May 2, 2008: Dr. Gordon Sarty, University of Saskatchewan, Canada, has requested our continuing assistance (see AAVSO Alert Notices 348 and 354) in his ongoing radial velocity observations of four High Mass X-ray Binaries (HMXBs). From Dr. Sarty:
"[Please obtain] BVRI photometry (or any subset thereof, in IVBR order of preference)...for the month of May 2008 to complement the spectroscopic data that will be obtained from May 14 to 27. Spectroscopy of the four (4) HMXBs, for the purpose of measuring their radial velocities, will be done with the Dominion Astrophysical Observatory (DAO) 1.85-m Plaskett telescope, in Victoria, B.C., Canada. The object is to determine the orbital periods of the HMXBs. Optical photometry will also reveal other periods and variation due to mass transfer, pulsations and other effects. The availability of photometry will be very valuable for interpreting the spectroscopic data and has already been very useful for the HMXB RX J0146.9+6121 (which, however, is not visible from DAO for this run). For more information on HMXBs and this project, please see our eJAAVSO article (Vol. 35, No. 2, p. 327, 2007):
"The table below lists the four target HMXBs for this observing campaign:
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 RX J2030.5+4751 20:30:30.9 +47:51:50.7 9.3 123 000-BDC-306 (AAVSO name used to be J2030.5+47) 2157+49 2202+501 22:01:38.2 +50:10:04.6 8.8 127 000-BDC-509 2204+54 2206+543 22:07:57.1 +54:31:05.8 9.9 128 000-BDC-531
where the LPH number is a cross-reference to the HMXB listing in the JAAVSO paper and the HMXB chart web page which may be found at:
"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."
Your continued observations of these bright HMXBs are extremely important. Many thanks for your efforts and your astronomical contributions.
Elizabeth O. Waagen
Senior Technical Assistant
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