October 17, 2017: BRITE-Constellation (http://www.brite-constellation.at), a network of nano-satellites, is currently taking photometric observations of the Taurus field (full target list and field specifications given http://brite.craq-astro.ca/doku.php?id=taui). Within this field is CE Tau, a red supergiant with significant (0.5 mag) variations over timescales of months. Dr. Bert Pablo (AAVSO Headquarters) would like to supplement BRITE observations of this target with AAVSO observations with a cadence of 1-3 days over the course of the 6-month BRITE observing run (through March 6, 2018). The full importance of this project and its necessity is explained in a post on the AAVSO Discussion forum thread for this campaign (https://www.aavso.org/ce-tau-campaign).
CE Tau is a bright star (4.23 - 4.54V) and as previously stated shows significant variations, so it is a perfect target for DSLR observations, but it is also open to PEP (it is in the AAVSO PEP Section observing program) and CCD observers as well. However, due to its brightness, finding comparison stars is difficult without having a several-degree field of view. An added bonus of this large field of view is that several other BRITE targets will also be visible, including one with significant variations, the Be star V960 Tau (5.43 - 5.72 V). Both stars’ small amplitudes make observing the details of variation very difficult visually.
CE Tau: 05 32 12.75 +18 35 39.3
V960 Tau: 05 33 31.63 +18 32 24.8
For DSLR observers: data do not have to be changed to the standard Johnson/Cousins filters and should be reported as TG, TB, TR (all three filters are encouraged). Due to the brightness of the stars in question I was unable to find 6 comparison stars for ensemble photometry, but this is not necessary. The standard CCD technique of using 1 to 2 comparison stars is fine. As a secondary note, this star is very red and finding another star with an R magnitude of 2.5 is simply not feasible. Therefore, it will be necessary to use a star a couple of magnitudes fainter, but it is an important color for this star and therefore worth the effort. Three comparison stars are given here which have well-determined (if fainter) R magnitudes (all from source 28 BSM North):
66 05:45:11.56 18:42:15.5
67 05:29:19.14 18:21:56.4
68 05:31:39.22 18:14:39.0
For PEP and CCD Observers: There are already a predefined comparison (SAO 94554) and check (SAO 94700) star for CE Tau. You are also welcome to observe V960 Tau, but the main point here is that it is an excellent secondary target if it is in the same field of view. R band is encouraged, but this may be difficult as the stars with well determined R magnitudes are not close (though listed above in the DSLR section).
Accompanying this Alert Notice is an AAVSO finder chart for CE Tau; V960 Tau, the comparison stars, and the SAO stars listed above are identified on it. Other charts for this field may be created using the AAVSO Variable Star Plotter (VSP; https://www.aavso.org/vsp). You will need to select the ‘AB’ scale to include all the above comp stars in the chart.
Please submit observations to the AAVSO International Database using the names CE TAU and V960 TAU.
This AAVSO Alert Notice was compiled by Bert Pablo.
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