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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"

27889 results found.

  1. GRB 260913A: SVOM detection of a faint burst
  2. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  3. GRB 260907A: SVOM/GRM observation
  4. GRB 260909A: CrAO and AbAO optical upper limits
  5. GRB 260909A: KAIT optical upper limit
  6. GRB 260903A: Swift-XRT observations
  7. GRB 260909A: OHP/T193 z-band upper limit
  8. GRB 260909A: VLT optical and near-infrared upper limits
  9. EP Alert 260909.53: Global MASTER-Net observations report
  10. GRB 260909A: EP-FXT follow-up observation
  11. EP260806a: NOEMA detection
  12. EP260623a: NOEMA detections
  13. GRB 260909A: Mondy optical observations and afterglow candidate
  14. GRB 260909A: Xinglong 2.16m optical upper limit
  15. GRB 260909A: SVOM/C-GFT optical upper limit
  16. GRB 260909A: SVOM detection of a burst
  17. Fermi trigger No 810554827: Global MASTER-Net observations report
  18. EP Alert 260908.60: Global MASTER-Net observations report
  19. GRB 260907A: Glowbug gamma-ray detection of a likely short burst
  20. Fermi GRB 260907B: Global MASTER-Net observations report
  21. GRB 260903A: SAO RAS optical upper limit
  22. Fermi GRB 260907A: Global MASTER-Net observations report
  23. EP260903a: EP-FXT follow-up observation
  24. EP Alert 260905.11: Global MASTER-Net observations report
  25. GRB 260903A: J-band upper limit with WINTER
  26. EP Alert 260903.47: Global MASTER-Net observations report
  27. GRB260903A: Liverpool Telescope optical observations
  28. GRB 260903A: SAO RAS optical observations
  29. GRB 260830A: GECAM-B detection of a burst
  30. EP260903a: EP-WXT detection of a fast X-ray transient
  31. EP Alert 260903.62: Global MASTER-Net observations report
  32. GRB 260830A: Insight-HXMT/HE detection
  33. GRB 260903A: EP-FXT follow-up observation
  34. GRB 260903A: OHP/T193 optical afterglow detection
  35. NuSTAR Transient 260828: SOAR Optical Upper Limits
  36. SVOM GRB260903A: Global MASTER-Net observations report
  37. GRB 260903A: LCO optical counterpart detection
  38. GRB 260827A: Insight-HXMT/HE detection
  39. EP260901a: SVOM/VT optical upper limits
  40. EP260901a: EP-FXT follow-up observation
  41. GRB 260829A: SVOM/GRM observation
  42. GRB 260818A: ATCA detection of a candidate radio counterpart
  43. EP260830a: EP-FXT follow-up observation
  44. EP260901a: Global MASTER-Net observations report
  45. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  46. NuSTAR Transient 260828: LCO Optical Upper Limits
  47. EP260901a: EP-WXT detection of a fast X-ray transient
  48. GRB 260830A: NuSTAR detection of prompt emission
  49. GRB 260831B: LCO optical upper limits
  50. EP260830a: Global MASTER-Net observations report
  51. EP260830a: EP-WXT detection of a fast X-ray transient
  52. GRB 260827A: SVOM/GRM observation
  53. NuSTAR 260828: a 1100s hard X-ray transient
  54. GRB 260831B: SVOM detection of a possible burst
  55. GRB 260827A: Glowbug gamma-ray detection
  56. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  57. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  58. GRB 260825A: SVOM/GRM observation of a long burst
  59. GRB 260829A: Fermi GBM Detection
  60. GRB 260825A: AstroSat CZTI detection
  61. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  62. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  63. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  64. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  65. GRB 260818B: Further EP-FXT observation
  66. GRB 260818B: VLT optical and nIR observations
  67. GRB 260818B: TNG NIR observations
  68. MAXI GRB260827.40: Global MASTER-Net observations report
  69. GRB 260818B: 6 GHz VLA observations
  70. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  71. GRB 260808B: SAO RAS observations of the optical rebrightening
  72. EP260822a: Global MASTER-Net observations report
  73. EP Alert 260820.31: Global MASTER-Net observations report
  74. GRB 260807A: EP-FXT follow-up observations
  75. IceCube Alert 260825A: Global MASTER-Net observations report
  76. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  77. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  78. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  79. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  80. EP260822a: EP-FXT non-detection and upper limit
  81. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  82. EP260822a: Einstein Probe detection of a fast X-ray transient
  83. GRB 260822A: LCO optical upper limits
  84. GRB 260822A: GROWTH-India Telescope Upper Limits
  85. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  86. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  87. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  88. GRB 260818B: VLA radio observations
  89. GRB 260818B: SVOM/C-GFT optical upper limit
  90. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  91. IceCube Alert 260821A: Global MASTER-Net observations report
  92. GRB 260820A: Insight-HXMT/HE detection
  93. EP detected a brightening of LMXB 1ES 1735-26.9
  94. GRB 260818A: J-band observations with WINTER
  95. GRB 260818A: SVOM/ECLAIRs refined analysis
  96. GRB 260818B: NOT optical upper limits
  97. GRB 260810A: SVOM/GRM observation
  98. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  99. GRB 260818B: LCO optical upper limits
  100. GRB 260818B: SVOM detection of a short burst

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