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

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