Photometry (and spectroscopy) requested for GK Per
Abstract:
GK Per, a known post nova, shows dwarf-nova outbursts. It becomes very bright in optical and X-rays during outbursts. We aim to identify the mechanism of quasi-periodic oscillations (QPOs) in this object, which are strong around the outburst maximum, by analyzing the iron line complex resolved by XRISM. XRISM is an X-ray satellite capable of obtaining high-resolution energy spectra and highly time-resolved light curves, which was launched in 2023 by JAXA. We have to trigger observations as soon as possible once we confirm GK Per will reach the maximum brightness in 10 days after this system becomes brighter than 11.5 mag. We have to predict when GK Per reaches the outburst maximum by using daily monitoring data at the rising phase. The outburst in this system usually continues for 70 days. The XRISM TOO has been triggered and observations are scheduled from August 8th to August 12th.
Justification:
M. Kimura writes: We use the monitoring data to determine the XRISM observational windows. Also, QPOs are observable in optical. Continuous photometry around the outburst maximum is helpful for identifying the QPO phase. Moreover, we would like to obtain the orbital motion of the white dwarf in this object from X-ray spectroscopy. He II emission line is possibly observed in optical, which may trace the white dwarf motion. We would like to check the consistency between the X-ray and optical measurements for the radial velocity of the white dwarf. Since the orbital period is very long, 2 days, taking a few spectra with intervals of a few hours per night is preferable. Spectroscopy is optional, but we are grateful if you are interested in it. The XRISM TOO has been triggered and observations are scheduled from August 8th to August 12th. Special attention to this time window would be appreciated
Requested Data Types:
Spectroscopy, Photometry
Targets
| Name | Magnitude | Variability Type | Photometry Notes | Spectroscopy Notes |
|---|---|---|---|---|
| GK Per | 0.20 | NA/DQ+UG |
Cadence: Hourly Precision: 100 mmag |
Cadence: Hourly Resolution: 5000 Desired SNR: 15 |
Spectroscopy Lines:
He II (4686.0 Å), H-alpha (6563.0 Å)
Photometry Filters:
V (Johnson)
Comparison Stars:
Finder charts with comparison stars may be created using the AAVSO Variable Star Plotter (VSP).
Co-Authorship
Observers are eligible for co-authorship.
Additional Observer Input:
Not provided
Additional Submission Location:
Not provided
Notes:
No public notes