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Decepticon
If TrES 2 Had any moons would that be detectable?
Holder of the Two Leashes
Moons would appear in the transit data if they were as large as Titan or Ganymede, but given how close they would be to the planet, it is unlikely they would show up as separate signals. They would be averaged into their planet during the time intervals that Kepler could distinguish.

An excerpt from the mission manager updates on the main Kepler site ...

"2009 April 20. Mission Manager Update - The Kepler science team has decided that further refinement of the telescope's focus would significantly improve the mission's science return. The project is therefore proceeding with these adjustments. "
Syrinx
http://www.nasa.gov/mission_pages/kepler/n...m-20090424.html

QUOTE
Kepler Mission Manager Update
04.23.09

by Jim Fanson, Kepler, JPL Project Manager

The Kepler telescope's focus has been successfully optimized. This involved moving the primary mirror of the telescope toward the focal plane array, the area where light is focused, by 40 microns (1.6 thousandths of an inch) and tilting it by 0.0072 degrees. Various other calibrations are underway, including: detailed measurement of star images formed by the telescope at various locations on the focal plane; determination of the exact sky coordinates of every one of the camera's 95 million pixels, and mapping of "ghost" images, which result when the light from bright stars reflects off the front of the camera's charge-coupled devices (CCDs), bounces off lenses inside the telescope, and winds up back on the CCDs in another location.
Holder of the Two Leashes
In an earlier reply I made to Deception's question about detecting moons around Tres-2, I gave myself some wiggle room by limiting the answer to "separate signals", without really answering the question (even though the answer "probably not" was implied). There would be some 30 minute intervals where a moon would show up alone, along with an equal number of cases where the planet would too, when the elongation was sufficient. My guess was there would not be enough of these intervals by themselves during the prime mission to add up to a detection. We're talking about a moon orbit here that is, at most, half the size of our own moon's orbit.

Provided, of course, that separate signals are really required. Whether there is a statistical methode for analysing the data in it's entirety, I didn't know, and still don't.

But now I found this little tidbit from Caltech:

"TrES-2 is the first transiting planet - or planet that passes directly between its star and Earth - to be found in an area of the sky known as the "Kepler field", ... Discovering TrES-2 beforehand allows Kepler's astronomers to plan additional observations of it, such as searching for moons."

Okay. My bad. My bad.
Mongo
I would have thought that the main technique for discovering a large moon around Tres-2 would be timing variations. Since the planet's primary will be monitored continuously, we should end up with three years worth of transits and their timing. If the transit timing varies periodically with a period significantly smaller than Tres-2's orbital period (it should be possible to disentangle the putative moon's period from Tres-2's orbital period), I would think that the cause would have to be a moon.

As far as I know, no such variations have been found to date (on a limited number of transits), but with the huge number of transit observations expected during Kepler's primary mission, the margin of error for any timing variations should be considerably reduced from the current value.
Holder of the Two Leashes
Again, I really don't know. But my understanding is that Kepler sums up a total of 30 minutes worth of observations ( the individual readouts being much, much shorter) and transmits this average value of half an hour as its reading for each pixel. Maybe I'm wrong about that. But if it is the case, it's a fairly coarse interval we're talking about.

The timing offset for the earth, caused by the moon, would be at most three minutes on either side of the average. Still, if you added up hundreds of transits... who knows?

Edit: from Wikipedia - "The CCDs are read out every three seconds and co-added on board for 15 minutes".
Hungry4info
It's very unlikely TrES-2 b has any detectable moons, being so close to its parent star and thus having such a small hill radius.
Mongo
I am sure that you are right, for that reason. Another Earth-Luna system might be detectable, provided that there were sufficient transits recorded. How close to its primary could an Earth-Luna twin be and remain stable, and would that result in sufficient monitored transits during the Kepler primary mission to tease out the satellite?

[searches ARXIV]

Timing Detection of Eclipsing Binary Planets and Transiting Extrasolar Moons

We investigate the improved detection of extrasolar planets around eclipsing binaries using eclipse minima timing, and extrasolar moons around transiting planets using transit timing, offered by the upcoming COROT (ESA, 2005), Kepler (NASA, 2007), and Eddington (ESA 2008) spacecraft missions. Hundreds of circum-binary planets should be discovered, and a thorough survey of moons around transiting planets will be accomplished by these missions.

Determination of the size, mass, and density of "exomoons" from photometric transit timing variations

Precise photometric measurements of the upcoming space missions allow the size, mass, and density of satellites of exoplanets to be determined. Here we present such an analysis using the photometric transit timing variation (TTV_p). We examined the light curve effects of both the transiting planet and its satellite. We define the photometric central time of the transit that is equivalent to the transit of a fixed photocenter. This point orbits the barycenter, and leads to the photometric transit timing variations. The exact value of TTV_p depends on the ratio of the density, the mass, and the size of the satellite and the planet. Since two of those parameters are independent, a reliable estimation of the density ratio leads to an estimation of the size and the mass of the exomoon. Upper estimations of the parameters are possible in the case when an upper limit of TTV_p is known. In case the density ratio cannot be estimated reliably, we propose an approximation with assuming equal densities. The presented photocenter TTV_p analysis predicts the size of the satellite better than the mass. We simulated transits of the Earth-Moon system in front of the Sun. The estimated size and mass of the Moon are 0.020 Earth-mass and 0.274 Earth-size if equal densities are assumed. This result is comparable to the real values within a factor of 2. If we include the real density ratio (about 0.6), the results are 0.010 Earth-Mass and 0.253 Earth-size, which agree with the real values within 20%.


So it looks like detection of sufficiently large exomoons via transit timing with both CoRoT and Kepler should be possible, if they exist.
Holder of the Two Leashes
As I mentioned earlier, any moon of Tres-2 would have to be within about half a lunar distance of the planet to be stable. Say about 130,000 mile radius (forgive my english units here) for the orbit. My back of the envelop calculations, using Wiki values, showed a hill sphere of about a lunar distance. Over the long haul, only orbits about half the size of a hill sphere are truly stable, even if the orbit is retrograde.

Earth has a hill sphere of about four lunar distances, so the moon could effectively orbit to twice its distance (or four times for a geologically brief period). You could also keep the moon at its current distance, move the earth to half its current distance to the sun (not recommended), and still have a stable earth-moon system.

The most massive moon in our solar system is Ganymede. The mass ratio of Tres-2 : Ganymede is about 16,000 : 1.

If we put Ganymede in orbit around Tres-2 at 130,000 miles, the center of mass of the system is offset from the center of mass of the planet by 8 miles. At 50 miles/sec orbital speed of the planet about the star, the difference in transit timings at greatest elongation amount to about plus or minus 0.15 seconds from the expected. Over a fifteen minute integration of photometry, you get about a 0.02 per cent lightening or darkening over what you would expect during that interval.

The moon, by the way, would preceed or follow the planet by about 40 minutes at greatest elongation.

I welcome any efforts to check (and correct) my math here.
Mongo
The math looks good to me.

Perhaps a more productive technique would be to look for any moons directly. The radius of TrES-2 is about 1.272 times that of Jupiter, or about 89,000 km. A large moon might be around 2,000 or 2,500 km in radius, for an areal ratio of 1270 to 1 (2,500 km) or 1980 to 1 (2,000 km). This would represent an additional dimming of up to about 0.08 percent of the drop due to the exoplanet occurring up to 40 minutes before or after second contact and a compensating rise occurring the same amount of time before or after third contact. Is 0.08% of the full lightcurve drop within the sensitivity of the Kepler detectors?

Actually, if both techniques were possible, both mass and radius (and hence density) of this hypothetical moon would be known, which would imply bulk composition -- very useful to know.

This would certainly be an easier task when dealing with hot Neptunes or superEarths, instead of TrES-2 in particular.
Syrinx
http://www.nasa.gov/mission_pages/kepler/n...m-20090501.html
QUOTE
by Jim Fanson, Kepler, JPL Project Manager

Kepler's calibration data collection is drawing to a close. Several hundred data sets have been acquired to characterize and map the optical and noise performance of the telescope and the electronics for the focal plane array (the area where light is focused).
Syrinx
http://www.nasa.gov/mission_pages/kepler/n...m-20090507.html
QUOTE
The project will convene a science operations readiness review on Monday, May 11, to determine if the team is ready to commence science data collection.
Holder of the Two Leashes
According to the last mission manager report, they were suppose to decide today whether Kepler is ready to proceed with science observations. Haven't heard anything yet.

QUOTE (Mongo @ Apr 27 2009, 12:57 PM) *
Is 0.08% of the full lightcurve drop within the sensitivity of the Kepler detectors?


Depends on how close it is to the star. If Kepler could detect a moon this size with an eighty minute transit time of its own, and you are lucky enough to always catch it far away from the planet, then clearly yes. The 0.08% variance simply matches the size of the object that is detectable, so it would be within the sensitivity. But it won't always be 40 minutes of separation.

The two papers you listed seem to hint at a very optimistic outlook for Kepler finding moons. So I'm at a loss to explain it. These graphs and charts from the Kepler website would indicate to me that our own moon around the earth would not be detectable by Kepler, although earth itself would be.

It would help a lot if the Kepler website addressed the issue directly. Given the fact that a Jupiter size planet, in an earth like orbit, might possibly have earth sized moons, the omission of any talk of Kepler's ability to detect such moons seems a bit of an oversight.

Or maybe I missed something. Like on one of the education/outreach pages?
Holder of the Two Leashes
The hunt is now underway! Best wishes for success.

Status Report
tacitus
Indeed. I guess we're entering the "hurry up and wait" stage as we wait for the first announcements of hot Jupiters and the like.

I assume they won't be announcing anything for several months, even if they find some short period planets within the next few weeks?
Drkskywxlt
QUOTE (tacitus @ May 13 2009, 03:45 PM) *
Indeed. I guess we're entering the "hurry up and wait" stage as we wait for the first announcements of hot Jupiters and the like.

I assume they won't be announcing anything for several months, even if they find some short period planets within the next few weeks?


The NASA press release says Jovians could be announced "as early as next year". I assume that allows them time to confirm the planets with radial velocity measurements. Hot Jupiters should pop out of their data immediately I would think...
MahFL
I believe they said it would take a while before Earth like planets could be identified for certain, like 3 years. But I bet before three years they will say, "yes we have X number of dimming's that might be Earth like".
I expect many Earth like planets will be discovered.
centsworth_II
QUOTE (MahFL @ May 14 2009, 06:51 AM) *
... I expect many Earth like planets will be discovered.

It will be really interesting to see what ratio of Earth-like to Jupiter-like planets emerges over the years. To see how typical our solar system is in that respect.
ustrax
Drink southwesterner hollow fog grog
tacitus
From the latest Kepler Project Manager Update:
QUOTE
Meanwhile, scientists at NASA Ames Research Center are continuing their analysis of the instrument calibration data taken during Kepler's commissioning phase. The data are of very high quality and the scientists are very pleased with the precision of the data. Hundreds of eclipsing binaries and variable stars were seen in this data.

You know, it's just not fair to tease us like this!

smile.gif
Greg Hullender
They did say that the first science data would be downloaded on June 18. I'm not expecting anything at all before then -- and not expecting much for a while afterwards, I'm afraid. They've been pretty clear that they don't intend to be generous with their data.

--Greg
nprev
I'd bet that it's more an abundance of caution then a lack of generosity. Expectation management's gonna be pretty important; you know there will be worldwide banner headlines trumpeting "New Earth(s)". It will be tough enough for the Kepler team to explain to the general public that the planets are really far away so there will be no pretty pictures & definitely no physical voyages to them. ph34r.gif
tacitus
Yeah, I was just kidding with the tease comment. Even if they see Earth-like planet transits in the first data download, they're not going to announce anything until they've seen it happen two more times, which might not be for another two years. It is nice to know that the telescope is working extremely well, by the sound of it.

(And I am fine with vague updates on the quality of the data -- beats not hearing anything for a year or more!)

Mind you, there should be ample time before June 18th to see three transits from a hot-Jupiter, so we should be hearing something fairly soon after that. I guess the question is will they announce confirmed results before any papers are written?
Greg Hullender
More charitably, there's some chance they'll spend months tweaking their classification software. I built a speech recognizer this week (part of a seminar at UW) and found lots of surprises in how the data interacted with my models. Speech reco is a very well studied field, whereas the Kepler guys are out in new territory -- studying much smaller changes in brightness than anyone has before. It wouldn't surprise me if they spend months arguing about what the data actually mean. I can't blame them for not wanting to have that argument in public.

Even though it would be really, really cool to be part of that argument. :-)

--Greg
ustrax
Dandy sargent hunts with sonnet.
imipak
QUOTE (ustrax @ May 27 2009, 07:24 AM) *
Drink southwesterner hollow fog grog
QUOTE (ustrax @ Jun 1 2009, 11:08 AM) *
Dandy sargent hunts with sonnet.

Yes, let's hope "they" will bring the distant stars closer to our eyes...

(EDIT: don't get me wrong - I've no idea what they mean, just a dim idea about what they are... smile.gif )
ngunn
What are they? Crossword clues? Sub-intelligible advertising? Paranoia food (obvious to everyone except me)? Randomness lures (even nonsense may have a purpose)?

I tried anagrams, but shunt tonnes with Dynad garnets doesn't seem like an improvement.
Pavel
QUOTE (ngunn @ Jun 1 2009, 05:26 PM) *
What are they? Crossword clues? Sub-intelligible advertising?

I guess it's anagrams for ideas that could be either true or crazy. If the idea confirmed, ustrax will show us that he knew it already. For examples of anagram use in astronomy, see
http://www.hps.cam.ac.uk/starry/galtele.html
ustrax
Anagrams they are.

Half hip mahatmas broken limitedness.

wink.gif
hendric
Ha, I thought they were difficult phrases for Greg's speech analyzer. smile.gif
belleraphon1
Spitzer warm mission will contribute to verifying and analyzing Kepler planet candidates...

From AAS abstracts session 210: http://aas.org/meetings/aas214/schedule_scientific.php

Confirmation and Characterization of Kepler Mission Exoplanets: The Era of Rock and Ice Exoplanets
Topic: None selected
Heather Knutson1, D. Charbonneau1
1Harvard-Smithsonian Center for Astrophysics.
Presentation Number: 210.03
Facility Keyword: Spitzer
In the past 4 years, the combination of ground-based transit surveys and the remarkable stability of the Spitzer Space Telescope permitted the direct investigation of the atmospheres of one specific class of exoplanet, namely the Hot Jupiters. The NASA Kepler mission (scheduled for launch early this year) will have the ability to discover dozens of transiting exoplanets that are not currently detectable from the ground, including large numbers of transiting hot Neptune and hot Super-Earth exoplanets, as well as cooler Jupiters. Our Exploration Science program will measure the two-color planetary emission for 20 representative members of these previously inaccessible exoplanets, providing the first opportunity to directly test theoretical models of exoplanetary atmospheres of varying compositions (notably Super-Earths and Neptunes) and under differing levels of irradiation (cooler Jovian companions). The same data will permit an estimate of the orbital eccentricities, thus providing a test of models of the orbital migration and tidal dissipation for these various types of exoplanets. We will also use Spitzer to follow up Kepler-identified candidate terrestrial exoplanets to prove that these signals are indeed planetary in origin. By gathering single color time series spanning times of primary transit, we will exclude a significant source of astrophysical false positives (resulting from blends of triple star systems containing an eclipsing binary) that can precisely mimic an exoplanetary signature in the Kepler data. These infrared data will provide a crucial confirmation of the planetary nature of the most exciting terrestrial-planet candidates.

Craig
Holder of the Two Leashes
Here are a couple of web pages on the topic of exomoon detection:

Centauri Dreams

Royal Astronomical Society

Also, there is an interesting full length article on the topic in the July issue of Sky and Telescope, which is out now.


QUOTE (MahFL @ May 14 2009, 06:51 AM) *
... I bet before three years they will say, "yes we have X number of dimming's that might be Earth like".

I'm sure you're right. The very first download, due in just a few days, stands a good chance of having a small planet detection somewhere in the data. A long time before they sort out false detections, eclipsing binary backgrounds, and establish orbital periods, they should have a real good statistical idea of just how many earth class detections they are going to end up with.
ustrax
Infighters often reign.
ugordan
QUOTE (ustrax @ Jun 9 2009, 08:48 AM) *
Infighters often reign.

Yeah, I'm not getting any of that.

You tease.
remcook
I hate anagrams. I'll just wait till the official announcement. tongue.gif
ngunn
Enter, offering insight (please!).
Holder of the Two Leashes
QUOTE (ustrax @ Jun 3 2009, 05:53 AM) *
Anagrams they are.


Is the source material for the anagrams in English, or are you scambling sentences in Portuguese (or some other language) into English words?
Stu
QUOTE (ustrax @ Jun 3 2009, 11:53 AM) *
Anagrams they are.


Ok, now you're scaring me; you really sounded like Yoda there... laugh.gif
Greg Hullender
Is anyone else ready for an anagram moratorium? Or at least a separate anagram thread? I get excited to see a new post under Kepler, then annoyed that it's just another anagram.

--Greg
djellison
I'm with you Greg.
Hungry4info
Same here. I've begun to realise that if you don't have anything to report, don't tease us.
Got angered at CoRoT for teasing everyone with "hints of a 1.7 Earth-radius transiting planet" for a couple years before CoRoT-7b was announced.
Anagrams, cryptic information, (and sometimes, as with CoRoT-2 b, press releases) just serve to raise public hopes beyond that which can be satisfied by what the piece of news actually is. This will backfire some, causing some animosity toward the mission.

Anyone remember that? CoRoT-2 b's announcement?
"Oh you guys are going to love this, wait for it... wait for it... wait for it.... history will be made...
OH MY GOSH!!! We found a HOT JUPIER!! OMG! Can you believe that?"

NASA's announcement of the SWEEPS planets back in October of 2006 was almost as bad.

My point is that if you sit on data, make sure it's all good, and then release it out of nowhere, everyone's surprised, and pleasantly excited, and we all love the mission that much more. It's a lot better than a CoRoT-2 style let-down.

Edit: Besides, if the data is scheduled for a Jun 18 download, what on Earth (har har) is there to make an anagram about anyway?
stevesliva
QUOTE (Hungry4info @ Jun 10 2009, 03:19 PM) *
My point is that if you sit on data, make sure it's all good, and then release it out of nowhere, everyone's surprised, and pleasantly excited, and we all love the mission that much more. It's a lot better than a CoRoT-2 style let-down.


Are there worries about not being credited with discovery in these games? Does the Haumea tempest have people pre-releasing these discoveries in encrypted form?
Holder of the Two Leashes
QUOTE (Hungry4info @ Jun 10 2009, 02:19 PM) *
... if the data is scheduled for a Jun 18 download, what ... is there to make an anagram about anyway?


Ten days worth of calibration data, which could easily have picked up an exoearth or two if they are as common as has been assumed.

For those looking for substance, there is a new (well, two days old) Project Managers Update out.

Edit: I'd better mention that it would be impossible to confirm said planets if they were in anything remotely resembling a habitable zone. Merely that their transits would be present.

Also, I believe that if it's something you're not suppose to come right out and say, whatever it is, then best not to mention it at all.
Syrinx
QUOTE (Greg Hullender @ Jun 10 2009, 10:54 AM) *
Is anyone else ready for an anagram moratorium? Or at least a separate anagram thread?

eys.
remcook
QUOTE (Holder of the Two Leashes @ Jun 10 2009, 08:06 PM) *
Ten days worth of calibration data, which could easily have picked up an exoearth or two if they are as common as has been assumed.


Unless it's a starspot of course. It's hard to tell anything from just one transit. You need the follow-up observations. And if you have multiple transits in just 10 days then I think it's save to say it's not in the 'habitable zone'.
belleraphon1
No anagrams please! I am neither pleased nor amused by them.

This is not a game.... we are talking about getting real answers to questions this species has had since we first had minds to appreciate the sky.

Craig

Holder of the Two Leashes
QUOTE (remcook @ Jun 11 2009, 02:25 AM) *
Unless it's a starspot of course. It's hard to tell anything from just one transit. You need the follow-up observations. And if you have multiple transits in just 10 days then I think it's save to say it's not in the 'habitable zone'.


My edit in the post you are quoting (and which you left out) was made within the hour of my first posting it, and addressed both those issues.

Any true detection at this point is only going to be regarded as a candidate detection, but as was previously pointed out, all the true and false detections together, at some point early on, will add up to a number higher than just the statistically anticipated false detections. Without being able to say exactly which detections are real, the Kepler team will be able to say about how many planets they have in the data. Whether they share this information any time soon, or only want to release confirmed planets at a later date, remains to be seen.
Syrinx
We're less than two days away from the first science data downlink! I don't think anyone expects the data to be released for quite some time. But hopefully we'll have confirmation that it was at least received.
Holder of the Two Leashes
First, everything is OK, and the first precious load of science data is safely on the ground.

Back on June 15th, there was a hiccup when Kepler went into safe mode for a day and a half. Some science time was lost, but they anticipated having this happen a few times during the mission.

Download occurred on scheduel, and the quarterly spacecraft roll was executed successfully.

I expect that somewhere in download number one, there are a few small golden nuggets to pan for. But it'll take some more buckets of data to sort out the "fools gold" from the real.

Mission managers report

Syrinx
http://www.nasa.gov/mission_pages/kepler/n...m-20090707.html

QUOTE
On July 4, Kepler passed a point 12,500,000 kilometers (7,767,140 miles) from Earth. In a regularly scheduled communication with Kepler on July 2, engineers determined the spacecraft had entered safe mode.
[...]
Science data collected since June 19 were downloaded to ground controllers, the photometer was powered back on, and Kepler was reoriented back to its science data collecting attitude.
[...]
Engineers determined that this event was caused by a processor reset, as it was with a similar safe mode event on June 15. They continue to evaluate data from both events to determine their root cause.
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