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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').
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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"

27029 results found.

  1. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  2. The EP-WXT trigger 01709248388 is likely a flaring star
  3. EP251118a: FTW optical and NIR observations
  4. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  5. EP251118a: VLT near-infrared observation
  6. GRB 251116D: SVOM/GRM observation of a long GRB
  7. EP251118a: GOTO optical afterglow detection
  8. GRB 251119A: SVOM detection of a possible burst
  9. EP251118a: Global MASTER-Net observations report
  10. EP251118a: preliminary result of EP-FXT follow-up observation
  11. LAT GRB251118.86: Global MASTER-Net observations report
  12. GRB 251118A: Fermi-LAT detection
  13. EP251118a: NOT candidate optical counterpart
  14. EP251118a: Einstein Probe detected of a fast X-ray transient
  15. Fermi GRB 251118B: Global MASTER-Net observations report
  16. GRB 251118B: Fermi GBM Final Real-time Localization
  17. GRB 251118A: BALROG localization (Fermi Trigger 785190695 / GRB 251118855)
  18. GRB 251117A: FTW Observations of Swift candidate X-ray sources
  19. GRB 251118A: Fermi GBM Final Real-time Localization
  20. GRB 251116C: SVOM/ECLAIRs refined analysis
  21. GRB 251116B: SVOM/ECLAIRs refined analysis
  22. GRB 251114B: GECAM-B detection of a short burst
  23. GRB 251117A: Fermi GBM observation
  24. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  25. GRB 251117A: SVOM/GRM observation of a short burst
  26. GRB 251117A: Fermi-LAT detection
  27. LAT GRB251117.51: Global MASTER-Net observations report
  28. GRB 251116B: SVOM/VT optical upper limit
  29. GRB 251116C: Swift-XRT observations
  30. GRB 251117A: Fermi GBM Final Localization Correction
  31. LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations
  32. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  33. GRB 251116C: SVOM/VT optical upper limit
  34. GRB 251116B: EP-FXT follow-up observation
  35. GRB 251116B: LCO optical upper limits
  36. GRB 251116C: LCO optical upper limits
  37. SVOM GRB251116C: Global MASTER-Net observations report
  38. GRB 251116C: SVOM detection of a burst
  39. GRB 251116B: SVOM detection of a burst
  40. GRB 251116A: Fermi GBM Final Real-time Localization
  41. LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
  42. GRB 251115A: Fermi-LAT detection
  43. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  44. Fermi GRB 251115A: Global MASTER-Net observations report
  45. GRB 251115A: Fermi GBM Final Real-time Localization
  46. GRB 251114B: Fermi GBM Final Real-time Localization
  47. GRB 251112A: Swift-BAT refined analysis
  48. Fermi trigger No 784717756: Global MASTER-Net observations report
  49. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  50. The EP-WXT trigger 01709248221 is likely a flaring star
  51. Fermi GRB 251114A: Global MASTER-Net observations report
  52. LIGO/Virgo/KAGRA S251112cm: Candidates from the Zwicky Transient Facility
  53. GRB 251114A: Fermi GBM Final Real-time Localization
  54. Fermi GRB 251113A: Global MASTER-Net observations report
  55. GRB 251113A: BALROG localization (Fermi Trigger 784748255 / GRB 251113734)
  56. GRB 251113A: Fermi GBM Final Real-time Localization
  57. GRB 251111A: SVOM/ECLAIRs refined analysis
  58. GRB 251025B: SVOM/ECLAIRs refined analysis
  59. Fermi Gamma-ray Burst Monitor trigger 784717756/251113381 is not a GRB
  60. GRB 251112A: Swift/UVOT Upper Limits
  61. GRB 251112A: Swift-XRT refined Analysis
  62. LIGO/Virgo/KAGRA S251112cm: Detection of two young transients by BlackGEM/MeerLICHT: AT2025adgp and AT2025adgq
  63. Fermi Gamma-ray Burst Monitor trigger 784687703/251113034 is not a GRB
  64. Fermi Gamma-ray Burst Monitor trigger 784687099/251113027 is not a GRB
  65. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  66. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  67. Swift Trigger 1413695: a possible GRB 251112A
  68. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  69. Fermi trigger No 784621743: Global MASTER-Net observations report
  70. Fermi Gamma-ray Burst Monitor trigger 784653403/251112637 is not a GRB
  71. GRB251111A: 1.3m DFOT optical upper limit
  72. GRB 251111A: SVOM/VT optical observations with X-band data
  73. SVOM GRB251111.42: Global MASTER-Net observations report
  74. GRB 251111A: Swift-XRT observations
  75. SVOM GRB251111.22: Global MASTER-Net observations report
  76. GRB 251111A: EP-FXT counterpart detection
  77. GRB 251013C: Chandra X-ray observations and jet break detection
  78. GRB 251111A: SVOM/VT optical observations with VHF data
  79. GRB 251111A: LCO optical observation
  80. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  81. GRB 251111A: SVOM detection of a soft burst
  82. GRB 251103B: Swift-BAT refined analysis
  83. GRB 251106A: Swift/UVOT Upper Limits
  84. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  85. LIGO/Virgo/KAGRA S251108fi: One counterpart neutrino candidate from IceCube neutrino searches
  86. GRB 251108A: Fermi GBM Final Localization Correction
  87. Fermi trigger No 784329591: Global MASTER-Net observations report
  88. Fermi trigger No 784279167: Global MASTER-Net observations report
  89. SVOM GRB251108.54: Global MASTER-Net observations report
  90. GRB 251102B: SVOM/GRM observation
  91. Fermi Gamma-ray Burst Monitor trigger 784279167/251108305 is not a GRB
  92. The EP-WXT trigger 01709248051 is likely a flaring star
  93. SVOM GRB251106.83: Global MASTER-Net observations report
  94. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  95. GRB 251106B: SVOM/GRM observation of a short burst
  96. GRB 251106A: Kilonova-Catcher optical upper limit
  97. Fermi GBM Sub-Threshold Detection of GRB 251106A
  98. GRB 251106A: Swift/BAT arcminute localization of a burst
  99. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  100. GRB 251106A: MASTER optical observations

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