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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"

32491 results found.

  1. Fermi GRB 260926A: Global MASTER-Net observations report
  2. GRB 260924A: Near-infrared detection with MDM/MIRAGE
  3. GRB 260924A: COLIBRÍ optical observations
  4. GRB 260924A: Second-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  5. EP260924a: J-band upper limit by SYSU 80cm infrared telescope
  6. GRB 260925A: J-band upper limit by SYSU 80cm infrared telescope
  7. EP260924a: EP-FXT follow-up observation
  8. GRB 260925A: Swift/UVOT Upper Limits
  9. Konus-Wind detection of GRB 260924A
  10. GRB 260924A: Extreme Isotropic-equivalent Gamma-ray Energy and encouragement for multiwavelength follow-up observations
  11. GRB 260923A: Glowbug gamma-ray detection
  12. GRB 260924A: Optical follow-up observations with Kinder
  13. GRB 260922A: Glowbug gamma-ray detection
  14. GRB 260925A: COLIBRÍ optical upper limits
  15. GRB 260925A: FRAM-Auger optical limit
  16. GRB 260924A: Ondrejov D50 optical afterglow detection
  17. EP260924a: J-band upper limit with WINTER
  18. GRB 260924A: SVOM/GRM observation
  19. GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
  20. GRB 260923A: Insight-HXMT/HE detection
  21. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  22. GRB 260924A: Swift/UVOT Detection
  23. GRB 260924A: GROWTH-India Telescope optical observations
  24. GRB 260924A: Swift-BAT refined analysis
  25. GRB 260924A: NuSTAR detection of prompt emission
  26. Konus-Wind detection of GRB 260922A
  27. GRB 260922A: NuSTAR detection of prompt emission
  28. GRB 260921A: NuSTAR detection of prompt emission
  29. Konus-Wind detection of GRB 260921A (correction to GCN 45722)
  30. GRB 260921A: SVOM/GRM observation
  31. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  32. GRB 260924A: Fermi GRB Observation
  33. Konus-Wind detection of GRB 260921A (possible merger-origin)
  34. GRB 260924A: Fermi-LAT detection of a bright burst
  35. GRB 260924A: AstroSat CZTI detection
  36. GRB 260920A: SVOM/GRM observation
  37. GRB 260924A: NOT optical counterpart confirmation
  38. GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
  39. GRB 260922A: CALET Gamma-Ray Burst Monitor detection
  40. Fermi GRB 260923A: Global MASTER-Net observations report
  41. Trigger_21914: Swift ToO observations
  42. EP260806a: e-MERLIN detection at 5 GHz
  43. GRB 260922A: Ondrejov D50 optical limit
  44. Fermi-LAT Gamma-ray Observations of IceCube-260919A
  45. Fermi-LAT Gamma-ray Observations of IceCube-260916A
  46. ATCA observations of GRB 260909A
  47. GRB 260922A: Swift-BAT refined analysis
  48. EP260920a: VLT/HAWK-I near-infrared counterpart confirmation
  49. GRB 260922A: J-band upper limit with WINTER
  50. GRB 260922A: Swift/UVOT Upper Limits
  51. GRB 260922A: COLIBRÍ Optical Counterpart Candidate (correction to GCN 45698)
  52. GRB 260922A: COLIBRÍ optical upper limits
  53. Fermi-LAT Gamma-ray Observations of IceCube-260805A
  54. Konus-Wind detection of GRB 260810A
  55. GRB 260920A: Glowbug gamma-ray detection
  56. GRB 260918A: SVOM/ECLAIRs refined analysis
  57. GRB 260922A: SVOM/C-GFT optical upper limit
  58. GRB 260917C: AstroSat CZTI detection
  59. GRB 260920B/EP260920b: GECAM-B detection of a burst
  60. GRB 260921A: AstroSat CZTI detection
  61. GRB 260921A: Swift-BAT refined analysis
  62. GRB 260921A: Fermi GBM Observation
  63. EP260920b: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  64. GRB 260917B:: SVOM/ECLAIRs refined analysis
  65. EP260920a: VLT/HAWK-I near-infrared candidate
  66. Swift GRB 260921A: Global MASTER-Net observations report
  67. EP260920b: VLT/X-shooter spectroscopic redshift z = 3.582
  68. EP260920b: LCO observations
  69. GRB 260920A: AstroSat CZTI detection
  70. EP260920b: SVOM/VT optical observation
  71. EP260920b: refined analysis of the EP-WXT and EP-FXT observations
  72. EP260920b: COLIBRÍ optical observations
  73. EP260920b: LCO optical counterpart detection
  74. EP260920b: Global MASTER-Net observations report
  75. IceCube-260919A: Upper limits from a search for additional neutrino events in IceCube
  76. EP260920a: NOT early time optical upper limits
  77. EP260920a: NOT optical upper limits
  78. EP260920a: SVOM/VT optical upper limits
  79. EP260917a: Global MASTER-Net observations report
  80. EP260920a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  81. EP260920a: COLIBRÍ optical upper limits
  82. EP260920a: Update of the LCO optical counterpart candidate
  83. EP260917b: EP-FXT non-detection and upper limit
  84. EP260920a: LCO optical counterpart candidate
  85. GRB 260915A: VLT optical and near-infrared upper limits
  86. EP260917a: refined analysis of the EP-FXT observations
  87. IceCube-260919A - IceCube observation of a high-energy neutrino candidate track-like event
  88. EP260806a: Yamaguchi Interferometer radio detections
  89. EP260917a: SVOM/VT optical upper limits
  90. GRB 260918A: SVOM/C-GFT optical upper limits
  91. Fermi GBM Sub-Threshold Detection of GRB 260918A
  92. Konus-Wind detection of GRB 260916B (short/hard)
  93. GRB 260918A: SVOM/VT optical upper limits
  94. GRB 260916B: Glowbug gamma-ray detection of a short burst
  95. GRB 260918A: EP-FXT follow-up observation
  96. GRB 260917B: Mondy optical upper limit
  97. IPN triangulation of GRB 260916B (short)
  98. EP260917A: J-band upper limit with WINTER
  99. IPN triangulation of GRB 260810A
  100. GRB 260917B: EP-FXT follow-up observation

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