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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"

27015 results found.

  1. GRB 260125A: Fermi GBM Final Real-time Localization
  2. GRB 260114A: SVOM/VT optical upper limits
  3. GRB 260122B: Swift-BAT refined analysis
  4. GRB 260120B: SVOM/GRM observation
  5. GRB 260120A: GECAM-B observation
  6. GRB 260122B: Swift detection of a burst
  7. Swift GRB260122.97: Global MASTER-Net observations report
  8. GRB 260122A: Fermi GBM Final Real-time Localization
  9. EP260119a: Xinglong optical upper limit
  10. The EP-WXT trigger 01709251871 is likely a flaring star
  11. Fermi GRB 260120C: Global MASTER-Net observations report
  12. GRB 260120B: Swift-BAT refined analysis
  13. GRB 260120B: Swift-XRT refined Analysis
  14. EP260116a: COLIBRÍ further observations
  15. GRB 260120B: Fermi GBM Observation
  16. EP260105a: GTC/HiPERCAM optical observations
  17. GRB 260120B: Swift/UVOT Detection
  18. GRB 260120B: COLIBRÍ optical upper limits
  19. SVOM GRB260121.06: Global MASTER-Net observations report
  20. GRB 260120B: SVOM/C-GFT optical counterpart detection
  21. GRB 260120C: Fermi GBM Final Real-time Localization
  22. EP260116a: COLIBRÍ observations of a tentative optical rebrightening
  23. GRB 260120B: Swift detection of a burst
  24. Swift GRB260120B: Global MASTER-Net observations report
  25. GRB 260120B: Fermi GBM Final Real-time Localization
  26. Fermi trigger No 790601190: Global MASTER-Net observations report
  27. Fermi trigger No 790570272: Global MASTER-Net observations report
  28. GRB 260114A: Swift/UVOT Upper Limits
  29. EP260119a: Liverpool Telescope optical follow-up observations
  30. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  31. EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
  32. GRB 260120A: Fermi GBM Final Real-time Localization
  33. EP260119a: SVOM/VT optical observation
  34. EP260119a: update of EP-FXT follow-up observation
  35. EP260119a: NOT optical observations
  36. SVOM GRB260119.92: Global MASTER-Net observations report
  37. SVOM GRB260119.92: Global MASTER-Net observations report
  38. SVOM GRB260119.90: Global MASTER-Net observations report
  39. EP260116a: COLIBRÍ detection of a fading optical source
  40. GRB 251208D: SVOM/ECLAIRs refined analysis
  41. GRB 251208D: SVOM/ECLAIRs refined analysis
  42. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  43. EP260119a: Global MASTER-Net observations report
  44. EP260119a: LCO optical observations
  45. EP260119a: COLIBRÍ optical counterpart candidate
  46. EP260119a: preliminary result from the EP-FXT observation
  47. GRB 260110A: SVOM detection of a burst through offline search
  48. EP260119a: EP-WXT detection of a fast X-ray transient
  49. Swift GRB260118.48: Global MASTER-Net observations report
  50. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  51. SVOM GRB260117.82: Global MASTER-Net observations report
  52. Swift trigger on the HMXB 1A 1118-61
  53. GRB 260117A: SVOM/VT optical candidate
  54. GRB 260117A: SVOM/C-GFT upper limit
  55. GRB 260117A: SVOM detection of a long faint burst
  56. EP 260116a: COLIBRÍ optical upper limit
  57. Swift triggered on the HMXB 1A 1118-61
  58. GRB 260115A: GECAM-B observation
  59. EP260116a: Liverpool Telescope upper limits
  60. EP260116A: 1.3m DFOT optical upper limit
  61. GRB 260114A: VLT/MUSE spectroscopic observations
  62. EP260116a: Global MASTER-Net observations report
  63. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  64. EP260116a: Xinglong optical upper limit
  65. EP260116a: Einstein Probe detection of an X-ray transient
  66. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  67. IceCube Alert 260115.73: Global MASTER-Net observations report
  68. GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
  69. Fermi GRB 260115A: Global MASTER-Net observations report
  70. GRB 260115A: Fermi GBM Final Real-time Localization
  71. GRB260114A: STEP/T80S optical limits
  72. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  73. GRB 260114A: Swift-XRT refined Analysis
  74. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  75. GRB 260114A : MITSuME Akeno optical upper limits
  76. GRB 260114A: COLIBRÍ optical upper limits
  77. GRB 260114A: NOT optical observations
  78. GRB 260114A: SVOM/GRM observation of a short burst
  79. Swift GRB 260114A: Global MASTER-Net observations report
  80. GRB 260114A: GECAM-B observation of a short burst
  81. GRB 260114A: Fermi GBM observation
  82. GRB 260112B: GECAM-B observation
  83. GRB 260114A: GMG Optical Observation
  84. GRB 260114A: Swift detection of a short burst
  85. GRB 260114A: Fermi GBM Final Real-time Localization
  86. EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
  87. Swift GRB260113.43: Global MASTER-Net observations report
  88. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  89. EP260110a: TRT optical upper limits
  90. Konus-Wind detection of GRB 260101A
  91. Swift Trigger 1439093: is probably not GRB 260113A
  92. GRB 260111A: COLIBRÍ optical afterglow candidate
  93. GRB 260111A: GECAM-B observation of a burst
  94. GRB 260111A: Fermi GBM Observation
  95. The EP-WXT trigger 01709251266 is likely a flaring star
  96. Swift Trigger 1434591 is not a GRB
  97. GRB 260111A: GOTO optical upper limits
  98. GRB 260112B: Fermi GBM Final Real-time Localization
  99. GRB 251230A: Mondy Optical Observations
  100. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst

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