(cba:news) Fwd: AAVSO Alert Notice 625: ASASSN-18ey = MAXI J1820+070 coverage needed for VLT and XMM

Joe Patterson jop at astro.columbia.edu
Thu Mar 22 09:09:53 EDT 2018

Hi CBAers,

This is right up our alley too - not just for the HST window, but for 
time series after the HST observation also.  Since everyone will have 
airmass problems in the eastern predawn sky, feel free to stretch your 
limits if you have a decent night - maybe as far as 3 airmasses.  Pick 
it up as soon as you can.  I know it conflicts somewhat with the CR Boo 
alert I just sent... but give the MAXI priority if it's available for 
observation. With such a short observation window, there may be pretty 
scant data obtained.


-------- Forwarded Message --------
Subject: 	AAVSO Alert Notice 625: ASASSN-18ey = MAXI J1820+070 coverage 
needed for VLT and XMM
Date: 	Wed, 21 Mar 2018 19:37:18 +0000
From: 	AAVSO <aavso at aavso.org>
Reply-To: 	AAVSO <aavso at aavso.org>
To: 	jop at astro.columbia.edu

AAVSO Alert Notice 625: ASASSN-18ey = MAXI J1820+070 coverage needed for 

   AAVSO Alert Notice 625

     *ASASSN-18ey = MAXI J1820+070 coverage needed for VLT and XMM*

/*March 21, 2018*/: Dr. Tom Maccarone (Texas Tech University) has 
requested AAVSO observers' assistance in monitoring the outbursting 
black hole X-ray binary ASASSN-18ey = MAXI J1820+070 in support of VLT 
and XMM observations scheduled for:

*29018 22 March 08-09:30 UT  and  29 March 08-09:30 UT*

V time series are requested, with as short a cadence as possible 
(ideally, a time resolution of 0.1 second or better).

Please see /AAVSO Alert Notice 624/ 
for more information about this object.

ASASSN-18ey = MAXI J1820+070 has a published optical range of 12.5 CV - 
18.3: V. The most recent observations submitted to the AAVSO 
International Database are:

2018 Mar. 20.38034 UT, 12.557 CV +/-0.015 (F.-J. Hambsch, Mol, Belgium);
20.38014, 12.341 CV +/-0.014 (Hambsch);
20.37994, 12.511 CV +/-0.016 (Hambsch);
20.37973, 12.426 CV +/-0.015 (Hambsch);
20.37953, 12.413 CV +/-0.015 (Hambsch);
20.37934, 12.535 CV +/-0.016 (Hambsch);
20.37913, 12.485 CV +/-0.016 (Hambsch);

Coordinates (2000.0):  R.A. 18 20 21.95   Dec. +07 11 07.3

Charts with a comparison star sequence for ASASSN-18ey may be created 
using the AAVSO Variable Star Plotter (VSP) 
You may use either ASASSN-18ey or MAXI J1820+070 as the name when 
creating a chart.

Please submit observations to the AAVSO International Database using the 
name ASASSN-18ey.

This observing campaign is being followed on the AAVSO Time Sensitive 
Alerts online forum at 

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

Information on submitting observations to the AAVSO may be found at:


An Alert Notice archive is available at the following URL:

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