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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 060105: Radio observations
  2. GRB 060105: MDM Observation
  3. Konus-Wind observation of GRB 060105
  4. GRB 060105: ISAS observations and near IR upper limit
  5. GRB 060105: Swift/UVOT upper limits
  6. GRB 060105: Mitsume optical observations
  7. GRB 060105: BAT refined analysis
  8. GRB 060102 - no XRT afterglow
  9. GRB 060105: XRT refined analysis
  10. GRB060105: Suzaku-XIS and -HXD observation plan
  11. GRB060105, optical observation
  12. GRB060105 : Kiso optical observation
  13. GRB060105: Swift detection of a bright long burst
  14. Swift-BAT trigger 175653 is not an astrophysical source
  15. GRB 060102: MDM Observation
  16. Swift-BAT trigger 175653 is probably not a GRB
  17. GRB 060102: Swift-BAT refined analysis
  18. Time Correction to GRB 060102
  19. GRB 060102: Swift-BAT detection of a burst
  20. GRB051211B: optical observations
  21. GRB051227: SARA Observations
  22. GRB 051221B: Optical Observations with Kuiper 1.54m
  23. GRB 051227: Likely host galaxy underlying afterglow position
  24. GRB 051227: optical observation
  25. GRB051221B: Radio observations
  26. GRB 051221A: VLA Radio Observations
  27. GRB051227: Radio Observations
  28. GRB 051227: Confirmed fading from Gemini observations
  29. GRB051227: further analysis of VLT images
  30. GRB 051227: optical afterglow
  31. GRB 051227: Swift/UVOT Upper Limits (Possible U-band
  32. GRB 051227: Gemini observations
  33. GRB 051227: Keck Spectroscopy
  34. GRB 051227: Magellan r'-band Imaging/Astrometry
  35. GRB 051227: refined analysis of VLT images
  36. GRB 051227: P60 Observations
  37. GRB 051227: MDM Observation
  38. GRB 051227: R-band object in the XRT error circle
  39. GRB 051227: Joint Swift-HETE Spectral Analysis
  40. GRB 051227: XRT refined analysis
  41. GRB 051227: Further analysis of the Swift-BAT burst
  42. GRB 051227: Refined analysis of the Swift-BAT burst
  43. GRB051227: SDSS pre-burst observations
  44. GRB 051227, optical observation
  45. GRB 051227: Swift detection of a burst
  46. GRB051117B: optical observation
  47. IBAS_alert n. 2719 : not a real GRB
  48. Konus-Wind observation of GRB 051221A
  49. GRB051221A: Suzaku WAM observation of the prompt emission
  50. GRB 051221A: MDM Optical Observations
  51. GRB051016: analysis of the XMM-Newton observation
  52. GRB 051221A: Detection at 251nm with Swift UVOT
  53. GRB 051221A: Chandra Afterglow Position
  54. GRB 051221A: Refined spectral and temporal analysis of the Swift-BAT short hard burst
  55. GRB 051221B: ROTSE-III Optical Limits
  56. GRB 051221B: TAROT optical limits
  57. GRB 051221A: WSRT Radio Observations
  58. GRB 051221: Redshift from Gemini
  59. GRB 051221: Continued fading of optical afterglow
  60. GRB 051221B: Refined analysis of the Swift-BAT burst
  61. Possible GRB 051221B: MDM Optical Detection
  62. GRB 051221A: RAPTOR Fading Counterpart Constraint
  63. GRB 051221B: BOOTES optical observations.
  64. Possible GRB 051221B: Swift XRT position
  65. GRB 051211A: Evidence This Is a Short Burst from Analysis of Spectral
  66. Swift-BAT detection of a possible burst
  67. GRB 051221: Discovery of fading optical afterglow
  68. GRB 051221: Swift XRT refined analysis
  69. GRB 051221: Swift/UVOT upper limits
  70. GRB 051221: Possible nearby cluster
  71. GRB 051221: No variability in Gemini data
  72. GRB 051221: Correction to GCN #4368
  73. GRB 051221: Gemini observations
  74. GRB 051221: Improved astrometry of the IR counterpart
  75. GRB051221: K-band source
  76. GRB 051221: XRT position
  77. GRB 051221: Refined analysis of the Swift-BAT short hard burst
  78. GRB 051221: IR Observations at GRB+1hr
  79. GRB 051221: Swift detection of a bright short burst
  80. Refined analysis of the SWIFT J1626.6-5156
  81. Swift-BAT discovery of hard x-ray transient SWIFT J1626.6-5156
  82. Refined analysis of the Swift-BAT detection of the RS CVn star II Peg
  83. GRB051211A (=H3979): Refined Analysis
  84. GRB 051211B: optical afterglow
  85. Swift detection of an RS CVn flare star
  86. GRB051211A: possible optical candidate
  87. Swift Trigger 172767 is not a GRB
  88. GRB 051215: near-infrared observations
  89. GRB051215 - SDSS pre-burst observations
  90. GRB 051215: Swift detection of a possible burst
  91. GRB 051215: A short GRB in a cluster?
  92. GRB051211B: Probable radio afterglow
  93. GRB051105: optical observations
  94. GRB 051213: Swift-BAT refined analysis
  95. GRB051211B: XRT refined analysis
  96. GRB 051211B, optical observation
  97. GRB 051213: Swift-BAT detection of a burst
  98. GRB 051211a: RTT150 optical observations
  99. GRB051211B, RBO optical observations
  100. GRB 051211A: Swift/UVOT upper limits

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