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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"

12390 results found.

  1. EP251124a: Xinglong GWAC-F60A optical observation
  2. Fermi GRB 251125A: Global MASTER-Net observations report
  3. EP251124a: NOT r- and z-band optical upper limits
  4. EP251124a: Global MASTER-Net observations report
  5. EP251124a: Swift-XRT observations
  6. EP251124a: Optical upper limit with Kinder observations
  7. Fermi GRB 251124a: Global MASTER-Net observations report
  8. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  9. EP251124a: GROWTH-India Telescope optical upper limits
  10. GRB 251122A / EP251122a: EP-FXT counterpart detection
  11. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  12. GRB 251122A / EP251122a: LCO optical upper limits
  13. EP251122a: Global MASTER-Net observations report
  14. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  15. Fermi trigger No 785388351: Global MASTER-Net observations report
  16. GRB 251118A: Swift/UVOT Detection
  17. GRB 251118A: Swift-XRT afterglow detection
  18. GRB 251117A: Swift-XRT observations
  19. EP251118a: Global MASTER-Net observations report
  20. LAT GRB251118.86: Global MASTER-Net observations report
  21. Fermi GRB 251118B: Global MASTER-Net observations report
  22. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  23. GRB 251115A: Swift-XRT observations
  24. LAT GRB251117.51: Global MASTER-Net observations report
  25. GRB 251116B: SVOM/VT optical upper limit
  26. GRB 251116C: Swift-XRT observations
  27. GRB 251116C: SVOM/VT optical upper limit
  28. GRB 251111A: Mondy optical upper limit
  29. GRB 251116B: LCO optical upper limits
  30. GRB 251116C: LCO optical upper limits
  31. SVOM GRB251116C: Global MASTER-Net observations report
  32. IceCube-Cascade 251112A: Upper limits from a search for additional neutrino events in IceCube
  33. Fermi GRB 251115A: Global MASTER-Net observations report
  34. Konus-Wind detection of GRB 251108C
  35. Fermi trigger No 784717756: Global MASTER-Net observations report
  36. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  37. Fermi GRB 251114A: Global MASTER-Net observations report
  38. Fermi GRB 251113A: Global MASTER-Net observations report
  39. GRB 251112A: Swift/UVOT Upper Limits
  40. LIGO/Virgo/KAGRA S251112cm: Detection of two young transients by BlackGEM/MeerLICHT: AT2025adgp and AT2025adgq
  41. GRB 251112B: MAXI/GSC detection
  42. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  43. Swift Trigger 1413695: a possible GRB 251112A
  44. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  45. Fermi trigger No 784621743: Global MASTER-Net observations report
  46. GRB251111A: 1.3m DFOT optical upper limit
  47. SVOM GRB251111.42: Global MASTER-Net observations report
  48. GRB 251111A: Swift-XRT observations
  49. SVOM GRB251111.22: Global MASTER-Net observations report
  50. GRB 251111A: KAIT optical upper limit
  51. GRB 251106A: Swift/UVOT Upper Limits
  52. IceCube-Cascade 251107A: Upper limits from a search for additional neutrino events in IceCube
  53. Fermi trigger No 784329591: Global MASTER-Net observations report
  54. Fermi trigger No 784279167: Global MASTER-Net observations report
  55. SVOM GRB251108.54: Global MASTER-Net observations report
  56. SVOM GRB251106.83: Global MASTER-Net observations report
  57. GRB 251106A: Swift-XRT afterglow detection
  58. GRB 251106A: Kilonova-Catcher optical upper limit
  59. GRB 251106A: MASTER optical observations
  60. Fermi trigger No 784034269: Global MASTER-Net observations report
  61. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  62. GRB 251103B: Swift/UVOT Upper Limits
  63. Fermi GRB 251105A: Global MASTER-Net observations report
  64. GRB 251103A: Optical afterglow detection by ZTF’s public survey
  65. GRB 251103B: Nanshan/HMT optical upper limit
  66. GRB 251103B: MITSuME Akeno optical upper limits
  67. Fermi GRB 251103A: Global MASTER-Net observations report
  68. EP251102a: NIR observations with WINTER
  69. GRB 251103A: J-band detection with WINTER
  70. Swift GRB 251103B: Global MASTER-Net observations report
  71. GRB 251103B: GROWTH-India Telescope optical upper limits
  72. GRB 251103B: Swift detection of a burst
  73. GRB 251103A: Swift-XRT afterglow detection
  74. GRB 251025B: OHP/T193 optical upper limit
  75. Fermi GRB 251102A: Global MASTER-Net observations report
  76. GRB 251026B: LBT near-infrared observations
  77. Fermi GRB 251028B: Global MASTER-Net observations report
  78. GRB251026B: PRIME H-band upper limit
  79. GRB 251028A: MAXI/GSC detection
  80. IceCube-251025A: Upper limits from a search for additional neutrino events in IceCube
  81. GRB 251026B: Swift-XRT observations of GOTO25jgl/AT2025absf
  82. Fermi-LAT Gamma-ray Observations of IceCube-251025A
  83. GRB 251023B: Swift-UVOT Upper Limits
  84. GRB 251027A: Swift-XRT observations
  85. EP251027.145: COLIBRÍ optical upper limits
  86. GRB 251027A: LCO optical upper limit
  87. GRB 251027A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  88. GRB 251023B / EP251023b: Mondy optical upper limit
  89. GRB 251026A: Mondy optical upper limit
  90. GRB 251026B: Tentative GOTO optical counterpart candidate
  91. Fermi GRB 251026B: Global MASTER-Net observations report
  92. Fermi GRB 251025C: Global MASTER-Net observations report
  93. GRB 251026A: Swift-XRT observations
  94. GRB 251026A: SVOM/C-GFT upper limit
  95. IceCube-251025A: DDOTI Optical Upper Limit
  96. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  97. GRB 251024A: Swift/UVOT Upper Limits
  98. GRB 251025B: Swift-XRT afterglow detection
  99. IceCube Alert 251025.57: Global MASTER-Net observations report
  100. GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit

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