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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 090515: ROVOR Upper Limit
  2. GRB 090515: MMT/MMIRS NIR Upper Limit
  3. GRB 090515: Swift/UVOT Observations
  4. GRB 090515: Swift-XRT refined analysis
  5. GRB 090515: Enhanced Swift-XRT position
  6. GRB 090509: Fermi GBM observation
  7. GRB 090515: Swift-BAT refined spectral analysis
  8. GRB 090515: Swift-BAT refined analysis
  9. GRB 090509 - Zadko Telescope observations
  10. GRB 090515: Gemini-N upper limit
  11. GRB 090515: WIYN NIR Upper Limit
  12. GRB 090515: Super-LOTIS Upper Limits
  13. GRB 090515: PAIRITEL Upper Limits
  14. GRB 090515: KAIT optical upper limits
  15. GRB 090515: ROTSE-III Optical Limits
  16. GRB 090515: Swift detection of a short burst
  17. GRB 090510: Suzaku WAM observation of the prompt emission
  18. GRB 090510, Radio limits
  19. GRB090510: VLT/FORS2 spectroscopic redshift
  20. GRB 090510: GROND observations
  21. GRB 090510: Swift/UVOT host galaxy candidates
  22. GRB 090510: Fermi-LAT follow-up analysis
  23. GRB 090509, further Swift-BAT refined analysis
  24. Fermi Gamma-ray Burst Monitor trigger 263649437 is not a GRB
  25. GRB 090510B: Fermi GBM detection
  26. GRB 090502: Fermi GBM detection
  27. GRB 090510: correction to GCN 9344
  28. Konus-Wind observation of GRB 090510
  29. AGILE detection of GRB 090510
  30. GRB 090510: UVOT refined analysis
  31. GRB 090510: Swift XRT refined analysis
  32. GRB 090510: correction to coordinates in GCN 9338
  33. GRB 090510: Enhanced Swift-XRT position
  34. GRB 090510: NOT afterglow confirmation
  35. GRB 090510: Swift-BAT refined analysis
  36. GRB 090510: Fermi GBM detection
  37. GRB 090509: Swift-BAT refined analysis
  38. Fermi LAT detection of GRB 090510
  39. GRB 090509, SMARTS optical/IR afterglow observations
  40. GRB 090510: Swift/UVOT Detection of a Candidate Optical Afterglow
  41. GRB 090510: Swift detection of a short hard burst
  42. GRB 090408: optical upper limit
  43. GRB 090418A: optical observation
  44. GRB 090509: GROND further analysis and redshift limit
  45. GRB 090509: REM NIR afterglow
  46. GRB 090509: GROND afterglow candidate
  47. GRB 090509: Swift detection of a burst
  48. GRB 090323: optical observations
  49. GRB 090423: optical limit
  50. GRB 090423: 250 GHz upper limit for a z=8.2 GRB with MAMBO-2 at the IRAM 30m
  51. GRB 080913: 250 GHz upper limit for a z=6.7 GRB with MAMBO-2 at the IRAM 30m
  52. GRB 090424: optical observations
  53. GRB 090427: GROND observations
  54. GRB 090429A: ROVOR magnitude limit
  55. ICSP VLF observation of GRB090427 from two receivers
  56. ICSP VLF observation of GRB090424 from four receivers
  57. Refined analysis of ICSP VLF observation of SGR J1550-5418 bursts on 22nd January, 2009
  58. GRB 090428B: Suzaku WAM observation of the prompt emission
  59. GRB 090424, SMARTS optical/IR afterglow monitoring
  60. GRB 090426: optical observations
  61. GRB 090429D: Fermi GBM detection
  62. GRB 090429C: Fermi GBM detection
  63. GRB 090429B: Swift/UVOT Upper Limits
  64. GRB 090429A: Swift/UVOT Upper Limits
  65. GRB 090427: pseudo-z= 1.48 from prompt emission spectrum
  66. GRB 090429B: Gemini-N further nIR observations
  67. GRB 090424: YNAO-GMG observations
  68. GRB 090429A: Swift-XRT refined analysis
  69. GRB 090429A: GROND upper limits
  70. GRB 090427C: Fermi GBM detection
  71. GRB 090427B: Fermi GBM detection
  72. GRB 090426C: Fermi GBM detection
  73. GRB 090426B: Fermi GBM detection/observation
  74. GRB 090429B: Swift XRT refined analysis
  75. GRB 090429A: Enhanced Swift-XRT position
  76. Konus-Wind observation of very bright GRB 090427
  77. GRB 090428B: Fermi GBM detection
  78. GRB 090428: Fermi GBM detection
  79. GRB 090418A BVRcIc field calibration
  80. GRB 090426: GAO 150cm telescope Optical Observation
  81. GRB 090429B: RIMOTS optical upper limits
  82. GRB 090429B: Swift-BAT refined analysis
  83. GRB 090429A: Swift-BAT refined analysis
  84. GRB 090429B: Enhanced Swift-XRT position
  85. GRB 090429A - Correction to XRT position
  86. GRB090429B: Gemini-N infrared IR candidate
  87. GRB 090426: YNAO-GMG observations
  88. GRB 090429B: VLT upper limits
  89. GRB 090429B: GROND Observations
  90. GRB 090429B: Super-LOTIS early observations
  91. GRB 090429B: Swift detection of a burst
  92. GRB 090429: Swift detection of a burst
  93. GRB 090423: pseudo burst at z=1 and its relation to GRB 080913
  94. GRB 090424 : Multiband Optical observation from Nainital
  95. IPN triangulation of very bright GRB 090427
  96. GRB 090426: R-band limit
  97. GRB 090424: Continued R-band monitoring
  98. GRB 090423: CARMA mm observations
  99. GRB 090423: millimeter detection
  100. GRB 090426: Swift/BAT spectral lag results

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