[vsnet-id 236] Re: ROSAT TDFs...

["Berto Monard" <lagmonar@csir.co.za>]

Hi,

I did some studies and had discussions on the ROSAT RXSP catalogues sometime ago, soon after the catalogues came on, exactly to find out how to detect spurious CVs amongst them. I did look for patterns in the data, mainly the X hardness ratios and comparisons to optical brightnesses. Magnetic CVs are very distinct in their high X contents, 'normal' DNe are not.

Most targets that looked as if they promised to be CVs turned out to be WDs (single or non interactive), the fainter ones nearly always were AGNs. Fortunately there are matching catalogues on AGNs and WDs but they are incomplete.
Somehow I selected a couple for monitoring. 
One of the publications did a probability matching of Rosat sources to nearby stars from the USNO catalogue. In one case they indicated a nearby brightish star (based on USNO values) as the candidate. In another publication I found that they indicated another nearby star as the probable counterpart of that same Rosat source. I put both stars on my programme and you know what. Both turned out to be variable.. Possibly they both are nearby red dwarfs (dMe) as most of the 'brightish Rosat sources are. 
Since I reside from memory I cannot give the exact RXSP code but  the coordinates of both stars I have listed at locations: 105205-5842 and 105224-5841. If someone is interested I can dig out the exact coordinates and the RXS denomination.

Best regards,


Berto Monard
Pretoria
observer mainly..

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