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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"

20519 results found.

  1. EP250612a / GRB 250612B: SVOM/VT optical candidate
  2. GRB 250612C: Fermi GBM Observation
  3. sb25061207: Swift-XRT observations
  4. EP250612a/GRB 250612B: JinShan optical upper limit
  5. sb25061207: SVOM/VT optical counterpart
  6. GRB 250610B: Swift-XRT refined Analysis
  7. EP250612a: Einstein Probe detection of an X-ray transient
  8. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  9. sb25061207: SVOM detection of a X-ray transient
  10. GRB 250610B - SVOM/ECLAIRs refined analysis
  11. Swift GRB250612.04: Global MASTER-Net observations report
  12. GRB 250610B: Swift/UVOT Detection
  13. EP250610A: Swift/UVOT Upper limits
  14. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  15. EP250610a: TNG NIR upper limit
  16. GRB 250610B: REM optical/NIR observations
  17. EP250610a: Liverpool Telescope optical upper limits
  18. GRB 250610B: additional Liverpool Telescope optical observations
  19. GRB 250610B: SVOM/VT optical counterpart
  20. GRB 250610B: OHP/T120 optical counterpart candidate
  21. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  22. GRB 250610B: SVOM detection of a long burst
  23. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  24. EP250610a: SVOM/VT optical upper limit
  25. EP250610a: REM optical/NIR observations
  26. GRB 250609A: Fermi GBM Observation
  27. GRBAlpha reentry on June 9, 2025
  28. EP250610a: COLIBRÍ optical upper limit
  29. EP250610a: Einstein Probe detection of an X-ray transient
  30. Fermi trigger No 771072240: Global MASTER-Net observations report
  31. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  32. GRB 250605A: Swift/UVOT Upper Limits
  33. GRB 250527C: CrAO Optical Upper Limit
  34. GRB 250607A: SVOM/GRM observation of a long burst
  35. The EP-WXT trigger 01709178244 is likely a flaring star
  36. The EP-WXT trigger 01709178069 is likely a flaring star
  37. GRB 250605A: Enhanced Swift-XRT position
  38. GRB 250605A: Swift detection of a burst
  39. IPN triangulation of GRB 250404B
  40. IPN triangulation of GRB 250529A
  41. GRB 250601A: PRIME H band upper limit.
  42. GRB 250601A: PRIME J band upper limit.
  43. GRB 250601A: VLT/FORS2 Optical Observation
  44. GRB 250602A: DDOTI Optical Follow-Up of the Fermi/LAT Localization
  45. GRB 250603A: Swift/UVOT Upper Limits
  46. GRB 250603A: Swift-XRT refined Analysis
  47. GRB 250603A: Enhanced Swift-XRT position
  48. GRB 250603A: Swift-XRT position and confirmation of GRB nature
  49. GRB 250603A: Swift detection of a burst or new Galactic transient Swift J0839.7-3916
  50. GRB 250602A: DDOTI Optical Upper Limit
  51. GRB 250521C / AT2025mgj: Pan-STARRS multi-band and multi-epoch imaging and photometry
  52. EP#01709177494: SVOM/VT optical observations
  53. GRB 250521C/ZTF25aarhkyn/AT2025mgj: COLIBRÍ optical observations
  54. GRB 250530A: TNG detection of a NIR source inside the Swift/XRT error circle
  55. GRB 250530C: Enhanced Swift-XRT position
  56. GRB 250530C: Swift detection of a burst
  57. GRB 250530A: SVOM/VT optical upper limit
  58. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate retraction and detection limit
  59. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  60. GRB 250530A: SVOM detection of a burst
  61. GRB 250527C: Swift/UVOT Upper Limits
  62. GRB 250527D: Swift/BAT-GUANO localization skymap of a burst
  63. GRB 250527B: Swift-XRT observations
  64. Fermi trigger No 770047117: Global MASTER-Net observations report
  65. EP250526a: refined analysis of the EP-WXT and EP-FXT observations
  66. GRB 250314A: CIDER NB1008 upper limit
  67. EP250526a: COLIBRÍ optical upper limits
  68. EP250526a: Einstein Probe detection of a fast X-ray transient
  69. EP J1350.0-8622: Einstein Probe detection of an X-ray transient candidate
  70. EP-WXT trigger 01709176712: SVOM/C-GFT observations of blue-to-red color variation
  71. The EP-WXT trigger 01709176612: SVOM/VT optical observations
  72. GRB 250521D: DDOTI Optical Upper Limit
  73. The EP-WXT trigger 01709176612 is likely a flaring star
  74. GRB 250521B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  75. GRB 250521D: LAST tentative optical counterpart candidate
  76. GRB 250520A: 10 GHz VLA radio source
  77. GRB 250521A: DDOTI Optical Upper Limit
  78. GRB 250520A: VLT/FORS2 Optical Observation
  79. GRB 250502A: Tautenburg observations
  80. GRB 250520A: Swift/UVOT Upper Limits
  81. Konus-Wind detection of GRB 250516B
  82. IPN triangulation of GRB 250516B
  83. GRB 250520A: J-band observations with WINTER
  84. GRB 250520A: Gemini-South optical observations
  85. GRB 250520A: REM optical/NIR early observations
  86. GRB 250520A：SVOM/VT optical candidate
  87. GRB 250520A: COLIBRÍ optical upper limit
  88. GRB 250520A: DDOTI Optical Upper Limit
  89. GRB 250520A: Enhanced Swift-XRT position
  90. GRB 250520A: Swift detection of a burst
  91. GRB 250516A: COLIBRÍ optical upper limit
  92. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  93. GRB 250515A: Swift-XRT observations
  94. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  95. GRB 250515A: 1.6m Mephisto optical detection
  96. GRB 250516A: Swift/UVOT Detection
  97. GRB 250516A: Enhanced Swift-XRT position
  98. GRB 250516A: Swift detection of a burst
  99. GRB 250424A: COLIBRÍ detection of the associated supernova
  100. GRB 250502A: TESS observations

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