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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"

28866 results found.

  1. Fermi GRB 260926A: Global MASTER-Net observations report
  2. GRB 260924A: Near-infrared detection with MDM/MIRAGE
  3. GRB 260926A: Fermi GBM Final Real-time Localization
  4. The EP-WXT trigger 01709320726 is likely a flaring star
  5. GRB 260924A: COLIBRÍ optical observations
  6. GRB 260924A: Second-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  7. EP260924a: J-band upper limit by SYSU 80cm infrared telescope
  8. GRB 260925A: J-band upper limit by SYSU 80cm infrared telescope
  9. GRB 260925A: Swift-XRT refined Analysis
  10. Swift Trigger 1513439 is probably not a GRB
  11. GRB 260925A: Swift/UVOT Upper Limits
  12. Konus-Wind detection of GRB 260924A
  13. GRB 260924A: Extreme Isotropic-equivalent Gamma-ray Energy and encouragement for multiwavelength follow-up observations
  14. GRB 260923A: Glowbug gamma-ray detection
  15. GRB 260924A: Optical follow-up observations with Kinder
  16. GRB 260925A: COLIBRÍ optical upper limits
  17. GRB 260925A: FRAM-Auger optical limit
  18. GRB 260924A: Ondrejov D50 optical afterglow detection
  19. EP260924a: J-band upper limit with WINTER
  20. GRB 260924A: SVOM/GRM observation
  21. GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
  22. GRB 260925A: Swift detection of a burst
  23. GRB 260923A: Insight-HXMT/HE detection
  24. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  25. GRB 260924A: Swift/UVOT Detection
  26. GRB 260924A: GROWTH-India Telescope optical observations
  27. GRB 260924A: Swift-BAT refined analysis
  28. GRB 260924A: NuSTAR detection of prompt emission
  29. GRB 260924A: Swift-XRT refined Analysis
  30. GRB 260921A: NuSTAR detection of prompt emission
  31. GRB 260921A: SVOM/GRM observation
  32. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  33. GRB 260924A: Fermi GRB Observation
  34. Konus-Wind detection of GRB 260921A (possible merger-origin)
  35. GRB 260924A: Fermi-LAT detection of a bright burst
  36. GRB 260924A: AstroSat CZTI detection
  37. GRB 260920A: SVOM/GRM observation
  38. GRB 260924A: NOT optical counterpart confirmation
  39. GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
  40. GRB 260922A: CALET Gamma-Ray Burst Monitor detection
  41. The EP-WXT trigger 01709319842 is likely a flaring star
  42. GRB 260924A: Swift detection of a burst
  43. GRB 260924A: Fermi GBM Final Real-time Localization
  44. Fermi GRB 260923A: Global MASTER-Net observations report
  45. GRB 260923A: Fermi GBM Final Real-time Localization
  46. GRB 260922A: Ondrejov D50 optical limit
  47. Fermi-LAT Gamma-ray Observations of IceCube-260919A
  48. Fermi-LAT Gamma-ray Observations of IceCube-260916A
  49. GRB 260922A: Swift-BAT refined analysis
  50. EP260920a: VLT/HAWK-I near-infrared counterpart confirmation
  51. GRB 260922A: J-band upper limit with WINTER
  52. GRB 260922A: Swift/UVOT Upper Limits
  53. GRB 260922A: COLIBRÍ optical upper limits
  54. GRB 260922A: Swift-XRT refined Analysis
  55. Fermi-LAT Gamma-ray Observations of IceCube-260805A
  56. GRB 260920A: Glowbug gamma-ray detection
  57. GRB 260918A: SVOM/ECLAIRs refined analysis
  58. GRB 260922A: SVOM/C-GFT optical upper limit
  59. GRB 260922A: Swift detection of a burst
  60. GRB 260917C: AstroSat CZTI detection
  61. GRB 260921A: AstroSat CZTI detection
  62. GRB 260921A: Swift-BAT refined analysis
  63. GRB 260921B: Fermi GBM Final Localization
  64. GRB 260921A: Fermi GBM Observation
  65. EP260920b: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  66. EP Alert 260921.58: Global MASTER-Net observations report
  67. GRB 260917B:: SVOM/ECLAIRs refined analysis
  68. The EP-WXT trigger 01709319528 is likely a flaring star
  69. EP260920a: VLT/HAWK-I near-infrared candidate
  70. Swift GRB 260921A: Global MASTER-Net observations report
  71. GRB 260921A: Swift detection of a burst
  72. EP260920b: VLT/X-shooter spectroscopic redshift z = 3.582
  73. GRB 260921A: Fermi GBM Final Real-time Localization
  74. EP260920b: LCO observations
  75. GRB 260920A: AstroSat CZTI detection
  76. EP260920b: SVOM/VT optical observation
  77. EP260920b: COLIBRÍ optical observations
  78. EP260920b: LCO optical counterpart detection
  79. The EP-WXT trigger 01709318601 is likely a flaring star
  80. EP Alert 260921.01: Global MASTER-Net observations report
  81. EP260920b: Global MASTER-Net observations report
  82. EP Alert 260920.66: Global MASTER-Net observations report
  83. EP260920a: NOT early time optical upper limits
  84. EP260920a: NOT optical upper limits
  85. GRB 260920A: Fermi GBM Final Real-time Localization
  86. EP260920a: SVOM/VT optical upper limits
  87. EP260917a: Global MASTER-Net observations report
  88. EP260920a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  89. EP260920a: COLIBRÍ optical upper limits
  90. IceCube Alert 260919A: Global MASTER-Net observations report
  91. EP260920a: LCO optical counterpart candidate
  92. EP Alert 260919.40: Global MASTER-Net observations report
  93. IceCube-260919A - IceCube observation of a high-energy neutrino candidate track-like event
  94. The EP-WXT trigger 01709318491 is likely a flaring star
  95. EP260917a: SVOM/VT optical upper limits
  96. GRB 260918A: SVOM/C-GFT optical upper limits
  97. EP Alert 260918.62: Global MASTER-Net observations report
  98. Fermi GBM Sub-Threshold Detection of GRB 260918A
  99. EP Alert 260918.24: Global MASTER-Net observations report
  100. SVOM GRB260918.16: Global MASTER-Net observations report

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