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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"

21784 results found.

  1. EP260623a: NOEMA detections
  2. GRB 260909A: Mondy optical observations and afterglow candidate
  3. GRB 260909A: SVOM/C-GFT optical upper limit
  4. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  5. Fermi trigger No 810554827: Global MASTER-Net observations report
  6. EP Alert 260908.60: Global MASTER-Net observations report
  7. GRB 260903A: Swift ToO observations
  8. Fermi GRB 260907B: Global MASTER-Net observations report
  9. GRB 260903A: SAO RAS optical upper limit
  10. Fermi GRB 260907A: Global MASTER-Net observations report
  11. EP260903a: EP-FXT follow-up observation
  12. EP Alert 260905.11: Global MASTER-Net observations report
  13. GRB 260903A: J-band upper limit with WINTER
  14. EP Alert 260903.47: Global MASTER-Net observations report
  15. GRB 260903A: SVOM/ECLAIRs refined analysis
  16. GRB260903A: Liverpool Telescope optical observations
  17. GRB 260903A: SAO RAS optical observations
  18. EP260903a: EP-WXT detection of a fast X-ray transient
  19. EP Alert 260903.62: Global MASTER-Net observations report
  20. GRB 260903A: OHP/T193 optical afterglow detection
  21. GRB 260903A: NOT optical observations and afterglow fading
  22. NuSTAR Transient 260828: SOAR Optical Upper Limits
  23. SVOM GRB260903A: Global MASTER-Net observations report
  24. GRB 260903A: LCO optical observations
  25. GRB 260903A: SVOM/VT optical candidate
  26. GRB 260818A: ATCA detection of a candidate radio counterpart
  27. EP260901a: Global MASTER-Net observations report
  28. IceCube-260827A: No transient candidates from the Zwicky Transient Facility
  29. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  30. NuSTAR Transient 260828: LCO Optical Upper Limits
  31. EP260901a: EP-WXT detection of a fast X-ray transient
  32. EP260830a: Global MASTER-Net observations report
  33. EP260830a: EP-WXT detection of a fast X-ray transient
  34. NuSTAR 260828: a 1100s hard X-ray transient
  35. EP260727a: ATCA 10 GHz detection
  36. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  37. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  38. GRB 260818B: VLT optical and nIR observations
  39. GRB 260818B: TNG NIR observations
  40. MAXI GRB260827.40: Global MASTER-Net observations report
  41. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  42. GRB 260818B: 6 GHz VLA observations
  43. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  44. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  45. GRB 260808B: SAO RAS observations of the optical rebrightening
  46. EP260822a: Global MASTER-Net observations report
  47. EP Alert 260820.31: Global MASTER-Net observations report
  48. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  49. GRB 260807A: EP-FXT follow-up observations
  50. GRB 260822A: SVOM/ECLAIRs refined analysis
  51. GRB 260809A: SVOM/ECLAIRs refined analysis
  52. GRB 260822A: SVOM/VT optical upper limits
  53. IceCube Alert 260825A: Global MASTER-Net observations report
  54. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  55. GRB 260822A: EP/FXT follow-up observations
  56. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  57. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  58. GRB 260822A: GOTO optical counterpart detection
  59. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  60. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  61. EP260822a: Einstein Probe detection of a fast X-ray transient
  62. GRB 260822A: LCO optical upper limits
  63. GRB 260822A: GOTO optical upper limit
  64. GRB 260822A: SVOM detection of a short burst
  65. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  66. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  67. GRB 260818B: VLA radio observations
  68. GRB 260818B: SVOM/C-GFT optical upper limit
  69. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  70. IceCube Alert 260821A: Global MASTER-Net observations report
  71. GRB 260818A: J-band observations with WINTER
  72. GRB 260818B: SVOM/ECLAIRs refined analysis
  73. GRB 260818A: SVOM/ECLAIRs refined analysis
  74. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  75. EP260806a: SAO RAS multicolor optical observations
  76. EP260812a: AbAO optical upper limit
  77. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  78. EP260806a: SVOM/ECLAIRs detection through targeted search
  79. EP260806a: NUTTELA-TAO optical observations
  80. EP260812a: AZT-22 optical upper limit
  81. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  82. EP260806a: WFST optical observations
  83. EP260812b: Optical upper limit with Kinder
  84. GRB 260808B: Liverpool Telescope further optical observations
  85. EP260812a: NOT and Liverpool Telescope upper limits:
  86. EP260812b: Liverpool Telescope observations
  87. EP260812b: GOTO detection of the optical counterpart
  88. EP260812a: SVOM/C-GFT optical upper limit
  89. EP260812b: COLIBRÍ optical observations
  90. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  91. Fermi GBM Sub-Threshold Detection of GRB 260809A
  92. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  93. GRB 260809A: SAO RAS optical observations
  94. GRB 260808B: SAO RAS optical observations
  95. GRB 260808B: SVOM/VT optical re-brightening at day 3
  96. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  97. GRB 260807A: SVOM/ECLAIRs refined analysis
  98. EP260806a: MAO/AZT-22 optical observations
  99. GRB260808B: MAO/AZT-22 optical observations
  100. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search

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