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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').
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"

37504 results found.

  1. GRB 251108C: AstroSat CZTI detection
  2. GRB 251112B: MAXI/GSC detection
  3. Fermi Gamma-ray Burst Monitor trigger 784687703/251113034 is not a GRB
  4. Fermi Gamma-ray Burst Monitor trigger 784687099/251113027 is not a GRB
  5. GRB 251108B: Glowbug gamma-ray detection
  6. Swift Trigger 1413695: a possible GRB 251112A
  7. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  8. Fermi trigger No 784621743: Global MASTER-Net observations report
  9. Fermi Gamma-ray Burst Monitor trigger 784653403/251112637 is not a GRB
  10. GRB 251106B: Glowbug gamma-ray detection of a likely short burst
  11. GRB 251111A: Swift-XRT afterglow detection
  12. GRB 251111A: SVOM/VT optical observations with X-band data
  13. GRB 251111A: Swift-XRT observations
  14. GRB 251111A: EP-FXT counterpart detection
  15. GRB 251013C: Chandra X-ray observations and jet break detection
  16. GRB 251111A: SVOM/VT optical observations with VHF data
  17. GRB 251111A: KAIT optical upper limit
  18. GRB 251111A: LCO optical observation
  19. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  20. GRB 251111A: SVOM detection of a soft burst
  21. GRB 251103B: Swift-BAT refined analysis
  22. GRB 251106A: Swift/UVOT Upper Limits
  23. GRB 251105B: Insight-HXMT/HE detection
  24. GRB 251106B: Insight-HXMT detection
  25. GRB 251105A: AstroSat CZTI detection
  26. GRB 251108A: Fermi GBM Final Localization Correction
  27. Fermi trigger No 784329591: Global MASTER-Net observations report
  28. Fermi trigger No 784279167: Global MASTER-Net observations report
  29. GRB 251102B: SVOM/GRM observation
  30. Fermi Gamma-ray Burst Monitor trigger 784279167/251108305 is not a GRB
  31. IPN triangulation of GRB 251105B (possible sGRB with EE)
  32. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  33. GRB 251106B: SVOM/GRM observation of a short burst
  34. GRB 251106A: Swift-XRT afterglow detection
  35. GRB 251106A: Kilonova-Catcher optical upper limit
  36. Fermi GBM Sub-Threshold Detection of GRB 251106A
  37. GRB 251106A: Swift/BAT arcminute localization of a burst
  38. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  39. GRB 251106A: MASTER optical observations
  40. GRB 251106A: SVOM detection of a burst
  41. GRB 251103B: AstroSat CZTI detection
  42. GRB 251025C: TERI Gamma-ray detection
  43. GRB 251016B: TERI Gamma-ray detection
  44. GRB 251016A: TERI Gamma-ray detection of a short burst
  45. GRB 250920C: TERI Gamma-ray detection
  46. Fermi trigger No 784034269: Global MASTER-Net observations report
  47. Fermi Gamma-ray Burst Monitor trigger 784109140/251106337 is not a GRB
  48. GRB 251105A: Fermi GBM Observation
  49. GRB 251105C: Fermi GBM Final Localization Correction
  50. GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
  51. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  52. GRB 251105B: AstroSat CZTI detection of a short burst with extended emission
  53. GRB 251023A: SVOM/ECLAIRs detection of a burst through targeted search
  54. Fermi GBM Sub-Threshold Detection of GRB 251105B
  55. GRB 251103B: Swift/UVOT Upper Limits
  56. GRB 251105B: SVOM/GRM observation of a possible short burst with extended emission
  57. Fermi GRB 251105A: Global MASTER-Net observations report
  58. GRB 251105A: Fermi GBM Final Real-time Localization
  59. Fermi Gamma-ray Burst Monitor trigger 783986701/251104920 is not a GRB
  60. GRB 251103B: Fermi GBM observation
  61. GRB 251104A: SVOM detection of a burst
  62. GRB 251028A: Insight-HXMT/HE detection
  63. GRB 251103A: Optical afterglow detection by ZTF’s public survey
  64. GRB 251103A: WFST optical observations
  65. EP251102a: OHP/T193 optical observations
  66. GRB 251103A: OHP/T193 optical observations
  67. GRB 251103A: Xinglong 2.16m optical detection
  68. GRB 251103A: Insight-HXMT detection
  69. GRB 251103A: KAIT optical observations
  70. GRB 251103B: Nanshan/HMT optical upper limit
  71. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  72. GRB 251103A: Swift/BAT-GUANO arcminute localization of a burst
  73. GRB 251103B: MITSuME Akeno optical upper limits
  74. GRB 251103B: Swift-XRT refined Analysis
  75. Fermi GRB 251103A: Global MASTER-Net observations report
  76. GRB 251103A: J-band detection with WINTER
  77. Swift GRB 251103B: Global MASTER-Net observations report
  78. GRB 251103B: GROWTH-India Telescope optical upper limits
  79. GRB 251103A: Kilonova-Catcher optical afterglow detection
  80. GRB 251103B: Enhanced Swift-XRT position
  81. GRB 251103B: Prompt enhanced Swift-XRT position
  82. GRB 251103B: Swift detection of a burst
  83. GRB 251103B: Fermi GBM Final Real-time Localization
  84. GRB 251103A: Swift/UVOT Detection
  85. GRB 251103A: Fermi GBM Observation
  86. GRB 251103A: SVOM/GRM observation
  87. GRB 251103A: Swift-XRT afterglow detection
  88. GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
  89. GRB 251025B: OHP/T193 optical upper limit
  90. GRB 251103A: LCO optical observation
  91. GRB 251103A: GOTO optical afterglow detection
  92. GRB 251102A: AstroSat CZTI detection
  93. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  94. GRB 251103A: NOT spectroscopic redshift z = 0.76
  95. GRB 251103A: BOOTES-2/TELMA optical afterglow
  96. GRB 251103A: LCO optical afterglow detection
  97. GRB 251103A: NOT optical afterglow candidate (duplicate submission)
  98. GRB 251103A: Fermi GBM Final Localization
  99. GRB 251103A: NOT optical afterglow candidate
  100. GRB 251103A: SVOM detection of a bright burst

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