Alert Notice 453: Monitoring of S Dor requested for multiwavelength campaign

February 23, 2012:  Dr. Noel Richardson, Georgia State University, has requested monitoring of the luminous blue variable (LBV) prototype S Doradus as part of a multiwavelength campaign he is coordinating to study the photosphere of this star. At present the observations planned include:

1. UV Spectroscopy from HST
2. Optical spectroscopy from CTIO and an amateur in Australia
3. Near-IR Spectroscopy from SOAR (pending approval)
4. Mid-IR photometry from Gemini (pending approval)

While these observations will likely take place in May 2012, optical monitoring beginning now is important. Your observations will not only be very interesting but also necessary to correlate all of the observations and interpret the variability taking place in S Dor. S Dor is particularly interesting at present because its current state allows the deepest look into its photosphere since the 1960s, leading to a better understanding of its stellar and wind properties. To quote Dr. Richardson, "...the types of variability we are really wanting to probe are the long term trends and the decline to optical minimum it is going through."

Visual and photometric observations are requested on a nightly basis. BVRI photometry would be ideal, but any filter(s) would be very helpful. According to observations in the AAVSO International Database, S Dor is currently at visual magnitude ~10.4. Its decline from visual magnitude 9.2 began in 2006, with a more rapid decline starting in early 2010.

Coordinates: RA = 05 18 14.35  Dec = -69 15 01.1 (2000.0)

Charts may be created using VSP (

Please submit observations to the AAVSO International Database using the name S DOR.

This campaign is also described on the AAVSO Observing Campaigns page.

Your observations are key to the success of this campaign. If you have been observing S Dor, please continue. If you have not, and if you can observe this far south, please add S Dor to your nightly list. Many thanks!

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


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