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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"

27907 results found.

  1. GRB 260915A: SVOM/VT optical upper limits from VHF data
  2. Fermi GBM Sub-Threshold Detection of GRB 260915A
  3. GRB 260915A: LCO optical upper limits
  4. EP Alert 260914.53: Global MASTER-Net observations report
  5. GRB 260914A: EP-FXT follow-up observation
  6. GRB 260915A: SVOM detection of a burst
  7. Fermi GBM Sub-Threshold Detection of GRB 260914A
  8. GRB 260914A: LCO optical observation
  9. GRB 260914A: SVOM/C-GFT optical observations
  10. GRB 260914A: SVOM/VT optical observation from VHF data
  11. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  12. SVOM GRB260914.47: Global MASTER-Net observations report
  13. GRB 260914A: SVOM detection of a burst
  14. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
  15. GRB 260818A: Continued ATCA observations
  16. SVOM GRB260913.32: Global MASTER-Net observations report
  17. GRB 260913A: SVOM/C-GFT optical upper limit
  18. GRB 260913A: SVOM detection of a faint burst
  19. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  20. GRB 260907A: SVOM/GRM observation
  21. GRB 260909A: CrAO and AbAO optical upper limits
  22. GRB 260909A: KAIT optical upper limit
  23. GRB 260903A: Swift-XRT observations
  24. GRB 260909A: OHP/T193 z-band upper limit
  25. GRB 260909A: VLT optical and near-infrared upper limits
  26. EP Alert 260909.53: Global MASTER-Net observations report
  27. GRB 260909A: EP-FXT follow-up observation
  28. EP260806a: NOEMA detection
  29. EP260623a: NOEMA detections
  30. GRB 260909A: Mondy optical observations and afterglow candidate
  31. GRB 260909A: Xinglong 2.16m optical upper limit
  32. GRB 260909A: SVOM/C-GFT optical upper limit
  33. GRB 260909A: SVOM detection of a burst
  34. Fermi trigger No 810554827: Global MASTER-Net observations report
  35. EP Alert 260908.60: Global MASTER-Net observations report
  36. GRB 260907A: Glowbug gamma-ray detection of a likely short burst
  37. Fermi GRB 260907B: Global MASTER-Net observations report
  38. GRB 260903A: SAO RAS optical upper limit
  39. Fermi GRB 260907A: Global MASTER-Net observations report
  40. EP260903a: EP-FXT follow-up observation
  41. EP Alert 260905.11: Global MASTER-Net observations report
  42. GRB 260903A: J-band upper limit with WINTER
  43. EP Alert 260903.47: Global MASTER-Net observations report
  44. GRB260903A: Liverpool Telescope optical observations
  45. GRB 260903A: SAO RAS optical observations
  46. GRB 260830A: GECAM-B detection of a burst
  47. EP260903a: EP-WXT detection of a fast X-ray transient
  48. EP Alert 260903.62: Global MASTER-Net observations report
  49. GRB 260830A: Insight-HXMT/HE detection
  50. GRB 260903A: EP-FXT follow-up observation
  51. GRB 260903A: OHP/T193 optical afterglow detection
  52. NuSTAR Transient 260828: SOAR Optical Upper Limits
  53. SVOM GRB260903A: Global MASTER-Net observations report
  54. GRB 260903A: LCO optical counterpart detection
  55. GRB 260827A: Insight-HXMT/HE detection
  56. EP260901a: SVOM/VT optical upper limits
  57. EP260901a: EP-FXT follow-up observation
  58. GRB 260829A: SVOM/GRM observation
  59. GRB 260818A: ATCA detection of a candidate radio counterpart
  60. EP260830a: EP-FXT follow-up observation
  61. EP260901a: Global MASTER-Net observations report
  62. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  63. NuSTAR Transient 260828: LCO Optical Upper Limits
  64. EP260901a: EP-WXT detection of a fast X-ray transient
  65. GRB 260830A: NuSTAR detection of prompt emission
  66. GRB 260831B: LCO optical upper limits
  67. EP260830a: Global MASTER-Net observations report
  68. EP260830a: EP-WXT detection of a fast X-ray transient
  69. GRB 260827A: SVOM/GRM observation
  70. NuSTAR 260828: a 1100s hard X-ray transient
  71. GRB 260831B: SVOM detection of a possible burst
  72. GRB 260827A: Glowbug gamma-ray detection
  73. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  74. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  75. GRB 260825A: SVOM/GRM observation of a long burst
  76. GRB 260829A: Fermi GBM Detection
  77. GRB 260825A: AstroSat CZTI detection
  78. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  79. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  80. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  81. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  82. GRB 260818B: Further EP-FXT observation
  83. GRB 260818B: VLT optical and nIR observations
  84. GRB 260818B: TNG NIR observations
  85. MAXI GRB260827.40: Global MASTER-Net observations report
  86. GRB 260818B: 6 GHz VLA observations
  87. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  88. GRB 260808B: SAO RAS observations of the optical rebrightening
  89. EP260822a: Global MASTER-Net observations report
  90. EP Alert 260820.31: Global MASTER-Net observations report
  91. GRB 260807A: EP-FXT follow-up observations
  92. IceCube Alert 260825A: Global MASTER-Net observations report
  93. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  94. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  95. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  96. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  97. EP260822a: EP-FXT non-detection and upper limit
  98. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  99. EP260822a: Einstein Probe detection of a fast X-ray transient
  100. GRB 260822A: LCO optical upper limits

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