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

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