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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"

28042 results found.

  1. GRB 260830A: NuSTAR detection of prompt emission
  2. GRB 260831B: LCO optical upper limits
  3. EP260830a: Global MASTER-Net observations report
  4. EP260830a: EP-WXT detection of a fast X-ray transient
  5. GRB 260827A: SVOM/GRM observation
  6. NuSTAR 260828: a 1100s hard X-ray transient
  7. GRB 260831B: SVOM detection of a possible burst
  8. GRB 260827A: Glowbug gamma-ray detection
  9. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  10. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  11. GRB 260825A: SVOM/GRM observation of a long burst
  12. GRB 260829A: Fermi GBM Detection
  13. GRB 260825A: AstroSat CZTI detection
  14. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  15. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  16. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  17. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  18. GRB 260818B: Further EP-FXT observation
  19. GRB 260818B: VLT optical and nIR observations
  20. GRB 260818B: TNG NIR observations
  21. MAXI GRB260827.40: Global MASTER-Net observations report
  22. GRB 260818B: 6 GHz VLA observations
  23. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  24. GRB 260808B: SAO RAS observations of the optical rebrightening
  25. EP260822a: Global MASTER-Net observations report
  26. EP Alert 260820.31: Global MASTER-Net observations report
  27. GRB 260807A: EP-FXT follow-up observations
  28. IceCube Alert 260825A: Global MASTER-Net observations report
  29. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  30. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  31. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  32. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  33. EP260822a: EP-FXT non-detection and upper limit
  34. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  35. EP260822a: Einstein Probe detection of a fast X-ray transient
  36. GRB 260822A: LCO optical upper limits
  37. GRB 260822A: GROWTH-India Telescope Upper Limits
  38. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  39. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  40. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  41. GRB 260818B: VLA radio observations
  42. GRB 260818B: SVOM/C-GFT optical upper limit
  43. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  44. IceCube Alert 260821A: Global MASTER-Net observations report
  45. GRB 260820A: Insight-HXMT/HE detection
  46. EP detected a brightening of LMXB 1ES 1735-26.9
  47. GRB 260818A: J-band observations with WINTER
  48. GRB 260818A: SVOM/ECLAIRs refined analysis
  49. GRB 260818B: NOT optical upper limits
  50. GRB 260810A: SVOM/GRM observation
  51. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  52. GRB 260818B: LCO optical upper limits
  53. GRB 260818B: SVOM detection of a short burst
  54. EP260806a: SAO RAS multicolor optical observations
  55. GRB 260818A: LCO optical upper limits
  56. EP260812a: AbAO optical upper limit
  57. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  58. GRB 260810A: Insight-HXMT/HE detection
  59. GRB 260818A: SVOM possible detection of a long and faint GRB
  60. EP260806a: NUTTELA-TAO optical observations
  61. The EP-WXT trigger 01709281429 is likely a flaring star
  62. EP260812a: AZT-22 optical upper limit
  63. EP260806a: WFST optical observations
  64. EP260812b: Optical upper limit with Kinder
  65. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  66. GRB 260808B: Liverpool Telescope further optical observations
  67. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  68. EP260812a: NOT and Liverpool Telescope upper limits:
  69. EP260812b: Liverpool Telescope observations
  70. EP260812b: GOTO detection of the optical counterpart
  71. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  72. EP260812a: SVOM/C-GFT optical upper limit
  73. EP260812b: COLIBRÍ optical observations
  74. EP260812b: SVOM/VT optical observation
  75. GRB 260808A: SVOM/GRM observation
  76. EP260812b: Einstein Probe detection of an X-ray transient
  77. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  78. Fermi GBM Sub-Threshold Detection of GRB 260809A
  79. GRB 260810A: Glowbug gamma-ray detection
  80. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  81. GRB 260810A: AstroSat CZTI detection of a long burst
  82. EP260812a: Einstein Probe detection of an X-ray transient
  83. GRB 260809A: SAO RAS optical observations
  84. GRB 260808B: SAO RAS optical observations
  85. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  86. EP260806a: MAO/AZT-22 optical observations
  87. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  88. GRB260808B: MAO/AZT-22 optical observations
  89. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  90. GRB 260809A: J-band upper limit with WINTER
  91. GRB 260806A: Glowbug gamma-ray detection
  92. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  93. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  94. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  95. GRB 260809A: NOT optical observations
  96. GRB260809A: MAO/AZT-22 optical observations
  97. GRB260809A: OHP/T193 optical observations
  98. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  99. EP260809a: J-band upper limit with WINTER
  100. GRB 260808B: J-band upper limit with WINTER

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