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LPV Double Trouble Campaign

SXN's picture
Joined: 2010-03-12

 Stars we call Double Trouble are stars that have close companions that create difficulties for visual and CCD observers alike. 

Observers reporting the combined magnitude of both members of a pair are over estimating the brightness of the variable.

Observers reporting the magnitude of the close companion, when in fact, the variable has faded below the brightness of its insidious partner, create "flat bottom light curves", which do not represent the actual behavioral characteristics of these stars.

We propose here, a long-term campaign on LPVs that are Double Trouble.

The initial goals of the campaign are as follows:

1- To raise awareness of the trouble they cause, and the affect it has on AAVSO data. We hope that bringing attention to these stars will cause observers to submit more accurate data. A side project in this campaign is to have a note regarding these special situations appear in the footer of every AAVSO chart plotted for them to assist in bringing these devils into the light.

2- Determine true minima of the variable members of these close pairs. Not all of these characteristics are well-known, or correctly listed in various catalogs.

3- Increase the density of coverage in hopes of characterizing these stars throughout their light cycles, not just at minimum. 

4- We also hope to create a program that utilizes the strengths of both visual and CCD observers working together. Visual observers providing intense coverage in the bright range of the stars, with occasional data provided by CCD observers, and CCD observers picking up the coverage when these stars get below the typical threshold for visual observations (<13.5).

5- Provide an observing challenge that is as much fun for the challenge as it is for the potential scientific payoff. Observing and splitting close double stars has been enjoyed as part of the traditional hobby space of observational astronomy for hundreds of years. These close pairs have the added advantage of never looking the same way twice, since at least one of the members is variable!  

As we learn more about these stars we may expand the goals of the campaign to include any serendipitous discoveries made along the way, and we will certainly expand the list of stars as more are brought to our attention. If you know of any LPVs (or other types of stars) with close companions that may affect the accuracy of the data submitted to the AAVSO please contact the section leader, Mike Simonsen at mikesimonsen at

For the list of campaign targets go to the AAVSO LPV Section page on Double Trouble 

TT Mon
paw's picture
Joined: 2010-08-07

I stopped doing TT Mon (the only target I've ever done on this list) becasue of this problem, and will gladly take it up again with more care. Thanks Mike.

Double Trouble
srb's picture
Joined: 2010-07-08

Thank you for initiating this interesting campaign.  Even if it were not currently known to be double, it occurs to me that a flat bottomed Mira might be an indicator of an extremely close (visually unresolvable to amateur scopes) double star.  So maybe, in that situation, we could make a case to have some big time (HST, Keck, other?) professional assets look for optical or spectroscopic indications of the Mira being a double star?

V0437 Per is for this reason,
BBI's picture
Joined: 2011-03-08

V0437 Per is for this reason, a difficult object in my 10cm refractor.

R Normae another example
SXN's picture
Joined: 2010-03-12

Arne brought R Nor to my attention this morning. It has a 13th mag companion ~6 arc seconds west of the variable. I added a note in VSX that will now show up on the charts when they are plotted. I think we may have to add this one to the list too!

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