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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"

28056 results found.

  1. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  2. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  3. IceCube Alert 260722A: Global MASTER-Net observations report
  4. GRB 260721A: NuSTAR detection of prompt emission
  5. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  6. Fermi trigger No 806104130: Global MASTER-Net observations report
  7. Fermi GRB 260718A: Global MASTER-Net observations report
  8. GRB 260718A: LCO optical upper limits
  9. GRB 260710A: SVOM/GRM observation
  10. GRB 260718A: Fermi GBM Observation
  11. GRB 260718A : GRANDMA and KNC upper limits
  12. GRB 260718A: SVOM/VT optical upper limits
  13. GRB 260718A: SVOM/VT optical upper limits from VHF data
  14. GRB 260714B: SVOM/GRM observation
  15. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  16. GRB 260714B: COLIBRÍ optical counterpart candidate
  17. SVOM sb26071506: Global MASTER-Net observations report
  18. sb26071506: SVOM detection of a X-ray transient
  19. EP260703a: SVOM/ECLAIRs Upper Limit
  20. GRB 260710A: AstroSat CZTI detection
  21. GRB 260714B: Fermi GBM Detection
  22. GRB 260714B: BALROG localization (Fermi Trigger 805746211 / GRB 260714766)
  23. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  24. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  25. EP260713a: Einstein Probe detection of an X-ray transient
  26. GRB 260619A: SVOM/VT continuous optical observations
  27. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  28. EP260623a: KAIT optical observations
  29. GRB 260708A: GRANDMA Optical Observations
  30. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  31. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  32. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  33. IceCube-260708A: Upper limits from a search for additional neutrino events in IceCube
  34. GRB 260708A: LCO optical observations
  35. EP260711a: Einstein Probe detection of an X-ray transient
  36. GRB 260709A: SVOM/GRM detection
  37. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  38. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  39. GRB 260708A: Glowbug gamma-ray detection
  40. GRB 260706A : GRANDMA Upper limits
  41. GRB 260708A: Kilonova-Catcher optical afterglow detection
  42. IceCube-260708A: One candidate from the Zwicky Transient Facility
  43. GRB 260708A: Fermi-GBM observation
  44. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  45. IceCube Alert 260709A: Global MASTER-Net observations report
  46. LAT GRB260708.42: Global MASTER-Net observations report
  47. GRB260708B: MAXI/GSC detection
  48. GRB 260705B: SVOM/GRM observation
  49. GRB 260706A: Further EP-FXT follow-up observation
  50. EP260707a (by EP-FXT): NOT optical upper limit
  51. EP260707a is not a real source
  52. EP260707a: LCOGT Optical Upper Limit
  53. EP260707a: TRT optical upper limit
  54. EP260707a: Einstein Probe detection of an X-ray transient
  55. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  56. GRB 260705C: Glowbug gamma-ray detection of a short burst
  57. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  58. GRB 260706A: REM optical/NIR observations
  59. GRB 260706A: LCO optical upper limit
  60. GRB 260706A: EP-FXT follow-up observation
  61. The EP-WXT trigger 01709274151 is likely a flaring star
  62. GRB 260706A: Fermi GBM Observation
  63. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  64. GRB 260706A: SVOM detection of a burst
  65. GRB 260705A: LCO optical upper limits
  66. GRB 260704A: NOT optical upper limits
  67. Fermi GBM Sub-Threshold Detection of GRB 260705A
  68. GRB 260704A: EP-FXT follow-up observation
  69. GRB 260629A: SVOM/GRM observation of a short burst
  70. GRB 260629A: AstroSat CZTI detection
  71. EP260703a: EP-FXT follow-up observation
  72. GRB 260704A: SVOM detection of a possible GRB
  73. EP260703a: EP-WXT detection of a fast X-ray transient
  74. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  75. Fermi trigger No 804738310: Global MASTER-Net observations report
  76. Fermi GRB 260703A: Global MASTER-Net observations report
  77. GRB 260623A: Glowbug gamma-ray detection
  78. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  79. Fermi trigger No 804552016: Global MASTER-Net observations report
  80. GRB 260701A: Fermi GBM Final Real-time Localization
  81. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  82. EP260628a: EP-FXT follow-up observation
  83. Fermi GRB 260628A: Global MASTER-Net observations report
  84. EP260628a: EP-WXT detection of a fast X-ray transient
  85. EP260626a: further Liverpool Telescope optical upper limits
  86. EP260626a: COLIBRÍ optical upper limit
  87. EP260626a: Liverpool Telescope upper limits
  88. EP260626a: EP-WXT detection of a fast X-ray transient
  89. EP260623a: TNG NIR afterglow detection
  90. GRB 260618A: Fermi GBM Observation
  91. GRB 260619A: SVOM/ECLAIRs refined analysis
  92. EP260623a: Liverpool Telescope optical observations
  93. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  94. EP260623a: WINTER J-band observations
  95. GRB 260617A: Glowbug gamma-ray detection of a short burst
  96. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  97. EP260623a: Optical follow-up observations with Kinder
  98. EP260623a: SVOM/VT optical observations
  99. EP260623a: TRT optical observations
  100. EP260623a: REM optical/NIR afterglow detection

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