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Gaia16aye microlensing event monitoring urgently requested

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發表於 2016-9-21 05:35:08 | 顯示全部樓層 |閱讀模式
[size=13.3333px]AAVSO Alert Notice 552
[size=13.3333px]September 20, 2016

[size=13.3333px]Gaia16aye microlensing event monitoring urgently requested

[size=13.3333px]Dr. Kirill Sokolovsky (National Observatory of Athens and Sternberg
[size=13.3333px]Astronomical Institute, Moscow State University), has requested
[size=13.3333px]AAVSO assistance in monitoring the ongoing microlensing event
[size=13.3333px]Gaia16aye beginning immediately to catch transient behavior
[size=13.3333px]occurring now and continuing through the end of October (or until
[size=13.3333px]further notice).

[size=13.3333px]Dr. Sokolovsky writes: "Gaia16aye was first identified as an
[size=13.3333px]unusual variable object by Gaia on 2016 August 5 (V. Bakis et al.,
[size=13.3333px]ATel #9376, [size=13.3333px]http://www.astronomerstelegram.org/?read=9376[size=13.3333px]) and it
[size=13.3333px]was later realized that its achromatic light variations are
[size=13.3333px]consistent with being caused by microlensing of a distant M-type
[size=13.3333px]giant star by a binary star system (possibly consisting of main
[size=13.3333px]sequence dwarfs) crossing the line of sight. The complex geometry
[size=13.3333px]of the lens causes multiple brightness peaks corresponding to
[size=13.3333px]caustic crossings. According to preliminary modeling, the object's
[size=13.3333px]variability was noticed during decline after the first caustic
[size=13.3333px]crossing. The second brightness peak was observed on August 13 and
[size=13.3333px]the third peak on September 19. The source is expected to decline
[size=13.3333px]quickly in next days from its current magnitude V~14 to reach the
[size=13.3333px]plateau around V~16 between the caustics, in order to start rising
[size=13.3333px]again to cross the caustic in one or couple of weeks (L. Wyrzykowski
[size=13.3333px]et al., ATel #9507, [size=13.3333px]http://www.astronomerstelegram.org/?read=9507[size=13.3333px]).
[size=13.3333px]A well-sampled lightcurve of the microlensing event, especially
[size=13.3333px]during the caustic crossing, is needed to constrain geometry and
[size=13.3333px]some physical parameters of the lens and the lensed star.

[size=13.3333px]"CCD observations of Gaia16aye using any subset of B, V, Rc, Ic, g,
[size=13.3333px]r, i filters are requested starting immediately and continuing for
[size=13.3333px]about four weeks (until the decline from the expected next caustic
[size=13.3333px]crossing). If the object is at its bright state around V~14, time
[size=13.3333px]series observations are needed. If the object is found at the
[size=13.3333px]plateau level around V~16, one-two observations per night are
[size=13.3333px]sufficient. Unfiltered CCD observations are also useful if
[size=13.3333px]photometric measurements are collected during multiple nights
[size=13.3333px](otherwise it would be difficult to match the unfiltered
[size=13.3333px]measurements to the data collected by other observers).

[size=13.3333px]"Observers are asked to... [reduce their data in their usual way
[size=13.3333px]using] UCAC4 601-089811 as the comparison star and submit
[size=13.3333px]observations to the AAVSO International Database using the standard
[size=13.3333px]procedure." UCAC4 601-089811 is the 145 comparison star in the
[size=13.3333px]AAVSO sequence for Gaia16aye.

[size=13.3333px]Observers are also requested to upload their calibrated
[size=13.3333px](dark and flat-field corrected) images to the anonymous FTP server
[size=13.3333px]ftp://scan.sai.msu.ru/uploads/[size=13.3333px] for semi-automated processing with
[size=13.3333px]the Cambridge Photometry Calibration Server pipeline."

[size=13.3333px]Coordinates (2000.0): R.A. 19 40 01.13  Dec. +30 07 53.4

[size=13.3333px]Charts with a comparison star sequence for Gaia16aye 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]Creating an 'e' or 'f' scale chart is recommended.

[size=13.3333px]Please submit observations to the AAVSO International Database
[size=13.3333px]using the name Gaia16aye (there are no spaces within the name).

[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/gaia16aye-microlensing-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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