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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"

32485 results found.

  1. EP260924a: EP-FXT follow-up observation
  2. GRB 260925A: Swift/UVOT Upper Limits
  3. Konus-Wind detection of GRB 260924A
  4. GRB 260924A: Extreme Isotropic-equivalent Gamma-ray Energy and encouragement for multiwavelength follow-up observations
  5. GRB 260923A: Glowbug gamma-ray detection
  6. GRB 260924A: Optical follow-up observations with Kinder
  7. GRB 260922A: Glowbug gamma-ray detection
  8. GRB 260925A: COLIBRÍ optical upper limits
  9. GRB 260925A: FRAM-Auger optical limit
  10. GRB 260924A: Ondrejov D50 optical afterglow detection
  11. EP260924a: J-band upper limit with WINTER
  12. GRB 260924A: SVOM/GRM observation
  13. GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
  14. GRB 260923A: Insight-HXMT/HE detection
  15. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  16. GRB 260924A: Swift/UVOT Detection
  17. GRB 260924A: GROWTH-India Telescope optical observations
  18. GRB 260924A: Swift-BAT refined analysis
  19. GRB 260924A: NuSTAR detection of prompt emission
  20. Konus-Wind detection of GRB 260922A
  21. GRB 260922A: NuSTAR detection of prompt emission
  22. GRB 260921A: NuSTAR detection of prompt emission
  23. Konus-Wind detection of GRB 260921A (correction to GCN 45722)
  24. GRB 260921A: SVOM/GRM observation
  25. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  26. GRB 260924A: Fermi GRB Observation
  27. Konus-Wind detection of GRB 260921A (possible merger-origin)
  28. GRB 260924A: Fermi-LAT detection of a bright burst
  29. GRB 260924A: AstroSat CZTI detection
  30. GRB 260920A: SVOM/GRM observation
  31. GRB 260924A: NOT optical counterpart confirmation
  32. GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
  33. GRB 260922A: CALET Gamma-Ray Burst Monitor detection
  34. Fermi GRB 260923A: Global MASTER-Net observations report
  35. Trigger_21914: Swift ToO observations
  36. EP260806a: e-MERLIN detection at 5 GHz
  37. GRB 260922A: Ondrejov D50 optical limit
  38. Fermi-LAT Gamma-ray Observations of IceCube-260919A
  39. Fermi-LAT Gamma-ray Observations of IceCube-260916A
  40. ATCA observations of GRB 260909A
  41. GRB 260922A: Swift-BAT refined analysis
  42. EP260920a: VLT/HAWK-I near-infrared counterpart confirmation
  43. GRB 260922A: J-band upper limit with WINTER
  44. GRB 260922A: Swift/UVOT Upper Limits
  45. GRB 260922A: COLIBRÍ Optical Counterpart Candidate (correction to GCN 45698)
  46. GRB 260922A: COLIBRÍ optical upper limits
  47. Fermi-LAT Gamma-ray Observations of IceCube-260805A
  48. Konus-Wind detection of GRB 260810A
  49. GRB 260920A: Glowbug gamma-ray detection
  50. GRB 260918A: SVOM/ECLAIRs refined analysis
  51. GRB 260922A: SVOM/C-GFT optical upper limit
  52. GRB 260917C: AstroSat CZTI detection
  53. GRB 260920B/EP260920b: GECAM-B detection of a burst
  54. GRB 260921A: AstroSat CZTI detection
  55. GRB 260921A: Swift-BAT refined analysis
  56. GRB 260921A: Fermi GBM Observation
  57. EP260920b: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  58. GRB 260917B:: SVOM/ECLAIRs refined analysis
  59. EP260920a: VLT/HAWK-I near-infrared candidate
  60. Swift GRB 260921A: Global MASTER-Net observations report
  61. EP260920b: VLT/X-shooter spectroscopic redshift z = 3.582
  62. EP260920b: LCO observations
  63. GRB 260920A: AstroSat CZTI detection
  64. EP260920b: SVOM/VT optical observation
  65. EP260920b: refined analysis of the EP-WXT and EP-FXT observations
  66. EP260920b: COLIBRÍ optical observations
  67. EP260920b: LCO optical counterpart detection
  68. EP260920b: Global MASTER-Net observations report
  69. IceCube-260919A: Upper limits from a search for additional neutrino events in IceCube
  70. EP260920a: NOT early time optical upper limits
  71. EP260920a: NOT optical upper limits
  72. EP260920a: SVOM/VT optical upper limits
  73. EP260917a: Global MASTER-Net observations report
  74. EP260920a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  75. EP260920a: COLIBRÍ optical upper limits
  76. EP260920a: Update of the LCO optical counterpart candidate
  77. EP260917b: EP-FXT non-detection and upper limit
  78. EP260920a: LCO optical counterpart candidate
  79. GRB 260915A: VLT optical and near-infrared upper limits
  80. EP260917a: refined analysis of the EP-FXT observations
  81. IceCube-260919A - IceCube observation of a high-energy neutrino candidate track-like event
  82. EP260806a: Yamaguchi Interferometer radio detections
  83. EP260917a: SVOM/VT optical upper limits
  84. GRB 260918A: SVOM/C-GFT optical upper limits
  85. Fermi GBM Sub-Threshold Detection of GRB 260918A
  86. Konus-Wind detection of GRB 260916B (short/hard)
  87. GRB 260918A: SVOM/VT optical upper limits
  88. GRB 260916B: Glowbug gamma-ray detection of a short burst
  89. GRB 260918A: EP-FXT follow-up observation
  90. GRB 260917B: Mondy optical upper limit
  91. IPN triangulation of GRB 260916B (short)
  92. EP260917A: J-band upper limit with WINTER
  93. IPN triangulation of GRB 260810A
  94. GRB 260917B: EP-FXT follow-up observation
  95. EP260917a: COLIBRÍ optical upper limits
  96. GRB 260915A: Swift-XRT afterglow detection
  97. GRB 260918A: LCO optical upper limits
  98. GRB 260918A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  99. GRB 260918A: SVOM detection of a burst
  100. GRB 260917B: FRAM-Auger optical limits

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