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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

35344 results found.

  1. GRB 050509c: ROTSE-III Optical Limits
  2. GRB 050509B: WSRT Radio Observations
  3. GRB050509c: REM NIR and Optical observations (errata corrige to GCN 3400)
  4. GRB 050505, early TAROT observation
  5. GRB050509c (=H3751): An X-Ray Flash Localized By HETE
  6. GRB 050509b: Further Analysis of Keck LRIS Images
  7. GRB050509c: REM NIR and Optical observations
  8. GRB 050509b: Physical Properties of the Candidate Host galaxy
  9. GRB 050505: SARA Observations
  10. Swift UVOT Follow-up Observations of GRB 050509B
  11. GRB 050509B, Optical Observations
  12. GRB 050509B: Swift/XRT refined analysis
  13. GRB 050509b: Optical observations
  14. GRB 050509b: Precision Astrometry
  15. GRB 050509b: Possible Optical Counterpart
  16. Keck/DEIMOS Spectrum of Possible Host Galaxy for GRB050509b
  17. GRB 050509A: Optical observations
  18. GRB 050509b: Optical Counterpart Candidate
  19. GRB 050509b: PAIRITEL and WIYN Observations
  20. GRB 050509b: Swift-BAT refined analysis of the short hard burst
  21. GRB 050509b: optical observations
  22. GRB 050509b: Swift XRT Position
  23. GRB 050509B: ROTSE-III Optical Limits
  24. GRB 050509a: Swift XRT Position
  25. Swift-BAT detection of GRB 050507
  26. GRB 050505: Keck I-band Magnitude
  27. GRB 050505: early time observations
  28. GRB 050505 - Faulkes Telescope North observations
  29. GRB 050502a: Swift XRT Upper Limit
  30. GRB 050505, simultaneous optical observation
  31. GRB 050505: Further Swift UVOT observations.
  32. GRB050505: AAVSO observations
  33. GRB050416A : 1 GHz limit from GMRT
  34. GRB 050505: Keck absorption spectrum and redshift (z=4.27)
  35. GRB 050505 UVOT
  36. GRB050505: Optical Afterglow Candidate
  37. GRB 050505: Swift XRT Position
  38. GRB 050502a: Optical Observations
  39. GRB 050416b:Swift XRT afterglow upper limits
  40. GRB 050416b:Swift XRT afterglow upper limits
  41. GRB 050504: Swift XRT position
  42. GRB050502: P200 Observations (Correction)
  43. GRB050502: P200 Observations
  44. GRB 050504 : R band observation at Lulin observatory
  45. Swift UVOT observation of GRB 050504
  46. GRB 050504, R band Observations
  47. GRB 050502b, V band Observations
  48. GRB050504: P60 Observations
  49. GRB 050504: A long GRB detected with INTEGRAL
  50. GRB (?) 050504: IR Observations, Intriguing Source
  51. GRB 050502b, Optical observations
  52. GRB050502a: P60 Observations (Correction)
  53. GRB050502a: P60 Observations
  54. Renewal of SGR 1806-20 activity
  55. GRB 050502a: RBO Observations
  56. GRB 050502A: WSRT Radio Observations
  57. GRB050502A: Optical Observations
  58. Swift UVOT refined analysis
  59. Retraction of Swift-BAT trigger 116145
  60. GRB 050502a : R band observation at Lulin observatory
  61. GRB 050502b : optical observation at Lulin observatory
  62. GRB 050502b: Swift XRT Position
  63. GRB 050502A: Redshift measurement based on Keck HIRES Observations
  64. GRB 050502: INTEGRAL results
  65. GRB050502: ANU 1m optical Observations
  66. GRB 050502: Confirmed variability of the afterglow candidate +
  67. GRB 050502: PAIRITEL IR Observations
  68. GRB050502 - Correction on the Optical Candidate from the Liverpool
  69. GRB 050502 - A long GRB detected with INTEGRAL
  70. GRB 050502: ROTSE-III Detection of Possible Counterpart
  71. Swift-BAT Trigger 115881 is not a real GRB
  72. Swift/BAT possible detection of a weak burst GRB050430
  73. GRB 050401: Rc observation
  74. GRB050416a: Radio Detection
  75. GRB 050422: Swift-UVOT observation
  76. GRB 050422: Swift-BAT refined analysis
  77. GRB 050422: Swift XRT Position
  78. Swift Detection of GRB 050422
  79. GRB 050421: NIR observations
  80. GRB 050416: Optical/NIR observations
  81. GRB 050421: SLOTIS observations
  82. GRB 050421: Further Analysis of IR imaging
  83. GRB050421: Radio Observations
  84. GRB050421: Radio Observations
  85. GRB 050421: Swift-UVOT observation
  86. GRB 050421: IR Observations
  87. GRB 050421: Swift-BAT refined analysis
  88. GRB 050421: ROTSE-III Optical Limits
  89. GRB 050421: NIR observations re-examination
  90. GRB 050421: early Swift XRT analysis results
  91. GRB 050421: NIR observations
  92. GRB050421: P60 Observations
  93. GRB 050421: BOOTES-2 simultaneous optical observations
  94. GRB 050421: Optical observations at the INT
  95. GRB 050416b: Tentative Swift XRT Position
  96. GRB 050315: potential host galaxy
  97. GRB 050412: Chandra observations
  98. GRB050416A, optical observations
  99. GRB 050418: Swift-BAT refined analysis
  100. Swift-BAT detection of the bright and long GRB 050418

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