Affiliation
American Association of Variable Star Observers (AAVSO)
Fri, 01/17/2020 - 16:08
If I am trying to model what might be a transit event of (possibly) a planet with an unknown orbital period, what do you enter as the orbital period in the "Data Set 2 Fit Settings" window of AIJ? This orbital parameter is not fit. It must be input. Do you simply try different periods to see what seems to give the best fit?
Brad Walter
Hi Brad,
Curious how you happened to detect a transit event for a planetary system with an unknown period-luck? As far as putting in an orbital period in AIJ, I would suggest trying values from 1 to 10 and see if there is much difference in the model fit results. How will you observe the next instance of a transit without knowing the period?
Dennis
Dennis,
Thanks for the optimism, but it is far from certain I have detected a transit of an unknown exoplanet. I may have detected an event that maybe a transit, but one observation is only an event worth following up as an indication that something might be there.
My question was simply about the mechanics of using AIJ. By generating light curves with a range of periods I found changing the period over a wide range has only small effect on BIC, at least in this case.
Discovering a transit would be lucky but not too curious. The Habitable Exoplanet Search Project is conducting intensive observing of selected K and M class stars thought to be good candidates for discovering planets through intensive and extended observation. Sort of an amateur WET for exoplanets that might be missed by very small aperture telescopes or by short observation periods. A three-month campaign just started for GJ 3470 that has one known super-Earth very close to the star. I have done four 3-hour to 5-hour runs on this star since 12/31 at PJMO. Weather has not been cooperating. This observation doesn't align with a transit or secondary eclipse of GJ 3470 b. However, it is about at the limit of our detection capability
I think the potential for success of the campaign will depend heavily on observation coverage. Over 30 amateur observatories around the world have signed up for the project including several AAVSO members, but the coverage is incomplete so far. Less than a dozen observing runs have been submitted for the first half of January.
Brad Walter