Aliased

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Woke up this morning to the startling news that the Geneva team has added an Msin(i)=1.9 Earth mass planet to the Gliese 581 system! The preprint (Mayor et al. 2009) is available from exoplanet.eu, and will appear in Astronomy and Astrophysics. With a radial velocity half-amplitude, K=1.85 m/s, Gl 581e is the lowest-mass planet detected to date.

“The orbital period of the new planet “e” is quite close to pi days. i would mark down a score of -1 for competing planet hunters, whose signals-to-noise are accumulating in proportion to the root of the number of measurements.” said Greg Laughlin, an astronomer at the University of California, Santa Cruz.

In addition to the detection of the new 1.9 Earth-mass planet in the system, the period of Gliese 581d has been revised (to great habitability fanfare) from 84 days to 66 days. Indeed, the new, shorter period raises the habitability value of Gliese 581d from about 0.5 cents to nearly one penny.

As often happens, a strong hint of the new planet was lurking unnoticed in the previously published radial velocity data, and it’s especially interesting to look at the details in this particular case to see how the period revision came about. Let’s work with the 50 radial velocities published by Udry et al. 2007.

The two strongest periodicities in the system come from planets b and c. Removing these planets with the assumption of circular orbits leaves a residuals periodogram that has its strongest peak at 84 days:

The 66 day periodicity is lagging in second place with 66% of the power. Nevertheless, both periodicities provide significant improvement to the fit. An 84-day planet has K=2.67 m/s, and leaves an RMS of 1.43 m/s to the three planet fit:

A best fit 66-day planet has a slightly higher K=2.77 m/s, but leaves an RMS of 1.72 m/s. The chi-square is also higher: 5.10 as compared to 3.65. In the 2007 data, the 84-d planet thus looked quite secure. With hindsight, though, one notices that the phase coverage in the 66-day fit is better than for the 84-day fit. As more data was obtained, it became clear that the 84-day period was an alias of the true 66-day periodicity. Fair enough — RVs are expensive to obtain, and revisions of this sort are an inevitable product of progress.

In the residuals to the fit with the 84-day planet, planet e is present, but it’s masked by a spurious periodicity at 3.45 days,

whereas in the residuals to the fit with the 66-day planet, planet-e is in the #1 spot — not yet significant, but certainly more tantalizing…

Zen++ for film

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Zen++ for film

Jonathan Langton took the Spitzer 8-micron time-series for HD 80606b and transformed it into a movie of an actual extrasolar planet. The money-minded studio execs, having never seen the the successful prequel, decided that the full 30-hour version might not do well in theaters, so the original “Director’s Cut” had to be edited. The final result? Thirty hours of one-pixel, gray-scale footage have been compressed into a 10-second movie showing the excitement surrounding perihelion at a rate of 3 hours per second.

Be sure to watch for the secondary eclipse!

scenario three

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null

Georges-Louis Leclerc, Comte de Buffon is well known to givers of planet talks as one of the original proponents of physical cosmogony. Further fame accrues to his long-distance tangle with Thomas Jefferson over the size and the valor of the North American fauna. Buffon also made interesting contributions to probability theory, including the very sensible proposition that 1/10,000th is the smallest practical probability [source].

I think it’s reasonable to apply Buffon’s rule of thumb in discussing scenarios for the detection of the first potentially habitable extrasolar planet. If a scenario has a less than 10^-4 chance of unfolding, then it’s not worth expounding on in a web log post.

There’s no getting around the fact that the extrasolar planets are a long way away. Traveling at just under the speed of light, one reaches Alpha Cen Bb during Obama’s second term, and Gliese 581c, the extrasolar planet with the highest current value on the habitable planet valuation scale, lies 20 light years away. For practically-minded types such as myself, it’s depressing to think of the realistic prospects (or lack thereof) of actually reaching these worlds in a lifetime. And why spend trillions of dollars to visit Gliese 581 c when Venus is basically right next door?

It’s imperative to know the addresses of the nearest potentially habitable planets, though, and this is a goal that should be reached within roughly a decade or two. Barring a strike with some household name like Alpha Centauri or Tau Ceti, it’s a reasonable bet that the closest million-dollar world is orbiting a red dwarf.

The general suitability of red dwarf planets is often viewed with suspicion. Atmosphere-eroding flares, tidally spin-synchronized orbits, and gloomy formation-by-accretion scenarios provide ample material for space-age Jeremiahs. But first things first. With what frequency are Earth-sized T_eff~300K planets actually to be found in orbit around red dwarfs?

If planets form from analogs of the so-called Minimum Mass Solar Nebula, then the answer is quite well established: almost never.

If, however, instead of scaling down from the Minimum Mass Solar Nebula, we scale up from the proto-Jovian, proto-Saturnian and proto-Uranian disks, then the prospects are quite good. Ryan Montgomery and I have an Icarus preprint out which looks in detail at the consequences of an optimistic planet formation scenario for red dwarfs. Perhaps the most redeeming aspect of our theory is that it will be put to the test over the next decade. If hefty terrestrial planets are common around red dwarfs, then the currently operating ground-based MEarth survey will have an excellent chance of finding several examples of million-dollar wolds during the next several years, and the forthcoming TESS Mission will quite literally clean up.

In the spirit of Buffon, though, for the exact specifics of scenario three, it’s fun to probe right down to the limit of practical odds. Consider: An Earth orbiting a star at the bottom of the Main Sequence produces a transit depth that can approach 1%. If Barnard’s Star harbors an optimally sized and placed planet, then its value is a cool 400 million dollars. Such a planet would have an orbital period of about 13 days, and an a-priori transit probability of roughly 2%. I estimate a 1% chance that such a planet actually exists, which leads to a 1 in 5000 chance that it’s sitting there waiting for a skilled small-telescope observer to haul it in. In expectation, it’s worth $87,200, more than the equivalent of a Keck night, to monitor Barnard’s star at several milli-magnitude precision for a full-phase 13 days. That’s $280 dollars per hour. There are few better uses to which a high-quality amateur telescope could be put during those warm and clear early-summer nights.

Give M a break

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Last weekend, I got e-mail from an A-list planet hunter who wrote in support of the little guys:

Why punish beloved M-dwarfs?

The last factor, currently written in terms of V, might be rewritten in terms of a less pejorative magnitude, like I or Z. Most stars in the Galaxy put their best (and brightest) foot forward at 1um!

Hard-working red dwarfs, like Barnard’s star or Proxima Centauri get the short end of the stick in the Oklo terrestrial planet valuation formula. Red dwarfs put out the bulk of their radiation in the near-infrared, rather than the optical, but dollar value is pegged to apparent magnitude in the V-band.

This leaves me in a position similar to that of a company spokesman trying to justify Wall Street bonuses.

“The fact of the matter, is that as a society, our planet-hunting values and priorities have been traditionally tied to the optical range of the spectrum. If we examine the resources that have been deployed to date, over a billion dollars have been spent on satellite-based planet-hunting programs that monitor stellar output in visible light. In the same way that an executive’s compensation is tied to the value that he or she brings to shareholders, a terrestrial planet’s value should therefore be tied to V-band magnitude.”

Flimsy, I admit. Therefore, in the interest of fairness, the first planet-hunting group or individual that discovers a planet worth USD 1M with Z-band apparent magnitude replacing V-band will receive an oklo.org T-shirt.

scenario two

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Several readers pointed out that the terrestrial planet valuation formula breaks down dramatically for Venus. Point taken! I’m not sure though, that a top-dollar Venus necessarily points to a flaw. The valuations are a quantitative measure of potential for a planet to be habitable, given only bulk physical properties currently measurable across light years of space. One is still faced with the quandry of whether to invest in to finding out whether a given planet measures up. If Venus were sheathed in water clouds rather than sulfur dioxide clouds, it would quite possibly achieve its potential as a quadrillion-dollar world.

At any rate, given its sky-high atmospheric D/H ratio, it’s not inconceivable that Venus was both habitable and inhabited, at least by microbes, in the distant past. Under the constraint of a zero-sum budget for solar system exploration, I would agitate for spending more exploring Venus and less exploring Mars.

It’s admittedly gauche to price planets like baseball cards. But it’s also true that taxpayer money, big money, well over a billion dollars of real money, is being spent to find planets, and astronomy has long since departed the ivory tower. We know from direct observation that an excitable media is more than eager to paint habitability-lottery losers in neon shades of blue and green. A middling $158.32 best-yet on a scale that will soon be registering million-dollar worlds underscores the importance of keeping the powder dry.

Which brings up scenario number two for how the first million-dollar detection (and indeed the first hundred-million dollar detection) could arise. It’s extremely likely that the first planets with genuine potential habitability will be detected from the ground. It’s also a good bet that these planets will arise from the same technique that’s produced the overwhelming majority of the big-ticket planet detections to date: Doppler radial velocity. If I were pressed to guess the particular star, I’d choose HD 40307. And if I were pressed to guess the time frame? Sometime within the next year.

The Mayor et al. (2009) HD 40307 paper rewards careful study, and indeed, may end up being as illuminating for what it reveals as for what it doesn’t reveal. In the paper, the evidence for the now-famous planets “b” (Msin(i)=4.2 M_Earth, P=4.3d), “c” (Msin(i)=6.8 M_Earth, P=9.6d), and “d” (Msin(i)=9.2 M_Earth, P=20.5d) is presented in the form of phase-folded plots of the radial velocities, and a periodogram of the velocities prior to any fitting. That all three planets are clearly visible in the raw periodogram is in itself quite remarkable. The orbits are close to circular, the system has been observed for many periods, and the signals (despite the small half-amplitudes) are unambiguous:

The actual radial velocities, however, are not included in the paper, and would-be Dexterers are thwarted by the fact that the only plots showing the full data set are phase-folded. The journal version of the paper reports that the velocities are available at: http://cdsarc.u-strasbg.fr/cgi-bin/qcat?J/A+A/493/639 , but the link is still empty…

In lieu of access to the actual data, we have carte blanche to engage in irresponsible (yet technically accurate) speculations to get a sense for what further secrets the HD 40307 system might harbor. Let’s construct a Monte-Carlo data set. An optimally habitable ten million-dollar planet in the HD 40307 system has a mass of ~2.3 Earth masses, an orbital period of 141 days, and induces a K=0.35 m/s radial velocity half-amplitude. We can make a model system that includes such a planet along with the three known planets (noting that the Mayor et al. 2009 paper contains an error for K_d in Table 2). We can generate a synthetic radial velocity data set by perturbing the four-planet model with the reported 0.32 m/s instrumental measurement error and 0.75 m/s of Gaussian stellar jitter, and observing at 135 randomly spaced times within a span of 1628 days.

We can put the resulting data set into the Systemic Console. Removing the 20-day planet gives a residuals periodogram that clearly shows the 9.6d and 4.3d planets, along with an alias peak at ~2 days. As with the actual periodogram in the Mayor paper, there’s nothing particularly interesting at 141 days. That is, there’s no sign of the ten million-dollar world that was baked into the data.

Remarkably, however, when the 9.6d and 4.3d planets are fitted and removed, the periodogram peak for the 141d planet is quite prominent. It’ll be very interesting to see if anything like this is present in the actual data set when it goes online:

It’s straightforward to recover the 141d planet in the orbital fit. Removing the three known inner planets and phase-folding the data at the period of the 141d planet shows what its current (as of last June) signature would look like:


A real planet with these properties would thus be right on the edge of announceability. HD 40307, furthermore, is by no means the only quiet Mv~7 K dwarf in the local galactic neighborhood…

scenario one

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HD 28185bb

Without regard to order of likelihood, I thought it’d be interesting to lay out a few very specific scenarios by which the first extrasolar world with a 1 million+ habitability valuation could be discovered.

A favorite space-art trope is the habitable moon orbiting the giant planet (which is generally well-endowed with an impressive ring system). Smoggy frigid Titan is the best our solar system can do along these lines, but there’s nothing preventing better opportunities for habitability lying further afield.

I’ve always been intrigued by the fact that the regular satellite systems of the solar system giants each contain of order 2 parts in 10,000 of the mass of the parent planet. At present, there’s no reason to expect that this scaling is any different for extrasolar planets, and given the example of Titan, there doesn’t seem to be anything to prevent the bulk of a given planet’s satellite mass from being tied up in a single large body. Furthermore, since it’s my weblog, I’ll take the liberty of assuming that the satellite mass fraction scales with stellar metallicity.

Image source.

It’s perfectly reasonable to imagine, then, that HD 28185b is accompanied by a 0.63 M_earth, 0.86 R_earth satellite with an orbital radius of a million kilometers. HD 28185b itself has Msin(i)=5.7 Mjup, and the metallicity of HD 28185 is [Fe/H]=+0.24.

Now, for a long shot: let’s assume that on July 11th, 2009, a cadre of small telescope observers in Australia, South Africa and South America discover that HD 28185b transits its parent star. The geometric a-priori odds of the transit are ~0.5%. The expected transit depth is an eminently detectable 1%. A transit of moderate impact parameter lasts about 12 hours.

If a detection is made on July 11th, 2009, it’s a sure thing that the following transit (July 29th, 2010) will be the subject of great scrutiny. The current ground-based state of the art using orthogonal transfer arrays is demonstrating 0.4 mmag photometry with 80 second cadence. At this level, with spot filters and several observatory-class telescopes participating, the piggyback detection of the satellite transit is a many-sigma detection.The cake would be iced on Aug 16th, 2011, when the ~25 second difference in midpoint-to-midpoint intervals would be detected. We’d then be in possession of a potentially habitable terrestrial world warmed by an admirably bright and nearby parent star. Accurate mass and radius determinations would be fully forthcoming. All from the ground, and all at a total cost measured in thousands of dollars of amortized telescope time on existing facilities.

Admittedly, the odds of this specific scenario are slim. I estimate one in two thousand. The payoff, however, is massive. HD 28185bb (with the properties given above) is worth a staggering 100 million dollars. In expectation, then, that’s 50,000 dollars for fully covering the transit window this July…

Habitable planets: more value for your dollar.

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I’m completely invigorated by the Kepler Mission. This is, of course, because of the fantastic discoveries it’ll make, but also (I’ll admit) because it establishes a crystal clear and present challenge to competitively-minded planet hunters everywhere. If you want to discover the first truly potentially habitable world orbiting another star, then you’ve got, in all likelihood, 3.5 years to do it.

A coveted oklo baseball cap (from a limited edition of five) will be sent to the first person or team that detects an extrasolar planet worth one million dollars or more as defined by the terrestrial planet valuation formula set out in Thursday’s post:

For purposes of definiteness, (1) terrestrial planet densities are assumed to be 5 gm/cm^3. (2) A measurement of Msin(i) is counted as a measurement of M. (3) Teff is computed assuming that the planet is a spherical blackbody radiator. (4) The parent star needs to be on the Main Sequence. (5) If the stellar age can’t be accurately determined, then it can be assumed to be half the Main Sequence lifetime or 5Gyr, whichever is shorter.

Gl 581 c

Gliese 581 c (see here for more details).

The formula is pretty stringent, and is not kind to planets of dubious habitability. Gliese 581c, which I believe is the extrasolar planet with the highest value found to date, clocks in at $158.32. Mars, taking outsize advantage of the Sun’s V=-26.7 apparent magnitude, is worth almost 100 times as much, at $13,988.

In upcoming posts, I’ll put forth some scenarios (spanning a wide range of likelihood) that could produce high-dollar detections during the next three and a half years.

Too cheap to meter

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In 1803, the fledgling United States purchased the Louisiana Territory from France, and thereby entered into what has wound up being one of history’s better real estate deals. Napoleon, as the principle on the sell side, remarked at the time, “This accession of territory affirms forever the power of the United States, and I have given England a maritime rival who sooner or later will humble her pride.” In somewhat typical fashion, the US House of Representatives was slower to grasp the stupendous advantage of the bargain, with Majority Leader John Randolph standing firmly against the purchase. Fortunately, a measure to axe the deal wound up failing by two votes, 59-57.

The Louisiana Purchase price was a (suspiciously spam-like) USD 15 million. For a payment of gold bullion and bonds, the United States obtained the entire western drainage of the Mississippi River. This constitutes ~2 million square miles, or roughly 1% of Earth’s ~200 million square mile total surface. Using the price of gold as a measure of inflation (Gold was USD 19.39 per oz. in 1803) the purchase in today’s currency was thus a mere USD 750 million.

Fast-forwarding two hundred years to the present, similarly good land deals are still to be had — not on Earth, but on potentially habitable terrestrial planets orbiting nearby stars! I think it’s fair to say that the successful launch of the Kepler Mission last weekend can be viewed as the first large-scale extraterrestrial land rush.

Oklo readers are doubtless familiar with the Kepler mission specs. The spacecraft will reside in an Earth-trailing orbit, and, during the 3.5-year mission will monitor ~100,000 main sequence stars with a photometric precision of 20ppm at 6.5h cadence. In all likelihood, it’ll detect of order 100 terrestrial planets. The total mission cost will be of order USD 600 million, remarkably close to the cost of the Louisiana purchase in 2009 dollars.

The advent of Kepler allows us to put meaningful prices on terrestrial extrasolar planets. I think the following valuation formula provides a reasonable start:

where $\tau_{\star}$ is the age of the planet-bearing star, and V is the apparent visual magnitude. Kepler’s best planets are likely going to come in with valuations of order 30 million dollars.

Applying the formula to an exact Earth-analog orbiting Alpha Cen B, the value is boosted to 6.4 billion dollars, which seems to be the right order of magnitude.

And applying the formula to Earth (using the Sun’s apparent visual magnitude) one arrives at a figure close to 5 quadrillion dollars, which is roughly the economic value of Earth (~100x the Earth’s current yearly GDP)…

The McLaughlin-Rossiter effect

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The visible universe contains of order 30,000,000,000,000,000,000,000 planets, and so this web log’s rather single-minded focus on HD 80606b (a staggering eight out of the nine most recent posts) is likely starting to wear a little thin, even for the Kid606 fan base. One more post, though, and then I’ll move along.

First, I was jazzed to get an e-mail from Mauro Barbieri (of 17156, etc. fame) reporting that two Italian amateur observers (Alessandro Marchini from Siena, Tuscany, and Giorgio Corfini, from Lucca, Tuscany) got discovery photometry of the HD 80606b transit on Feb. 13th/14th. Their light curves are of quite high quality, and, like all the European observations show the leisurely egress from transit:

Excellent work!

A few long-time readers may recall that in the transit fever post from several years ago, I tried on a “tough guy” persona with regards to partial transits:

The transit detection problem is tough in part because it’s extraordinarily easy for systematic effects to seemingly conspire to produce an apparent signal. I would not feel confident in announcing a transit until I’ve seen multiple full-transit light curves. On the other hand, though, the false alarms play an important role. They get observers out on the sky, and spur the collection of enough data to truly rule out an event.

This hard-line attitude resulted from catching numerous infections of ingressia in which a time-series seems to show a transit starting just as observations are ending:

ingressia

and egressia in which a transit seems to be ending just as observations are starting:

egressia

With HD 80606b, however, it’s perfectly certain that we’re not dealing with a virulent case of egressia. The transit did occur and that it will occur in the future. This confidence stems both from the fact that there are at least seven independent photometric data sets showing the egress, and from the fact that the French-Swiss team (Moutou et al. 2009) observed the transit spectroscopically via the Rossiter-McLaughlin effect.

The Rossiter-McLaughlin effect arises when a transiting planet occults part of a rotating star. When a planet passes in front of the oncoming limb, it blocks out blue-shifted light, whereas it blocks out red-shifted light when covering the outgoing limb. The resulting distortions in the spectra are interpreted as a positive and then negative shift in the radial velocity of the star. The amplitude of this effect is thus due both to the spin velocity of the star as well as to the total flux blocked out during transit:

schematic diagram showing rossiter effect

Moutou et al.’s detection of the Rossiter-McLaughlin effect for HD 80606b provided drop-dead confirmation of the transit, and also hinted that the planetary orbital plane is not aligned with the equator of the star (which is not surprising, given the probable history of the ‘606 system). Here’s a re-working of the diagram from the Moutou et al. paper that takes the London and Arizona photometry into account (you may want to make your browser window wider):

Illustrator .ai file for above image

The Arizona and London photometry rule out transits longer than ~12 hours, which strengthens Moutou et al.’s conclusion that the system is far from having the stellar equator aligned with the orbital plane.

Earlier this week, I was having an e-mail conversation with Bruce Gary, who runs the Amateur Exoplanet Archive (a.k.a. AXA). The AXA is a repository for photometric transit data from small telescopes, and a first stop for anyone interested in the detection of planets via transit timing.

Bruce wrote:

By the way, does the Rossiter-McLaughlin effect refer to the Dean McLaughlin who speculated about Mars, and who worked at the Univ Michigan Observatory in the late 1950s & early 1960s?

A bit of ADS sleuthing reveals that the two McLaughlins are one and the same. In 1924, Richard Rossiter and Dean McLaughlin simultaneously published the first measurements of spin-orbit alignment in eclipsing binary systems. Both men were at the University of Michigan — Rossiter as an assistant professor and McLaughlin as a 23-year old graduate student. McLaughlin used the famous eclipsing binary Algol to measure the time-dependent radial velocity skew in the brighter star of the system during the partial eclipse. His paper, “Some Results from a Spectroscopic Study of the Algol System”, makes a nice read today, and has garnered 45 citations since 2000. Its single figure shows the now-familiar effect, albeit with a factor-of-a-thousand increase in the scale of the y-axis:

McLaughlin remained at the University of Michigan during a productive career that ended with his untimely death in 1965. He seemed to have had a sensibility that was quite in line with oklo.org. Consider, for instance, this abstract from 1944:

Bruce later wrote back with small-world anecdote:

As I was finishing high school my father counseled me to not choose astronomy for a profession because Dean McLaughlin’s two boys were in his Ann Arbor High School English class and their clothes gave the impression that the McLaughlins were a poor family! That influenced my decision to enter the University of Michigan’s School of Engineering, but after a year my childhood hobby won out and I switched to Literature, Science and Arts so I could major in astronomy.

Nice!

‘606

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The primary transit of HD 80606b

After 10 days of no news, definitively flat news (Arizona) and tantalizing hints in my inbox, the HD 80606b transit story is resolving itself dramatically.

Earlier today, Stephen Fossey, Ingo Waldmann and David Kipping submitted their paper on the detection. I based the diagram on the results of their photometry, which points to a twelve hour transit, and a planetary radius just larger than Jupiter:

Fossey et al. photometry of the primary transit of HD 80606b

The Fossey et al observations were made using two small telescopes at the University College London’s observatory in Mill Hill, North London. (Co-author Ingo Waldmann is a final-year undergraduate project student.) It’s certainly been a long time since an observational astronomical discovery of this magnitude has made from within the London City Limits!

Also in my inbox this morning was an e-mail from Jose Manuel Almenara Villa, who made the definitive initial observation of HD 17156 (and made the initial announcement on the comment section of this weblog). He writes, I know it’s late, but here there are the data from Tenerife. The egress is fully there, fully present. Nice work!

Jose Manuel Almenara Villa Photometry for HD 80606

And then, no more than an hour ago, another dramatic update. In an e-mail to myself and Jean Schneider, Enrique Garcia-Melendo writes:

Dear Greg and Jean,

We observed the transit of HD80606b.

Please find attached the submitted paper to the ApJ. The manuscript will also appear at http://arXiv.org/abs/0902.4493

Best regards,
Enrique Garcia-Melendo

Title: Unconfirmed Detection of a Transit of HD 80606b
Authors: E. Garcia-Melendo and P. R. McCullough
Categories: astro-ph.EP
Comments: Submitted to ApJ, 11 pages, 4 figures.

We report a times series of B-band photometric observations initiated on the eve of Valentine’s day, February 14, 2009, at the anticipated time of a transit of the extrasolar planet HD 80606b. A transit model favored by the data has minimum light of 0.990 times the nominal brightness of HD 80606. The heliocentric Julian date (HJD) of the model’s minimum light is 2454876.33, which combined with the orbital period P = 111.4277 pm 0.0032 days, longitude of periastron, omega = 300.4977 pm 0.0045 degrees, and time of mid-secondary eclipse HJD 2454424.736 pm 0.003 (Laughlin et al. 2009), refines the eccentricity, e = 0.9337 +0.0012 -0.0004}, and the inclination, i = 89.26 +0.24 -0.04 degrees. The duration of the model transit is 0.47 days, and its four contacts occur at HJD 2454876 plus 0.10, 0.24, 0.42, and 0.57 days. We observed only the last two contacts, not the first two. We obtained “control” time series of HD 80606 on subsequent nights; as expected, the “controls” do not exhibit transit-like features. We caution that 1) the transit has not been confirmed independently [note: no longer true.]; 2) we did not observe the transit’s ingress; 3) consequently, we cannot reliably measure the relative sizes of the planet and its star in a model-independent manner, and 4) hence, the other values derived herein are also model dependent.

Now here’s the kicker — the Garcia-Melendo & McCullough paper was submitted on Feb. 23rd…

Update: I just heard from Shigeru Ida at Tokyo Institute of Technology, who has coordinated a number of photometric campaigns by amateur observers in Japan. It turns out that it was either rainy or totally cloudy on the night of the transit ingress (Feb. 13/14) for all of the observers. Bummer. The following night, the conditions were a little better, allowing several observers to get noisy baseline data.