CH Cygni B and V photometry urgently requested

Exoplanet occultation, asteroid occultation,
solar research, comet observation, astrometry, etc.
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CH Cygni B and V photometry urgently requested

文章 PTS » 週六 04 6月, 2016 06:45

AAVSO Special Notice #417

June 3, 2016

CH Cygni B and V photometry urgently requested

Dr. Margarita Karovska (Harvard-Smithosonian Center for Astrophysics)
is urgently requesting B and V photometry of the symbiotic variable
CH Cyg from now until at least the end of August. Observations made
twice a week are sufficient; time series observations are not needed.
Spectroscopy would also be very welcome and appreciated.

The AAVSO has had a campaign on CH Cyg for Dr. Karovska ongoing for
the past several years (links below). However, Dr. Karovska is
making this urgent request now because the most recent AAVSO
observations show that the B light curve is declining considerably
more rapidly than the V, and it is extremely important to follow
this activity. Both B and V are needed to keep track of the
relative rates of dimming.

Until the campaign launched by the AAVSO at Dr. Karovska's request
a few years ago, there was little coverage of CH Cyg in B, so its
complex longterm behavior in that band is not well known. Thus,
obtaining solid coverage in B (and in V for correlation) is vital.

Visual observations have been valuable throughout this campaign and
visual observers are encouraged to continue their observations.

Information on the CH Cyg campaign may be found in: AAVSO Alert
Notice 454 ( and AAVSO
Special Notices #267, #268, #294, and #320
(, -268, -294, -320).

Please report observations to the AAVSO International Database as

Coordinates: RA 19 24 33.07 Dec. +50 14 29.1 (J2000.0)

Charts with a comparison star sequence for CH Cyg may be plotted
using the Variable Star Plotter (VSP) at

This campaign is being followed on the AAVSO Observing Campaigns
page (

Thank you for your astronomical efforts and valuable contributions!

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


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