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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"

38156 results found.

  1. GRB 241025A: SAO RAS optical observations
  2. GRB 241026A: Las Cumbres optical detection
  3. GRB 241025A: Mondy optical observations
  4. EP241021a: further SAO RAS optical observations
  5. EP241026a (GRB 241026A): EP on-board trigger and follow-up observation
  6. GRB 241026A: Swift-XRT refined Analysis
  7. EP 241026b: LBT optical observations
  8. EP EP241026b: Global MASTER-Net observations report
  9. GRB 241026A: Enhanced Swift-XRT position
  10. GRB 241026A: KAIT optical observations
  11. Fermi trigger No 751616906: Global MASTER-Net observations report
  12. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  13. GRB 241026A: SAO RAS observations of possible optical afterglow
  14. Fermi GRB 241026A: Global MASTER-Net observations report
  15. GRB 241026A: Prompt enhanced Swift-XRT position
  16. GRB 241026A: Swift detection of a burst
  17. Swift GRB241026.95: Global MASTER-Net observations report
  18. GRB 241026A: Fermi GBM Final Real-time Localization
  19. GRB241025A: 1.3m DFOT optical afterglow detection
  20. ​GRB 241025A: optical photometry from Konkoly
  21. GRB 241025A: GROWTH-India Telescope optical observations
  22. GRB 241025A: COLIBRÍ Detection of the Afterglow
  23. GRB 241025A: Swift-XRT refined Analysis
  24. GRB 241025C: Fermi GBM Detection
  25. GRB 241025A: Fermi GBM Observation
  26. IPN triangulation of GRB 241022A (short/hard)
  27. LIGO/Virgo/KAGRA S241009l: Upper limits from Swift/BAT-GUANO
  28. GRB 241025C: Fermi GBM Final Localization
  29. GRB 241025A: GRANDMA and Kilonova-Catcher optical afterglow detections and upperlimits
  30. GRB 241025B: Fermi GBM Final Localization
  31. Fermi trigger No 751563375: Global MASTER-Net observations report
  32. Fermi trigger No 751554401: Global MASTER-Net observations report
  33. EP 241021a: Swift-XRT observations
  34. Fermi GRB 241025A: Global MASTER-Net observations report
  35. Swift GRB 241025A: Global MASTER-Net observations report
  36. EP241025a (GRB 241025A): EP observations update
  37. GRB 241025A : SVOM/VT optical afterglow observations
  38. EP 241021A: Swift ToO observations
  39. GRB 241025A: Enhanced Swift-XRT position
  40. GRB 241001A: JWST spectroscopic identification of a supernova counterpart
  41. GRB 241025A: NOT spectroscopic redshift of z = 4.20
  42. GRB 241025A: DDOTI Afterglow detection
  43. EP241025a (GRB 241025A): EP on-board trigger and autonomous follow-up observation
  44. GRB 241025A: SVOM/GRM observation
  45. GRB 241025A: TRT optical afterglow observation
  46. Fermi GRB 241024B: Global MASTER-Net observations report
  47. GRB 241025A: Fermi GBM Final Real-time Localization
  48. GRB 241025A: Swift detection of a burst with an optical counterpart
  49. GRB 241001A: ATCA radio observations
  50. GRB 241024B: Fermi GBM Final Localization
  51. EP241021a: No Detection in Fermi-GBM Observation
  52. GRB 241010A: VIRT Optical Upper Limit
  53. GRB 241024A: Fermi GBM Final Localisation
  54. EP241021a: VLT/FORS2 redshift z = 0.75
  55. Fermi trigger No 751449953: Global MASTER-Net observations report
  56. EP241021a: SAO RAS optical observations
  57. EP241021a: KAIT optical observations
  58. IPN triangulation of GRB 241021A (long)
  59. EP241021a: 1.3m DFOT Optical observations
  60. EP241021a: GSP detects optical candidate counterpart
  61. EP241021a: TRT optical observations
  62. GRB 241018A: SVOM/C-GFT optical observations
  63. EP EP241021a: Global MASTER-Net observations report
  64. GRB241017A: 1.3m DFOT optical upper limit
  65. GRB 241018A: 1.3m DFOT Optical upper limit
  66. GRB 241018A: EP-FXT afterglow detection
  67. Konus-Wind detection of GRB 241018A
  68. GRB 241018A: SVOM/GRM observation
  69. GRB 241018A/sb24101802: Mephisto optical upper limit
  70. GRB 241017A/sb24101702: Mephisto optical upper limit
  71. GRB 241018A: BOOTES-4/MET optical upper limit
  72. GRB 241018A: Mondy optical upper limit
  73. GRB 241018A: SVOM/VT further analysis and counterpart confirmed
  74. GRB 241018A: GROWTH-India telescope optical upper limit
  75. GRB 241018A: Swift-XRT observations
  76. GRB 241018A: REM optical/NIR upper limits
  77. GRB 241018A: NOT optical observations
  78. GRB 241017A: SVOM/VT follow-up and optical upper limit
  79. GRB 241018A: SVOM/VT follow-up and optical candidate
  80. GRB 241018A: LCO/0.4m optical upper limits
  81. GRB 241018A: Swift ToO observations
  82. GRB 241006A: VIRT Optical Upper Limit
  83. GRB 240727A: VIRT Optical Upper Limit
  84. GRB 241018A: X-ray afterglow candidate observed by MXT
  85. GRB 241016B: Fermi GBM Observations
  86. GRB 241018A: Detection of a bright long GRB by SVOM
  87. GRB 241017A: Swift-XRT observations
  88. GRB 241001A: EP-FXT afterglow detection
  89. GRB 241017A: GROWTH-India Telescope optical upper limit
  90. GRB 241016B: Swift/BAT-GUANO localization skymap of a short burst
  91. GRB 241017A: J-band upper limit from WINTER
  92. Fermi trigger No 750788395: Global MASTER-Net observations report
  93. GRB 241016B: SVOM/GRM observation
  94. GRB241016C: Fermi GBM Final Localization
  95. Fermi Gamma-ray Burst Monitor trigger 750792698/241016730 is not a GRB
  96. GRB 241017A: Swift ToO observations
  97. GRB 241017A : Detection of a weak and soft long duration GRB by SVOM/ECLAIRs
  98. Fermi GRB 241016B: Global MASTER-Net observations report
  99. GRB 241016B: Fermi GBM Final Localization
  100. Fermi GRB 241016A: Global MASTER-Net observations report

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