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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"

27022 results found.

  1. GRB 260917C: Fermi GBM Final Real-time Localization
  2. GRB 260917B: FRAM-Auger optical limits
  3. GRB 260916B: Fermi GBM Detection
  4. GRB 260916B: Fermi GBM Final Localization
  5. GRB 260915A: SVOM/ECLAIRs refined analysis
  6. GRB 260917B: WINTER J-band observations
  7. GRB 260917B: SVOM/VT optical observations
  8. SVOM GRB260917.16: Global MASTER-Net observations report
  9. GRB 260917B: LCO optical observation
  10. GRB 260917B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  11. GRB 260917B: SVOM detection of a faint burst
  12. GRB 260914A: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  13. GRB 260917A: BALROG localization (Fermi Trigger 811304653 / GRB 260917100)
  14. GRB 260917A: Fermi GBM Final Real-time Localization
  15. Fermi trigger No 811304653: Global MASTER-Net observations report
  16. The EP-WXT trigger 01709317235 is likely a flaring star
  17. GRB 260915A: J-band upper limit with WINTER
  18. Fermi trigger No 811264269: Global MASTER-Net observations report
  19. GRB 260914A: SVOM/GRM observation
  20. GRB 260914A: Mondy and TShAO optical observations
  21. GRB 260914A: SVOM/ECLAIRs refined analysis
  22. MAXI GRB260916.37: Global MASTER-Net observations report
  23. GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
  24. GRB 260915A: SVOM/C-GFT optical upper limits
  25. GRB 260915A: EP-FXT follow-up observation
  26. GRB 260915A: SVOM/VT refined early optical upper limits
  27. GRB 260915A: REM optical/NIR observations
  28. GRB 260914A: REM optical/NIR observations
  29. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  30. GRB 260915A: SVOM/VT optical upper limits
  31. GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  32. GRB 260914A: VLT/X-shooter spectroscopic redshift z = 0.778
  33. GRB 260915A: 10.4m GTC deep optical limits
  34. GRB 260915A: NOT optical upper limit
  35. SVOM GRB260915.05: Global MASTER-Net observations report
  36. GRB 260915A: SVOM/VT optical upper limits from VHF data
  37. Fermi GBM Sub-Threshold Detection of GRB 260915A
  38. GRB 260915A: LCO optical upper limits
  39. EP Alert 260914.53: Global MASTER-Net observations report
  40. GRB 260914A: EP-FXT follow-up observation
  41. GRB 260915A: SVOM detection of a burst
  42. Fermi GBM Sub-Threshold Detection of GRB 260914A
  43. GRB 260914A: LCO optical observation
  44. GRB 260914A: SVOM/C-GFT optical observations
  45. GRB 260914A: SVOM/VT optical counterpart confirmation
  46. GRB 260914A: SVOM/VT optical observation from VHF data
  47. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  48. SVOM GRB260914.47: Global MASTER-Net observations report
  49. GRB 260914A: SVOM detection of a burst
  50. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
  51. GRB 260818A: Continued ATCA observations
  52. SVOM GRB260913.32: Global MASTER-Net observations report
  53. GRB 260913A: SVOM/C-GFT optical upper limit
  54. GRB 260913A: SVOM detection of a faint burst
  55. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  56. GRB 260907A: SVOM/GRM observation
  57. GRB 260909A: CrAO and AbAO optical upper limits
  58. GRB 260909A: SVOM/ECLAIRs refined analysis
  59. GRB 260910B: GOTO tentative optical counterpart candidates
  60. GRB 260910B: Fermi GBM Final Real-time Localization
  61. EP Alert 260909.53: Global MASTER-Net observations report
  62. GRB 260909A: EP-FXT follow-up observation
  63. GRB 260910A: Fermi GBM Final Real-time Localization
  64. GRB 260909A: SVOM/VT optical upper limits
  65. GRB 260909A: SVOM/GRM observation
  66. GRB 260909A: Mondy optical observations and afterglow candidate
  67. GRB 260909A: Xinglong 2.16m optical upper limit
  68. GRB 260909A: SVOM/C-GFT optical upper limit
  69. GRB 260909A: SVOM detection of a burst
  70. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  71. Fermi trigger No 810554827: Global MASTER-Net observations report
  72. EP Alert 260908.60: Global MASTER-Net observations report
  73. Fermi GRB 260907B: Global MASTER-Net observations report
  74. The EP-WXT trigger 01709305715 is likely a flaring star
  75. GRB 260907B: Fermi GBM Final Real-time Localization
  76. Fermi GRB 260907A: Global MASTER-Net observations report
  77. GRB 260907A: Fermi GBM Final Real-time Localization
  78. EP260903a: EP-FXT follow-up observation
  79. EP Alert 260905.11: Global MASTER-Net observations report
  80. The EP-WXT trigger 01709302592 is likely a flaring star
  81. GRB 260903A: J-band upper limit with WINTER
  82. EP Alert 260903.47: Global MASTER-Net observations report
  83. GRB 260903A: SVOM/ECLAIRs refined analysis
  84. GRB260903A: Liverpool Telescope optical observations
  85. GRB 260830A: GECAM-B detection of a burst
  86. EP260903a: EP-WXT detection of a fast X-ray transient
  87. EP Alert 260903.62: Global MASTER-Net observations report
  88. GRB 260903A: EP-FXT follow-up observation
  89. GRB 260903A: NOT optical observations and afterglow fading
  90. SVOM GRB260903A: Global MASTER-Net observations report
  91. GRB 260903A: LCO optical observations
  92. GRB 260903A: SVOM/VT optical candidate
  93. GRB 260831A: GECAM-B observation
  94. GRB 260903A: LCO optical counterpart detection
  95. GRB 260903A: SVOM detection of a soft faint burst
  96. EP260901a: SVOM/VT optical upper limits
  97. EP260901a: EP-FXT follow-up observation
  98. GRB 260829A: SVOM/GRM observation
  99. GRB 260818A: ATCA detection of a candidate radio counterpart
  100. EP260830a: EP-FXT follow-up observation

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