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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 080310: Magellan redshift
  2. GRB 080310 afterglow candidate (correction to UT time)
  3. GRB 080310: Swift detection of a burst with optical afterglow
  4. GRB 080310 afterglow candidate
  5. GRB080229, optical upper limit (Correction)
  6. GRB080307, optical upper limit
  7. GRB080307 BOAO optical afterglow observation - detection of a possible OT
  8. GRB080229, optical upper limit
  9. GRB 080307: Swift-XRT Team refined analysis
  10. GRB 080307: Swift/UVOT Upper Limits
  11. GRB 080307: Early RAPTOR Limits
  12. GRB 080307, Swift-BAT refined analysis
  13. GRB080307 - SDSS Pre-Burst Observations
  14. GRB 080307: TNT optical observation
  15. GRB080307: Optical upper limits
  16. GRB 080307: Gemini-N i-band observations - candidate afterglow
  17. GRB 080307: BOAO imaging - retraction and new limit
  18. GRB 080307: retraction of UVOT candidate
  19. GRB 080307: Enhanced Swift-XRT position
  20. GRB 080307, Preliminary Swift-BAT refined analysis
  21. GRB 080307 : BOAO optical afterglow observation
  22. GRB 080307: Optical observation with DMC/KANATA
  23. GRB 080307: Swift detection of a burst
  24. VLA possible radio detection of GRB 080229
  25. GRB 080303: Swift/UVOT follow-up of afterglow detection
  26. GRB 080303, Swift-BAT refined analysis
  27. GRB 080303: Rapid PROMPT Detections
  28. GRB080303: Swift XRT refined analysis
  29. GRB 080303: Enhanced Swift-XRT position
  30. Swift UVOT observations of GRB080229B
  31. GRB080229B: Swift XRT afterglow observation
  32. GRB 080303A: Faulkes Telescope South optical afterglow observations
  33. GRB 080303
  34. GRB 080303: Swift detection of a burst with optical afterglow
  35. GRB 080303: REM NIR afterglow candidate
  36. GRB 080303A: ROTSE-III Optical Limits
  37. GRB 080229: I-band observations from OSN
  38. GRB 080229: VLT NIR observations
  39. GRB080229: Swift XRT refined analysis
  40. GRB 080229: TNG NIR observations
  41. GRB 080229: Deep Gemini/GMOS optical observations
  42. GRB 080229: Enhanced Swift-XRT position
  43. GRB 080229: REM NIR observations
  44. GRB080229: Possible optical afterglow
  45. GRB 080229B: Gamma Ray Burst Localization by SuperAGILE
  46. UVOT analysis for GRB080229
  47. GRB 080229, Swift-BAT refined analysis
  48. GRB 080229: Faulkes Telescope South optical limit
  49. GRB 080229A: ROTSE-III Optical Limits
  50. GRB 080229: Swift detection of a bright burst
  51. Early optical shallow decay in GRB 071112C
  52. GRB080207: optical observations
  53. GRB080205: optical observations
  54. GRB080211: optical observations
  55. XRF 080109/SN2008D : GMRT upper limit at 1.28 GHz
  56. GRB 071010B : Early optical brightening detected by TAOS
  57. Swift-XRT improved positions, and new redshift limits.
  58. ESO optical and NIR observations of GRB 080218B
  59. GRB 080204: Suzaku WAM observation of the prompt emission
  60. GRB 080218B, Swift-BAT refined analysis
  61. GRB 080218B: Swift-XRT refined analysis
  62. Swift/UVOT observations of GRB080218B
  63. GRB 080218B: REM NIR early upper limits
  64. GRB 080212: Mount Abu NIR observations
  65. GRB 080218B: Enhanced Swift-XRT position
  66. GRB 080218B: GROND upper limits
  67. GRB 080218b, SMARTS optical/IR limits
  68. GRB 080218A, Swift-BAT refined analysis
  69. GRB080218B: Watcher prompt limit
  70. GRB 080211: Suzaku WAM observation of the prompt emission
  71. GRB 080218B: Swift detection of a burst
  72. GRB 080218: Swift detection of a burst
  73. Swift-XRT and UVOT observations of the IPN burst GRB 080211
  74. GRB 080212: VLT optical rapid decay
  75. GRB 080212: REM refined analysis
  76. Konus-Wind observation of GRB 080211
  77. VLA radio upper limit on GRB 080212
  78. Swift/UVOT refined analysis of GRB080212
  79. GRB 080212, Swift-BAT refined analysis
  80. GRB080212: Optical afterglow candidate observed by MITSuME Telescope
  81. GRB 080212: Gemini-South optical observations
  82. GRB 080212: GROND detects afterglow
  83. GRB 080212: REM NIR afterglow?
  84. GRB 080212: optical observations
  85. GRB 080212: Enhanced Swift-XRT position
  86. GRB 080212: Swift-XRT Team refined analysis
  87. GRB 080210: Keck photometry
  88. VLA non-detection of GRB 080210
  89. GRB 080212: Swift detection of a burst
  90. IPN localization of GRB 080211
  91. GRB 080212: DSS/2MASS Galaxy at XRT position
  92. GRB 080207: VLT NIR early upper limits
  93. GRB 080210: Swift/UVOT Refined Analysis
  94. GRB 080207: optical observations.
  95. GRB 080210: Hobby-Eberly Telescope Absorption Spectroscopy
  96. GRB 080210, Swift-BAT refined analysis
  97. GRB 080210: Super-LOTIS observations
  98. GRB 080210: Swift-XRT Refined Analysis
  99. GRB 080210: VLT redshift
  100. GRB 080210: Enhanced Swift-XRT position

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