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Photometry of V725 TauP needed immediately

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發表於 2016-11-16 05:59:25 | 顯示全部樓層 |閱讀模式
[size=13.3333px]AAVSO Alert Notice 562

[size=13.3333px]November 15, 2016

[size=13.3333px]Photometry of V725 Tau[size=13.3333px]P[size=13.3333px] needed immediately

[size=13.3333px]Dr. Franco Giovannelli (Istituto di Astrofisica e Planetologia
[size=13.3333px]Spaziali di Roma) has requested AAVSO assistance in monitoring
[size=13.3333px]V725 Tau, the Be star in the high-mass X-ray transient
[size=13.3333px]A0535+26/HDE245770, in order to plan for the X-ray outburst that
[size=13.3333px]follows 8 days after the optical brightening that occurs at
[size=13.3333px]periastron passage.

[size=13.3333px]Periastron passage will occur on 16 November 2016, so coverage is
[size=13.3333px]needed beginning immediately and continuing for at least 15 days
[size=13.3333px]after periastron, until December 2.

[size=13.3333px]BVRI photometry - V is most important - is requested. V725 Tau has
[size=13.3333px]a range of V=8.88-9.47; visual and V observations in the AAVSO
[size=13.3333px]International Database show it between about 8.6 and 9.2 since
[size=13.3333px]late 2011, about 8.6-8.9 as of May 2016.

[size=13.3333px]Dr. Giovannelli writes: "The cadence [needed] is at least one
[size=13.3333px]photometric point each night, maybe averaged with several images
[size=13.3333px](or photoelectric points if photon counting photometers are used).
[size=13.3333px]However, if it is possible to get more points (2-3 in the same
[size=13.3333px]night) it is of course better. We are searching for variations of
[size=13.3333px]order 0.02-0.05 magnitudes. Sometimes these variations can reach
[size=13.3333px]about 0.2 mag depending on the state of the O9.7 IIIe star."

[size=13.3333px]Coordinates (2000.0): R.A. 05 38 54.57   Dec. +26 18 56.8

[size=13.3333px]Charts with a comparison star sequence for V725 Tau may be created
[size=13.3333px]using the AAVSO Variable Star Plotter (VSP, [size=13.3333px]https://www.aavso.org/vsp[size=13.3333px]).

[size=13.3333px]Please submit observations to the AAVSO International Database
[size=13.3333px]using the name V725 TAU.

[size=13.3333px]This campaign is being followed on the AAVSO Observing Campaigns
[size=13.3333px]webpage ([size=13.3333px]https://www.aavso.org/observing-campaigns[size=13.3333px]). A thread has
[size=13.3333px]been created on the Campaigns and Observation Reports forum at
[size=13.3333px]([size=13.3333px]https://www.aavso.org/content/v725-tau-observing-campaign[size=13.3333px]).


[size=13.3333px]This AAVSO Alert Notice was compiled by Elizabeth O. Waagen.

[size=13.3333px]----------------------------------
[size=13.3333px]SUBMIT OBSERVATIONS TO THE AAVSO

[size=13.3333px]Information on submitting observations to the AAVSO may be found at:
[size=13.3333px]https://www.aavso.org/webobs

[size=13.3333px]ALERT NOTICE ARCHIVE AND SUBSCRIPTION INFORMATION

[size=13.3333px]An Alert Notice archive is available at the following URL:
[size=13.3333px]https://www.aavso.org/alert-notice-archive

[size=13.3333px]Subscribing and Unsubscribing may be done at the following URL:
[size=13.3333px]https://www.aavso.org/observation-notification#alertnotices

[size=13.3333px]-------------------------------------------------
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