Alert Notice 785: Monitoring of V452 Vul = HD 189733 requested

Note: HST observations were postponed. Please continue to monitor V452 Vul as instructed below until further notice.  -  Elizabeth O. Waagen, October 25, 2022

July 5, 2022

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Dr. Rob Zellem (NASA Jet Propulsion Laboratory) requests the assistance of AAVSO observers in monitoring the exoplanet host star V452 Vul (= HD 189733, exoplanet HD 189733b) in support of a HST/WFC3 observing campaign currently underway.

Dr. Zellem writes: "This campaign will be to monitor for stellar variability on HD 189733, the host star of a hot Jupiter exoplanet. These observations will crucially support an ongoing Hubble/WFC3 campaign to perform 2D spectroscopic mapping of this canonical exoplanet. The AAVSO observations will allow us to determine if variability is impacting the measured signal by Hubble or place constraints on any measured planetary variability. We hope that this AAVSO observing campaign will help shine additional light on the awesome work being done by AAVSO for the professional exoplanet community and hopefully result in additional observing run requests.

"Stellar monitoring should begin as soon as possible and continue through the end of August 2022. That will give us sufficient baseline for our Hubble/WFC3 observations."

All types of observations - CCD, DSLR, PEP, visual - are welcome. All filters and cadences are welcome. As Dr. Zellem states: "We are happy to take any variable star measurements that we can get! But the Hubble/WFC3 observations will be taking place in the near-IR (~1.1-1.7 um), so ideally filters closer to this wavelength range would be great. However, as stated above, we are happy to take all the data we can get, regardless of the filter and/or camera."

Observers interested in spectroscopy should contact Dr. Zellem (

Coordinates (2000.0): R.A. 20 00 43.71 Dec. +22 42 39.0  (from VSX page for V452 Vul)  
Range: 7.67 (0.03) V

Charts with comparison stars for V452 Vul may be created using the AAVSO Variable Star Plotter (VSP).

Please submit stellar variability observations using the name V452 Vul to the AAVSO International Database. Any transit observations should be acquired, processed, and reduced appropriately and submitted to the AAVSO Exoplanet Database.

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen using material provided by Dr. Zellem.


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