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

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