AAVSONet proposal for TU Tau, submitted by Robert Buchheim (BHU) 8-10-2023
Target name: TU Tau (aka WDS J05452+2425AB, aka 000-BBK-105) = 000-BBK-105
RA= 05 45 13.73 = 86.30721
Dec= +24 25 12.4 = +24.42011
Min mag≈ 8.8 (V) Max mag≈ 7.7 (V) per VSX
This is a follow-on effort to Proposal #287.
Why this target? TU Tau is a binary system comprised of a Carbon star, and an early-type companion (spectral type A). AAVSONet photometry under Prop #287, along with spectroscopic monitoring, provided the first evidence for a probable eclipse in TU Tau (paper submitted, in review). At the end of the observing season in April 2023, the eclipse was still underway.
Goal: The purpose of this follow-on effort is to re-start photometric observations of TU Tau as soon as it is observable before morning twilight (mid August), to assess the status of the probable eclipse. We are also re-starting spectroscopic monitoring. The onset of the probable eclipse was indicated by photometric fading (particularly in B-band) and changes to the spectrum between 3500 - 4500Å. Contemporaneous photometry and spectroscopy will highlight the photometric signal of the eclipse, and will allow us to flux-calibrate the spectra, thereby correlating spectral changes with brightness changes.
Requested observations: I request B-V-R observations of this star every two to three days, beginning August 15 and continuing through October 15, 2023. At the start of this campaign, the target will be barely 30 deg elevation before astronomical twilight.
The observations under Proposal #287 were made at NH2, with the following exposures: B-band =60 sec, V-band= 15 sec, R-band= 10 sec, two images in each filter. These exposures were satisfactory. For Proposal #287, the telescope aiming was offset from the target in order to accommodate the then-available comp stars. The offset is no longer necessary, since Comps 98 and 107 are now available – please place the target at the center of the image for this run.