AAVSO Alert Notice 589 announces an optical and spectroscopic campaign on the symbiotic variable R Aqr in support of Chandra and HST observations scheduled for October 2017. Please see the notice for details and observing instructions.
Many thanks and Good observing,
Elizabeth O. Waagen, AAVSO HQ
As the HST is current I have startd taking spectra and UBV images if this star. The spectra are interesting and ave available at http://www.astrosurf.com/aras/Aras_DataBase/Symbiotics/RAqr.htm
The B and V values I obtained were as expected and consistent with other observers.
The interesting observation was when I used my U filter. The star is much brighter than I expected for a symbiotic star. It is much brighter in U than in B or V. It is about U=8.0 and V=10.0
I took 3 exposures that all seemed to be consistent. Unfortunately there are no other U measurements in Webobs for me to compare with. Has anyone else taken U measurements?
I've added UBV estimates for Oct 3 and Oct 7. The U mags were indeed very bright as compared to a few other ZANDs I've looked at. There's alot going on here besides the LPV pulsations ! The U-B color is very inflated.
In a table included with 'Symbiotic Stars Multi-epoch UBV(RI)c Photometry' (Henden+, 2008) , the U-B values for R Aqr are between -0.59 and -0.66. Not a single symbiotic in the table has a U-B index of more than -1.0. Something seems amiss.
While the Astrodon Sloan u' filter was modified in gen2 to have more IR blocking, as was the Johnson B filter in gen3, I don't think the Johnson U filter was checked for red leaks. For red stars, this is important. You might specify what U filter you are using.
I will check with iTel to see what U filters they have on T21 and T30. Thankyou Arne for bringing this to our attention. I will remove my poor U mags from the AID.
Spectroscopists may wish to consult the article by G. Wallerstein & J.L. Greenstein in Pub ASP, Vol 92, June 1980, pp 275-283. The spectrum, taken using the 5 meter telescope at Mt. Palomar, shows a very strong (O III) emission line at 500 nm. I asked whether the presence of that line (the strongest of several) made DSLR photometry useless, but did not receive a reply. My model indicates, however, that it is. Perhaps someone who really knows what they are talking about should advise me if it is otherwise.