Proposal #578

I am submitting a proposal for an intense but short campaign related to my ongoing project, Proposal #467.

The motivation follows, extracted from Dr. Dirk Froebrich's (University of Kent, Dublin, Ireland) communication with the project participants. HOYS is the acronym for the Hunting Outbursting Young Stars project (https://hoys.space/), a Citizen Science initiative whose P.I. is Dr. Froebrich.

“During our investigations of the HOYS data, we have identified a quite unusual object, the star 2MASS J05393511-0247299, also identified as ATO J084.8963-02.7916, a T Tauri Star. It is situated in the Sigma-Ori target region of the HOYS Citizen Science initiative. Analysis of the light curve shows that it has two dominant periods, close together. These are either near two days, or near 16 hours. Due to our usual cadence of about one day, the light curve looks a bit like an interference pattern with beats roughly every 23 days.
To determine which set of periods is correct, we need more than once-a-night coverage. Thus, we aim to run a campaign of the field during the next best, moon-free period of visibility of the source from 23.11.2024. to 08.12.2024. We would like every participant to take images in all available broad-band filters once every hour, for the entire night. This should then settle the periods, especially if we combine observations from Europe and America (unfortunately we still lack participants in Asia).
The target for this campaign, ATO J084.8963-02.7916, a T Tauri Star, is at R.A. 05 39 35.1, Dec. -02 47 29.9.
We also aim to take some high-resolution spectra of the object to identify what is causing this behavior - this is the only source in our entire sample that is behaving like this. Current thoughts on the nature of the object range from a binary system with spots, extreme differential rotation and spots, spots, and a warped disk, to a combination of spots and pulsations. All of which have their problems explaining the current data, however.”

Therefore, I would like to have observing time as follows, as a new proposal, or within Proposal # 467, as you find fit:

Main target: ATO J084.8963-02.7916 -- T Tauri Star at R.A. 05 39 35.1, Dec. -02 47 29.9
Or: the sigma Ori cluster at R.A. 05 38 45, Dec. -02 36 00, but including the main target’s position in the FOV.
Observing period: every night from November 23 until December 8, 2024.
Cadence: one image with each filter every hour for the length of the night.
Exposure: 300 seconds (each filter).
Note: the fluxes are V 14.33 [0.01], R 13.53 [0.02]), and its spectral type is K5.5.
Filters: B-V-R-I.
Optics: any available AAVSOnet Bright Star Monitor telescope with clear skies, especially those in Australia, but also the BSMs in the USA.