CYGNUS_X-1
Cyg X-1 is the prototypical wind-fed black hole high-mass X-ray binary. The initial XRISM/Resolve observation revealed, for the first time in the low/hard state, a high-resolution Fe-K spectrum with mildly blueshifted ionized absorption (~100 km/s), directly confirming structured photoionized wind material. However, the existing exposure sampled only a limited range of orbital phase and could not establish whether the observed Fe-K variability is stochastic or phase-locked to the 5.6-day orbital geometry. We propose a 240 ks XRISM observation covering one full orbital cycle. This program will provide the first phase-resolved Fe-K tomography of Cyg X-1.
obsid = 203046010 / Unique Observation/Sequence Number
object = CYGNUS_X-1 / Object name
pi_name = YAMADA SHINYA / Proposal Principal Investigator Name
ra = 299.591283832027 / Right Ascension (Pointing Position) (deg)
dec = 35.2018857588509 / Declination (Pointing Position) (deg)
roll_angle = 44.7867369301243 / Roll Angle (deg)
start_time = 2026-06-04T02:22:04 / Start Time of the Observation
stop_time = 2026-06-10T21:18:04 / Stop Time of the Observation
exposure = 317267.93097309 / Effective Total Observation Exposure (s)
public_date= 2099-12-31 / Public Date