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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 100704A: Swift XRT refined analysis
  2. GRB 100704: Swift/UVOT Upper Limits
  3. GRB 100704A: Fermi GBM observation
  4. GRB 100704A: Swift-BAT refined analysis
  5. GRB100704A: MOA optical upper limit
  6. GRB 100704A: Enhanced Swift-XRT position
  7. GRB 100704A: Swift detection of a burst
  8. GRB 100615A: Additional Gemini/NIRI observations
  9. GRB 100526A: Gemini/NIRI afterglow confirmation and host galaxy
  10. GRB 100702A, Swift-BAT refined analysis
  11. Fermi GBM trigger 299767472 (100702531) is not a GRB
  12. GRB 100702A: Swift XRT refined analysis
  13. Swift/UVOT observations of GRB100702A - correction
  14. Swift/UVOT observations of GRB100702A
  15. GRB 100702A: Second epoch of Magellan near-IR observations and afterglow limits
  16. GRB 100701B: Fermi GBM detection
  17. GRB 100702A: Magellan near-IR observations
  18. GRB 100702A: VLT optical observations
  19. GRB 100702: ROTSE-III Optical Limits
  20. GRB 100702A: Swift detection of a short burst
  21. GRB 100615A: Chandra X-ray ToO Observation
  22. XRF 100701A : MAXI/GSC detection of a probable XRF
  23. GRB 100213B: Detection of Fading Optical Afterglow
  24. GRB 100625A: Fermi GBM detection
  25. GRB 100628A: Second epoch of Magellan near-IR observations
  26. GRB 100628A: GROND optical/NIR observations of the host candidate
  27. GRB 100628A: Gemini North Observations
  28. GRB 100628A: Coincidence of source "G1" with revised XRT error circle
  29. GRB 100628A: Swift XRT refined position
  30. GRB100625A: GROND confirmation of constant source
  31. GRB 100625A Gemini-South 2nd epoch imaging
  32. GRB100628A : MOA optical upper limit
  33. GRB 090709A: Host galaxy detection
  34. GRB 100628A: Magellan near-IR observations
  35. GRB 100628A: Swift/UVOT Upper Limits
  36. GRB100628A: RTT150 optical observations
  37. GRB 100628A: Swift XRT detection of a possible X-ray afterglow
  38. GRB 100628A: INTEGRAL SPI-ACS light curve
  39. GRB 100625A: Magellan near-IR Observations
  40. GRB 100628A: Swift-BAT refined analysis
  41. GRB 100628A: Swift detection of a short hard burst
  42. Swift-BAT trigger 426048 is not a burst
  43. GRB 100614A: CrAO optical limit
  44. GRB 100625A: Swift/UVOT Upper Limits
  45. GRB 100625A: Swift-BAT refined analysis
  46. Konus-Wind observation of GRB 100625A
  47. GRB 100625A : IRSF/SIRIUS NIR upper limit
  48. GRB 100625A: Swift-XRT Team refined analysis
  49. GRB 100625A: Gemini candidate afterglow
  50. GRB 100625A: Enhanced Swift-XRT position
  51. GRB100625A : MOA optical upper limit
  52. GRB 100625A: Swift detection of a short hard burst
  53. GRB 100418A: late time optical observations
  54. Konus-Wind observation of GRB 100621A
  55. GRB 100621A: IRSF/SIRIUS NIR Observation
  56. GRB 100621A MOA-II optical limit
  57. GRB 100619A: Correction to the Fermi GBM trigger time
  58. GRB 100621A: Swift/UVOT observations
  59. GRB 100621A: Swift XRT refined analysis
  60. GRB 100621A: VLT/X-shooter redshift
  61. GRB 100621A: Swift-BAT refined analysis
  62. GRB 100621A: GROND observation of bright NIR afterglow
  63. GRB 100621A: Enhanced Swift-XRT position
  64. GRB 100621A: Prompt enhanced Swift-XRT position
  65. GRB 100621A: ROTSE-III Optical Limits
  66. GRB 100621A: Swift detection of a burst
  67. GRB 100606A: Optical Limits
  68. GRB 100619A: Fermi GBM detection
  69. GRB 100619A: Swift/UVOT Upper Limits
  70. GRB 100619A: Swift-XRT refind analysis
  71. GRB 100619A: Enhanced Swift-XRT position
  72. GRB 100619A: Swift-BAT refined analysis
  73. GRB 100619A: Swift detection of a burst
  74. GRB 100614A: Gemini/NIRI Observations
  75. GRB 100615A: Gemini/NIRI Observations
  76. XRF 100616a : MAXI/GSC detection of a probable XRF
  77. Fermi GBM trigger 100612038 is not a GRB
  78. GRB 100615A: Swift/UVOT Upper Limits
  79. GRB 100614A: Swift/UVOT Upper Limits
  80. GRB 100614A: NOT optical upper limits
  81. GRB 100614A: MASTER-Net optical alert observations
  82. GRB 100614A: Swift-BAT refined analysis
  83. GRB 100615A: Fermi GBM detection
  84. GRB 100615A: Swift-BAT refined analysis
  85. GRB 100614A: Enhanced Swift-XRT position
  86. GRB 100615A: Enhanced Swift-XRT position
  87. GRB 100615A: Swift-XRT refined analysis
  88. GRB 100614A: Swift-XRT refined analysis
  89. GRB 100614 : XMM-Newton observation
  90. GRB 100615A: GROND observations, upper limits
  91. GRB 100615A: PAIRITEL NIR Upper Limits
  92. GRB 100615A: NTT/Ultracam imaging
  93. GRB 100615A: Swift detection of a burst
  94. GRB 100614A: WHT I-band observations
  95. GRB 100614A: BOOTES-2/TELMA optical observations
  96. GRB 100614A: Liverpool Telescope Observations
  97. GRB 100614A: Swift detection of a burst
  98. GRB 100606A: Suzaku WAM observation of the prompt emission
  99. GRB 100606A: GROND observations
  100. Trigger 424161: Swift/BAT trigger on XTE J1946+274/GRO J1944+26

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