Observing Campaign: Photometry requested for Hat-P-23 in exoplanet study

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View: Details for Photometry requested for Hat-P-23 in exoplanet study

Abstract: Drs. Bradley Hutson (Arizona State University) and Robert Zellum (NASA Goddard Space Flight Center) request photometry in support of their exoplanet study of Hat-P-23. Dr. Hutson writes: “We have detected variability using TESS data, but it matches up suspiciously with the spacecraft’s momentum dump cadences. So we are trying to determine if the detected variability is caused by the space craft or if it is in fact, variable.”

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Submitting 45 time-series obs in V with magnitude STD at 0.004 across all observations which seems very stable and non-variant…but its just one short view of Hat-P-23.
Gary

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Submitted one time series and working on processing a second in V. No real variation in magnitude.

Phil Kuebler

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Hello everybody,

Doing a very quick light curve analysis of HAT-P-23, specifically trying to find a period, if any, gave me the following results.

For this analysis I used only the V observations, which sum 3306 up to the present time, this taking into account the past 169 days, although most of the observations lie within the time range asked for.

Period analysis by applying the Generalized Lomb-Scargle method:

The power spectrum is the following:

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image847×436 87 KB

This shows a peak in frequency 0.86118 c/d +/- 0.00019, which means a period of 1.16120 days. However, there are other peaks that although not with the same Θ value, are very close to it. The period is 0.05169 below the one published at the VSX.

Period analysis by applying the CLEANest method:

The power spectrum obtained is the following:

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This shows a peak (?) on frequency 0.88822 c/d +/- 0.00032 days and a Θ of 201.14.

However, there are very similar peaks in the graph that show slight variations, which might be due to observation cadences, and that could be as well be equally “valid” as the highest peak found with this method. Converting this frequency into a period, it results in a P ~ 1.12585, which is 0.08703 below of what is published at the VSX.

But periodicity means not variability.

By filtering the existing observations with the Johnson V filter to only consider those that have been transformed and that have an uncertainty < 0.03, we end up with the following light curve.

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The bulk of observations lie within the range of about 12.200 V to 12.135 V (I am disregarding only three observations that might be outliers), which is not such a significant difference in brightness (maybe?).

I cannot conclude that this star is not variable, but I suspect that the period being so close to one day and the light curve showing a difference in brightness of only 0.065 V leads me to think that the variability seen in TESS’s data was indeed due to “the spacecraft’s momentum dump cadences”. Want to add that some comp stars we regularly use are more variable than HAT-P-23.

Cheers,

Enrique Boeneker (BETB)

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I just uploaded 90 new observations from last night, in “v.” Does anyone know how long this request for data will last?

Tom (rth)

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I finished processing and uploading a 45 image run done on 11/11/24. There is no obvious variability in magnitude.

Phil