Amateur astronomer helps pros study super-Saturn orbiting another star

The exoplanet J1407b has a ring system so vast - 200 times larger than Saturn's - that it blocks as much as 95% of the light from its parent star when it transits between the star and Earth. Artist's Concept Cedit: Ron Miller Source: University of Rochester

The exoplanet J1407b has a ring system so vast - 200 times larger than Saturn's - that it blocks as much as 95% of the light from its parent star when it transits between the star and Earth. Artist's Concept Cedit: Ron Miller Source: University of Rochester

None of last week’s coverage of super-Saturn J1407b explored the role amateurs played in the research. When the economics of science limit the kind of observations professional astronomers can make, thousands of amateur astronomers around the world are ready to help. I spoke with Franz-Josef Hambsch - his nickname is Josch - about his passion for variable star astronomy and how that led to his participation in the super-Saturn research.

For background you can read the original University of Rochester press release that triggered the news coverage or read the arXiv preprint (1501.05652) for the science.

Josch, could you explain how you transitioned from the hobby of amateur astronomy to making scientific variable star observations?

I have quite some history in terms of being an amateur astronomer - from my childhood.  I came from astrophotography, but after so many thousand observations of M42 - which is nice to see - in the end it doesn’t matter if there’s one more picture out there. 

I went to variable star observations because of my scientific background (I am a nuclear physicist working on the interaction of neutrons and matter) and because as an amateur with a rather moderate telescope - I have a 16” telescope - you can still do science. I get lots of data as you can imagine. I observe about 40 stars a night - half of them in snapshot mode and many in time series mode for different organizations like the Center for Backyard Astrophysics and the VSNet. Most of my data go to the American Association of Variable Star Observers - the AAVSO - actually so professional astronomers can take the data from there.

Since 2011 I have a remote observatory in Chile. Due to the fact that I’m living in Belgium which is a different time zone, most of the time when my telescope is working I sleep or I work. Thanks to the weather I can more or less every night observe variable stars which is my favorite object. 

How did you go from amateur astronomy in Belgium to observing half a world away with your own telescope in Chile?

I live in Europe which is not well known for perfect weather - especially Belgium. We have maybe three hundred nights and days when its raining so on average you get maybe fifty clear nights. I have had an observatory in my backyard for the past fifteen years. I actually increased the amount of telescopes in my backyard to compensate for the bad weather. You can observe one star with one telescope. If you have two telescopes you can observe two stars - that’s already doubled the output! 

I have been in a collaboration with some amateurs having a telescope in New Mexico where I thought the weather should be much better. Actually its definitely better than Belgium - it can’t be worse! But in the end over there they have monsoon periods where you cannot use the telescope for quite some weeks in a row. I was talking to some guys I knew “how about another place with better weather?”  One of those guys who had just been in Chile installing a telescope, he said Chile has much better weather than we have here in New Mexico. So that triggered the plan to go to Chile.

[CC: Josch describes his Remote Observatory Atacama Desert in the Journal of the AAVSO. (PDF)]

Variable star observers collect data rather than pictures. In response to the AAVSO Alert, Josch and other astronomers measured the brightness of the star J1407 (Josch's data are the blue boxes). They are looking for the tell-tale drop in brightness as the exoplanet J1407b passes between the star and Earth (it hasn't happened yet). The monitoring work Josch and others conduct will trigger observations at the big observatories. Professional astronomers can't afford to make these kinds of regular observations which is why they turn to amateurs. Source: AAVSO

Variable star observers collect data rather than pictures. In response to the AAVSO Alert, Josch and other astronomers measured the brightness of the star J1407 (Josch's data are the blue boxes). They are looking for the tell-tale drop in brightness as the exoplanet J1407b passes between the star and Earth (it hasn't happened yet). The monitoring work Josch and others conduct will trigger observations at the big observatories. Professional astronomers can't afford to make these kinds of regular observations which is why they turn to amateurs. Source: AAVSO

Could you tell me about the work you did supporting the J1407b research?

We are asking for nightly photometry in one or more visible photometric bands (preferably V) to search for the start of the next eclipse. This star is no longer being monitored by the surveys that led to the initial discovery of this object. As soon as the first eclipses are confirmed, we will conduct a large multiple observatory monitoring campaign to capture in detail the structure and composition of this ring system based on the monitoring photometry from the AAVSO.
— AAVSO Alert Notice 462

I think maybe it was two years ago. Before of course I had not heard of this object. There was a request via the AAVSO website on observations of J1407. I have followed J1407 until now. I started observation in so-called snapshot mode. That means every clear night I observed the object with the CCD camera and my telescope. One single measurement could be an error so I always get two images.

A couple of months ago I was approached by Matthew Kenworthy who was busy writing a paper about this object based on mainly observations they have taken with one of the Prompt telescopes [CC: the University of North Carolina's Panchromatic Robotic Optical Monitoring and Polarimetry Telescopes] at Cerro Tololo Inter-American Observatory. He apparently looked at the AAVSO database to see who has sent in data for J1407. That actually made me part of the team because my observations were somehow complimentary to observations on the Prompt telescope - sometimes occurring at the same time and sometimes extending a little bit more in time due to weather conditions. And yah, that’s how I came into the business.

[CC: Josch's contribution earned him a co-author listing on the paper Kenworthy and his co-investigators published last year. The paper lies behind the paywall at the Monthly Notices of the Royal Astronomical Society (DOI: 10.1093/mnras/stu2067, $28/day) but you can read the free arXiv preprint (1410.6577)]

J1407 is the star at the center of this image from the Digitized Sky Survey. As a pretty picture, there's nothing too spectacular about it. But as astronomers measure its brightness night by night they can derive an exoplanet's size, orbit, and other properties. J1407b is the first exoplanet whose rings scientists have detected. Credit: STScI, ROE, AAO, UK-PPARC, CalTech, National Geographic Society Source: Digitized Sky Survey via Nasa SkyView

J1407 is the star at the center of this image from the Digitized Sky Survey. As a pretty picture, there's nothing too spectacular about it. But as astronomers measure its brightness night by night they can derive an exoplanet's size, orbit, and other properties. J1407b is the first exoplanet whose rings scientists have detected. Credit: STScI, ROE, AAO, UK-PPARC, CalTech, National Geographic Society Source: Digitized Sky Survey via Nasa SkyView

How is exoplanet observing different from variable star observing?

Exoplanets take much more concentration and time because the difference in brightness is only a few milli Mags which is not the case if you do just variable stars which change brightness several tenths of a magnitude or even magnitudes. You have to be much more careful in terms of flat fielding, that your telescope’s pointing is very good, that it’s tracking very well and so on and so on.

The general public thinks amateur and professional astronomy are two very different things. Why do professional astronomers turn to amateur astronomers like you for help?

Because amateurs have much more time on their telescope than professionals. I can use my telescope at any moment it’s clear and for as many weeks or months I think its appropriate to observe an object. Normally professional astronomers have only a week or two - or maybe even less time - available on big telescopes. There are surveys but even surveys do not observe the same object for hours and hours at a time during the night which is sometimes necessary to see variations in brightness and follow periodical phenomena and changes.

For example, I also work together with a professor in Chile - Nikolaus Vogt at Valparaiso University. He is actually German and I am of German origin. We have a couple of stars that I observe. He and his team, which are mainly students doing their PhD and masters theses, work the analysis of the data.

You mentioned that you contribute to several international variable star organizations like the AAVSO, CBA, and VSNet. You’re also a member of Belgian astronomy groups. What role have they played in your development as an amateur variable star astronomer? 

Ten to fifteen years ago the Internet was not that popular yet. Nowadays the world became much smaller. You live in California and I am here in Europe and we can talk to each other via Skype without cost. Local groups are interesting because you live in the country and they are close by. 

They actually triggered my interest in variable stars by observing, for instance, gamma ray bursts. I think it was in 2003 there was a strong gamma ray burst which was observable with amateur instruments over several weeks. That was the first variable star I observed. That somehow triggered my passion for variable star astronomy.

I am part of a group of amateurs observing so-called High Amplitude Delta Scuti stars with their CCD cameras and telescopes. We have a list of stars on the Internet where we can edit a spreadsheet and put our observations in there. One of our group members is analyzing the data and writing publications mainly in the International Bulletin of Variable Stars

[CC: Here’s an example of one of their papers.]

Do you have any advice for amateurs who want to transition from astrophotography to scientific observing as you did?

Japanese amateur astronomer first detected Nova Delphini 2013, sparking worldwide observations by professionals and amateurs alike. More than 50,000 observations from the AAVSO's members around the world produced this light curve of the fading explosion. Source: AAVSO 

Japanese amateur astronomer first detected Nova Delphini 2013, sparking worldwide observations by professionals and amateurs alike. More than 50,000 observations from the AAVSO's members around the world produced this light curve of the fading explosion. Source: AAVSO 

Nowadays everybody has a DSLR camera which many use for astrophotography. They can use their DSLR for work on variable stars. Once in a while a bright nova pops up like Nova Delphini 2013 hich attracted many people to photometry with their DSLRs. 

They can participate in campaigns which the AAVSO promotes - like epsilon Aurigae which is a rather bright variable and had an eclipse which happens every 27 years. Information for a campaign is distributed via the AAVSO website. 

The AAVSO has a manual on how to use a DSLR for work on variable stars. You can split the different colors of the DSLR. The green channel is very close to the so-called V filter - V stands for visible. It is a greenish kind of filter which is used for most of the observations. Professionals use this kind of standardized photometric filter to compare data from different telescopes.

There are many possibilities to try something else than just making pictures and maybe for the one it becomes more interesting.