Special Notice #428: YZ Cnc Chandra observing window delayed

January 25, 2017: The beginning of the observing window for the Chandra TOO observations of the SU
UMa-type dwarf nova YZ Cnc that are the focus of AAVSO Alert Notice 565 and AAVSO Special Notice #427 has been delayed.

Principal Investigator Dr. Christian Knigge (University of Southampton) informs us that Chandra Mission Planning has informed him that the beginning of the Chandra-observable window for YZ Cnc has been delayed until 2017 February 5.

This means that the dense coverage requested earlier for YZ Cnc does not need to begin until February 2. At that time, please resume observing YZ Cnc closely (one to a few times, widely spaced, per night) until further notice, possibly through the end of the observing season. Your observations will be used to decide when to trigger the TOO observations, so they are crucial.

As mentioned in the earlier notices, YZ Cnc has normal outbursts about every 7-10 days, and superoutbursts about every 100-110 days. The astronomers are planning to use a superoutburst to trigger the TOO observations.

Observers will be informed when the Chandra observations have been carried out and the campaign ends. Visual and V or CV band observations are requested; other bands are welcome but are not essential. Please report your observations to the AAVSO via WebObs as soon after you make them as possible, especially if you see YZ Cnc at visual magnitude 13.8 or brighter. Typical normal outbursts reach visual magnitude ~12.0, and superoutbursts ~11.0-11.3. In recent years at minimum YZ Cnc has been ~14.6-14.8.

Coordinates (2000.0):  R.A. 08 10 56.65   Dec. +28 08 33.2

Charts: Charts with a comparison star sequence for YZ Cnc may be created using the AAVSO Variable Star Plotter (VSP).

Please submit observations to the AAVSO International Database using the name YZ CNC.

This campaign is being monitored on the AAVSO Observing Campaigns webpage and is being followed on the Campaigns and Observation Reports Forum at https://www.aavso.org/content/yz-cnc-observing-campaign.

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


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