Observing Campaign to Monitor Tremendous Outburst Amplitude Dwarf Novae (TOADs) for Spitzer Space Telescope Observations

Spitzer Space Telescope (Courtesy: NASA)

Dr. Steve Howell (NOAO) requests continued monitoring of a subset of the known and suspected tremendous outburst amplitude dwarf novae (TOADs) in support of Spitzer Space Telescope observations of these objects. Observers are asked to increase their monitoring of the objects in the list below, in order to provide the following information:

• Verification that the object is in outburst,
• Whether the outburst is a superoutburst for objects known to show both normal and superoutbursts,
• Multicolor photometry of the object at maximum, and during the course of the superoutburst

The most critical observation for this project is verification of whether the observed outburst is a normal one or a superoutburst. For this project, rapid notification is not as critical as verification of outburst type. However, we note that several of the objects are known to be extremely rare outbursters, and for that reason, outburst observations should be reported as promptly as possible. Observers are also asked to obtain filtered photometry, in at least two filters if available. Time-series observations are not required except for cases where superhumps have not yet been observed or the orbital period is unknown.

The table below lists a subset of stars known or suspected of being TOADs. We note that several of these objects -- notably the WZ Sge stars WZ Sge, GW Lib, and V455 And -- are not expected to superoutburst during the next year, but observations are still encouraged in case they exhibit unexpected behavior. Fainter-than observations (both visual and CCD) are important for this project, and should be reported as promptly as possible. The table lists the observed magnitude range and an outburst threshold for each star. Any observation above the threshold should be considered in outburst, and any observation at or near the maximum is likely a superoutburst. Please report all observations regardless of whether they're in outburst or quiescence promptly to the AAVSO. If the object is in outburst or near maximum, please contact the AAVSO immediately. Spitzer observations will not be triggered immediately; however, a Special or Alert Notice will be issued requesting concentrated coverage of the star.

Campaign duration and schedule

This campaign begins now (May 07, 2008) and continues through May 2009. Once an object has been verified in superoutburst, Spitzer observations will be scheduled within 2-4 weeks of maximum, and will be repeated twice -- 4-6 weeks and 6-10 weeks later. Observers are asked to provide nightly monitoring of these stars, and to begin intensive observations if and when any of them go into outburst to determine whether the star is in superoutburst.

Both visual and CCD observations are requested, and multicolor photometry would be greatly appreciated. CCD observers are aske to use exposure times such that you can obtain a signal-to-noise of 50 per observation.

Notification

Observers are requested to submit all data via the WebObs feature of the Blue & Gold section of our website. This will enable our server to automatically notify the observer community when one of these objects goes into outburst. We have set up another list within MyNewsFlash which will enable you to subscribe to notifications for all of these objects at once. Simply check the "TOADs" box on the MyNewsFlash subscription page and enter your email address, observer initials, and the delivery schedule that you want for News Flashes. "Daily" is acceptable for this campaign, although we note many targets are of very great scientific interest beyond our needs, and you may wish to receive more immediate notification.