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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 051221B: Optical Observations with Kuiper 1.54m
  2. GRB 051227: Likely host galaxy underlying afterglow position
  3. GRB 051227: optical observation
  4. GRB051221B: Radio observations
  5. GRB 051221A: VLA Radio Observations
  6. GRB051227: Radio Observations
  7. GRB 051227: Confirmed fading from Gemini observations
  8. GRB051227: further analysis of VLT images
  9. GRB 051227: optical afterglow
  10. GRB 051227: Swift/UVOT Upper Limits (Possible U-band
  11. GRB 051227: Gemini observations
  12. GRB 051227: Keck Spectroscopy
  13. GRB 051227: Magellan r'-band Imaging/Astrometry
  14. GRB 051227: refined analysis of VLT images
  15. GRB 051227: P60 Observations
  16. GRB 051227: MDM Observation
  17. GRB 051227: R-band object in the XRT error circle
  18. GRB 051227: Joint Swift-HETE Spectral Analysis
  19. GRB 051227: XRT refined analysis
  20. GRB 051227: Further analysis of the Swift-BAT burst
  21. GRB 051227: Refined analysis of the Swift-BAT burst
  22. GRB051227: SDSS pre-burst observations
  23. GRB 051227, optical observation
  24. GRB 051227: Swift detection of a burst
  25. GRB051117B: optical observation
  26. IBAS_alert n. 2719 : not a real GRB
  27. Konus-Wind observation of GRB 051221A
  28. GRB051221A: Suzaku WAM observation of the prompt emission
  29. GRB 051221A: MDM Optical Observations
  30. GRB051016: analysis of the XMM-Newton observation
  31. GRB 051221A: Detection at 251nm with Swift UVOT
  32. GRB 051221A: Chandra Afterglow Position
  33. GRB 051221A: Refined spectral and temporal analysis of the Swift-BAT short hard burst
  34. GRB 051221B: ROTSE-III Optical Limits
  35. GRB 051221B: TAROT optical limits
  36. GRB 051221A: WSRT Radio Observations
  37. GRB 051221: Redshift from Gemini
  38. GRB 051221: Continued fading of optical afterglow
  39. GRB 051221B: Refined analysis of the Swift-BAT burst
  40. Possible GRB 051221B: MDM Optical Detection
  41. GRB 051221A: RAPTOR Fading Counterpart Constraint
  42. GRB 051221B: BOOTES optical observations.
  43. Possible GRB 051221B: Swift XRT position
  44. GRB 051211A: Evidence This Is a Short Burst from Analysis of Spectral
  45. Swift-BAT detection of a possible burst
  46. GRB 051221: Discovery of fading optical afterglow
  47. GRB 051221: Swift XRT refined analysis
  48. GRB 051221: Swift/UVOT upper limits
  49. GRB 051221: Possible nearby cluster
  50. GRB 051221: No variability in Gemini data
  51. GRB 051221: Correction to GCN #4368
  52. GRB 051221: Gemini observations
  53. GRB 051221: Improved astrometry of the IR counterpart
  54. GRB051221: K-band source
  55. GRB 051221: XRT position
  56. GRB 051221: Refined analysis of the Swift-BAT short hard burst
  57. GRB 051221: IR Observations at GRB+1hr
  58. GRB 051221: Swift detection of a bright short burst
  59. Refined analysis of the SWIFT J1626.6-5156
  60. Swift-BAT discovery of hard x-ray transient SWIFT J1626.6-5156
  61. Refined analysis of the Swift-BAT detection of the RS CVn star II Peg
  62. GRB051211A (=H3979): Refined Analysis
  63. GRB 051211B: optical afterglow
  64. Swift detection of an RS CVn flare star
  65. GRB051211A: possible optical candidate
  66. Swift Trigger 172767 is not a GRB
  67. GRB 051215: near-infrared observations
  68. GRB051215 - SDSS pre-burst observations
  69. GRB 051215: Swift detection of a possible burst
  70. GRB 051215: A short GRB in a cluster?
  71. GRB051211B: Probable radio afterglow
  72. GRB051105: optical observations
  73. GRB 051213: Swift-BAT refined analysis
  74. GRB051211B: XRT refined analysis
  75. GRB 051211B, optical observation
  76. GRB 051213: Swift-BAT detection of a burst
  77. GRB 051211a: RTT150 optical observations
  78. GRB051211B, RBO optical observations
  79. GRB 051211A: Swift/UVOT upper limits
  80. GRB 051211B: Swift/UVOT upper limits - correction
  81. GRB 051211B: Swift/UVOT upper limits
  82. GRB 051211A,optical observation
  83. GRB 051211B: Swift XRT confirmation of the afterglow
  84. GRB051211B: Liverpool Telescope observation
  85. GRB 051211b: RTT150 optical observations
  86. GRB051211b: P60 Observations
  87. GRB 051211A and GRB051211B: BOOTES simultaneous observations
  88. GRB 051211B: Swift XRT Observations
  89. GRB 051210: Swift/UVOT upper limits
  90. GRB 051210: Magellan Imaging
  91. GRB 051211: TAROT optical limits
  92. GRB 051211B: a possible optical detection by TAROT
  93. GRB 051211B: a long GRB detected by INTEGRAL
  94. GRB 051211: Swift XRT upper limit
  95. GRB 051211:IAC80 optical observations
  96. HETE SXC localization of GRB 051211 (=H3979)
  97. GRB 051210: Optical imaging from Las Campanas
  98. GRB 051210: SALT detection limit
  99. GRB 051210: BAT further refined analysis of the short burst
  100. GRB 051210: Swift XRT refined analysis

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