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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"

22054 results found.

  1. GRB260914A: MAO/AZT-22 optical observations
  2. Fermi GRB 260926A: Global MASTER-Net observations report
  3. GRB 260924A: Near-infrared detection with MDM/MIRAGE
  4. GRB 260924A: COLIBRÍ optical observations
  5. GRB 260924A: Second-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  6. EP260924a: J-band upper limit by SYSU 80cm infrared telescope
  7. GRB 260925A: J-band upper limit by SYSU 80cm infrared telescope
  8. Swift Trigger 1513439 is probably not a GRB
  9. GRB 260925A: Swift/UVOT Upper Limits
  10. Konus-Wind detection of GRB 260924A
  11. GRB 260924A: Extreme Isotropic-equivalent Gamma-ray Energy and encouragement for multiwavelength follow-up observations
  12. GRB 260924A: Optical follow-up observations with Kinder
  13. GRB 260924A: Ondrejov D50 optical afterglow detection
  14. EP260924a: J-band upper limit with WINTER
  15. EP260924a: EP-WXT detection of an X-ray transient
  16. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  17. GRB 260924A: Swift/UVOT Detection
  18. GRB 260924A: GROWTH-India Telescope optical observations
  19. Konus-Wind detection of GRB 260922A
  20. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  21. Konus-Wind detection of GRB 260921A (possible merger-origin)
  22. GRB 260924A: NOT optical counterpart confirmation
  23. GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
  24. GRB 260922A: CALET Gamma-Ray Burst Monitor detection
  25. Fermi GRB 260923A: Global MASTER-Net observations report
  26. Trigger_21914: Swift ToO observations
  27. EP260806a: e-MERLIN detection at 5 GHz
  28. Fermi-LAT Gamma-ray Observations of IceCube-260919A
  29. Fermi-LAT Gamma-ray Observations of IceCube-260916A
  30. ATCA observations of GRB 260909A
  31. EP260920a: VLT/HAWK-I near-infrared counterpart confirmation
  32. GRB 260922A: J-band upper limit with WINTER
  33. GRB 260922A: Swift/UVOT Upper Limits
  34. Fermi-LAT Gamma-ray Observations of IceCube-260805A
  35. Konus-Wind detection of GRB 260810A
  36. GRB 260918A: SVOM/ECLAIRs refined analysis
  37. GRB 260922A: SVOM/C-GFT optical upper limit
  38. EP Alert 260921.58: Global MASTER-Net observations report
  39. GRB 260917B:: SVOM/ECLAIRs refined analysis
  40. EP260920a: VLT/HAWK-I near-infrared candidate
  41. Swift GRB 260921A: Global MASTER-Net observations report
  42. GRB 260921A: Swift detection of a burst
  43. EP260920b: VLT/X-shooter spectroscopic redshift z = 3.582
  44. EP260920b: LCO observations
  45. EP260920b: refined analysis of the EP-WXT and EP-FXT observations
  46. EP260920b: COLIBRÍ optical observations
  47. EP Alert 260921.01: Global MASTER-Net observations report
  48. EP260920b: Global MASTER-Net observations report
  49. EP Alert 260920.66: Global MASTER-Net observations report
  50. EP260920a: NOT early time optical upper limits
  51. EP260920a: NOT optical upper limits
  52. EP260917a: Global MASTER-Net observations report
  53. EP260920a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  54. IceCube Alert 260919A: Global MASTER-Net observations report
  55. EP Alert 260919.40: Global MASTER-Net observations report
  56. GRB 260915A: VLT optical and near-infrared upper limits
  57. EP260917a: refined analysis of the EP-FXT observations
  58. EP260806a: Yamaguchi Interferometer radio detections
  59. GRB 260918A: SVOM/C-GFT optical upper limits
  60. EP Alert 260918.62: Global MASTER-Net observations report
  61. EP Alert 260918.24: Global MASTER-Net observations report
  62. SVOM GRB260918.16: Global MASTER-Net observations report
  63. EP260917b: EP-WXT detection of an X-ray transient
  64. EP260917A: J-band upper limit with WINTER
  65. EP Alert 260917.32: Global MASTER-Net observations report
  66. GRB 260915A: Swift-XRT afterglow detection
  67. GRB 260918A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  68. GRB 260918A: SVOM detection of a burst
  69. GRB 260915A: SVOM/ECLAIRs refined analysis
  70. GRB 260917B: WINTER J-band observations
  71. GRB 260917B: SVOM/VT optical observations
  72. SVOM GRB260917.16: Global MASTER-Net observations report
  73. GRB 260917B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  74. Fermi trigger No 811304653: Global MASTER-Net observations report
  75. GRB 260915A: J-band upper limit with WINTER
  76. Fermi trigger No 811264269: Global MASTER-Net observations report
  77. GRB 260909A: NOEMA detection
  78. GRB 260914A: Mondy and TShAO optical observations
  79. GRB 260914A: SVOM/ECLAIRs refined analysis
  80. GRB 260909A: Swift-XRT observations
  81. MAXI GRB260916.37: Global MASTER-Net observations report
  82. GRB 260915A: Swift ToO observations
  83. GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
  84. GRB 260915A: SVOM/C-GFT optical upper limits
  85. GRB 260915A: REM optical/NIR observations
  86. GRB 260914A: REM optical/NIR observations
  87. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  88. GRB 260915A: SVOM/VT optical upper limits
  89. GRB 260914A: VLT/X-shooter spectroscopic redshift z = 0.778
  90. GRB 260915A: NOT optical upper limit
  91. SVOM GRB260915.05: Global MASTER-Net observations report
  92. GRB 260915A: SVOM/VT optical upper limits from VHF data
  93. EP Alert 260914.53: Global MASTER-Net observations report
  94. GRB 260914A: SVOM/C-GFT optical observations
  95. GRB 260914A: SVOM/VT optical counterpart confirmation
  96. GRB 260914A: SVOM/VT optical observation from VHF data
  97. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  98. SVOM GRB260914.47: Global MASTER-Net observations report
  99. GRB 260818A: Continued ATCA observations
  100. SVOM GRB260913.32: Global MASTER-Net observations report

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