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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"

23574 results found.

  1. GRB 260925A: Swift-BAT refined analysis
  2. Swift Trigger 1513439: consistent with noise and not astrophysical
  3. Fermi GRB 260926C: Global MASTER-Net observations report
  4. Fermi GRB 260926A: Global MASTER-Net observations report
  5. GRB 260924A: Near-infrared detection with MDM/MIRAGE
  6. GRB 260924A: COLIBRÍ optical observations
  7. GRB 260925A: Swift-XRT refined Analysis
  8. Swift Trigger 1513439 is probably not a GRB
  9. Konus-Wind detection of GRB 260924A
  10. GRB 260923A: Glowbug gamma-ray detection
  11. GRB 260924A: Optical follow-up observations with Kinder
  12. GRB 260922A: Glowbug gamma-ray detection
  13. GRB 260925A: COLIBRÍ optical upper limits
  14. GRB 260924A: Ondrejov D50 optical afterglow detection
  15. EP260924a: J-band upper limit with WINTER
  16. GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
  17. GRB 260925A: Swift detection of a burst
  18. GRB 260924A: Swift-BAT refined analysis
  19. GRB 260924A: Swift-XRT refined Analysis
  20. Konus-Wind detection of GRB 260922A
  21. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  22. Konus-Wind detection of GRB 260921A (possible merger-origin)
  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. The EP-WXT trigger 01709319842 is likely a flaring star
  26. GRB 260924A: Swift detection of a burst
  27. Fermi GRB 260923A: Global MASTER-Net observations report
  28. GRB 260922A: Ondrejov D50 optical limit
  29. GRB 260922A: Swift-BAT refined analysis
  30. EP260920a: VLT/HAWK-I near-infrared counterpart confirmation
  31. GRB 260922A: J-band upper limit with WINTER
  32. GRB 260922A: COLIBRÍ Optical Counterpart Candidate (correction to GCN 45698)
  33. GRB 260922A: COLIBRÍ optical upper limits
  34. Konus-Wind detection of GRB 260810A
  35. GRB 260920A: Glowbug gamma-ray detection
  36. GRB 260918A: SVOM/ECLAIRs refined analysis
  37. GRB 260921A: Swift-BAT refined analysis
  38. EP260920b: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  39. EP Alert 260921.58: Global MASTER-Net observations report
  40. GRB 260917B:: SVOM/ECLAIRs refined analysis
  41. EP260920a: VLT/HAWK-I near-infrared candidate
  42. Swift GRB 260921A: Global MASTER-Net observations report
  43. GRB 260921A: Swift detection of a burst
  44. EP260920b: VLT/X-shooter spectroscopic redshift z = 3.582
  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. EP260917a: Global MASTER-Net observations report
  51. EP260920a: COLIBRÍ optical upper limits
  52. IceCube Alert 260919A: Global MASTER-Net observations report
  53. EP Alert 260919.40: Global MASTER-Net observations report
  54. GRB 260915A: VLT optical and near-infrared upper limits
  55. EP260917a: refined analysis of the EP-FXT observations
  56. EP Alert 260918.62: Global MASTER-Net observations report
  57. EP Alert 260918.24: Global MASTER-Net observations report
  58. SVOM GRB260918.16: Global MASTER-Net observations report
  59. Konus-Wind detection of GRB 260916B (short/hard)
  60. The EP-WXT trigger 01709318279 is likely a flaring star
  61. GRB 260916B: Glowbug gamma-ray detection of a short burst
  62. IPN triangulation of GRB 260916B (short)
  63. EP260917A: J-band upper limit with WINTER
  64. IPN triangulation of GRB 260810A
  65. EP Alert 260917.32: Global MASTER-Net observations report
  66. GRB 260917B: EP-FXT follow-up observation
  67. EP260917a: COLIBRÍ optical upper limits
  68. GRB 260915A: Swift-XRT afterglow detection
  69. GRB 260918A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  70. GRB 260917A: Glowbug gamma-ray detection
  71. GRB 260915A: SVOM/ECLAIRs refined analysis
  72. GRB 260917B: WINTER J-band observations
  73. SVOM GRB260917.16: Global MASTER-Net observations report
  74. GRB 260917B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  75. GRB 260914A: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  76. Fermi trigger No 811304653: Global MASTER-Net observations report
  77. GRB 260915A: J-band upper limit with WINTER
  78. Fermi trigger No 811264269: Global MASTER-Net observations report
  79. GRB 260909A: NOEMA detection
  80. GRB 260914A: SVOM/ECLAIRs refined analysis
  81. GRB 260909A: Swift-XRT observations
  82. GRB 260916A: MAXI/GSC detection
  83. MAXI GRB260916.37: Global MASTER-Net observations report
  84. GRB 260915A: REM optical/NIR observations
  85. GRB 260914A: REM optical/NIR observations
  86. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  87. GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  88. GRB 260914A: VLT/X-shooter spectroscopic redshift z = 0.778
  89. GRB 260915A: 10.4m GTC deep optical limits
  90. SVOM GRB260915.05: Global MASTER-Net observations report
  91. GRB 260915A: SVOM/VT optical upper limits from VHF data
  92. EP Alert 260914.53: Global MASTER-Net observations report
  93. GRB 260914A: EP-FXT follow-up observation
  94. GRB 260914A: SVOM/VT optical observation from VHF data
  95. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  96. SVOM GRB260914.47: Global MASTER-Net observations report
  97. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
  98. SVOM GRB260913.32: Global MASTER-Net observations report
  99. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  100. GRB 260909A: CrAO and AbAO optical upper limits

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