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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"

27008 results found.

  1. GRB 251114B: GECAM-B detection of a short burst
  2. GRB 251117A: Fermi GBM observation
  3. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  4. GRB 251117A: SVOM/GRM observation of a short burst
  5. GRB 251117A: Fermi-LAT detection
  6. LAT GRB251117.51: Global MASTER-Net observations report
  7. GRB 251116B: SVOM/VT optical upper limit
  8. GRB 251116C: Swift-XRT observations
  9. GRB 251117A: Fermi GBM Final Localization Correction
  10. LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations
  11. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  12. GRB 251116C: SVOM/VT optical upper limit
  13. GRB 251116B: EP-FXT follow-up observation
  14. GRB 251116B: LCO optical upper limits
  15. GRB 251116C: LCO optical upper limits
  16. SVOM GRB251116C: Global MASTER-Net observations report
  17. GRB 251116C: SVOM detection of a burst
  18. GRB 251116B: SVOM detection of a burst
  19. GRB 251116A: Fermi GBM Final Real-time Localization
  20. LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
  21. GRB 251115A: Fermi-LAT detection
  22. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  23. Fermi GRB 251115A: Global MASTER-Net observations report
  24. GRB 251115A: Fermi GBM Final Real-time Localization
  25. GRB 251114B: Fermi GBM Final Real-time Localization
  26. GRB 251112A: Swift-BAT refined analysis
  27. Fermi trigger No 784717756: Global MASTER-Net observations report
  28. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  29. The EP-WXT trigger 01709248221 is likely a flaring star
  30. Fermi GRB 251114A: Global MASTER-Net observations report
  31. LIGO/Virgo/KAGRA S251112cm: Candidates from the Zwicky Transient Facility
  32. GRB 251114A: Fermi GBM Final Real-time Localization
  33. Fermi GRB 251113A: Global MASTER-Net observations report
  34. GRB 251113A: BALROG localization (Fermi Trigger 784748255 / GRB 251113734)
  35. GRB 251113A: Fermi GBM Final Real-time Localization
  36. GRB 251111A: SVOM/ECLAIRs refined analysis
  37. GRB 251025B: SVOM/ECLAIRs refined analysis
  38. Fermi Gamma-ray Burst Monitor trigger 784717756/251113381 is not a GRB
  39. GRB 251112A: Swift/UVOT Upper Limits
  40. GRB 251112A: Swift-XRT refined Analysis
  41. LIGO/Virgo/KAGRA S251112cm: Detection of two young transients by BlackGEM/MeerLICHT: AT2025adgp and AT2025adgq
  42. Fermi Gamma-ray Burst Monitor trigger 784687703/251113034 is not a GRB
  43. Fermi Gamma-ray Burst Monitor trigger 784687099/251113027 is not a GRB
  44. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  45. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  46. Swift Trigger 1413695: a possible GRB 251112A
  47. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  48. Fermi trigger No 784621743: Global MASTER-Net observations report
  49. Fermi Gamma-ray Burst Monitor trigger 784653403/251112637 is not a GRB
  50. GRB251111A: 1.3m DFOT optical upper limit
  51. GRB 251111A: SVOM/VT optical observations with X-band data
  52. SVOM GRB251111.42: Global MASTER-Net observations report
  53. GRB 251111A: Swift-XRT observations
  54. SVOM GRB251111.22: Global MASTER-Net observations report
  55. GRB 251111A: EP-FXT counterpart detection
  56. GRB 251013C: Chandra X-ray observations and jet break detection
  57. GRB 251111A: SVOM/VT optical observations with VHF data
  58. GRB 251111A: LCO optical observation
  59. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  60. GRB 251111A: SVOM detection of a soft burst
  61. GRB 251103B: Swift-BAT refined analysis
  62. GRB 251106A: Swift/UVOT Upper Limits
  63. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  64. LIGO/Virgo/KAGRA S251108fi: One counterpart neutrino candidate from IceCube neutrino searches
  65. GRB 251108A: Fermi GBM Final Localization Correction
  66. Fermi trigger No 784329591: Global MASTER-Net observations report
  67. Fermi trigger No 784279167: Global MASTER-Net observations report
  68. SVOM GRB251108.54: Global MASTER-Net observations report
  69. GRB 251102B: SVOM/GRM observation
  70. Fermi Gamma-ray Burst Monitor trigger 784279167/251108305 is not a GRB
  71. The EP-WXT trigger 01709248051 is likely a flaring star
  72. SVOM GRB251106.83: Global MASTER-Net observations report
  73. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  74. GRB 251106B: SVOM/GRM observation of a short burst
  75. GRB 251106A: Kilonova-Catcher optical upper limit
  76. Fermi GBM Sub-Threshold Detection of GRB 251106A
  77. GRB 251106A: Swift/BAT arcminute localization of a burst
  78. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  79. GRB 251106A: MASTER optical observations
  80. GRB 251106A: SVOM detection of a burst
  81. Fermi trigger No 784034269: Global MASTER-Net observations report
  82. Fermi Gamma-ray Burst Monitor trigger 784109140/251106337 is not a GRB
  83. EP251102a: Xinglong 2.16-m clear-band observations of the optical counterpart
  84. GRB 251105A: Fermi GBM Observation
  85. GRB 251105C: Fermi GBM Final Localization Correction
  86. LIGO/Virgo/KAGRA S251031dw: Candidates from the Zwicky Transient Facility
  87. GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
  88. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  89. GRB 251023A: SVOM/ECLAIRs detection of a burst through targeted search
  90. Fermi GBM Sub-Threshold Detection of GRB 251105B
  91. GRB 251103B: Swift/UVOT Upper Limits
  92. GRB 251105B: SVOM/GRM observation of a possible short burst with extended emission
  93. Fermi GRB 251105A: Global MASTER-Net observations report
  94. GRB 251105A: Fermi GBM Final Real-time Localization
  95. Fermi Gamma-ray Burst Monitor trigger 783986701/251104920 is not a GRB
  96. GRB 251103B: Fermi GBM observation
  97. GRB 251104A: SVOM detection of a burst
  98. EP251102a: FTW optical and NIR observations
  99. GRB 251103A: WFST optical observations
  100. EP251102a: update of EP-FXT follow-up observation

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