Alert Notice 584: Monitoring of PDS 110 requested to cover upcoming eclipse by exoplanet

Note: This campaign is officially over, but the astronomers would appreciate it very much if observers could make an occasional observation of PDS 110.  EOW March 29, 2018

Note: This Alert Notice was edited to add the magnitude range of PDS 110. EOW

June 21, 2017: Dr. Joey Rodriguez (Harvard-Smithsonian Center for Astrophysics), Dr. Hugh Osborn (University of Warwick), Dr. Matthew Kenworthy (Leiden Observatory), and colleagues have requested AAVSO assistance in monitoring PDS 110 (HD 290380), a very interesting young star that may have a large orbiting body with an extremely large ring system (on the order of 200 times wider than that of Saturn). An eclipse of PDS 110 is expected in mid-September 2017, and monitoring is requested through October.

PDS 110, a member of the Ori OB1a association, was observed with the SuperWASP and KELT surveys. Several articles and press releases have been published about PDS 110 and the research underway on it, including the ones linked to below.

Photometric monitoring is requested beginning as soon as PDS 110 becomes visible this August and continuing through October 2017. One to two observations per night (and per band if multicolor) are sufficient until the eclipse begins. Time series observations should be obtained throughout the eclipse, which is expected to last about two weeks. After the eclipse, nightly observations should be resumed and continued for three to four weeks, until the end of October (or later if necessary).

The eclipse has been predicted for mid-September, with an uncertainty of ~ seven to ten days, thus the long monitoring window. The depth of the eclipse is expected to be about 30%.

BVRI (or SDSS u’,g’,r’,i’,z’) photometry is preferred, although all bandpasses are welcome. Visual observations are also welcome. PDS 110 is magnitude V = 10.40-10.75.

Support spectroscopy is not requested at this time. If it is needed at a later date, observers will be notified.

Observations should be reported to the AAVSO via WebObs as soon as practical. When the eclipse onset is detected, please inform the AAVSO immediately via email and/or a posting to the relevant discussion thread (see below), and submit your observations as soon as possible. This immediate reporting will allow the astronomers to trigger additional resources to observe PDS 110.

Dr. Rodriguez writes: "The multi-band observations requested here will provide high-cadence precise photometric observations of the potential sub-stellar ringed companion. The observations will be crucial in our follow-up analysis since they will 1) allow us to re-model the system with 3 eclipses, improving our parameters and allowing us to look for changes in the occulting body’s size and opacity. 2) The multi-band observations provide information on the grain size and distribution in the surrounding ring system. 3) Continuous monitoring of PDS 110 by the AAVSO can trigger the community when PDS 110 begins to eclipse. This trigger will allow us to increase the cadence of additional observations to support the AAVSO data."

Articles and press releases about PDS 110 include the following:

arXiv paper:
Scientific American article:
University of Warwick press release:
Leiden Observatory press release:
Other news:

Coordinates for PDS 110 (2000.0):   R.A.  05 23 31.00   Dec  -01 04 23.68

Charts with a comparison star sequence for PDS 110 may be created using the AAVSO Variable Star Plotter (VSP).

Please report observations to the AAVSO International Database using WebObs and the name PDS 110.

An AAVSO discussion forum thread on this campaign has been created at

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


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