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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"

27415 results found.

  1. EP Alert 260918.24: Global MASTER-Net observations report
  2. SVOM GRB260918.16: Global MASTER-Net observations report
  3. The EP-WXT trigger 01709318279 is likely a flaring star
  4. GRB 260918A: EP-FXT follow-up observation
  5. GRB 260917B: Mondy optical upper limit
  6. IPN triangulation of GRB 260916B (short)
  7. EP Alert 260917.32: Global MASTER-Net observations report
  8. GRB 260917B: EP-FXT follow-up observation
  9. EP260917a: COLIBRÍ optical upper limits
  10. GRB 260918A: LCO optical upper limits
  11. GRB 260918A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  12. GRB 260918A: SVOM detection of a burst
  13. GRB 260917C: Fermi GBM Final Real-time Localization
  14. GRB 260917B: FRAM-Auger optical limits
  15. GRB 260916B: Fermi GBM Detection
  16. GRB 260916B: Fermi GBM Final Localization
  17. GRB 260915A: SVOM/ECLAIRs refined analysis
  18. GRB 260917B: WINTER J-band observations
  19. SVOM GRB260917.16: Global MASTER-Net observations report
  20. GRB 260917B: LCO optical observation
  21. GRB 260917B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  22. GRB 260917B: SVOM detection of a faint burst
  23. GRB 260914A: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  24. GRB 260917A: BALROG localization (Fermi Trigger 811304653 / GRB 260917100)
  25. GRB 260917A: Fermi GBM Final Real-time Localization
  26. Fermi trigger No 811304653: Global MASTER-Net observations report
  27. The EP-WXT trigger 01709317235 is likely a flaring star
  28. GRB 260915A: J-band upper limit with WINTER
  29. Fermi trigger No 811264269: Global MASTER-Net observations report
  30. GRB 260914A: Mondy and TShAO optical observations
  31. GRB 260914A: SVOM/ECLAIRs refined analysis
  32. MAXI GRB260916.37: Global MASTER-Net observations report
  33. GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
  34. GRB 260915A: SVOM/C-GFT optical upper limits
  35. GRB 260915A: EP-FXT follow-up observation
  36. GRB 260915A: REM optical/NIR observations
  37. GRB 260914A: REM optical/NIR observations
  38. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  39. GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  40. GRB 260914A: VLT/X-shooter spectroscopic redshift z = 0.778
  41. GRB 260915A: 10.4m GTC deep optical limits
  42. GRB 260915A: NOT optical upper limit
  43. SVOM GRB260915.05: Global MASTER-Net observations report
  44. GRB 260915A: SVOM/VT optical upper limits from VHF data
  45. Fermi GBM Sub-Threshold Detection of GRB 260915A
  46. GRB 260915A: LCO optical upper limits
  47. EP Alert 260914.53: Global MASTER-Net observations report
  48. GRB 260914A: EP-FXT follow-up observation
  49. GRB 260915A: SVOM detection of a burst
  50. Fermi GBM Sub-Threshold Detection of GRB 260914A
  51. GRB 260914A: LCO optical observation
  52. GRB 260914A: SVOM/C-GFT optical observations
  53. GRB 260914A: SVOM/VT optical counterpart confirmation
  54. GRB 260914A: SVOM/VT optical observation from VHF data
  55. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  56. SVOM GRB260914.47: Global MASTER-Net observations report
  57. GRB 260914A: SVOM detection of a burst
  58. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
  59. GRB 260818A: Continued ATCA observations
  60. SVOM GRB260913.32: Global MASTER-Net observations report
  61. GRB 260913A: SVOM/C-GFT optical upper limit
  62. GRB 260913A: SVOM detection of a faint burst
  63. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  64. GRB 260909A: CrAO and AbAO optical upper limits
  65. GRB 260909A: SVOM/ECLAIRs refined analysis
  66. GRB 260910B: GOTO tentative optical counterpart candidates
  67. GRB 260910B: Fermi GBM Final Real-time Localization
  68. EP Alert 260909.53: Global MASTER-Net observations report
  69. GRB 260909A: EP-FXT follow-up observation
  70. GRB 260910A: Fermi GBM Final Real-time Localization
  71. GRB 260909A: SVOM/GRM observation
  72. GRB 260909A: Mondy optical observations and afterglow candidate
  73. GRB 260909A: Xinglong 2.16m optical upper limit
  74. GRB 260909A: SVOM/C-GFT optical upper limit
  75. GRB 260909A: SVOM detection of a burst
  76. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  77. Fermi trigger No 810554827: Global MASTER-Net observations report
  78. EP Alert 260908.60: Global MASTER-Net observations report
  79. Fermi GRB 260907B: Global MASTER-Net observations report
  80. The EP-WXT trigger 01709305715 is likely a flaring star
  81. GRB 260907B: Fermi GBM Final Real-time Localization
  82. Fermi GRB 260907A: Global MASTER-Net observations report
  83. GRB 260907A: Fermi GBM Final Real-time Localization
  84. EP Alert 260905.11: Global MASTER-Net observations report
  85. The EP-WXT trigger 01709302592 is likely a flaring star
  86. GRB 260903A: J-band upper limit with WINTER
  87. EP Alert 260903.47: Global MASTER-Net observations report
  88. GRB 260903A: SVOM/ECLAIRs refined analysis
  89. GRB260903A: Liverpool Telescope optical observations
  90. EP Alert 260903.62: Global MASTER-Net observations report
  91. GRB 260903A: EP-FXT follow-up observation
  92. GRB 260903A: NOT optical observations and afterglow fading
  93. SVOM GRB260903A: Global MASTER-Net observations report
  94. GRB 260903A: LCO optical observations
  95. GRB 260903A: SVOM/VT optical candidate
  96. GRB 260903A: LCO optical counterpart detection
  97. GRB 260903A: SVOM detection of a soft faint burst
  98. EP260901a: SVOM/VT optical upper limits
  99. GRB 260818A: ATCA detection of a candidate radio counterpart
  100. EP260901a: Global MASTER-Net observations report

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