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

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