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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"

27937 results found.

  1. GRB 260916B: Fermi GBM Detection
  2. IceCube-260916A: Upper limits from a search for additional neutrino events in IceCube
  3. GRB 260917A: Glowbug gamma-ray detection
  4. GRB 260915A: SVOM/ECLAIRs refined analysis
  5. GRB 260917B: WINTER J-band observations
  6. GRB 260917B: SVOM/VT optical observations
  7. SVOM GRB260917.16: Global MASTER-Net observations report
  8. GRB 260917B: LCO optical observation
  9. GRB 260917B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  10. GRB 260917B: SVOM detection of a faint burst
  11. GRB 260917A: BALROG localization (Fermi Trigger 811304653 / GRB 260917100)
  12. Fermi trigger No 811304653: Global MASTER-Net observations report
  13. GRB 260915A: J-band upper limit with WINTER
  14. Fermi trigger No 811264269: Global MASTER-Net observations report
  15. GRB 260909A: NOEMA detection
  16. GRB 260914A: Mondy and TShAO optical observations
  17. GRB 260914A: SVOM/ECLAIRs refined analysis
  18. GRB 260909A: Swift-XRT observations
  19. GRB 260916A: MAXI/GSC detection
  20. MAXI GRB260916.37: Global MASTER-Net observations report
  21. GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
  22. GRB 260915A: SVOM/C-GFT optical upper limits
  23. GRB 260915A: EP-FXT follow-up observation
  24. GRB 260915A: SVOM/VT refined early optical upper limits
  25. GRB 260915A: REM optical/NIR observations
  26. GRB 260914A: REM optical/NIR observations
  27. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  28. GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  29. GRB 260915A: NOT optical upper limit
  30. SVOM GRB260915.05: Global MASTER-Net observations report
  31. GRB 260915A: SVOM/VT optical upper limits from VHF data
  32. Fermi GBM Sub-Threshold Detection of GRB 260915A
  33. GRB 260915A: LCO optical upper limits
  34. EP Alert 260914.53: Global MASTER-Net observations report
  35. GRB 260914A: EP-FXT follow-up observation
  36. GRB 260915A: SVOM detection of a burst
  37. Fermi GBM Sub-Threshold Detection of GRB 260914A
  38. GRB 260914A: LCO optical observation
  39. GRB 260914A: SVOM/C-GFT optical observations
  40. GRB 260914A: SVOM/VT optical observation from VHF data
  41. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  42. SVOM GRB260914.47: Global MASTER-Net observations report
  43. GRB 260914A: SVOM detection of a burst
  44. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
  45. GRB 260818A: Continued ATCA observations
  46. SVOM GRB260913.32: Global MASTER-Net observations report
  47. GRB 260913A: SVOM/C-GFT optical upper limit
  48. GRB 260913A: SVOM detection of a faint burst
  49. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  50. GRB 260907A: SVOM/GRM observation
  51. GRB 260909A: CrAO and AbAO optical upper limits
  52. GRB 260909A: KAIT optical upper limit
  53. GRB 260903A: Swift-XRT observations
  54. GRB 260909A: OHP/T193 z-band upper limit
  55. GRB 260909A: VLT optical and near-infrared upper limits
  56. EP Alert 260909.53: Global MASTER-Net observations report
  57. GRB 260909A: EP-FXT follow-up observation
  58. EP260806a: NOEMA detection
  59. EP260623a: NOEMA detections
  60. GRB 260909A: Mondy optical observations and afterglow candidate
  61. GRB 260909A: Xinglong 2.16m optical upper limit
  62. GRB 260909A: SVOM/C-GFT optical upper limit
  63. GRB 260909A: SVOM detection of a burst
  64. Fermi trigger No 810554827: Global MASTER-Net observations report
  65. EP Alert 260908.60: Global MASTER-Net observations report
  66. GRB 260907A: Glowbug gamma-ray detection of a likely short burst
  67. Fermi GRB 260907B: Global MASTER-Net observations report
  68. GRB 260903A: SAO RAS optical upper limit
  69. Fermi GRB 260907A: Global MASTER-Net observations report
  70. EP260903a: EP-FXT follow-up observation
  71. EP Alert 260905.11: Global MASTER-Net observations report
  72. GRB 260903A: J-band upper limit with WINTER
  73. EP Alert 260903.47: Global MASTER-Net observations report
  74. GRB260903A: Liverpool Telescope optical observations
  75. GRB 260903A: SAO RAS optical observations
  76. GRB 260830A: GECAM-B detection of a burst
  77. EP260903a: EP-WXT detection of a fast X-ray transient
  78. EP Alert 260903.62: Global MASTER-Net observations report
  79. GRB 260830A: Insight-HXMT/HE detection
  80. GRB 260903A: EP-FXT follow-up observation
  81. GRB 260903A: OHP/T193 optical afterglow detection
  82. NuSTAR Transient 260828: SOAR Optical Upper Limits
  83. SVOM GRB260903A: Global MASTER-Net observations report
  84. GRB 260903A: LCO optical counterpart detection
  85. GRB 260827A: Insight-HXMT/HE detection
  86. EP260901a: SVOM/VT optical upper limits
  87. EP260901a: EP-FXT follow-up observation
  88. GRB 260829A: SVOM/GRM observation
  89. GRB 260818A: ATCA detection of a candidate radio counterpart
  90. EP260830a: EP-FXT follow-up observation
  91. EP260901a: Global MASTER-Net observations report
  92. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  93. NuSTAR Transient 260828: LCO Optical Upper Limits
  94. EP260901a: EP-WXT detection of a fast X-ray transient
  95. GRB 260830A: NuSTAR detection of prompt emission
  96. GRB 260831B: LCO optical upper limits
  97. EP260830a: Global MASTER-Net observations report
  98. EP260830a: EP-WXT detection of a fast X-ray transient
  99. GRB 260827A: SVOM/GRM observation
  100. NuSTAR 260828: a 1100s hard X-ray transient

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