Single Transits

Should PLATO have separate multi vs single pipelines? (And why would this matter?)

  • Not planned to be separate pipeline – small number of modules possible to be turned on/off if mono?
  • Detection may need seperate route (as criteria on detection may be >2 planets)
  • TESS has two detection pipelines – mono vs multi.
  • Does SNR threshold need to be different for monos vs periodic (eg BLS). (Remember that detected transits have to be removed from LC sent from EAS to SAS. Better to retain transits at moderate SNR so that they can be removed, then reduce their rank as potential planets.)
  • Multiple detection pipelines already predicted
  • For vetting/ranking some steps (e.g. search for secondary/phase/etc) not useful.

Will we gain additional period constraints from TESS + PLATO lightcurves?

  • Possibly 2 years of TESS overlapping lightcurves for large proportion of PLATO field
  • Does PLATO want to overlap with TESS continuous viewing zone? Or avoid them?
  • Data from past (e.g. TESS) transit surveys should be used when modelling monos to constrain period. (the response: this is already going to happen)

Can we place priors on the eccentricity from transit asymmetry? What precision would be required?

  • Simulations now will show what the SNR threshold of monotransits would be needed to detect this.
  • Don’t expect it for 90% of monotransits – likely only long-period giants.
  • Also, many transit models include this effect anyway, so if it is there the model may find it – i.e. no prior needed!

What should the criteria be for following up monotransits?

  • Be scientifically more interesting than other candidates
  • Follow-up possibilities: low-res RVs, high-res RVs, photometry, high contrast imaging, Ariel as photometer.
  • Depends on period prediction – if short enough orbit that we’re likely to re-detect a transit, we can wait.
  • We also want follow-up simultaneous with RVs and PLATO for an orbit.
  • Scientific interest / observing cost.
  • Mono-transit of a planet with a moon !
  • Mono-transit in a multiple system (like HIP41378)

If PLATO sees one transit and is predicted to observe only one more, is there anything we should do to prepare (simultaneous observing or early RV?)

  • May not have good enough period prediction (especially with eccentricities)
  • Probably can’t start unless we’re sure it’s real – may only be possible for (extremely) high SNR, and other small candidates need 2 transits to be sure!
  • Want to start RVs early (with simult photometry) but only for targets we are sure are real.
  • Doppler RM effect could confirm small planets during 3rd transit (ie after PLATO)

Are there other good ways constrain period (except lightcurve-only)?

  • Limit from inner planet dynamics (stability)
  • Limit from outer planet dynamics (e.g. longer-period Gaia or RV planet suggests transiting planet must be interior)
  • Non-transiting inner planets are a limitation

When should we stop observing monos (expensive observationally)
CoRoT monotransits were 90% FPs.
Want an accurate false positive probability for monos


Hugh Osborn
Melvyn B. Davies
Ben Cooke
Hannu Parveinen
David Anderson
Giampaolo Piotto
Guy Rixon
Paul A. Wilson
Joshua Pepper
Dan Bayliss
Peter Wheatley
Geza Kovacs
Stephane Udry
Magali Deleuil
Dominic Ford
Alex. Santerne (remote from the train)