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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"

28050 results found.

  1. GRB 260710A: SVOM/GRM observation
  2. GRB 260718A: Fermi GBM Observation
  3. GRB 260718A : GRANDMA and KNC upper limits
  4. GRB 260718A: SVOM/VT optical upper limits
  5. GRB 260718A: SVOM/VT optical upper limits from VHF data
  6. GRB 260714B: SVOM/GRM observation
  7. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  8. GRB 260714B: COLIBRÍ optical counterpart candidate
  9. SVOM sb26071506: Global MASTER-Net observations report
  10. sb26071506: SVOM detection of a X-ray transient
  11. EP260703a: SVOM/ECLAIRs Upper Limit
  12. GRB 260710A: AstroSat CZTI detection
  13. GRB 260714B: Fermi GBM Detection
  14. GRB 260714B: BALROG localization (Fermi Trigger 805746211 / GRB 260714766)
  15. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  16. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  17. EP260713a: Einstein Probe detection of an X-ray transient
  18. GRB 260619A: SVOM/VT continuous optical observations
  19. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  20. EP260623a: KAIT optical observations
  21. GRB 260708A: GRANDMA Optical Observations
  22. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  23. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  24. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  25. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  26. GRB 260708A: LCO optical observations
  27. EP260711a: Einstein Probe detection of an X-ray transient
  28. GRB 260709A: SVOM/GRM detection
  29. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  30. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  31. GRB 260708A: Glowbug gamma-ray detection
  32. GRB 260706A : GRANDMA Upper limits
  33. GRB 260708A: Kilonova-Catcher optical afterglow detection
  34. IceCube-260708A: One candidate from the Zwicky Transient Facility
  35. GRB 260708A: Fermi-GBM observation
  36. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  37. IceCube Alert 260709A: Global MASTER-Net observations report
  38. LAT GRB260708.42: Global MASTER-Net observations report
  39. GRB260708B: MAXI/GSC detection
  40. GRB 260705B: SVOM/GRM observation
  41. GRB 260706A: Further EP-FXT follow-up observation
  42. EP260707a (by EP-FXT): NOT optical upper limit
  43. EP260707a is not a real source
  44. EP260707a: LCOGT Optical Upper Limit
  45. EP260707a: TRT optical upper limit
  46. EP260707a: Einstein Probe detection of an X-ray transient
  47. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  48. GRB 260705C: Glowbug gamma-ray detection of a short burst
  49. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  50. GRB 260706A: REM optical/NIR observations
  51. GRB 260706A: LCO optical upper limit
  52. GRB 260706A: EP-FXT follow-up observation
  53. The EP-WXT trigger 01709274151 is likely a flaring star
  54. GRB 260706A: Fermi GBM Observation
  55. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  56. GRB 260706A: SVOM detection of a burst
  57. GRB 260705A: LCO optical upper limits
  58. GRB 260704A: NOT optical upper limits
  59. Fermi GBM Sub-Threshold Detection of GRB 260705A
  60. GRB 260704A: EP-FXT follow-up observation
  61. GRB 260629A: SVOM/GRM observation of a short burst
  62. GRB 260629A: AstroSat CZTI detection
  63. EP260703a: EP-FXT follow-up observation
  64. GRB 260704A: SVOM detection of a possible GRB
  65. EP260703a: EP-WXT detection of a fast X-ray transient
  66. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  67. Fermi trigger No 804738310: Global MASTER-Net observations report
  68. Fermi GRB 260703A: Global MASTER-Net observations report
  69. GRB 260623A: Glowbug gamma-ray detection
  70. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  71. Fermi trigger No 804552016: Global MASTER-Net observations report
  72. GRB 260701A: Fermi GBM Final Real-time Localization
  73. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  74. EP260628a: EP-FXT follow-up observation
  75. Fermi GRB 260628A: Global MASTER-Net observations report
  76. EP260628a: EP-WXT detection of a fast X-ray transient
  77. EP260626a: further Liverpool Telescope optical upper limits
  78. EP260626a: COLIBRÍ optical upper limit
  79. EP260626a: Liverpool Telescope upper limits
  80. EP260626a: EP-WXT detection of a fast X-ray transient
  81. EP260623a: TNG NIR afterglow detection
  82. GRB 260618A: Fermi GBM Observation
  83. GRB 260619A: SVOM/ECLAIRs refined analysis
  84. EP260623a: Liverpool Telescope optical observations
  85. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  86. EP260623a: WINTER J-band observations
  87. GRB 260617A: Glowbug gamma-ray detection of a short burst
  88. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  89. EP260623a: Optical follow-up observations with Kinder
  90. EP260623a: SVOM/VT optical observations
  91. EP260623a: TRT optical observations
  92. EP260623a: REM optical/NIR afterglow detection
  93. EP 260623a: COLIBRÍ optical observations
  94. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  95. EP260623a: Las Cumbres discovery of the optical counterpart
  96. EP260623a: Einstein Probe detection of an X-ray transient
  97. GRB 260614B: EP-FXT follow-up observation
  98. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  99. EP260618a: Liverpool Telescope optical observations
  100. GRB 260618B: LCO optical observations

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