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

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