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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"

38253 results found.

  1. EP241021a: further SAO RAS optical observations
  2. EP241026a (GRB 241026A): EP on-board trigger and follow-up observation
  3. GRB 241026A: Swift-XRT refined Analysis
  4. EP 241026b: LBT optical observations
  5. EP EP241026b: Global MASTER-Net observations report
  6. GRB 241026A: Enhanced Swift-XRT position
  7. GRB 241026A: KAIT optical observations
  8. Fermi trigger No 751616906: Global MASTER-Net observations report
  9. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  10. GRB 241026A: SAO RAS observations of possible optical afterglow
  11. Fermi GRB 241026A: Global MASTER-Net observations report
  12. GRB 241026A: Prompt enhanced Swift-XRT position
  13. GRB 241026A: Swift detection of a burst
  14. Swift GRB241026.95: Global MASTER-Net observations report
  15. GRB 241026A: Fermi GBM Final Real-time Localization
  16. GRB241025A: 1.3m DFOT optical afterglow detection
  17. ​GRB 241025A: optical photometry from Konkoly
  18. GRB 241025A: GROWTH-India Telescope optical observations
  19. GRB 241025A: COLIBRÍ Detection of the Afterglow
  20. GRB 241025A: Swift-XRT refined Analysis
  21. GRB 241025C: Fermi GBM Detection
  22. GRB 241025A: Fermi GBM Observation
  23. IPN triangulation of GRB 241022A (short/hard)
  24. LIGO/Virgo/KAGRA S241009l: Upper limits from Swift/BAT-GUANO
  25. GRB 241025C: Fermi GBM Final Localization
  26. GRB 241025A: GRANDMA and Kilonova-Catcher optical afterglow detections and upperlimits
  27. GRB 241025B: Fermi GBM Final Localization
  28. Fermi trigger No 751563375: Global MASTER-Net observations report
  29. Fermi trigger No 751554401: Global MASTER-Net observations report
  30. EP 241021a: Swift-XRT observations
  31. Fermi GRB 241025A: Global MASTER-Net observations report
  32. Swift GRB 241025A: Global MASTER-Net observations report
  33. EP241025a (GRB 241025A): EP observations update
  34. GRB 241025A : SVOM/VT optical afterglow observations
  35. EP 241021A: Swift ToO observations
  36. GRB 241025A: Enhanced Swift-XRT position
  37. GRB 241001A: JWST spectroscopic identification of a supernova counterpart
  38. GRB 241025A: NOT spectroscopic redshift of z = 4.20
  39. GRB 241025A: DDOTI Afterglow detection
  40. EP241025a (GRB 241025A): EP on-board trigger and autonomous follow-up observation
  41. GRB 241025A: SVOM/GRM observation
  42. GRB 241025A: TRT optical afterglow observation
  43. Fermi GRB 241024B: Global MASTER-Net observations report
  44. GRB 241025A: Fermi GBM Final Real-time Localization
  45. GRB 241025A: Swift detection of a burst with an optical counterpart
  46. GRB 241001A: ATCA radio observations
  47. GRB 241024B: Fermi GBM Final Localization
  48. EP241021a: No Detection in Fermi-GBM Observation
  49. GRB 241010A: VIRT Optical Upper Limit
  50. GRB 241024A: Fermi GBM Final Localisation
  51. EP241021a: VLT/FORS2 redshift z = 0.75
  52. Fermi trigger No 751449953: Global MASTER-Net observations report
  53. EP241021a: SAO RAS optical observations
  54. EP241021a: KAIT optical observations
  55. IPN triangulation of GRB 241021A (long)
  56. EP241021a: 1.3m DFOT Optical observations
  57. EP241021a: GSP detects optical candidate counterpart
  58. EP241021a: TRT optical observations
  59. GRB 241018A: SVOM/C-GFT optical observations
  60. EP EP241021a: Global MASTER-Net observations report
  61. GRB241017A: 1.3m DFOT optical upper limit
  62. GRB 241018A: 1.3m DFOT Optical upper limit
  63. GRB 241018A: EP-FXT afterglow detection
  64. Konus-Wind detection of GRB 241018A
  65. GRB 241018A: SVOM/GRM observation
  66. GRB 241018A/sb24101802: Mephisto optical upper limit
  67. GRB 241017A/sb24101702: Mephisto optical upper limit
  68. GRB 241018A: BOOTES-4/MET optical upper limit
  69. GRB 241018A: Mondy optical upper limit
  70. GRB 241018A: SVOM/VT further analysis and counterpart confirmed
  71. GRB 241018A: GROWTH-India telescope optical upper limit
  72. GRB 241018A: Swift-XRT observations
  73. GRB 241018A: REM optical/NIR upper limits
  74. GRB 241018A: NOT optical observations
  75. GRB 241017A: SVOM/VT follow-up and optical upper limit
  76. GRB 241018A: SVOM/VT follow-up and optical candidate
  77. GRB 241018A: LCO/0.4m optical upper limits
  78. GRB 241018A: Swift ToO observations
  79. GRB 241006A: VIRT Optical Upper Limit
  80. GRB 240727A: VIRT Optical Upper Limit
  81. GRB 241018A: X-ray afterglow candidate observed by MXT
  82. GRB 241016B: Fermi GBM Observations
  83. GRB 241018A: Detection of a bright long GRB by SVOM
  84. GRB 241017A: Swift-XRT observations
  85. GRB 241001A: EP-FXT afterglow detection
  86. GRB 241017A: GROWTH-India Telescope optical upper limit
  87. GRB 241016B: Swift/BAT-GUANO localization skymap of a short burst
  88. GRB 241017A: J-band upper limit from WINTER
  89. Fermi trigger No 750788395: Global MASTER-Net observations report
  90. GRB 241016B: SVOM/GRM observation
  91. GRB241016C: Fermi GBM Final Localization
  92. Fermi Gamma-ray Burst Monitor trigger 750792698/241016730 is not a GRB
  93. GRB 241017A: Swift ToO observations
  94. GRB 241017A : Detection of a weak and soft long duration GRB by SVOM/ECLAIRs
  95. Fermi GRB 241016B: Global MASTER-Net observations report
  96. GRB 241016B: Fermi GBM Final Localization
  97. Fermi GRB 241016A: Global MASTER-Net observations report
  98. GRB 241016A: Fermi GBM Final Real-time Localization
  99. IceCube Alert 241016.04: Global MASTER-Net observations report
  100. GRB 241010A: Swift-BAT refined analysis

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