Skip to main content

Special Notice #417: CH Cygni B and V photometry urgently requested


June 3, 2016: 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.

Please report observations to the AAVSO International Database as CH CYG.

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 AAVSO Variable Star Plotter (VSP).

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.


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


A Special Notice archive is available at the following URL:

Subscribing and Unsubscribing may be done at the following URL:


Please support the AAVSO and its mission -- Join or donate today:

AAVSO 49 Bay State Rd. Cambridge, MA 02138 617-354-0484