, and even during the New Mexico winter. That is an interesting proposition this year.

As soon as it gets most of the way down in the northern hemisphere sky then we’ll move it to the south and work our way up from the south and try to cover the entire sky.

We do have an NSF proposal in that if accepted would fund a second one of these systems and we don’t have to move it and we can actually do it a little bit faster.

It is an entire sky survey. Five colors covering kind of the magnitude range that you would have with an amateur telescope. It seems to have a lot of applications.

Mike: So the sweet spot is like about tenth magnitude to about seventeenth magnitude?

Arne: That’s right.

Mike: Then there’ll be comparison stars for people that are chasing asteroids or comets or variable stars for the whole sky eventually that can be had out of this catalog.

Arne: That is correct.

Mike: As well as other uses of course. We’re mostly concerned with spherical stars and stuff. [Laughter] You also have the bright star monitor. This is a little tiny telescope. What is its purpose?

Arne: It’s kind of funny, when I was the amateur my first telescope was a 2.4 inch (I can’t remember the model number) but anyway, it was a dime-store telescope. So, 60mm, 2.4 inch and I worked my way up to the sort of 6, 7 and 8 meter class telescopes.

Now I’m back down to the 60mm telescope. [Laughter] The reason for this was we were looking at surveys and how they were going to influence the AAVSO two or three years ago in the governing council meetings. We realized that there were gaps in the way that the surveys were covering things. The biggest gap was that none of the surveys was covering bright stars.

There are about a thousand known nice variable stars that are sort of naked-eye and maybe a little bit fainter (small binocular) that just aren’t being covered by any of the surveys.

I said well, I can do this with some small telescope and some of the council members took me to task on that and said: “here’s some money, go do it”. So we designed a small telescope and found a relatively inexpensive mount and we found a way to put this up in New Mexico and it’s up and running.

Mike: Does it just do specific stars? Is it on like a specific program? It’s not like a survey telescope doing the whole sky; it does specific fields each night?

Arne: Well, it is a survey telescope in the sense that it does every known variable in the sky within a certain brightness range; basically, anything brighter than eighth magnitude.

It doesn’t do it by covering the entire sky. It does it by pointing to each of the fields. So we get about 300 stars per night off of that system.

Mike: How big is the field of view on that telescope?

Arne: It is about two and a quarter degrees by one and a half degrees.

Mike: So, it is big but not as big as taking a 50 mm camera out.

Arne: Right.

Michael: And we have to end it there. But like I said there’s more over at slackerastronomy.org come check it out.

And Michael Simonson in the interest of full-disclosure, Arne is your boss, is he not?

Mike: Yes he is. And I am his boss. [Laughter]

Michael: To make matters worse.

Doug: It is the same sort of thing you’ve been watching on Wall Street the last couple of years.

Mike: With a few less orders of magnitude.

Doug: Much less money involved.

Michael: Anyway, AAVSONet – you can check it out at aavso.org and follow links from there. You can use it if you’re an AAVSO member. Being an AAVSO member is easy, not very expensive and it brings you into a hundred plus year-long tradition of observing variable stars as citizen scientists.

Go check it out. We are Slacker astronomy – slackerastronomy.org come say hi. Let’s say good-bye.

Doug: Bye again.

Mike: Good bye for now.

Michael: Adios.

This transcript is not an exact match to the audio file. It has been edited for clarity. Transcription and editing by Cindy Leonard.

End of podcast:

365 Days of Astronomy
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