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IAU logo IAU Commission G1: Binary and Multiple Star Systems
(formerly Commission 26: Binary and Multiple Stars)

Note: The IAU reorganized its commission structure, effective as of the August 2015 General Assembly. Information regarding the new double star commission, as well as historic information about Commission 26, may be found on the new
Commission G1 website.

Commission G1 Information Circulars

Observing Opportunities & Requests

As we all know, there are many doubles to observe and few of us to observe them! Following a great suggestion by Vakhtang Tamazian, we are attempting an experiment that may invite more collaboration among our group. In this section of the Commission 26 webpage, observers (amateur or professional) may advertise their upcoming observing runs or ongoing projects and invite anyone who wishes to participate. These may range from requests for a few observations to proposals for major collaborations. In addition, anyone who has a few specific objects in need of observation may post a request for either archival or new data.

Information to be included on upcoming observing runs should include:
  • Date and duration (preferably a few months in advance)
  • Telescope size, location, and instrumentation (CCD, lucky imaging, speckle, RV, etc.)
  • Limiting magnitude and dynamic range (delta m), wavelength range or photometric bands
  • Resolving power of the telescope and spectrograph (R), if spectroscopy
  • The option to participate in the run: "yes" or "no". If "yes", the possibility of any kind of support (further details to be arranged with the contact person)
  • Contact person: name, email/postal address(es)

Information to be included on data requests should include:
  • Object name(s), coordinates, magnitudes
  • Type of data needed: astrometry, spectroscopy, photometry, etc.
  • Other relevant information (for example, predicted periastron or occultation timings, etc.)

Publication arrangements for any measures obtained will probably vary, depending on the size of the contribution, and should be worked out on a case-by-case basis between requester and observer.

Observations may be requested for the following programs:

  • Student Double Star Speckle Interferometry Program
    • Date: ongoing
    • Telescopes: numerous
    • Camera: Andor Luca-S EMCCD, Rc filter, no atmospheric dispersion correction
    • Separation: 0.4" < sep > 10.0"
    • Limiting magnitude: V<11, DV<3 (less at separations close to the magnitude limit)
    • Paper describing program and results on previous run this telescope on request
    • Contact person: Russ Genet, russmgenet[at]aol.com

  • USNO Speckle Program
    • Date: ongoing
    • Telescope: USNO 26inch (66cm) refractor, Washington, DC (lat. 38.921, long. -77.067); speckle
    • Limiting magnitude V < 11.5, dV < 3 (less at separations close to limit)
    • dec > -15, 0.5" < sep < 50",
    • Option to participate: yes, but limited. No restriction on number of objects (within reason!)
    • Contact person: Brian Mason, wds[at]usno.navy.mil

Meeting Announcements

The list below includes meetings in the planning/proposed stages, as well as those definitely scheduled. Information on these proposed meetings will be updated as it becomes available. Please let me know of other meetings you feel should be added, as well as corrections or additional information on the ones listed below. A list of international astronomy meetings covering all topics is available
here .

Proceedings of Past Meetings, etc.

Bibliographies of binary star papers

Binary and Multiple Star Catalogues

Astrometric Systems
Spectroscopic Systems Multiple Systems Close (Interacting and Eclipsing) Systems

Your feedback, please ...

Your reactions to the Double Star Library are appreciated. Please send your comments (reports of errors, suggestions for additional catalogues or web links, etc.) to the editor via the WDS feedback form.