Special Notice #118: Request extended to observe High-Mass X-Ray Binaries (HMXBs) in support of radial velocity observations

HMXB campaign extended until further notice. It has been updated numerous times and covered in AAVSO Alert Notices 348, 354, and 377, and in AAVSO Special Notices #118, #129, #143, #213, and #220.

August 14, 2008

Dr. Gordon Sarty, University of Saskatchewan, Canada, has requested our continuing assistance (see AAVSO Alert Notices 348, 354, 377) in his ongoing radial velocity observations of High Mass X-ray Binaries (HMXBs).   The following text was provided by Dr. Sarty:

"Please obtain BVRI photometry (or any subset thereof, VI preferred) of the following two HMXBs

Desig.   Name         R.A.(2000)  Dec.(2000)   Mag  LPH no.  AUID

1930+53  1936+541     19:32:52.3  +53:52:45.5  9.8  115    000-BDC-070 [1H 1936+541]
0140+60B V831 Cas     01:47:00.2  +61:21:23.7 11.3   29    000-BCY-758

for the time period of our radial velocity observations from August 14 to 22. The objective is to obtain simultaneous color photometry and radial velocity measurements of these two objects. Past AAVSO data has shown that both of these stars are likely beta Cephei pulsators and the simultaneous observations can confirm that. If confirmed, future observations aimed at astro-seismology of those two stars may be possible. The objective of measuring pulsations is a new objective, adding to the one of finding orbital periods, in the HMXB project made possible by past AAVSO observations of HMXBs.

"Our radial velocity measurements will be done with the Dominion Astrophysical Observatory (DAO) 1.85-m Plaskett telescope, in Victoria, B.C., Canada. We will be observing LPH115 (1H 1936+541) for the first part of the night until it is 6h past the meridian and then we will switch to LPH029 (V831 Cas) for the remainder of the night. AAVSO observers may follow a similar observing strategy, or they may concentrate on just one object for the whole night. All night time-series observations over the course of our DAO observing run are essential for detecting and confirming the pulsations.

For more background information on the HMXB project, please see our JAAVSO preprint at http://www.aavso.org/publications/ejaavso/ej56.shtml

Charts may be found on the HMXB chart web page at: http://homepage.usask.ca/~ges125/AAVSO_HMXB_Charts.html

"As mentioned in the earlier Alert Notices, please follow the observing instructions given on the chart web page and on the charts and submit your results directly to the AAVSO International Database.

"Please direct any questions about this observing campaign to Dr. Gordon Sarty at gordon.sarty@usask.ca or to Rick Huziak at rickhuziak@shaw.ca.

"Your observations of these two bright HMXBs are extremely important. Many thanks for your efforts and your astronomical contributions."

This AAVSO Special Notice was prepared by Dr. Gordon Sarty (posted by M. Templeton).


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