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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"

26136 results found.

  1. LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results
  2. EP251118a / GRB 251118C: SVOM/VT optical observation
  3. The EP-WXT trigger 01709248403 is likely a flaring star
  4. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  5. GRB 251116C: NOT optical observations
  6. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  7. GRB 251018A: FRAM-Auger optical detection
  8. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  9. The EP-WXT trigger 01709248388 is likely a flaring star
  10. EP251118a: FTW optical and NIR observations
  11. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  12. EP251118a: VLT near-infrared observation
  13. GRB 251116D: SVOM/GRM observation of a long GRB
  14. EP251118a: GOTO optical afterglow detection
  15. GRB 251119A: SVOM detection of a possible burst
  16. EP251118a: Global MASTER-Net observations report
  17. EP251118a: preliminary result of EP-FXT follow-up observation
  18. LAT GRB251118.86: Global MASTER-Net observations report
  19. GRB 251118A: Fermi-LAT detection
  20. EP251118a: NOT candidate optical counterpart
  21. EP251118a: Einstein Probe detected of a fast X-ray transient
  22. Fermi GRB 251118B: Global MASTER-Net observations report
  23. GRB 251118B: Fermi GBM Final Real-time Localization
  24. GRB 251118A: BALROG localization (Fermi Trigger 785190695 / GRB 251118855)
  25. GRB 251117A: FTW Observations of Swift candidate X-ray sources
  26. GRB 251118A: Fermi GBM Final Real-time Localization
  27. GRB 251116C: SVOM/ECLAIRs refined analysis
  28. GRB 251116B: SVOM/ECLAIRs refined analysis
  29. GRB 251114B: GECAM-B detection of a short burst
  30. GRB 251117A: Fermi GBM observation
  31. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  32. GRB 251117A: SVOM/GRM observation of a short burst
  33. GRB 251117A: Fermi-LAT detection
  34. LAT GRB251117.51: Global MASTER-Net observations report
  35. GRB 251116B: SVOM/VT optical upper limit
  36. GRB 251116C: Swift-XRT observations
  37. GRB 251117A: Fermi GBM Final Localization Correction
  38. LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations
  39. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  40. GRB 251116C: SVOM/VT optical upper limit
  41. GRB 251116B: EP-FXT follow-up observation
  42. GRB 251116B: LCO optical upper limits
  43. GRB 251116C: LCO optical upper limits
  44. SVOM GRB251116C: Global MASTER-Net observations report
  45. GRB 251116C: SVOM detection of a burst
  46. GRB 251116B: SVOM detection of a burst
  47. GRB 251116A: Fermi GBM Final Real-time Localization
  48. LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
  49. GRB 251115A: Fermi-LAT detection
  50. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  51. Fermi GRB 251115A: Global MASTER-Net observations report
  52. GRB 251115A: Fermi GBM Final Real-time Localization
  53. GRB 251114B: Fermi GBM Final Real-time Localization
  54. GRB 251112A: Swift-BAT refined analysis
  55. Fermi trigger No 784717756: Global MASTER-Net observations report
  56. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  57. The EP-WXT trigger 01709248221 is likely a flaring star
  58. Fermi GRB 251114A: Global MASTER-Net observations report
  59. LIGO/Virgo/KAGRA S251112cm: Candidates from the Zwicky Transient Facility
  60. GRB 251114A: Fermi GBM Final Real-time Localization
  61. Fermi GRB 251113A: Global MASTER-Net observations report
  62. GRB 251113A: BALROG localization (Fermi Trigger 784748255 / GRB 251113734)
  63. GRB 251113A: Fermi GBM Final Real-time Localization
  64. GRB 251111A: SVOM/ECLAIRs refined analysis
  65. GRB 251025B: SVOM/ECLAIRs refined analysis
  66. Fermi Gamma-ray Burst Monitor trigger 784717756/251113381 is not a GRB
  67. GRB 251112A: Swift/UVOT Upper Limits
  68. GRB 251112A: Swift-XRT refined Analysis
  69. LIGO/Virgo/KAGRA S251112cm: Detection of two young transients by BlackGEM/MeerLICHT: AT2025adgp and AT2025adgq
  70. Fermi Gamma-ray Burst Monitor trigger 784687703/251113034 is not a GRB
  71. Fermi Gamma-ray Burst Monitor trigger 784687099/251113027 is not a GRB
  72. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  73. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  74. Swift Trigger 1413695: a possible GRB 251112A
  75. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  76. Fermi trigger No 784621743: Global MASTER-Net observations report
  77. Fermi Gamma-ray Burst Monitor trigger 784653403/251112637 is not a GRB
  78. GRB251111A: 1.3m DFOT optical upper limit
  79. GRB 251111A: SVOM/VT optical observations with X-band data
  80. SVOM GRB251111.42: Global MASTER-Net observations report
  81. GRB 251111A: Swift-XRT observations
  82. SVOM GRB251111.22: Global MASTER-Net observations report
  83. GRB 251111A: EP-FXT counterpart detection
  84. GRB 251013C: Chandra X-ray observations and jet break detection
  85. GRB 251111A: SVOM/VT optical observations with VHF data
  86. GRB 251111A: LCO optical observation
  87. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  88. GRB 251111A: SVOM detection of a soft burst
  89. GRB 251103B: Swift-BAT refined analysis
  90. GRB 251106A: Swift/UVOT Upper Limits
  91. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  92. LIGO/Virgo/KAGRA S251108fi: One counterpart neutrino candidate from IceCube neutrino searches
  93. GRB 251108A: Fermi GBM Final Localization Correction
  94. Fermi trigger No 784329591: Global MASTER-Net observations report
  95. Fermi trigger No 784279167: Global MASTER-Net observations report
  96. SVOM GRB251108.54: Global MASTER-Net observations report
  97. GRB 251102B: SVOM/GRM observation
  98. Fermi Gamma-ray Burst Monitor trigger 784279167/251108305 is not a GRB
  99. The EP-WXT trigger 01709248051 is likely a flaring star
  100. SVOM GRB251106.83: Global MASTER-Net observations report

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