----------------------------------- Procyon 26 Ian 2017 01:12 Alerta AAVSO #428 ----------------------------------- AAVSO Special Notice #428 January 25, 2017 YZ Cnc Chandra observing window delayed 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 (https://www.aavso.org/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 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. Dr. Christian Knigge a informat AAVSO ca o perioada in care satelitul Chandra a fost reprogamata incepand de pe 5 februarie anul curent. Observatiile cu o densitate mare nu sunt necesare pana pe 2 februarie. La momentul respectiv AAVSO informeaza sa reluam observatiile (una sau mai mult, la distante mari de timp (probabil se refera la cateva ore) pe noapte). Observatiile sunt necesare pentru outburstului stelei YZ Cnc cu satelitul Chandra X-Ray. Sunt necesare observatiile vizuale, in filtru Johnson V sau nefiltrate cu zeropoint in Johnson V, alte benzi fiind acceptate dar nu sunt necesare. AAVSO va roaga sa raportati observatiile cat de repede posibil prin intermediul serviciului WebObs(https://www.aavso.org/webobs), in special daca observati steaua ca steaua YZ Cnc are magnitudea 13.8 sau mai stralucitoare vizual. Outbursturile normale ating magnitudinea vizuala ~12.0, iar superoutbursturile magnitudinea ~11.0-11.3 vizuala. Steaua YZ Cnc are outbursturi la 10-12 zile si super-outbursturi la 100-110 zile. Coordonate: R.A. 08 10 56.65 Dec. +28 08 33.2 VSX: https://www.aavso.org/vsx/index.php?view=detail.top&oid=4857