HD 139966 is an RR Lyrae star, previously incorrectly identified as an
eclipsing binary. It is part of the multiple system HH Nor. Time series
spectra are required to cover several pulsation cycles.
HH Nor (RA=15:43:29.4 Dec=-51:50:37.5) is actually a
visual double star, there is an eclipsing binary nearby (separation is 12''6).
The brighter one (changing betweeen 8.8 and 9.3 mag) is the RR Lyrae
component and has the designation HD139966. A
finder chart is provided to aid
in locating the correct target.
The pulsation period is ~0.6 days.
Preferred wavelength range is 5800-6700A
Ideally R > 6000, S/N at least ~40-50.
If limited by instrumentation, it is preferable to sacrifice R for wider
wavelength coverage, down to a limit of R ~ 3500.
Please keep integrations below 1800 seconds to ensure temporal changes
are not lost.
Please take accompanying spectra of the RV standard alp TrA (HD150798) for all observations.