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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"

5706 results found.

  1. GRB 260914A: SVOM/GRM observation
  2. GRB 260914A: Mondy and TShAO optical observations
  3. GRB 260914A: SVOM/ECLAIRs refined analysis
  4. GRB 260916A: MAXI/GSC detection
  5. MAXI GRB260916.37: Global MASTER-Net observations report
  6. GRB 260915A: SVOM/C-GFT optical upper limits
  7. GRB 260915A: EP-FXT follow-up observation
  8. GRB 260915A: REM optical/NIR observations
  9. GRB 260914A: REM optical/NIR observations
  10. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  11. GRB 260915A: SVOM/VT optical upper limits
  12. GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  13. GRB 260915A: NOT optical upper limit
  14. SVOM GRB260915.05: Global MASTER-Net observations report
  15. GRB 260915A: SVOM/VT optical upper limits from VHF data
  16. Fermi GBM Sub-Threshold Detection of GRB 260915A
  17. GRB 260915A: LCO optical upper limits
  18. EP Alert 260914.53: Global MASTER-Net observations report
  19. GRB 260914A: EP-FXT follow-up observation
  20. GRB 260915A: SVOM detection of a burst
  21. Fermi GBM Sub-Threshold Detection of GRB 260914A
  22. GRB 260914A: LCO optical observation
  23. GRB 260914A: SVOM/C-GFT optical observations
  24. GRB 260914A: SVOM/VT optical counterpart confirmation
  25. GRB 260914A: SVOM/VT optical observation from VHF data
  26. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  27. SVOM GRB260914.47: Global MASTER-Net observations report
  28. GRB 260914A: SVOM detection of a burst
  29. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
  30. GRB 260818A: Continued ATCA observations
  31. SVOM GRB260913.32: Global MASTER-Net observations report
  32. GRB 260913A: SVOM/C-GFT optical upper limit
  33. GRB 260913A: SVOM detection of a faint burst
  34. GRB 260907A: SVOM/GRM observation
  35. GRB 260909A: CrAO and AbAO optical upper limits
  36. GRB 260909A: SVOM/ECLAIRs refined analysis
  37. GRB 260910B: GOTO tentative optical counterpart candidates
  38. EP Alert 260909.53: Global MASTER-Net observations report
  39. GRB 260909A: EP-FXT follow-up observation
  40. GRB 260909A: SVOM/VT optical upper limits
  41. GRB 260909A: SVOM/GRM observation
  42. GRB 260909A: Mondy optical observations and afterglow candidate
  43. GRB 260909A: Xinglong 2.16m optical upper limit
  44. GRB 260909A: SVOM/C-GFT optical upper limit
  45. GRB 260909A: SVOM detection of a burst
  46. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  47. Fermi trigger No 810554827: Global MASTER-Net observations report
  48. EP Alert 260908.60: Global MASTER-Net observations report
  49. GRB 260907A: Glowbug gamma-ray detection of a likely short burst
  50. Fermi GRB 260907B: Global MASTER-Net observations report
  51. GRB 260903A: SAO RAS optical upper limit
  52. The EP-WXT trigger 01709305715 is likely a flaring star
  53. Fermi GRB 260907A: Global MASTER-Net observations report
  54. EP260903a: EP-FXT follow-up observation
  55. EP Alert 260905.11: Global MASTER-Net observations report
  56. The EP-WXT trigger 01709302592 is likely a flaring star
  57. GRB 260903A: J-band upper limit with WINTER
  58. EP Alert 260903.47: Global MASTER-Net observations report
  59. GRB 260903A: SVOM/ECLAIRs refined analysis
  60. GRB260903A: Liverpool Telescope optical observations
  61. GRB 260903A: SAO RAS optical observations
  62. EP260903a: EP-WXT detection of a fast X-ray transient
  63. EP Alert 260903.62: Global MASTER-Net observations report
  64. GRB 260903A: EP-FXT follow-up observation
  65. NuSTAR Transient 260828: SOAR Optical Upper Limits
  66. SVOM GRB260903A: Global MASTER-Net observations report
  67. GRB 260903A: SVOM/VT optical candidate
  68. GRB 260831A: GECAM-B observation
  69. GRB 260903A: LCO optical counterpart detection
  70. GRB 260903A: SVOM detection of a soft faint burst
  71. EP260901a: SVOM/VT optical upper limits
  72. EP260901a: EP-FXT follow-up observation
  73. EP260830a: EP-FXT follow-up observation
  74. EP260901a: Global MASTER-Net observations report
  75. NuSTAR Transient 260828: LCO Optical Upper Limits
  76. EP260901a: EP-WXT detection of a fast X-ray transient
  77. GRB 260831B: LCO optical upper limits
  78. EP260830a: Global MASTER-Net observations report
  79. IPN triangulation of GRB 260829A
  80. GRB 260831A: Fermi GBM Final Real-time Localization
  81. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  82. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  83. GRB 260825A: AstroSat CZTI detection
  84. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  85. GRB 260829A: Fermi GBM Final Real-time Localization
  86. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  87. EP260822a: Global MASTER-Net observations report
  88. IceCube Alert 260825A: Global MASTER-Net observations report
  89. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  90. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  91. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  92. GRB 260818B: SVOM/C-GFT optical upper limit
  93. IceCube Alert 260821A: Global MASTER-Net observations report
  94. GRB 260810A: SVOM/GRM observation
  95. GRB 260810A: Insight-HXMT/HE detection
  96. EP260812a: NOT and Liverpool Telescope upper limits:
  97. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  98. Fermi GBM Sub-Threshold Detection of GRB 260809A
  99. GRB 260810A: Glowbug gamma-ray detection
  100. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening

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