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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"

20951 results found.

  1. GRB 260903A: SAO RAS optical upper limit
  2. Fermi GRB 260907A: Global MASTER-Net observations report
  3. EP260903a: EP-FXT follow-up observation
  4. EP Alert 260905.11: Global MASTER-Net observations report
  5. GRB 260903A: J-band upper limit with WINTER
  6. EP Alert 260903.47: Global MASTER-Net observations report
  7. GRB 260903A: SVOM/ECLAIRs refined analysis
  8. GRB260903A: Liverpool Telescope optical observations
  9. GRB 260903A: SAO RAS optical observations
  10. EP260903a: EP-WXT detection of a fast X-ray transient
  11. EP Alert 260903.62: Global MASTER-Net observations report
  12. GRB 260903A: OHP/T193 optical afterglow detection
  13. GRB 260903A: NOT optical observations and afterglow fading
  14. NuSTAR Transient 260828: SOAR Optical Upper Limits
  15. SVOM GRB260903A: Global MASTER-Net observations report
  16. GRB 260903A: LCO optical observations
  17. GRB 260903A: SVOM/VT optical candidate
  18. GRB 260818A: ATCA detection of a candidate radio counterpart
  19. EP260901a: Global MASTER-Net observations report
  20. IceCube-260827A: No transient candidates from the Zwicky Transient Facility
  21. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  22. NuSTAR Transient 260828: LCO Optical Upper Limits
  23. EP260901a: EP-WXT detection of a fast X-ray transient
  24. EP260830a: Global MASTER-Net observations report
  25. EP260830a: EP-WXT detection of a fast X-ray transient
  26. NuSTAR 260828: a 1100s hard X-ray transient
  27. EP260727a: ATCA 10 GHz detection
  28. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  29. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  30. GRB 260818B: VLT optical and nIR observations
  31. GRB 260818B: TNG NIR observations
  32. MAXI GRB260827.40: Global MASTER-Net observations report
  33. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  34. GRB 260818B: 6 GHz VLA observations
  35. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  36. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  37. GRB 260808B: SAO RAS observations of the optical rebrightening
  38. EP260822a: Global MASTER-Net observations report
  39. EP Alert 260820.31: Global MASTER-Net observations report
  40. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  41. GRB 260807A: EP-FXT follow-up observations
  42. GRB 260822A: SVOM/ECLAIRs refined analysis
  43. GRB 260809A: SVOM/ECLAIRs refined analysis
  44. GRB 260822A: SVOM/VT optical upper limits
  45. IceCube Alert 260825A: Global MASTER-Net observations report
  46. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  47. GRB 260822A: EP/FXT follow-up observations
  48. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  49. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  50. GRB 260822A: GOTO optical counterpart detection
  51. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  52. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  53. EP260822a: Einstein Probe detection of a fast X-ray transient
  54. GRB 260822A: LCO optical upper limits
  55. GRB 260822A: GOTO optical upper limit
  56. GRB 260822A: SVOM detection of a short burst
  57. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  58. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  59. GRB 260818B: VLA radio observations
  60. GRB 260818B: SVOM/C-GFT optical upper limit
  61. IceCube Alert 260821A: Global MASTER-Net observations report
  62. GRB 260818A: J-band observations with WINTER
  63. GRB 260818B: SVOM/ECLAIRs refined analysis
  64. GRB 260818A: SVOM/ECLAIRs refined analysis
  65. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  66. EP260806a: SAO RAS multicolor optical observations
  67. EP260812a: AbAO optical upper limit
  68. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  69. EP260806a: NUTTELA-TAO optical observations
  70. EP260812a: AZT-22 optical upper limit
  71. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  72. EP260806a: WFST optical observations
  73. EP260812b: Optical upper limit with Kinder
  74. GRB 260808B: Liverpool Telescope further optical observations
  75. EP260812a: NOT and Liverpool Telescope upper limits:
  76. EP260812b: Liverpool Telescope observations
  77. EP260812b: GOTO detection of the optical counterpart
  78. EP260812a: SVOM/C-GFT optical upper limit
  79. EP260812b: COLIBRÍ optical observations
  80. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  81. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  82. GRB 260809A: SAO RAS optical observations
  83. GRB 260808B: SAO RAS optical observations
  84. GRB 260808B: SVOM/VT optical re-brightening at day 3
  85. GRB 260807A: SVOM/ECLAIRs refined analysis
  86. EP260806a: MAO/AZT-22 optical observations
  87. GRB260808B: MAO/AZT-22 optical observations
  88. GRB 260809A: J-band upper limit with WINTER
  89. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  90. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  91. GRB 260809A: NOT optical observations
  92. GRB260809A: MAO/AZT-22 optical observations
  93. GRB260809A: OHP/T193 optical observations
  94. GRB 260809A: SVOM/VT optical counterpart
  95. EP260809a: J-band upper limit with WINTER
  96. GRB 260808B: J-band upper limit with WINTER
  97. GRB 260808B: SVOM/ECLAIRs refined analysis
  98. GRB 260808B: Liverpool Telescope optical observations
  99. GRB 260808B: NOT optical observations
  100. GRB 260808B: LCO optical observations

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