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  <VOEvent xmlns="http://www.ivoa.net/xml/VOEvent/v2.0" xmlns:voe="http://www.ivoa.net/xml/VOEvent/v2.0" version="2.0" role="observation" ivorn="ivo://archive.aavso/archive/voevents#alertnotice451" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.ivoa.net/xml/VOEvent/v2.0  http://www.ivoa.net/xml/VOEvent/VOEvent-v2.0.xsd">
    <Description xmlns="http://jabber.org/protocol/pubsub#event">
      Alert Notice from the AAVSO
    </Description>
    <Who xmlns="http://jabber.org/protocol/pubsub#event">
      <AuthorIVORN>
        ivo://archive.aavso/
      </AuthorIVORN>
      <Author>
        <shortName>
          AAVSO
        </shortName>
        <contactName>
          Richard C.S. Kinne
        </contactName>
        <contactEmail>
          rkinne at aavso.org
        </contactEmail>
      </Author>
      <Date>
        2012-01-27T16:00:16
      </Date>
    </Who>
    <Reference xmlns="http://jabber.org/protocol/pubsub#event" uri="http://www.aavso.org/publications_files/alerts/alert451.shtml" />
    <What xmlns="http://jabber.org/protocol/pubsub#event">
      <Param name="aavsoNumber" value="451" />
      <Param name="event" value="AAVSO Alert Notice 451: Monitoring of the Symbiotic Variable RT Cru Requested" />
      <Param ucd="meta.link.url" name="link" value="http://www.aavso.org/aavso-alert-notice-451">
        <Description>
          Link back to the AAVSO web page
        </Description>
      </Param>
      <Param ucd="meta.id" name="objectName" value="RT Cru">
        <Description>
          Standard name for the astronomical object
        </Description>
      </Param>
      <Param dataType="float" ucd="phot.mag" name="magnitude" value="10.7">
        <Description>
          Approximate magnitude of the object.
        </Description>
      </Param>
      <Param name="body">
        <Value>
          The symbiotic variable RT Cru has brightened in hard x-rays. Dr. 
Jeno Sokoloski, Columbia University, has requested AAVSO assistance 
in monitoring RT Cru both now and in the future to see if it is 
doing anything unusual in the optical. The Swift/BAT hard X-ray 
light curve shows RT Cru has apparently been gradually brightening 
over the past few years.  

Dr. Sokoloski writes: &quot;The hard X-ray emission from RT Cru suggests 
that the accreting white dwarf is close to the Chandrasekhar limit 
(e.g., Luna and Sokoloski 2007) and that it is therefore a candidate 
supernova Type-Ia progenitor.  Also, since it is a massive white 
dwarf accreting at a reasonably high rate, it is similar to T CrB -
so why isn't it a recurrent nova??

&quot;Fast photometry (to look for CV-like flickering from the accretion
disk) and optical spectroscopy would also be very interesting and
could potentially help us interpret the current hard X-ray
brightening.&quot;

Dr. Sokoloski requests time series photometry now for a few days, 
and then weekly or monthly observations for the forseeable future.
Visual observations are also welcome. At magnitude B=10.7 and 
R=11.100 it is too faint for BVRI photoelectric photometry, but at 
magnitude J=6.646 and H=5.583 it may be a suitable target for 
near-IR photometrists.

Coordinates: R.A. 12 34 53.74 Dec. -64 33 56.0 (2000.0)

Finder charts may be made using VSP (http://www.aavso.org/vsp).

Please report your observations to the AAVSO International Database 
using the name &quot;RT CRU&quot;.

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen.
        </Value>
      </Param>
    </What>
    <WhereWhen xmlns="http://jabber.org/protocol/pubsub#event">
      <ObsDataLocation>
        <ObservatoryLocation id="TOPOCEN" />
        <ObservationLocation>
          <AstroCoordSystem id="UTC-FK5-TOPO" />
          <AstroCoords coord_system_id="UTC-FK5-TOPO">
            <Time unit="s">
              <TimeInstant>
                <ISOTime>
                  2012-01-27T16:00:16
                </ISOTime>
              </TimeInstant>
            </Time>
            <Position2D unit="deg">
              <Name1>
                RA
              </Name1>
              <Name2>
                Dec
              </Name2>
              <Value2>
                <C1>
                  188.72391666667
                </C1>
                <C2>
                  -64.565555555556
                </C2>
              </Value2>
              <Error2Radius>
                0.0
              </Error2Radius>
            </Position2D>
          </AstroCoords>
        </ObservationLocation>
      </ObsDataLocation>
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