Monitoring of AM Her urgently requested

PTS

AAVSO Alert Notice 517

April 2, 2015

Monitoring of AM Her urgently requested in support ofXMM-Newton and NuSTAR observations

Dr. Axel Schwope (Leibniz Institute for AstrophysicsPotsdam,

Germany) has requested AAVSO observers' assistance inmonitoring

the magnetic variable AM Her in support of upcomingXMM-Newton plus

NuSTAR (Nuclear Spectroscopic Telescope Array)observations.

The XMM-Newton observations are scheduled for 2015 April06

02:37:02-15:07:02 UT. The NuSTAR observations have notbeen made

final yet but are expected to run longer. A SpecialNotice will be

issued when the NuSTAR schedule is known.

Observers are requested to observe AM Her using standardBVRI

filters (V filter preferred). The preferred manner ofobserving is

to use only one filter and observe with the highestpossible time

resolution (aiming for a S/N=10). Dr. Schwope writes thattiming

accuracy is an issue for these observations and all CCDclocks need

to be synchronized via NTP.

Observations are requested nightly from now until April4, then

time series observations through April 8, and thennightly

observations through April 16.

The prototype of the class of magnetic cataclysmicvariables known

as polars, AM Her has "high" and"low" states, ranging approximately

V=12.7-13.8 in its high state and V=15.3-15.7 in its lowstate.

Currently it is in its high state at visual magnitude13.2 on 2015

March 30.107 UT (JD 2457111.607, G. Poyner, Birmingham,England).

Its orbital period is 3.1 hours.

To learn more about polars and AM Her, see the AAVSOVariable Star

of the Season web presentation "AM Herculis"

(http://www.aavso.org/vsots_amher).

Coordinates:  R.A.18 16 13.34   Dec. +49 52 04.1  (2000.0)

Charts with a comparison star sequence for AM Her may becreated

using the AAVSO Variable Star Plotter (VSP, http://www.aavso.org/vsp).

Please submit observations to the AAVSO InternationalDatabase

using the name AM HER.

This campaign is being followed on the AAVSO ObservingCampaigns

page (http://www.aavso.org/observing-campaigns).

Your filtered photometry is extremely important for these

observations, and your contributions are greatlyappreciated.

This AAVSO Alert Notice was compiled by Elizabeth O.Waagen.

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