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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"

24281 results found.

  1. GRB 260831B: LCO optical upper limits
  2. EP260830a: Global MASTER-Net observations report
  3. GRB 260827A: SVOM/GRM observation
  4. GRB 260831B: SVOM detection of a possible burst
  5. IPN triangulation of GRB 260829A
  6. GRB 260831A: Fermi GBM Final Real-time Localization
  7. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  8. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  9. GRB 260829A: GECAM-B observation of a long burst
  10. GRB 260825A: SVOM/GRM observation of a long burst
  11. GRB 260829A: Fermi GBM Detection
  12. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  13. GRB 260829A: Fermi GBM Final Real-time Localization
  14. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  15. IceCube-260825A: 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. GRB 260818B: Further EP-FXT observation
  18. GRB 260818B: TNG NIR observations
  19. MAXI GRB260827.40: Global MASTER-Net observations report
  20. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  21. GRB 260827A: Fermi GBM Final Real-time Localization
  22. GRB 260818B: 6 GHz VLA observations
  23. EP260822a: Global MASTER-Net observations report
  24. EP Alert 260820.31: Global MASTER-Net observations report
  25. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  26. GRB 260807A: EP-FXT follow-up observations
  27. GRB 260822A: SVOM/ECLAIRs refined analysis
  28. GRB 260809A: SVOM/ECLAIRs refined analysis
  29. IceCube Alert 260825A: Global MASTER-Net observations report
  30. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  31. GRB 260825A: Fermi GBM Final Real-time Localization
  32. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  33. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  34. GRB 260822A: EP/FXT follow-up observations
  35. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  36. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  37. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  38. GRB 260822A: LCO optical upper limits
  39. The EP-WXT trigger 01709287395 is likely a flaring star
  40. GRB260822B: Fermi GBM Final Localization
  41. GRB 260822A: GROWTH-India Telescope Upper Limits
  42. GRB 260822A: GOTO optical upper limit
  43. GRB 260822A: SVOM detection of a short burst
  44. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  45. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  46. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  47. GRB 260818B: SVOM/C-GFT optical upper limit
  48. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  49. IceCube Alert 260821A: Global MASTER-Net observations report
  50. The EP-WXT trigger 01709286204 is likely a flaring star
  51. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  52. GRB 260818B: SVOM/GRM observation
  53. EP detected a brightening of LMXB 1ES 1735-26.9
  54. GRB260820A: Fermi GBM Final Real-Time Localization
  55. GRB 260818B: EP-FXT follow-up observation
  56. GRB 260818B: SVOM/ECLAIRs refined analysis
  57. GRB 260818A: SVOM/ECLAIRs refined analysis
  58. GRB 260810A: SVOM/GRM observation
  59. GRB260818A: EP-FXT follow-up observation
  60. GRB 260818B: LCO optical upper limits
  61. GRB 260818B: SVOM detection of a short burst
  62. GRB 260818A: LCO optical upper limits
  63. GRB 260818A: SVOM possible detection of a long and faint GRB
  64. EP260806a: SVOM/ECLAIRs detection through targeted search
  65. The EP-WXT trigger 01709281429 is likely a flaring star
  66. The EP-WXT trigger 01709280562 is likely a flaring star
  67. The EP-WXT trigger 01709279838 is likely a flaring star
  68. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  69. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  70. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  71. GRB 260813A: Fermi GBM Final Real-time Localization
  72. EP260812a: NOT and Liverpool Telescope upper limits:
  73. EP260812b: Liverpool Telescope observations
  74. EP260812b: GOTO detection of the optical counterpart
  75. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  76. EP260812a: SVOM/C-GFT optical upper limit
  77. EP260812b: SVOM/VT optical observation
  78. GRB 260808A: SVOM/GRM observation
  79. Fermi GBM Sub-Threshold Detection of GRB 260809A
  80. GRB 260808B: SVOM/VT optical re-brightening at day 3
  81. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  82. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  83. GRB 260807A: SVOM/ECLAIRs refined analysis
  84. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  85. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  86. EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
  87. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  88. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  89. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  90. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  91. The EP-WXT trigger 01709278015 is likely a flaring star
  92. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  93. GRB 260809A: SVOM/VT optical counterpart
  94. GRB 260808B: SVOM/ECLAIRs refined analysis
  95. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  96. GRB 260809A: SVOM detection of a faint burst
  97. GRB 260808B: NOT optical observations
  98. GRB 260808B: LCO optical observations
  99. GRB 260808A: NuSTAR detection of prompt emission
  100. EP260809a: LCO optical observation

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