Optical Photometry and Spectroscopy of V635 Cas / 4U0115+63
ATel #9172; I. A. Steele (Liverpool JMU)
on 20 Jun 2016; 12:56 UT
Credential Certification: Iain Steele (iainsteele@mac.com)
Subjects: Optical, Binary, Neutron Star, Transient, Variables, Pulsar
A programme of occasional monitoring of High Mass X-ray binary (HMXRB) stars is underway at the Liverpool Telescope (La Palma).
The HMXRB 4U0115+63 has recently been reported in X-ray outburst (Atel #9149, Atel #9159). A giant outburst also occurred in October 2015 (Atel #8179).
Here I report the results of optical (R band) photometry and medium resolution spectroscopy of the optical counterpart (V635 Cas) obtained with the IO:O and FRODOSpec instruments over the last ~2 years.
DATE EW (Halpha) Rmag
20140913 <1 14.64
20141107 <1 14.64
20151127 9.5 14.30
20151219 9.2 14.30
20151225 7.4 14.31
20160525 6.3 14.08
20160619 7.5 14.03
H alpha equivalent widths are reported such that a positive value indicates emission. The 2014 spectra show neither emission or absorption within the limits of measurement. The spectra from 2015 onwards all show Halpha emission.
Photometry was carried out relative to the R2 magnitudes of the two USNO-B1 stars 1537-0047955 and 1537-0047968.
The source can be seen to have brightened by ~0.6 magnitudes over the last two years in the R band.
Liverpool Telescope