Alert Notice 674: UU Aqr being observed with Chandra

July 25, 2019

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Further to AAVSO Alert Notice 652, Dr. Koji Mukai (NASA-Greenbelt Space Flight Center) informs us that UU Aqr, the last of the novalike variables in his target list, will be observed with Chandra on 2019 August 3 06:16 UT - 10:10 UT.

Knowing the status of the target is essential for interpreting the X-ray data. Dr. Mukai thanks observers for the observations they have already made of UU Aqr, and asks if more observations (a snapshot every night through August 4, and then every one to two nights) could be made between now and August 13. V filter is optimal. Visual observations are welcome. The CV range of UU Aqr is 12.85 - 15.5 V.

As Dr. Mukai wrote in Alert Notice 652, "We think we know how dwarf novae behave in X-rays, through various campaigns (famously that one on SS Cyg in outburst that Janet Mattei [and AAVSO observers] was heavily involved in, with Pete Wheatley and Chris Mauche, 2003MNRAS.345...49W): they are X-ray bright in optical quiescence, and fainter and softer in X-rays during outburst. In the optical, we think of nova-likes as systems in permanent outburst — but in X-rays, they don’t quite resemble dwarf novae in outburst. In fact, we haven’t seen a clear pattern, when we made X-ray observations of nova-like systems at various optical magnitudes. This Chandra program is part of an effort to look for patterns and to understand their X-ray emission."

UU Aqr is the sixth and final target on the list given in Alert Notice 652 (KQ Mon, V378 Peg, EC 21178-5417, 1SWASP J022916.91-395901.4, LQ Peg, UU Aqr). Once UU Aqr has been observed successfully with Chandra, this campaign will come to a close, and no additional observations of any of the targets will be required.

Coordinates (2000) of UU Aqr: RA  22 09 05.70  Dec -03 46 17.5

Charts with comparison star sequences for UU Aqr may be created using the AAVSO Variable Star Plotter (VSP).

Please submit observations to the AAVSO International Database using the name UU AQR.

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


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