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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"

27008 results found.

  1. Fermi trigger No 811304653: Global MASTER-Net observations report
  2. The EP-WXT trigger 01709317235 is likely a flaring star
  3. GRB 260915A: J-band upper limit with WINTER
  4. Fermi trigger No 811264269: Global MASTER-Net observations report
  5. GRB 260914A: SVOM/GRM observation
  6. GRB 260914A: Mondy and TShAO optical observations
  7. GRB 260914A: SVOM/ECLAIRs refined analysis
  8. MAXI GRB260916.37: Global MASTER-Net observations report
  9. GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
  10. GRB 260915A: SVOM/C-GFT optical upper limits
  11. GRB 260915A: EP-FXT follow-up observation
  12. GRB 260915A: SVOM/VT refined early optical upper limits
  13. GRB 260915A: REM optical/NIR observations
  14. GRB 260914A: REM optical/NIR observations
  15. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  16. GRB 260915A: SVOM/VT optical upper limits
  17. GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  18. GRB 260914A: VLT/X-shooter spectroscopic redshift z = 0.778
  19. GRB 260915A: 10.4m GTC deep optical limits
  20. GRB 260915A: NOT optical upper limit
  21. SVOM GRB260915.05: Global MASTER-Net observations report
  22. GRB 260915A: SVOM/VT optical upper limits from VHF data
  23. Fermi GBM Sub-Threshold Detection of GRB 260915A
  24. GRB 260915A: LCO optical upper limits
  25. EP Alert 260914.53: Global MASTER-Net observations report
  26. GRB 260914A: EP-FXT follow-up observation
  27. GRB 260915A: SVOM detection of a burst
  28. Fermi GBM Sub-Threshold Detection of GRB 260914A
  29. GRB 260914A: LCO optical observation
  30. GRB 260914A: SVOM/C-GFT optical observations
  31. GRB 260914A: SVOM/VT optical counterpart confirmation
  32. GRB 260914A: SVOM/VT optical observation from VHF data
  33. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  34. SVOM GRB260914.47: Global MASTER-Net observations report
  35. GRB 260914A: SVOM detection of a burst
  36. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
  37. GRB 260818A: Continued ATCA observations
  38. SVOM GRB260913.32: Global MASTER-Net observations report
  39. GRB 260913A: SVOM/C-GFT optical upper limit
  40. GRB 260913A: SVOM detection of a faint burst
  41. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  42. GRB 260907A: SVOM/GRM observation
  43. GRB 260909A: CrAO and AbAO optical upper limits
  44. GRB 260909A: SVOM/ECLAIRs refined analysis
  45. GRB 260910B: GOTO tentative optical counterpart candidates
  46. GRB 260910B: Fermi GBM Final Real-time Localization
  47. EP Alert 260909.53: Global MASTER-Net observations report
  48. GRB 260909A: EP-FXT follow-up observation
  49. GRB 260910A: Fermi GBM Final Real-time Localization
  50. GRB 260909A: SVOM/VT optical upper limits
  51. GRB 260909A: SVOM/GRM observation
  52. GRB 260909A: Mondy optical observations and afterglow candidate
  53. GRB 260909A: Xinglong 2.16m optical upper limit
  54. GRB 260909A: SVOM/C-GFT optical upper limit
  55. GRB 260909A: SVOM detection of a burst
  56. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  57. Fermi trigger No 810554827: Global MASTER-Net observations report
  58. EP Alert 260908.60: Global MASTER-Net observations report
  59. Fermi GRB 260907B: Global MASTER-Net observations report
  60. The EP-WXT trigger 01709305715 is likely a flaring star
  61. GRB 260907B: Fermi GBM Final Real-time Localization
  62. Fermi GRB 260907A: Global MASTER-Net observations report
  63. GRB 260907A: Fermi GBM Final Real-time Localization
  64. EP260903a: EP-FXT follow-up observation
  65. EP Alert 260905.11: Global MASTER-Net observations report
  66. The EP-WXT trigger 01709302592 is likely a flaring star
  67. GRB 260903A: J-band upper limit with WINTER
  68. EP Alert 260903.47: Global MASTER-Net observations report
  69. GRB 260903A: SVOM/ECLAIRs refined analysis
  70. GRB260903A: Liverpool Telescope optical observations
  71. GRB 260830A: GECAM-B detection of a burst
  72. EP260903a: EP-WXT detection of a fast X-ray transient
  73. EP Alert 260903.62: Global MASTER-Net observations report
  74. GRB 260903A: EP-FXT follow-up observation
  75. GRB 260903A: NOT optical observations and afterglow fading
  76. SVOM GRB260903A: Global MASTER-Net observations report
  77. GRB 260903A: LCO optical observations
  78. GRB 260903A: SVOM/VT optical candidate
  79. GRB 260831A: GECAM-B observation
  80. GRB 260903A: LCO optical counterpart detection
  81. GRB 260903A: SVOM detection of a soft faint burst
  82. EP260901a: SVOM/VT optical upper limits
  83. EP260901a: EP-FXT follow-up observation
  84. GRB 260829A: SVOM/GRM observation
  85. GRB 260818A: ATCA detection of a candidate radio counterpart
  86. EP260830a: EP-FXT follow-up observation
  87. EP260901a: Global MASTER-Net observations report
  88. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  89. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  90. EP260901a: EP-WXT detection of a fast X-ray transient
  91. SVOM trigger sb26083106 is not a GRB
  92. GRB 260831B: EP-FXT follow-up observation
  93. GRB 260831B: LCO optical upper limits
  94. EP260830a: Global MASTER-Net observations report
  95. EP260830a: EP-WXT detection of a fast X-ray transient
  96. GRB 260827A: SVOM/GRM observation
  97. GRB 260831B: SVOM detection of a possible burst
  98. IPN triangulation of GRB 260829A
  99. EP260727a: ATCA 10 GHz detection
  100. GRB 260831A: Fermi GBM Final Real-time Localization

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