AAVSO Alert Notice 441

Monitoring of Bright Giant Variables requested in support of ground-based spectroscopy and for long-term study

May 27, 2011: Dr. Steve Howell (NASA) and Dr. Travis Rector (University of Alaska, Anchorage) have requested AAVSO observations of several bright giant variable stars of diverse classes.  This request is for immediate support of spectroscopic observations to be made at Kitt Peak National Observatory between 2011 May 30 and 2011 June 01 (JD 2455712 - 714).  However, observers are encouraged to continue long-term monitoring of these objects.

Using the spectroscopy, as well as parallax measurements from Hipparcos and contemporary photometry from the AAVSO, the distance, luminosity, temperature and radius of these stars are determined.  The goal of the project is to determine if the surface temperatures and radii of these stars change in a recognizable pattern over long timescales.

Spectroscopic observations will be made with the Kitt Peak Coude Spectrograph from May 30th to June 1st.  Visual and photometric BVRI observations of these stars around this time are requested.

Below is the list of objects being monitored. The list is divided into two groups by priority.

Priority Targets

NAME           RA(J2000)      DEC(J2000)    CURRENT MAG        SEQ?
Z UMa     11:56:30.22    +57:52:17.6   m(vis) ~ 7.3
R CrB     15:48:34.4     +28:09:24.2   m(vis) ~ 13.1
SX Her    16:07:27.24    +24:54:29.9   m(vis) ~ 8.4
TT Oph    16:49:35.88    +03:37:54     m(vis) ~ 10.0
TX Oph    17:04:00.09    +04:59:00.7   m(vis) ~ 10.5(?)
AC Her    18:30:16.24    +21:52:00.5   m(vis) ~ 8.3
R Sct     18:47:28.94    -05:42:18.5   m(vis) ~ 5.3

Other Targets:

NAME      RA(J2000)      DEC(J2000)    CURRENT MAG        SEQ?
R Vir     12:38:29.94    +06:59:18.9    m(vis) ~ 11.1
Y CVn     12:45:07.82    +45:26:24.8    m(vis) ~ 5.4
g Her     16:28:38.54    +41:52:54      m(vis) ~ 5.1
UU Her    16:35:57.28    +37:58:02      m(vis) ~ 9.0
UZ Oph    17:21:59.26    +06:54:42.1    m(vis) ~ 11.3
V453 Oph  17:26:49.13    -02:23:36.3    m(vis) = ?        ***
XX Oph    17:43:56.5     -06:16:08.7    m(vis) ~ 8.9
TZ Oph    16:29:07.71    -20:14:03.9    m(vis) = ?        ***
V564 Oph  17:52:01.25    +07:56:29.1    m(vis) ~ 10.3
T Lyr     18:32:20.08    +36:59:55.6    m(vis) ~ 8.7
AD Aql    18:59:08.69    -08:10:14      m(vis) = ?
AR Sgr    18:59:42.14    -23:42:26.6    m(vis) = ?
V5569 Sgr 18:50:03.56    -26:24:15.4    m(vis) = ?        ***
EP Lyr    19:18:19.55    +27:51:03      m(vis) ~ 10.6
EU Del    20:37:54.71    +18:16:06.3    m(vis) ~ 6.0

Starred (***) objects do not currently have good AAVSO sequences -- they either lack sequences entirely or have poorly placed stars -- but finder charts may still be plotted with our Variable Star Plotter (http://www.aavso.org/vsp [1]).  Those without asterisks do have good current sequences available through VSP.  Requests for sequences will be made to the AAVSO Sequence Team, but these may not be available until after the KPNO observing run is complete.  Until then, do your best with what is available. CCD observers can take observations and store their images for later reduction when better sequences are available.

This AAVSO Alert Notice was prepared by Travis Rector with assistance from Aaron Price and Matthew Templeton.

110527 Update: Tim Crawford and the Sequence Team have updated the sequence for V5569 Sgr and V453 Oph.

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