V404 Cyg observations needed tonight for Chandra observations

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V404 Cyg observations needed tonight for Chandra observations

文章 PTS » 週六 12 8月, 2017 06:46

AAVSO Alert Notice 592
V404 Cyg observations needed tonight for Chandra observations
August 11, 2017: Dr. Gregory Sivakoff (University of Alberta) and colleagues have requested AAVSO observers' assistance in observing the black hole X-ray transient LMXB V404 Cyg in support of Chandra observations taking place TONIGHT. The Chandra schedule is

2017 Aug 11 23:49:04.072 - 2017 Aug 12 13:42:14.730 UTC

The astronomers expect V404 Cyg (plus its unresolved interloper star ~1.4" away) to be around R ~ 16.2, V ~ 18.0 mag. Observers are requested to concentrate on R (or i') photometry, with the hope that "some observers will be willing to observe the source all night at as rapid a cadence as they can get and make a 10 sigma detection for R ~ 16.2, V ~ 18.0 mag. The Chandra and VLA data will likely be binned to 5 minutes, so we want to get better cadence than that.

"Observers are also requested please to use an aperture that is about 3 to 4 arcsec radius, if possible. There is another star which is 6 arcsec to the south of V404 Cyg that is about the same magnitude."

Two finding charts (links below) have been prepared by the astronomers with stars that should be used for calibration. Please make sure to calibrate using the magnitudes in the list below.

The star labeled C1 is the same as the 128 in the AAVSO sequence for V404 Cyg. Please use the stars in the list below for your observations. Be sure to indicate which comparison stars you used.

Star RA(J2000) Dec(J2000) Mags
C1 20:24:07.2 +33:50:52 B = 13.52, V = 12.82, R = 12.39, r' = 12.54, i' = 12.01
C2 20:24:06.7 +33:52:55 B = 18.41, V = 15.94
C3 20:24:04.7 +33:52:53 B = 17.88, V = 16.72
C4 20:24:02.5 +33:52:09 B = 20.44, V = 18.01, R = 16.07
A 20:24:05.7 +33:52:17 B = ? V = 18.78, R = 16.89, r' = 17.70, i' = 16.31
B 20:24:03.6 +33:52:15 B = ? V = 18.50, R = 16.52, r' = 17.37, i' = 15.86
C 20:24:05.4 +33:51:54 B = ? V = 17.93, R = 16.35, r' = 17.11, i' = 15.97
D 20:24:03.0 +33:51:29 B = ? V = 17.34, R = 14.98, r' = 15.98, i' = 14.03

The above mags are from Udalski & Kaluzny (1991), Casares et al. (1993), Wagner, Shrader & Starrfield (2000), IPHAS DR2 catalogue, APASS DR9, and some derived from the above papers using Faulkes images.

V404 Cyg chart 1

V404 Cyg chart 2

Dr. Sivakoff asks observers please to keep their data as he and his colleagues will likely contact observers for followup.

Coordinates for V404 Cyg: 20 24 03.83 +33 52 02.2 (J2000.0)

Please report observations to the AAVSO International Database using the name V404 CYG. Be sure to include error values and comparison star information.

This observing campaign is being followed on the AAVSO Campaigns and Observing Reports online forum at https://www.aavso.org/v404-cyg-chandra- ... s-aug-2017

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

----------------------------------
SUBMIT OBSERVATIONS TO THE AAVSO

Information on submitting observations to the AAVSO may be found at:
https://www.aavso.org/webobs

ALERT NOTICE ARCHIVE AND SUBSCRIPTION INFORMATION

An archive of Alert Notices is available at the following URL:
https://www.aavso.org/aavso-alert-notic ... iscoveries

Subscribing and Unsubscribing may be done at the following URL:
https://www.aavso.org/observation-notif ... ertnotices

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