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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"

2336 results found.

  1. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  2. GRB 260907A: SVOM/GRM observation
  3. GRB 260909A: CrAO and AbAO optical upper limits
  4. GRB 260909A: SVOM/ECLAIRs refined analysis
  5. GRB 260909A: Swift ToO observations
  6. GRB 260909A: KAIT optical upper limit
  7. GRB 260903A: Swift-XRT observations
  8. GRB 260909A: OHP/T193 z-band upper limit
  9. GRB 260909A: VLT optical and near-infrared upper limits
  10. GRB 260909A: EP-FXT follow-up observation
  11. GRB 260909A: SVOM/VT optical upper limits
  12. GRB 260909A: SVOM/GRM observation
  13. GRB 260909A: Mondy optical observations and afterglow candidate
  14. GRB 260909A: Xinglong 2.16m optical upper limit
  15. GRB 260909A: SVOM/C-GFT optical upper limit
  16. GRB 260909A: SVOM detection of a burst
  17. GRB 260903A: Swift ToO observations
  18. GRB 260903A: SAO RAS optical upper limit
  19. GRB 260903A: J-band upper limit with WINTER
  20. GRB 260903A: SVOM/ECLAIRs refined analysis
  21. GRB260903A: Liverpool Telescope optical observations
  22. GRB 260903A: SAO RAS optical observations
  23. GRB 260903A: EP-FXT follow-up observation
  24. GRB 260903A: OHP/T193 optical afterglow detection
  25. GRB 260903A: NOT optical observations and afterglow fading
  26. SVOM GRB260903A: Global MASTER-Net observations report
  27. GRB 260903A: LCO optical observations
  28. GRB 260903A: SVOM/VT optical candidate
  29. GRB 260903A: Retraction of optical counterpart of GCN 45501
  30. GRB 260903A: LCO optical counterpart detection
  31. GRB 260827A: Insight-HXMT/HE detection
  32. GRB 260903A: SVOM detection of a soft faint burst
  33. EP260901a: SVOM/VT optical upper limits
  34. Konus-Wind detection of GRB 260829A
  35. GRB 260829A: SVOM/GRM observation
  36. GRB 260818A: ATCA detection of a candidate radio counterpart
  37. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  38. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  39. SVOM trigger sb26083106 is not a GRB
  40. GRB 260831B: EP-FXT follow-up observation
  41. GRB 260831B: LCO optical upper limits
  42. GRB 260827A: SVOM/GRM observation
  43. GRB 260831B: SVOM detection of a possible burst
  44. GRB 260825A: SVOM/GRM observation of a long burst
  45. GRB 260818B: Further EP-FXT observation
  46. GRB 260818B: VLT optical and nIR observations
  47. GRB 260818B: TNG NIR observations
  48. GRB 260818B: 6 GHz VLA observations
  49. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  50. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  51. GRB 260808B: SAO RAS observations of the optical rebrightening
  52. GRB 260807A: EP-FXT follow-up observations
  53. GRB 260822A: SVOM/ECLAIRs refined analysis
  54. GRB 260809A: SVOM/ECLAIRs refined analysis
  55. GRB 260822A: SVOM/VT optical upper limits
  56. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  57. GRB 260822A: EP/FXT follow-up observations
  58. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  59. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  60. GRB 260822A: GOTO optical counterpart detection
  61. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  62. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  63. GRB 260822A: LCO optical upper limits
  64. GRB 260822A: GROWTH-India Telescope Upper Limits
  65. GRB 260822A: GOTO optical upper limit
  66. GRB 260822A: SVOM detection of a short burst
  67. GRB 260818B: SVOM/C-GFT optical upper limit
  68. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  69. GRB 260818B: SVOM/GRM observation
  70. GRB 260818B: Insight-HXMT detection
  71. GRB 260818B: EP-FXT follow-up observation
  72. GRB 260818A: J-band observations with WINTER
  73. GRB 260818B: SVOM/ECLAIRs refined analysis
  74. GRB 260818A: SVOM/ECLAIRs refined analysis
  75. GRB 260818B: NOT optical upper limits
  76. GRB 260810A: SVOM/GRM observation
  77. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  78. GRB260818A: EP-FXT follow-up observation
  79. GRB 260818B: LCO optical upper limits
  80. GRB 260818B: SVOM detection of a short burst
  81. SVOM trigger sb26081806 is not a GRB
  82. GRB 260818A: LCO optical upper limits
  83. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  84. GRB 260818A: SVOM possible detection of a long and faint GRB
  85. EP260806a: SVOM/ECLAIRs detection through targeted search
  86. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  87. GRB 260808B: Liverpool Telescope further optical observations
  88. EP260812a: SVOM/C-GFT optical upper limit
  89. EP260812b: COLIBRÍ optical observations
  90. EP260812b: SVOM/VT optical observation
  91. GRB 260808A: SVOM/GRM observation
  92. Fermi GBM Sub-Threshold Detection of GRB 260809A
  93. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  94. GRB 260809A: SAO RAS optical observations
  95. GRB 260808B: SAO RAS optical observations
  96. GRB 260808B: SVOM/VT optical re-brightening at day 3
  97. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  98. GRB 260807A: SVOM/ECLAIRs refined analysis
  99. GRB260808B: MAO/AZT-22 optical observations
  100. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search

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