Dr. Robert Zavala (USNO-Flagstaff) and collaborators request
observations of the bright variable star b Persei for the next two
weeks, in hopes of catching a predicted eclipse on 2015 January 15 UT.
This is a follow-up to the February 2013 campaign announced in Alert
Notice 476, and will be used as a photometric comparison for upcoming
interferometric observations with the Navy Prototype Optical
Interferometer (NPOI) in Arizona. Observers are asked to obtain
time-series observations beginning immediately, with the most critical
window of coverage being between 2015 January 9 and 2015 January 17 UT.

b Persei is located at the following (J2000) coordinates:

RA: 04 18 14.62 , Dec: +50 17 43.7

b Per is a bright star (V=4.598, B-V=0.054) and so is ideal for
observers with photoelectric photometers or those using DSLR cameras.
Telescopic CCD observers may also be able to observe by stopping down
larger apertures. Time-series observations with a V-filter are ideal;
other filters may be used, but multicolor photometry is not required.
For photoelectric photometry, we have assigned the following stars as
comparison and check:

Comparison star:
SAO 24412, RA: 04 06 35.044 , Dec: +50 21 04.55 ,
V=4.285, B-V = -0.013

Check star:
SAO 24512, RA: 04 16 43.087 , Dec: +53 36 42.47 ,
V=5.19, B-V = -0.05

DSLR observers may also find the nearby star SAO 39457 / HR 1330 a
useful comparison star; it is available via VSP as the "55" comparison
(V=5.456, B-V=0.219).

Dr. Zavala sends the following along with his request:

"[W]e wanted to try and involve AAVSO observers in a follow up to our
successful detection of the b Persei eclipse of Feb 2013, AAVSO Alert
Notice 476 and Special Notice 333.

Our goal now is to get good time resolution photometry as the third star
passes in front of the close ellipsoidal binary. The potential for
multiple eclipses exists. The close binary has a 1.5 day orbital period,
and the eclipsing C component requires about 4 days to pass across the
close binary pair.

For AAVSO observations a single filter would be fine, as our goal is to
imporve the timing resolution for the eclipse of the primary, and if
possible detect an eclipse of the B component by C. The primary eclipse
depth is 0.15 magnitudes. Photometry to 0.02 or 0.03 mags would be fine
to detect this eclipse.

The eclipse prediction date is based on one orbital period from the 2013
eclipse and is:

JD 2457033.79 = 2015 01 11 UT

We'd like to see a baseline light level before and after eclipse(s) so
observing roughly Jan 5-17 would be good. The period for high time
resolution, if possible by AAVSO observers, is Jan 9-13 UT. This
predicted eclipse time of minimum light is nominally daylight for the
U.S. and we have about a +/- 1 day or less uncertainty."

Please promptly submit all observations to the AAVSO via WebObs using
the name "B PER".