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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"
  1. GRB 060110: Optical limit
  2. GRB 060110: Swift-BAT detection of a burst
  3. GRB 060109: Refined Swift-XRT analysis
  4. GRB 060109: Swift/UVOT upper limits
  5. GRB060109, optical observation
  6. GRB 060108: ISAS early observations and near IR upper limit
  7. GRB060108: P200 Ks Observations
  8. GRB 060108: early UKIRT K-band observations
  9. Swift UVOT correction to GCN 4455
  10. GRB 060109: Swift Detection of a long burst
  11. GRB 060108: a dark burst?
  12. GRB 060108: Refined XRT analysis
  13. GRB 060108: VLT J-band observations
  14. GRB 060108: Mitsume optical observations
  15. GRB 060108: Swift/UVOT upper limits
  16. GRB 060105: quick look analysis of the Suzaku/XIS afterglow observation
  17. GRB060108: SDSS pre-burst observations
  18. GRB060108: Faulkes Telescope observation
  19. GRB060108, optical observation
  20. GRB 060108: Refined analysis of the Swift-BAT burst
  21. GRB 060108: Swift XRT position
  22. GRB060108: Swift detection of its 100th GRB
  23. GRB 060105: pseudo-z from spectral parameters of the prompt emission
  24. GRB 060105: Radio observations
  25. GRB 060105: MDM Observation
  26. Konus-Wind observation of GRB 060105
  27. GRB 060105: ISAS observations and near IR upper limit
  28. GRB 060105: Swift/UVOT upper limits
  29. GRB 060105: Mitsume optical observations
  30. GRB 060105: BAT refined analysis
  31. GRB 060102 - no XRT afterglow
  32. GRB 060105: XRT refined analysis
  33. GRB060105: Suzaku-XIS and -HXD observation plan
  34. GRB060105, optical observation
  35. GRB060105 : Kiso optical observation
  36. GRB060105: Swift detection of a bright long burst
  37. Swift-BAT trigger 175653 is not an astrophysical source
  38. GRB 060102: MDM Observation
  39. Swift-BAT trigger 175653 is probably not a GRB
  40. GRB 060102: Swift-BAT refined analysis
  41. Time Correction to GRB 060102
  42. GRB 060102: Swift-BAT detection of a burst
  43. GRB051211B: optical observations
  44. GRB051227: SARA Observations
  45. GRB 051221B: Optical Observations with Kuiper 1.54m
  46. GRB 051227: Likely host galaxy underlying afterglow position
  47. GRB 051227: optical observation
  48. GRB051221B: Radio observations
  49. GRB 051221A: VLA Radio Observations
  50. GRB051227: Radio Observations
  51. GRB 051227: Confirmed fading from Gemini observations
  52. GRB051227: further analysis of VLT images
  53. GRB 051227: optical afterglow
  54. GRB 051227: Swift/UVOT Upper Limits (Possible U-band
  55. GRB 051227: Gemini observations
  56. GRB 051227: Keck Spectroscopy
  57. GRB 051227: Magellan r'-band Imaging/Astrometry
  58. GRB 051227: refined analysis of VLT images
  59. GRB 051227: P60 Observations
  60. GRB 051227: MDM Observation
  61. GRB 051227: R-band object in the XRT error circle
  62. GRB 051227: Joint Swift-HETE Spectral Analysis
  63. GRB 051227: XRT refined analysis
  64. GRB 051227: Further analysis of the Swift-BAT burst
  65. GRB 051227: Refined analysis of the Swift-BAT burst
  66. GRB051227: SDSS pre-burst observations
  67. GRB 051227, optical observation
  68. GRB 051227: Swift detection of a burst
  69. GRB051117B: optical observation
  70. IBAS_alert n. 2719 : not a real GRB
  71. Konus-Wind observation of GRB 051221A
  72. GRB051221A: Suzaku WAM observation of the prompt emission
  73. GRB 051221A: MDM Optical Observations
  74. GRB051016: analysis of the XMM-Newton observation
  75. GRB 051221A: Detection at 251nm with Swift UVOT
  76. GRB 051221A: Chandra Afterglow Position
  77. GRB 051221A: Refined spectral and temporal analysis of the Swift-BAT short hard burst
  78. GRB 051221B: ROTSE-III Optical Limits
  79. GRB 051221B: TAROT optical limits
  80. GRB 051221A: WSRT Radio Observations
  81. GRB 051221: Redshift from Gemini
  82. GRB 051221: Continued fading of optical afterglow
  83. GRB 051221B: Refined analysis of the Swift-BAT burst
  84. Possible GRB 051221B: MDM Optical Detection
  85. GRB 051221A: RAPTOR Fading Counterpart Constraint
  86. GRB 051221B: BOOTES optical observations.
  87. Possible GRB 051221B: Swift XRT position
  88. GRB 051211A: Evidence This Is a Short Burst from Analysis of Spectral
  89. Swift-BAT detection of a possible burst
  90. GRB 051221: Discovery of fading optical afterglow
  91. GRB 051221: Swift XRT refined analysis
  92. GRB 051221: Swift/UVOT upper limits
  93. GRB 051221: Possible nearby cluster
  94. GRB 051221: No variability in Gemini data
  95. GRB 051221: Correction to GCN #4368
  96. GRB 051221: Gemini observations
  97. GRB 051221: Improved astrometry of the IR counterpart
  98. GRB051221: K-band source
  99. GRB 051221: XRT position
  100. GRB 051221: Refined analysis of the Swift-BAT short hard burst

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