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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. GRB060114: Faulkes North observation
  2. GRB 060108: IR observations of afterglow
  3. GRB060108: Faulkes North afterglow evidence
  4. GRB 060108: further analysis of VLT images
  5. GRB 060108: Evidence for an XRT Position Offset
  6. GRB 060110: KAIT observations
  7. GRB 060111B: Swift XRT refined analysis
  8. GRB 060111A: refined UVOT anaysis
  9. GRB 060111B: MITSuME detection of optical afterglow
  10. GRB 060111B: TAROT optical observation
  11. GRB060111A: RTT150 optical observations
  12. GRB060111B: RTT150, possible host galaxy
  13. GRB 060111B: Refined analysis of the Swift-BAT burst
  14. GRB 060110: MARGE observations
  15. GRB 060111(a): P60 Observations
  16. GRB 060111B: Gualba observatory limit
  17. GRB 060111B: ROTSE-III Detection of Optical Counterpart Flare
  18. GRB 060111B: Swift detection of a burst
  19. GRB 060111: Swift-BAT Refined Analysis
  20. GRB060111.2:_MASTER optical limit
  21. GRB 060108: VLT K-band observations
  22. GRB 060111: TAROT optical observation
  23. GRB 060111: possible UVOT counterpart
  24. GRB060111 : XRT refined analysis
  25. GRB 060111: ROTSE-III Optical Limits
  26. GRB 060111: Swift detection of a burst
  27. GRB 060110: Mitsume optical observations
  28. GRB 060110: Swift-BAT refined analysis
  29. GRB 060109: Swift-BAT refined analysis
  30. GRB 060108: z-band imaging from Gemini-North
  31. GRB 060110a: RAPTOR detection of early optical emission.
  32. GRB 060110: UKIRT K-band observations
  33. GRB 060110: ROTSE-III Confirmation of Optical Counterpart
  34. GRB 060110: IR Candidate Afterglow
  35. GRB060110, optical observation
  36. GRB 060110: Super-LOTIS observations
  37. GRB 060110: Optical observation
  38. GRB 060110: Correction
  39. Correction to GRB 060109 XRT analysis
  40. GRB 050110: IR Observations
  41. GRB 060110: Optical limit
  42. GRB 060110: Swift-BAT detection of a burst
  43. GRB 060109: Refined Swift-XRT analysis
  44. GRB 060109: Swift/UVOT upper limits
  45. GRB060109, optical observation
  46. GRB 060108: ISAS early observations and near IR upper limit
  47. GRB060108: P200 Ks Observations
  48. GRB 060108: early UKIRT K-band observations
  49. Swift UVOT correction to GCN 4455
  50. GRB 060109: Swift Detection of a long burst
  51. GRB 060108: a dark burst?
  52. GRB 060108: Refined XRT analysis
  53. GRB 060108: VLT J-band observations
  54. GRB 060108: Mitsume optical observations
  55. GRB 060108: Swift/UVOT upper limits
  56. GRB 060105: quick look analysis of the Suzaku/XIS afterglow observation
  57. GRB060108: SDSS pre-burst observations
  58. GRB060108: Faulkes Telescope observation
  59. GRB060108, optical observation
  60. GRB 060108: Refined analysis of the Swift-BAT burst
  61. GRB 060108: Swift XRT position
  62. GRB060108: Swift detection of its 100th GRB
  63. GRB 060105: pseudo-z from spectral parameters of the prompt emission
  64. GRB 060105: Radio observations
  65. GRB 060105: MDM Observation
  66. Konus-Wind observation of GRB 060105
  67. GRB 060105: ISAS observations and near IR upper limit
  68. GRB 060105: Swift/UVOT upper limits
  69. GRB 060105: Mitsume optical observations
  70. GRB 060105: BAT refined analysis
  71. GRB 060102 - no XRT afterglow
  72. GRB 060105: XRT refined analysis
  73. GRB060105: Suzaku-XIS and -HXD observation plan
  74. GRB060105, optical observation
  75. GRB060105 : Kiso optical observation
  76. GRB060105: Swift detection of a bright long burst
  77. Swift-BAT trigger 175653 is not an astrophysical source
  78. GRB 060102: MDM Observation
  79. Swift-BAT trigger 175653 is probably not a GRB
  80. GRB 060102: Swift-BAT refined analysis
  81. Time Correction to GRB 060102
  82. GRB 060102: Swift-BAT detection of a burst
  83. GRB051211B: optical observations
  84. GRB051227: SARA Observations
  85. GRB 051221B: Optical Observations with Kuiper 1.54m
  86. GRB 051227: Likely host galaxy underlying afterglow position
  87. GRB 051227: optical observation
  88. GRB051221B: Radio observations
  89. GRB 051221A: VLA Radio Observations
  90. GRB051227: Radio Observations
  91. GRB 051227: Confirmed fading from Gemini observations
  92. GRB051227: further analysis of VLT images
  93. GRB 051227: optical afterglow
  94. GRB 051227: Swift/UVOT Upper Limits (Possible U-band
  95. GRB 051227: Gemini observations
  96. GRB 051227: Keck Spectroscopy
  97. GRB 051227: Magellan r'-band Imaging/Astrometry
  98. GRB 051227: refined analysis of VLT images
  99. GRB 051227: P60 Observations
  100. GRB 051227: MDM Observation

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