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Special Notice #427: Please continue YZ Cnc coverage for Chandra TOO observations

January 23, 2017: The observing campaign is continuing for the SU UMa-type dwarf nova YZ Cnc. In AAVSO Alert Notice 565, Dr. Christian Knigge (University of Southampton) and colleagues requested AAVSO coverage in support of Chandra X-ray observations to be carried out via a Target of Opportunity (TOO) triggering when the system was in a suitable outburst.

Observers have been providing excellent coverage of YZ Cnc - very much appreciated by Dr. Knigge and colleagues - but unfortunately, for logistical reasons, Dr. Knigge was not able to trigger during the recent series of outbursts and superoutburst.

Thus, it is essential to keep up the dense coverage of YZ Cnc that observers were providing over the past month. Please continue 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.

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 at https://www.aavso.org/observing-campaigns 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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