AAVSO Alert Notice 570|
March 7, 2017
NR TrA (Nova TrA 2008) monitoring in support of XMM observations
Dr. Fred Walter (Stony Brook University) has requested AAVSO
observers' assistance in monitoring NR TrA (Nova TrA 2008) in
support of upcoming XMM Newton observations. The XMM observations
will take place 2017 March 13 06:21 through March 14 10:34 UT.
Dr. Walter writes: "NR TrA (Nova TrA 2008) is a compact eclipsing
system with a 5.5 hour period. It was a normal Fe II nova that,
upon reaching quiescence, took on the appearance of a super-soft
source in the optical high state, which suggests an extremely high
mass accretion rate. The optical spectrum is dominated by hot
permitted lines of O VI, N V, C IV, and He II. Some nova-like
variables have similar spectra, though generally without the hot
"Primary eclipse is broad - nearly 40% of the orbit - and deeper at
shorter wavelengths, which suggests the eclipse of a hot accretion
disk. Primary eclipse depth is about 1 mag at V. There appears to
be a shallow secondary eclipse.
"We have a day-long XMM observation of NR TrA scheduled starting at
0621 UT 13 March and running through 1034 UT 14 March. The primary
aim is to detect and characterize the eclipse at X-ray and UV
wavelengths. We will obtain low cadence BVRI/JHK observations with
"We request AAVSO support to obtain continuous photometric time
series simultaneous with the XMM observation. Any filters are
acceptable, but standard Johnson B, V or Cousins R, I are preferred.
Clear filters are acceptable. Differential photometry is acceptable,
as the shape and depth of the eclipse is of paramount importance;
we can calibrate after the fact. Time resolution better than 5
minutes and uncertainties (outside of eclipse) <0.02 mag are
"The current out-of-eclipse V magnitude is about 16.5. The B-V and
V-I colors are both about 0.3. The best ephemeris I have is:
minimum light at JD 55956.822 + 0.219109E
This is based on data from 2013-2015."
Dr. Walter adds that while obtaining exactly simultaneous
observations would be ideal and so preferred, obtaining a good
light curve within a few days of the XMM observations is crucial.
Beginning now, observers are requested to monitor NR TrA with
nightly snapshots through March 9, then switch to the cadence given
above and - paying particular attention to the XMM observation
interval - continue time series through March 18, and then return
to nightly snapshots through March 22.
Coordinates for NR TrA: R.A. 16 18 48.21 Dec. -60 27 49.2 (2000.0)
Charts: Charts with a comparison star sequence for NR TrA may be
created using the AAVSO Variable Star Plotter (VSP) at
Please submit observations to the AAVSO International Database
using the name NR TRA. IF YOU SUBMIT DIFFERENTIAL PHOTOMETRY, be
sure that in your data file, the MTYPE field reads DIF.
This campaign is being monitored on the AAVSO Observing Campaigns
webpage at https://www.aavso.org/observing-campaigns and is being
followed on the Campaigns and Observation Reports Forum at
This AAVSO Alert Notice was compiled by Elizabeth O. Waagen.
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