17 citations
4 papers
The permanent tide and the International Height Reference Frame IHRF
Jaakko Mäkinen
The International Height Reference System (IHRS) adopted by the IAG in 2015 contains two novelties. First, the mean-tide system is adopted for handling the permanent tide. Second,…
Simultaneous optical and near-IR photometry of 4U 1957+115 - a missing secondary star
Pasi Hakala, Panu Muhli, Phil Charles
We report the results of quasi-simultaneous optical and NIR photometry of the low-mass X-ray binary, 4U 1957+115. Our observations cover B, V, R, I, J, H and K-bands and additional…
Phase-resolved optical and X-ray spectroscopy of low-mass X-ray binary X1822-371
A. Somero, P. Hakala, P. Muhli +2
(Abridged) X1822-371 is the prototypical accretion disc corona X-ray source, a low-mass X-ray binary viewed at very high inclination, thereby allowing the disc structure and extend…
Fast Optical and X-ray Variability in the UCXB 4U0614+09
Pasi Hakala, Phil Charles, Panu Muhli
We present results from several years of fast optical photometry of 4U0614+091 (V1055 Orionis), a candidate ultracompact X-ray binary most likely consisting of a neutron star and a…