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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"

26922 results found.

  1. GRB 251119A: SVOM detection of a possible burst
  2. EP251118a: Global MASTER-Net observations report
  3. EP251118a: preliminary result of EP-FXT follow-up observation
  4. LAT GRB251118.86: Global MASTER-Net observations report
  5. GRB 251118A: Fermi-LAT detection
  6. EP251118a: NOT candidate optical counterpart
  7. EP251118a: Einstein Probe detected of a fast X-ray transient
  8. Fermi GRB 251118B: Global MASTER-Net observations report
  9. GRB 251118B: Fermi GBM Final Real-time Localization
  10. GRB 251118A: BALROG localization (Fermi Trigger 785190695 / GRB 251118855)
  11. GRB 251117A: FTW Observations of Swift candidate X-ray sources
  12. GRB 251118A: Fermi GBM Final Real-time Localization
  13. GRB 251116C: SVOM/ECLAIRs refined analysis
  14. GRB 251116B: SVOM/ECLAIRs refined analysis
  15. GRB 251114B: GECAM-B detection of a short burst
  16. GRB 251117A: Fermi GBM observation
  17. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  18. GRB 251117A: SVOM/GRM observation of a short burst
  19. GRB 251117A: Fermi-LAT detection
  20. LAT GRB251117.51: Global MASTER-Net observations report
  21. GRB 251116B: SVOM/VT optical upper limit
  22. GRB 251116C: Swift-XRT observations
  23. GRB 251117A: Fermi GBM Final Localization Correction
  24. LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations
  25. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  26. GRB 251116C: SVOM/VT optical upper limit
  27. GRB 251116B: EP-FXT follow-up observation
  28. GRB 251116B: LCO optical upper limits
  29. GRB 251116C: LCO optical upper limits
  30. SVOM GRB251116C: Global MASTER-Net observations report
  31. GRB 251116C: SVOM detection of a burst
  32. GRB 251116B: SVOM detection of a burst
  33. GRB 251116A: Fermi GBM Final Real-time Localization
  34. LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
  35. GRB 251115A: Fermi-LAT detection
  36. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  37. Fermi GRB 251115A: Global MASTER-Net observations report
  38. GRB 251115A: Fermi GBM Final Real-time Localization
  39. GRB 251114B: Fermi GBM Final Real-time Localization
  40. GRB 251112A: Swift-BAT refined analysis
  41. Fermi trigger No 784717756: Global MASTER-Net observations report
  42. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  43. The EP-WXT trigger 01709248221 is likely a flaring star
  44. Fermi GRB 251114A: Global MASTER-Net observations report
  45. LIGO/Virgo/KAGRA S251112cm: Candidates from the Zwicky Transient Facility
  46. GRB 251114A: Fermi GBM Final Real-time Localization
  47. Fermi GRB 251113A: Global MASTER-Net observations report
  48. GRB 251113A: BALROG localization (Fermi Trigger 784748255 / GRB 251113734)
  49. GRB 251113A: Fermi GBM Final Real-time Localization
  50. GRB 251111A: SVOM/ECLAIRs refined analysis
  51. GRB 251025B: SVOM/ECLAIRs refined analysis
  52. Fermi Gamma-ray Burst Monitor trigger 784717756/251113381 is not a GRB
  53. GRB 251112A: Swift/UVOT Upper Limits
  54. GRB 251112A: Swift-XRT refined Analysis
  55. LIGO/Virgo/KAGRA S251112cm: Detection of two young transients by BlackGEM/MeerLICHT: AT2025adgp and AT2025adgq
  56. Fermi Gamma-ray Burst Monitor trigger 784687703/251113034 is not a GRB
  57. Fermi Gamma-ray Burst Monitor trigger 784687099/251113027 is not a GRB
  58. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  59. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  60. Swift Trigger 1413695: a possible GRB 251112A
  61. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  62. Fermi trigger No 784621743: Global MASTER-Net observations report
  63. Fermi Gamma-ray Burst Monitor trigger 784653403/251112637 is not a GRB
  64. GRB251111A: 1.3m DFOT optical upper limit
  65. GRB 251111A: SVOM/VT optical observations with X-band data
  66. SVOM GRB251111.42: Global MASTER-Net observations report
  67. GRB 251111A: Swift-XRT observations
  68. SVOM GRB251111.22: Global MASTER-Net observations report
  69. GRB 251111A: EP-FXT counterpart detection
  70. GRB 251013C: Chandra X-ray observations and jet break detection
  71. GRB 251111A: SVOM/VT optical observations with VHF data
  72. GRB 251111A: LCO optical observation
  73. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  74. GRB 251111A: SVOM detection of a soft burst
  75. GRB 251103B: Swift-BAT refined analysis
  76. GRB 251106A: Swift/UVOT Upper Limits
  77. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  78. LIGO/Virgo/KAGRA S251108fi: One counterpart neutrino candidate from IceCube neutrino searches
  79. GRB 251108A: Fermi GBM Final Localization Correction
  80. Fermi trigger No 784329591: Global MASTER-Net observations report
  81. Fermi trigger No 784279167: Global MASTER-Net observations report
  82. SVOM GRB251108.54: Global MASTER-Net observations report
  83. GRB 251102B: SVOM/GRM observation
  84. Fermi Gamma-ray Burst Monitor trigger 784279167/251108305 is not a GRB
  85. The EP-WXT trigger 01709248051 is likely a flaring star
  86. SVOM GRB251106.83: Global MASTER-Net observations report
  87. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  88. GRB 251106B: SVOM/GRM observation of a short burst
  89. GRB 251106A: Kilonova-Catcher optical upper limit
  90. Fermi GBM Sub-Threshold Detection of GRB 251106A
  91. GRB 251106A: Swift/BAT arcminute localization of a burst
  92. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  93. GRB 251106A: MASTER optical observations
  94. GRB 251106A: SVOM detection of a burst
  95. Fermi trigger No 784034269: Global MASTER-Net observations report
  96. Fermi Gamma-ray Burst Monitor trigger 784109140/251106337 is not a GRB
  97. EP251102a: Xinglong 2.16-m clear-band observations of the optical counterpart
  98. GRB 251105A: Fermi GBM Observation
  99. GRB 251105C: Fermi GBM Final Localization Correction
  100. LIGO/Virgo/KAGRA S251031dw: Candidates from the Zwicky Transient Facility

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