AAVSO Special Notice #159: Request for observations of high-mass X-ray binaries

Dr. Gordon Sarty, University of Saskatchewan, Canada, has requested ourcontinuing assistance (see AAVSO Alert Notices 348, 354, 377, special notices 118, 129, 143) 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 four 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

2027+47 J2030.5+47 20:30:30.9 +47:51:50.7 9.3 123 000-BDC-306

2157+49 2202+501 22:01:38.2 +50:10:04.6 8.8 127 000-BFS-469

2204+54 2206+543 22:07:57.1 +54:31:05.8 9.9 128 000-BDC-531

for the time period of our radial velocity observations from May 29 to June 11. The objective is to obtain simultaneous color photometry and radial velocity measurements of these four objects.

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 alternate observations of the four stars throughout the night. The observer will be Neil Johnson, who can be reached on the AAVSO chat-line during the observations. Interested AAVSO observers should concentrate on one star per night, all night, for as many nights as you can devote, while we are observing.

For more background information on the HMXB project, please see our JAAVSO preprint at

http://www.aavso.org/publications/ejaavso/v35n2/327.shtml

Charts may be downloaded at:

http://homepage.usask.ca/~ges125/Astronomy/LPH115_aavso.pdf
http://homepage.usask.ca/~ges125/Astronomy/LPH123_aavso.pdf
http://homepage.usask.ca/~ges125/Astronomy/LPH127_aavso.pdf
http://homepage.usask.ca/~ges125/Astronomy/LPH128_aavso.pdf

Please submit your observations directly to the AAVSO International Database.

Thanks for your ongoing coverage of the HMXBs.

Please direct any questions about this observing campaign to

Dr. Gordon Sarty at gordon.sarty@usask.ca ."

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