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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"

32490 results found.

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

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