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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"

26166 results found.

  1. Fermi Gamma-ray Burst Monitor trigger 784687099/251113027 is not a GRB
  2. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  3. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  4. Swift Trigger 1413695: a possible GRB 251112A
  5. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  6. Fermi trigger No 784621743: Global MASTER-Net observations report
  7. Fermi Gamma-ray Burst Monitor trigger 784653403/251112637 is not a GRB
  8. GRB251111A: 1.3m DFOT optical upper limit
  9. GRB 251111A: SVOM/VT optical observations with X-band data
  10. SVOM GRB251111.42: Global MASTER-Net observations report
  11. GRB 251111A: Swift-XRT observations
  12. SVOM GRB251111.22: Global MASTER-Net observations report
  13. GRB 251111A: EP-FXT counterpart detection
  14. GRB 251013C: Chandra X-ray observations and jet break detection
  15. GRB 251111A: SVOM/VT optical observations with VHF data
  16. GRB 251111A: LCO optical observation
  17. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  18. GRB 251111A: SVOM detection of a soft burst
  19. GRB 251103B: Swift-BAT refined analysis
  20. GRB 251106A: Swift/UVOT Upper Limits
  21. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  22. LIGO/Virgo/KAGRA S251108fi: One counterpart neutrino candidate from IceCube neutrino searches
  23. GRB 251108A: Fermi GBM Final Localization Correction
  24. Fermi trigger No 784329591: Global MASTER-Net observations report
  25. Fermi trigger No 784279167: Global MASTER-Net observations report
  26. SVOM GRB251108.54: Global MASTER-Net observations report
  27. GRB 251102B: SVOM/GRM observation
  28. Fermi Gamma-ray Burst Monitor trigger 784279167/251108305 is not a GRB
  29. The EP-WXT trigger 01709248051 is likely a flaring star
  30. SVOM GRB251106.83: Global MASTER-Net observations report
  31. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  32. GRB 251106B: SVOM/GRM observation of a short burst
  33. GRB 251106A: Kilonova-Catcher optical upper limit
  34. Fermi GBM Sub-Threshold Detection of GRB 251106A
  35. GRB 251106A: Swift/BAT arcminute localization of a burst
  36. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  37. GRB 251106A: MASTER optical observations
  38. GRB 251106A: SVOM detection of a burst
  39. Fermi trigger No 784034269: Global MASTER-Net observations report
  40. Fermi Gamma-ray Burst Monitor trigger 784109140/251106337 is not a GRB
  41. EP251102a: Xinglong 2.16-m clear-band observations of the optical counterpart
  42. GRB 251105A: Fermi GBM Observation
  43. GRB 251105C: Fermi GBM Final Localization Correction
  44. LIGO/Virgo/KAGRA S251031dw: Candidates from the Zwicky Transient Facility
  45. GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
  46. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  47. GRB 251023A: SVOM/ECLAIRs detection of a burst through targeted search
  48. Fermi GBM Sub-Threshold Detection of GRB 251105B
  49. GRB 251103B: Swift/UVOT Upper Limits
  50. GRB 251105B: SVOM/GRM observation of a possible short burst with extended emission
  51. Fermi GRB 251105A: Global MASTER-Net observations report
  52. GRB 251105A: Fermi GBM Final Real-time Localization
  53. Fermi Gamma-ray Burst Monitor trigger 783986701/251104920 is not a GRB
  54. GRB 251103B: Fermi GBM observation
  55. GRB 251104A: SVOM detection of a burst
  56. EP251102a: FTW optical and NIR observations
  57. GRB 251103A: WFST optical observations
  58. EP251102a: update of EP-FXT follow-up observation
  59. GRB 251103A: Xinglong 2.16m optical detection
  60. GRB 251103B: Nanshan/HMT optical upper limit
  61. GRB 251103A: Swift/BAT-GUANO arcminute localization of a burst
  62. GRB 251103B: MITSuME Akeno optical upper limits
  63. GRB 251103B: Swift-XRT refined Analysis
  64. Fermi GRB 251103A: Global MASTER-Net observations report
  65. EP251102a: NIR observations with WINTER
  66. GRB 251103A: J-band detection with WINTER
  67. Swift GRB 251103B: Global MASTER-Net observations report
  68. GRB 251103B: GROWTH-India Telescope optical upper limits
  69. GRB 251103A: Kilonova-Catcher optical afterglow detection
  70. GRB 251103B: Swift detection of a burst
  71. GRB 251103B: Fermi GBM Final Real-time Localization
  72. GRB 251103A: Swift/UVOT Detection
  73. GRB 251103A: Fermi GBM Observation
  74. GRB 251103A: SVOM/GRM observation
  75. GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
  76. EP251102a: Einstein Probe detection of a fast X-ray transient
  77. EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
  78. GRB 251103A: LCO optical observation
  79. EP251102.890: COLIBRÍ optical counterpart candidate
  80. GRB 251103A: GOTO optical afterglow detection
  81. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  82. GRB 251103A: BOOTES-2/TELMA optical afterglow
  83. GRB 251103A: LCO optical afterglow detection
  84. GRB 251103A: Fermi GBM Final Localization
  85. GRB 251103A: NOT optical afterglow candidate
  86. GRB 251103A: SVOM detection of a bright burst
  87. GRB 251102B: Fermi GBM Final Real-time Localization
  88. Fermi GRB 251102A: Global MASTER-Net observations report
  89. GRB 251102A: Fermi GBM Final Real-time Localization
  90. GRB 251031A: Fermi GBM Observation
  91. GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
  92. GRB 251031A: BALROG localization (Fermi Trigger 783588065 / GRB 251031306)
  93. GRB 251031A: Fermi GBM Final Real-time Localization
  94. GRB 251025C: SVOM/GRM observation
  95. GRB 251028A: GECAM-B detection
  96. GRB 251028A: SVOM/GRM observation
  97. GRB 251028A: Fermi GBM Observation
  98. GRB 251026B: LBT near-infrared observations
  99. GRB 250926A: VZLUSAT-2 detection
  100. GRB 251026B: Fermi GBM Observation

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