V405 Peg (RBS1955)
MDM 2.4m finding chart (click to get the full resolution)
The comparison star is the star SE to the target labeled 14.49 (I-band
A UBVI sequence of field stars is
available in tabular form.
Finding chart, list of field stars, light curves and spectrum below are adapted
Thorstensen et al. 2009, PASP 121, 465: V405 Peg: a nearby, low-luminosity
SDSS high state magnitudes: u=15.78 g=16.10 r=15.35 i=14.65 z=14.09
Low state magnitudes (Bessel): I=14.14, B ~ 17.9
Light curves (I-band) and optical spectra through high and low states
The orbital period is Porb = Pspec=4.263hrs
Low-state photometric period agrees with spectroscopic period.
No stable photometric pattern (I-band) observed in a high state. Photometric
periods appear and disappear.
Photometric support for XMM-Newton observations
XMM-Newton is scheduled with start time 2009-12-29, UT18:51:56. The
observations will last 44000 seconds, more than 12 hours, and cover
almost three orbital cycles of the binary. The optical monitor onboard the
satellite will be used in fast mode and serves as fast photometer in the
ultraviolet. Supporting ground-based optical photometry helps to uncover the
accretion state of the binary, update the optical ephemeris, and establish the
broad-band spectral energy distribution from the optical to the UV and X-rays
and thus uncover the true nature of the binary. Ideally, optical and X-ray
observations are performed simultaneously, weather and visibility constraints
may prevent this. We therefore ask for time-resolved, near-coincident
observations in I- and B-bands during the period December 27/28 to December
30/31. The I-band shall be used for comparison with the large body of existing
data, the B-band is expected to show the highest variability (orbital
variability and transition between high, low and intermediate(?) states). The
occurrence of high and low states cannot be predicted in advance and the
transition time scale between different states is likely days.
Potential observers are kindly asked to go for the shortest observation
times feasible depending on aperture and brightness of the target.
Data can be sent directly to firstname.lastname@example.org (PI of the XMM-observations)
Clear skies and Merry Christmas.
Thankfully, Axel Schwope