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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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 241029A: GOTO optical afterglow detection
  2. EP241021a: continued SOAR observations confirm optical rebrightening
  3. GRB 241029A: MASTER early optical counterpart detection
  4. GRB 241029A: Xinglong-2.16m optical afterglow confirmation
  5. GRB 241029A: Mephisto observations
  6. EP 241026b: LBT possible optical counterpart (brightening source)
  7. GRB 241029A: TRT optical afterglow candidate detection
  8. GRB 241029A: Swift ToO observations
  9. GRB 241029A: SVOM/GRM observation
  10. GRB 241029A : Detection and localization of a bright long GRB by SVOM/ECLAIRs
  11. Fermi trigger No 751861204: Global MASTER-Net observations report
  12. GRB 241029A: Fermi GBM Final Real-time Localization
  13. GRB 240821A: Keck/LRIS spectroscopic observations
  14. EP241021a: Gemini-South detection of optical rebrightening
  15. GRB 241026A: the 100th GRB detected by GRBAlpha
  16. GRB 241026A: TNOT optical counterpart detection
  17. Konus-Wind detection of GRB 241025A
  18. GRB 241025A (EP241025a): Optical afterglow observations with the Tsinghua-Nanshan Optical Telescope
  19. GRB 241026A: LBT redshift confirmation
  20. GRB 241026A: GECAM detection
  21. GRB 241025A: further SAO RAS optical observations
  22. GRB 241026A: BTA and Zeiss-1000 optical observations
  23. GRB 241026A: SVOM/GRM observation
  24. EP241026B: GROWTH-India Telescope optical upper limit
  25. GRB 241025A: Swift/UVOT Detection
  26. GRB 241026A: GROWTH-India Telescope optical observations
  27. GRB 241026A Fermi GBM Analysis
  28. GRB 241026A: BTA redshift identification of z = 2.79
  29. GRB 241026A: J-band observations with WINTER
  30. GRB 241025A: SAO RAS optical observations
  31. GRB 241026A: Las Cumbres optical detection
  32. GRB 241025A: Mondy optical observations
  33. EP241021a: SOAR observations of the optical counterpart
  34. EP241021a: further SAO RAS optical observations
  35. EP241026a (GRB 241026A): EP on-board trigger and follow-up observation
  36. GRB 241026A: Swift-XRT refined Analysis
  37. EP 241026b: LBT optical observations
  38. EP241021a: e-MERLIN radio observation
  39. EP EP241026b: Global MASTER-Net observations report
  40. GRB 241026A: Enhanced Swift-XRT position
  41. GRB 241026A: KAIT optical observations
  42. EP241026b: EP detection of a fast X-ray transient
  43. Fermi trigger No 751616906: Global MASTER-Net observations report
  44. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  45. GRB 241026A: SAO RAS observations of possible optical afterglow
  46. Fermi GRB 241026A: Global MASTER-Net observations report
  47. GRB 241026A: Prompt enhanced Swift-XRT position
  48. GRB 241026A: Swift detection of a burst
  49. Swift GRB241026.95: Global MASTER-Net observations report
  50. GRB 241026A: Fermi GBM Final Real-time Localization
  51. GRB241025A: 1.3m DFOT optical afterglow detection
  52. EP241021a: optical follow-up observations with Xinglong Observatory
  53. ​GRB 241025A: optical photometry from Konkoly
  54. GRB 241025A: GROWTH-India Telescope optical observations
  55. GRB 241025A: COLIBRÍ Detection of the Afterglow
  56. GRB 241025A: Swift-XRT refined Analysis
  57. GRB 241025C: Fermi GBM Detection
  58. GRB 241025A: Fermi GBM Observation
  59. IPN triangulation of GRB 241022A (short/hard)
  60. LIGO/Virgo/KAGRA S241009l: Upper limits from Swift/BAT-GUANO
  61. GRB 241025C: Fermi GBM Final Localization
  62. GRB 241025A: GRANDMA and Kilonova-Catcher optical afterglow detections and upperlimits
  63. GRB 241025B: Fermi GBM Final Localization
  64. Fermi trigger No 751563375: Global MASTER-Net observations report
  65. Fermi trigger No 751554401: Global MASTER-Net observations report
  66. EP241021a: Optical and NIR observations of counterpart with the Fraunhofer Telescope at Wendelstein Observatory
  67. EP241021a: Optical and NIR observations of counterpart with the Fraunhofer Telescope at Wendelstein Observatory
  68. EP 241021a: Swift-XRT observations
  69. EP241021a: optical follow-up observations with the Liverpool Telescope
  70. Fermi GRB 241025A: Global MASTER-Net observations report
  71. Swift GRB 241025A: Global MASTER-Net observations report
  72. EP241025a (GRB 241025A): EP observations update
  73. GRB 241025A : SVOM/VT optical afterglow observations
  74. EP 241021A: Swift ToO observations
  75. EP241021a: Liverpool Telescope optical follow-up observations
  76. GRB 241025A: Enhanced Swift-XRT position
  77. GRB 241001A: JWST spectroscopic identification of a supernova counterpart
  78. GRB 241025A: NOT spectroscopic redshift of z = 4.20
  79. GRB 241025A: DDOTI Afterglow detection
  80. EP241025a (GRB 241025A): EP on-board trigger and autonomous follow-up observation
  81. GRB 241025A: SVOM/GRM observation
  82. GRB 241025A: TRT optical afterglow observation
  83. Fermi GRB 241024B: Global MASTER-Net observations report
  84. GRB 241025A: Fermi GBM Final Real-time Localization
  85. GRB 241025A: Swift detection of a burst with an optical counterpart
  86. EP241021a: GTC OSIRIS+ spectroscopy of the optical counterpart
  87. GRB 241001A: ATCA radio observations
  88. GRB 241024B: Fermi GBM Final Localization
  89. EP241021a: No Detection in Fermi-GBM Observation
  90. GRB 241010A: VIRT Optical Upper Limit
  91. GRB 241024A: Fermi GBM Final Localisation
  92. EP241021a: VLT/FORS2 redshift z = 0.75
  93. Fermi trigger No 751449953: Global MASTER-Net observations report
  94. EP241021a: SAO RAS optical observations
  95. EP241021a: KAIT optical observations
  96. EP241021a: EP-FXT follow-up observation update
  97. IPN triangulation of GRB 241021A (long)
  98. EP241021a: Optical counterpart observations with the Liverpool Telescope
  99. EP241021a: 1.3m DFOT Optical observations
  100. EP241021a: GSP detects optical candidate counterpart

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