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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 060206: Super-LOTIS observations
  2. GRB060204A: Swift/UVOT observations
  3. GRB 060206: Swift-BAT refined analysis
  4. GRB 060206 : Lulin optical observations
  5. GRB060206: SDSS Pre-Burst Observations
  6. GRB060206: Swift XRT Refined Analysis
  7. GRB060206: Liverpool Telescope observation
  8. GRB 060206: Spectroscopic Redshift
  9. GRB060206: P60 Optical Observations
  10. GRB 060206: KAIT observations
  11. GRB060206: Swift XRT Position
  12. GRB060206: SARA Detection
  13. GRB 060206: RAPTOR observations of afterglow candidate variability.
  14. GRB 060206: High redshift burst
  15. GRB060204a: Swift XRT Detection of an Afterglow Candidate
  16. GRB060206 - Swift UVOT Confirmation of Optical Afterglow
  17. GRB060206: Optical afterglow
  18. GRB060206: Swift-BAT detection of a burst
  19. GRB 060204C: XRT analysis of Swift J061223.0+701243.9
  20. GRB060203: WHT Z-band observations
  21. BAT GRB 060204C is probably not a GRB
  22. GRB060204C: optical observation
  23. GRB 060204B: BVRi-band detections of optical afterglow
  24. GRB 060204A: Swift XRT upper limit
  25. GRB 060204A: FRAM optical observations
  26. GRB060204B: Swift/UVOT refined analysis
  27. GRB 060204C: optical observations
  28. Swift XRT Observation of GRB 060204C
  29. GRB 060204B: Swift-BAT refined analysis
  30. GRB 060204B: ART early limit
  31. GRB060204B: Swift XRT Team Refined Analysis
  32. GRB 060204C: OSN limits
  33. GRB 060204b: Keck/LRIS Afterglow Confirmation
  34. GRB 060204C: BOOTES-IR optical limits
  35. GRB 060204C: Liverpool Telescopes optical limit
  36. GRB 060204C: ROTSE-III Optical Limits
  37. GRB 060204C: Swift-BAT detection of a burst
  38. GRB 060124: Radio Observations
  39. GRB060204B: Faulkes OT candidate
  40. GRB 060204B: ART optical limit
  41. GRB 060204A: further INTEGRAL results
  42. GRB060204B, optical observation
  43. GRB060204B - SDSS pre-burst observations
  44. GRB 060203: Swift-BAT refined analysis
  45. GRB 060204B: Swift detection of a burst
  46. GRB 060204: a long GRB detected by INTEGRAL
  47. GRB 060202: UKIRT/WFCAM K-band and KeckI/LRIS I-band Observation
  48. GRB 060203: RTT150 optical observations
  49. GRB060203: Swift XRT Team Refined Analysis
  50. GRB060203 - Swift UVOT observation
  51. Swift-BAT trigger is GRB 060203
  52. GRB 060203: IR Counterpart
  53. GRB060203: Observations with SARA
  54. GRB 060203: P60 Confirmation of Optical Afterglow
  55. Possible GRB 060203: candidate optical counterpart
  56. Swift BAT Trigger 180151: Swift XRT source detection
  57. Possible GRB 060203: optical observations at Asiago
  58. GRB 060202: PROMPT Observations
  59. Swift-BAT trigger 180151 is unknown origin at this time
  60. GRB 060202: GETS observation
  61. GRB 060202: Gemini-N J, H, K_s observations
  62. GRB 060202 : Kiso B and R band limit
  63. GRB 060202: Near-IR Observation with UKIRT/WFCAM
  64. GRB 060202: Optical Afterglow Candidate from Keck/LRIS
  65. GRB 060202: Refined analysis of the Swift-BAT burst
  66. GRB060202, optical observation
  67. GRB 060202: Swift/UVOT upper limits
  68. GRB 060202: Swift XRT Team Refined Analysis
  69. GRB 060202 : Lulin R and I band limit
  70. GRB060202: Faulkes North observation
  71. GRB 060202: Swift detection of a burst
  72. GRB 060121: Gemini Late-time Observations
  73. Erratum: SDSS pre-burst observations of GRB fields
  74. GRB 060130: PROMPT Observations
  75. GRB060130: Further R-band imaging
  76. GRB 060130: Swift/XRT observation
  77. GRB 051211A: MDM Observations
  78. GRB 060123: Gemini spectroscopy of the putative host galaxy
  79. GRB 060123: VLA Radio Observations
  80. GRB060130: Optical imaging
  81. GRB060130: REM infrared observations
  82. GRB 060130, SMARTS optical observations
  83. GRB 060130: FRAM optical observations
  84. GRB 060130: further INTEGRAL IBIS results
  85. GRB 060130: a long GRB detected with INTEGRAL
  86. Possible GRB 051221B: MDM Correction
  87. GRB050121: optical observation
  88. GRB050121b: optical observation
  89. GRB 060121: Confirmation of NIR Afterglow
  90. GRB060124: optical observation
  91. GRB060124: optical observations
  92. GRB 060123: Swift refined analysis of an unusual GRB
  93. GRB060124, BVRcIc field calibration
  94. GRB060105: refined analysis of the Suzaku observation
  95. GRB060124 optical observations
  96. GRB 060121: Probable Detection of NIR Afterglow
  97. GRB060124: optical observation
  98. GRB 060116 HST observations
  99. GRB 060124: HETE detection and spectrum of the main peak
  100. Refined XRT Position for GRB 060123

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