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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"

37565 results found.

  1. GRB 241029A: Swift-XRT observations
  2. GRB 241029A: Fermi GBM Observation
  3. GRB 241029A: AKO Optical Afterglow Detection
  4. GRB 241029A: GOTO optical afterglow detection
  5. GRB 241029A: MASTER early optical counterpart detection
  6. GRB 241029A: Xinglong-2.16m optical afterglow confirmation
  7. GRB 241029A: Mephisto observations
  8. EP 241026b: LBT possible optical counterpart (brightening source)
  9. GRB 241029A: TRT optical afterglow candidate detection
  10. GRB 241029A: Swift ToO observations
  11. GRB 241029A: SVOM/GRM observation
  12. GRB 241029A : Detection and localization of a bright long GRB by SVOM/ECLAIRs
  13. Fermi trigger No 751861204: Global MASTER-Net observations report
  14. GRB 241029A: Fermi GBM Final Real-time Localization
  15. GRB 240821A: Keck/LRIS spectroscopic observations
  16. GRB 241026A: the 100th GRB detected by GRBAlpha
  17. GRB 241026A: TNOT optical counterpart detection
  18. Konus-Wind detection of GRB 241025A
  19. GRB 241025A (EP241025a): Optical afterglow observations with the Tsinghua-Nanshan Optical Telescope
  20. GRB 241026A: LBT redshift confirmation
  21. GRB 241026A: GECAM detection
  22. GRB 241025A: further SAO RAS optical observations
  23. GRB 241026A: BTA and Zeiss-1000 optical observations
  24. GRB 241026A: SVOM/GRM observation
  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: further SAO RAS optical observations
  34. EP241026a (GRB 241026A): EP on-board trigger and follow-up observation
  35. GRB 241026A: Swift-XRT refined Analysis
  36. GRB 241026A: Enhanced Swift-XRT position
  37. GRB 241026A: KAIT optical observations
  38. Fermi trigger No 751616906: Global MASTER-Net observations report
  39. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  40. GRB 241026A: SAO RAS observations of possible optical afterglow
  41. Fermi GRB 241026A: Global MASTER-Net observations report
  42. GRB 241026A: Prompt enhanced Swift-XRT position
  43. GRB 241026A: Swift detection of a burst
  44. GRB 241026A: Fermi GBM Final Real-time Localization
  45. GRB241025A: 1.3m DFOT optical afterglow detection
  46. ​GRB 241025A: optical photometry from Konkoly
  47. GRB 241025A: GROWTH-India Telescope optical observations
  48. GRB 241025A: COLIBRÍ Detection of the Afterglow
  49. GRB 241025A: Swift-XRT refined Analysis
  50. GRB 241025C: Fermi GBM Detection
  51. GRB 241025A: Fermi GBM Observation
  52. IPN triangulation of GRB 241022A (short/hard)
  53. LIGO/Virgo/KAGRA S241009l: Upper limits from Swift/BAT-GUANO
  54. GRB 241025C: Fermi GBM Final Localization
  55. GRB 241025A: GRANDMA and Kilonova-Catcher optical afterglow detections and upperlimits
  56. GRB 241025B: Fermi GBM Final Localization
  57. Fermi trigger No 751563375: Global MASTER-Net observations report
  58. Fermi trigger No 751554401: Global MASTER-Net observations report
  59. EP 241021a: Swift-XRT observations
  60. Fermi GRB 241025A: Global MASTER-Net observations report
  61. Swift GRB 241025A: Global MASTER-Net observations report
  62. EP241025a (GRB 241025A): EP observations update
  63. GRB 241025A : SVOM/VT optical afterglow observations
  64. GRB 241025A: Enhanced Swift-XRT position
  65. GRB 241001A: JWST spectroscopic identification of a supernova counterpart
  66. GRB 241025A: NOT spectroscopic redshift of z = 4.20
  67. GRB 241025A: DDOTI Afterglow detection
  68. EP241025a (GRB 241025A): EP on-board trigger and autonomous follow-up observation
  69. GRB 241025A: SVOM/GRM observation
  70. GRB 241025A: TRT optical afterglow observation
  71. Fermi GRB 241024B: Global MASTER-Net observations report
  72. GRB 241025A: Fermi GBM Final Real-time Localization
  73. GRB 241025A: Swift detection of a burst with an optical counterpart
  74. EP241021a: GTC OSIRIS+ spectroscopy of the optical counterpart
  75. GRB 241001A: ATCA radio observations
  76. GRB 241024B: Fermi GBM Final Localization
  77. EP241021a: No Detection in Fermi-GBM Observation
  78. GRB 241010A: VIRT Optical Upper Limit
  79. GRB 241024A: Fermi GBM Final Localisation
  80. EP241021a: VLT/FORS2 redshift z = 0.75
  81. Fermi trigger No 751449953: Global MASTER-Net observations report
  82. EP241021a: SAO RAS optical observations
  83. EP241021a: KAIT optical observations
  84. IPN triangulation of GRB 241021A (long)
  85. GRB 241018A: SVOM/C-GFT optical observations
  86. GRB241017A: 1.3m DFOT optical upper limit
  87. GRB 241018A: 1.3m DFOT Optical upper limit
  88. GRB 241018A: EP-FXT afterglow detection
  89. Konus-Wind detection of GRB 241018A
  90. GRB 241018A: SVOM/GRM observation
  91. GRB 241018A/sb24101802: Mephisto optical upper limit
  92. GRB 241017A/sb24101702: Mephisto optical upper limit
  93. GRB 241018A: BOOTES-4/MET optical upper limit
  94. GRB 241018A: Mondy optical upper limit
  95. GRB 241018A: SVOM/VT further analysis and counterpart confirmed
  96. GRB 241018A: GROWTH-India telescope optical upper limit
  97. GRB 241018A: Swift-XRT observations
  98. GRB 241018A: REM optical/NIR upper limits
  99. GRB 241018A: NOT optical observations
  100. GRB 241017A: SVOM/VT follow-up and optical upper limit

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