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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"

28862 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. GRB 260925A: Swift-XRT refined Analysis
  6. Swift Trigger 1513439 is probably not a GRB
  7. GRB 260925A: Swift/UVOT Upper Limits
  8. Konus-Wind detection of GRB 260924A
  9. GRB 260924A: Extreme Isotropic-equivalent Gamma-ray Energy and encouragement for multiwavelength follow-up observations
  10. GRB 260923A: Glowbug gamma-ray detection
  11. GRB 260924A: Optical follow-up observations with Kinder
  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 260925A: Swift detection of a burst
  19. GRB 260923A: Insight-HXMT/HE detection
  20. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  21. GRB 260924A: Swift/UVOT Detection
  22. GRB 260924A: GROWTH-India Telescope optical observations
  23. GRB 260924A: Swift-BAT refined analysis
  24. GRB 260924A: NuSTAR detection of prompt emission
  25. GRB 260924A: Swift-XRT refined Analysis
  26. GRB 260921A: NuSTAR detection of prompt emission
  27. GRB 260921A: SVOM/GRM observation
  28. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  29. GRB 260924A: Fermi GRB Observation
  30. Konus-Wind detection of GRB 260921A (possible merger-origin)
  31. GRB 260924A: Fermi-LAT detection of a bright burst
  32. GRB 260924A: AstroSat CZTI detection
  33. GRB 260920A: SVOM/GRM observation
  34. GRB 260924A: NOT optical counterpart confirmation
  35. GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
  36. GRB 260922A: CALET Gamma-Ray Burst Monitor detection
  37. The EP-WXT trigger 01709319842 is likely a flaring star
  38. GRB 260924A: Swift detection of a burst
  39. GRB 260924A: Fermi GBM Final Real-time Localization
  40. Fermi GRB 260923A: Global MASTER-Net observations report
  41. GRB 260923A: Fermi GBM Final Real-time Localization
  42. GRB 260922A: Ondrejov D50 optical limit
  43. Fermi-LAT Gamma-ray Observations of IceCube-260919A
  44. Fermi-LAT Gamma-ray Observations of IceCube-260916A
  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 upper limits
  50. GRB 260922A: Swift-XRT refined Analysis
  51. Fermi-LAT Gamma-ray Observations of IceCube-260805A
  52. GRB 260920A: Glowbug gamma-ray detection
  53. GRB 260918A: SVOM/ECLAIRs refined analysis
  54. GRB 260922A: SVOM/C-GFT optical upper limit
  55. GRB 260922A: Swift detection of a burst
  56. GRB 260917C: AstroSat CZTI detection
  57. GRB 260921A: AstroSat CZTI detection
  58. GRB 260921A: Swift-BAT refined analysis
  59. GRB 260921B: Fermi GBM Final Localization
  60. GRB 260921A: Fermi GBM Observation
  61. EP260920b: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  62. EP Alert 260921.58: Global MASTER-Net observations report
  63. GRB 260917B:: SVOM/ECLAIRs refined analysis
  64. The EP-WXT trigger 01709319528 is likely a flaring star
  65. EP260920a: VLT/HAWK-I near-infrared candidate
  66. Swift GRB 260921A: Global MASTER-Net observations report
  67. GRB 260921A: Swift detection of a burst
  68. EP260920b: VLT/X-shooter spectroscopic redshift z = 3.582
  69. GRB 260921A: Fermi GBM Final Real-time Localization
  70. EP260920b: LCO observations
  71. GRB 260920A: AstroSat CZTI detection
  72. EP260920b: SVOM/VT optical observation
  73. EP260920b: COLIBRÍ optical observations
  74. EP260920b: LCO optical counterpart detection
  75. The EP-WXT trigger 01709318601 is likely a flaring star
  76. EP Alert 260921.01: Global MASTER-Net observations report
  77. EP260920b: Global MASTER-Net observations report
  78. EP Alert 260920.66: Global MASTER-Net observations report
  79. EP260920a: NOT early time optical upper limits
  80. EP260920a: NOT optical upper limits
  81. GRB 260920A: Fermi GBM Final Real-time Localization
  82. EP260920a: SVOM/VT optical upper limits
  83. EP260917a: Global MASTER-Net observations report
  84. EP260920a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  85. EP260920a: COLIBRÍ optical upper limits
  86. IceCube Alert 260919A: Global MASTER-Net observations report
  87. EP260920a: LCO optical counterpart candidate
  88. EP Alert 260919.40: Global MASTER-Net observations report
  89. IceCube-260919A - IceCube observation of a high-energy neutrino candidate track-like event
  90. The EP-WXT trigger 01709318491 is likely a flaring star
  91. EP260917a: SVOM/VT optical upper limits
  92. GRB 260918A: SVOM/C-GFT optical upper limits
  93. EP Alert 260918.62: Global MASTER-Net observations report
  94. Fermi GBM Sub-Threshold Detection of GRB 260918A
  95. EP Alert 260918.24: Global MASTER-Net observations report
  96. SVOM GRB260918.16: Global MASTER-Net observations report
  97. Konus-Wind detection of GRB 260916B (short/hard)
  98. The EP-WXT trigger 01709318279 is likely a flaring star
  99. GRB 260916B: Glowbug gamma-ray detection of a short burst
  100. GRB 260918A: EP-FXT follow-up observation

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