Author Topic: NASA - Transiting Exoplanet Survey Satellite ( TESS ) updates  (Read 73186 times)

Offline jgoldader

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Thereís always a lot of calibration work that has to be done, both on the spacecraft side (pointing and such) and the instrument.  There could also be outgassing, and you have to wait for things to settle down.  Finally, itís one thing to run your PSF-fitting (photometry) and transit detection algorithms on simulated data, but you need to make sure everything works on real data.  All these things take time.  Iím sure the team is anxious to get data out the door, but Iím just as sure they want to get it right first.
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Offline jcm

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Thereís always a lot of calibration work that has to be done, both on the spacecraft side (pointing and such) and the instrument.  There could also be outgassing, and you have to wait for things to settle down.  Finally, itís one thing to run your PSF-fitting (photometry) and transit detection algorithms on simulated data, but you need to make sure everything works on real data.  All these things take time.  Iím sure the team is anxious to get data out the door, but Iím just as sure they want to get it right first.

Exactly. I don't know anything for sure, but my understanding is that they are still commissioning the instruments doing calibrations and so on, making sure they have everything they need. My guess is that the first science run will begin Jul 10 and complete a month later.
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Offline Alpha_Centauri

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I wouldn't expect anything straight away after commissioning either as presumably they'll be looking to do ground-based followup to reject false-positives.  This is a more serious issue for TESS over Kepler.

Offline Star One

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NASA - Transiting Exoplanet Survey Satellite ( TESS ) updates
« Reply #63 on: 06/26/2018 04:00 pm »
I wouldn't expect anything straight away after commissioning either as presumably they'll be looking to do ground-based followup to reject false-positives.  This is a more serious issue for TESS over Kepler.

In an article sourced from Astronomy Now magazine March 2018 principle investigator George Ricker stated that the first batch of discoveries will be ready to be released by the end of 2018. He also stated that it would begin the first part of its survey in June. With Tess launching later than expected you can probably just add a month onto these.
« Last Edit: 06/26/2018 05:21 pm by Star One »

Offline TakeOff

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Okay, so real science data will take a while. But when TESS will make its first perigee?

Offline theinternetftw

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According to the TESS Observatory Guide (PDF):

Quote
The instrument calibration phase nominally ends on day 55 after launch. TESS will then begin science collection with an initial science test orbit and data downlink. Science operations and the collection of data in the first observing sector are expected to start day 68 of the mission.

If that plan was followed, science operations started yesterday, June 25th.

[Edit: Just to be clear, I'd guess that Jonathan probably knows better than the guide, and that he thinks it's going to be another orbit before science ops start is a pretty good sign of that being how it is]

I've been watching the DSN and saw a 1Mb/s downlink from TESS on Sunday, June 24th. It looked like about 1.2GB of data was received. Don't know if that was the perigee for the initial test orbit or not. I know the downlink speed for TESS is supposed to be much higher than that, though (100Mb/s).  Right now though, it looks like TESS's fast rate is 1Mb/s, and it's slow rate is 16Kb/s.

when TESS will make its first perigee?

TESS has completed two 13.7 day orbits since its final adjustment maneuver.
« Last Edit: 06/26/2018 11:08 pm by theinternetftw »

Offline speedevil

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I wouldn't expect anything straight away after commissioning either as presumably they'll be looking to do ground-based followup to reject false-positives.  This is a more serious issue for TESS over Kepler.
Has any thought been given to timing the observations early on so GAIA and TESS fields overlap for a pointing?
Or did it not work out to be plausible/useful

Offline Alpha_Centauri

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I assume you mean K2 rather than Gaia, which is all sky?

Kepler's K2 can only observe in the ecliptic plane to maintain stability.  This is the one part of the sky TESS does not observe!

There will however be small overlaps on the edges of K2's fields, though I doubt the TESS obs have been designed to happen simultaneously.  Scientifically there isn't a huge benefit though, they're still going to want to do follow-up anyway as even Kepler can be fooled if the background eclipsing binary is close enough.

Edit: Here's a map of the overlaps (in red);
https://twitter.com/lacalaca85/status/910234769421676544
« Last Edit: 06/30/2018 05:50 pm by Alpha_Centauri »

Offline speedevil

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I assume you mean K2 rather than Gaia, which is all sky?
Gaia is all-sky, but it does not cover the whole sky at once, and has a much different scan than TESS.
The similar wavelength sensors (IIRC), and broadly comparable resolutions would seem to be a good check, if there was an overlap early in commissioning.

Offline Dao Angkan

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But the next Gaia data release won't be until after TESS has finished it's primary mission.

Offline Alpha_Centauri

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I don't see what benefit there would be to simultaneous Gaia-TESS observations.  Gaia has a considerably better pixel scale than TESS but Gaia would only provide a single epoch and thus not be able to characterise any background time-variant phenomena.  It would not be able to confirm TESS transits.
« Last Edit: 06/30/2018 07:27 pm by Alpha_Centauri »

Offline Star One

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But the next Gaia data release won't be until after TESS has finished it's primary mission.

TESS all being well I saw quoted can itís calculated last in operations for over thirty years due to its orbit.

Offline Dao Angkan

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http://sci.esa.int/gaia/58784-exoplanets/

Quote
Surveys to search for transiting exoplanets are usually designed so that the observations of the parent stars are frequent Ė to catch as many transits as possible. The way that Gaia surveys the sky means that it will observe each star an average of 70 times during the five years of the nominal mission but when and how often the observations are made will be determined by the scanning law and cannot be changed. However, if a star is orbited by a transiting planet, then a few observations acquired by the satellite during transits might be sufficient to obtain a detection.

Scientists predict that, with the precision of Gaia's photometric measurements [6], it will be possible to discover a few hundred to a few thousand transiting, massive planets of the hot Jupiter and very hot Jupiter types. These are gaseous giant planets, about the mass of Jupiter, that orbit their parent star at very short distances, much smaller than the distance of Mercury from the Sun, completing one orbit on time scales of a few days.

So TESS would have to change it's field to match that of GAIA, but what's the point when by the time that GAIA releases it's data TESS has already scanned all of it's fields?

Note that GAIA's exoplanet list won't be released until the end of 2022. It might be possible to match some single transits seen in both TESS and GAIA to narrow down the orbital period for longer period planets, but by then TESS should hopefully be well into it's extended mission, scanning fields for longer periods of time (there are several options for the extended mission).


Offline hop

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Another mission with the potential to overlap slightly with TESS is NEOWISE. One pole at least should overlap for any amount of time they are in simultaneous operation.

NEOWISE is supposed to end soon (or perhaps has already ended? IIRC seeing "June 2018" but can't find a good reference) when the orbit drifts into an orientation negatively impacted by scattered light.

Offline jebbo

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Plato should also overlap, given how long TESS might last.  In this case, TESS might be a reasonable "scout" for Plato, identifying interesting fields for Plato to stare at

--- Tony

Offline Tomness

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Quote
@LucaPlanets
9 hours ago

The orbit adjust burns of @NASA_TESS were 10 times more precise than expected! It was so good that the spacecraft has fuel for >20 years of stable operations (!!) #Exoplanets2

CROSS REFRENCING

Offline jebbo

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Early flight results have been downloaded and analysed and were previewed at Exoplanets2 here in Cambridge. But they are embargoed.

--- Tony

Offline Star One

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Early flight results have been downloaded and analysed and were previewed at Exoplanets2 here in Cambridge. But they are embargoed.

--- Tony

Are you allowed to say when to?

Online Svetoslav

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I do hope we won't have another Kepler debacle. I hope a reasonable period will be decided, and then the data will be distributed to 3rd parties and the public.

Offline Star One

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I do hope we won't have another Kepler debacle. I hope a reasonable period will be decided, and then the data will be distributed to 3rd parties and the public.

Completely agree with you there.

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