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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"

39059 results found.

  1. GRB 241026A Fermi GBM Analysis
  2. GRB 241026A: BTA redshift identification of z = 2.79
  3. GRB 241026A: J-band observations with WINTER
  4. GRB 241025A: SAO RAS optical observations
  5. GRB 241026A: Las Cumbres optical detection
  6. GRB 241025A: Mondy optical observations
  7. EP241021a: further SAO RAS optical observations
  8. EP241026a (GRB 241026A): EP on-board trigger and follow-up observation
  9. GRB 241026A: Swift-XRT refined Analysis
  10. EP 241026b: LBT optical observations
  11. EP EP241026b: Global MASTER-Net observations report
  12. GRB 241026A: Enhanced Swift-XRT position
  13. GRB 241026A: KAIT optical observations
  14. Fermi trigger No 751616906: Global MASTER-Net observations report
  15. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  16. GRB 241026A: SAO RAS observations of possible optical afterglow
  17. Fermi GRB 241026A: Global MASTER-Net observations report
  18. GRB 241026A: Prompt enhanced Swift-XRT position
  19. GRB 241026A: Swift detection of a burst
  20. Swift GRB241026.95: Global MASTER-Net observations report
  21. GRB 241026A: Fermi GBM Final Real-time Localization
  22. GRB241025A: 1.3m DFOT optical afterglow detection
  23. ​GRB 241025A: optical photometry from Konkoly
  24. GRB 241025A: GROWTH-India Telescope optical observations
  25. GRB 241025A: COLIBRÍ Detection of the Afterglow
  26. GRB 241025A: Swift-XRT refined Analysis
  27. GRB 241025C: Fermi GBM Detection
  28. GRB 241025A: Fermi GBM Observation
  29. IPN triangulation of GRB 241022A (short/hard)
  30. LIGO/Virgo/KAGRA S241009l: Upper limits from Swift/BAT-GUANO
  31. GRB 241025C: Fermi GBM Final Localization
  32. GRB 241025A: GRANDMA and Kilonova-Catcher optical afterglow detections and upperlimits
  33. GRB 241025B: Fermi GBM Final Localization
  34. Fermi trigger No 751563375: Global MASTER-Net observations report
  35. Fermi trigger No 751554401: Global MASTER-Net observations report
  36. EP 241021a: Swift-XRT observations
  37. Fermi GRB 241025A: Global MASTER-Net observations report
  38. Swift GRB 241025A: Global MASTER-Net observations report
  39. EP241025a (GRB 241025A): EP observations update
  40. GRB 241025A : SVOM/VT optical afterglow observations
  41. EP 241021A: Swift ToO observations
  42. GRB 241025A: Enhanced Swift-XRT position
  43. GRB 241001A: JWST spectroscopic identification of a supernova counterpart
  44. GRB 241025A: NOT spectroscopic redshift of z = 4.20
  45. GRB 241025A: DDOTI Afterglow detection
  46. EP241025a (GRB 241025A): EP on-board trigger and autonomous follow-up observation
  47. GRB 241025A: SVOM/GRM observation
  48. GRB 241025A: TRT optical afterglow observation
  49. Fermi GRB 241024B: Global MASTER-Net observations report
  50. GRB 241025A: Fermi GBM Final Real-time Localization
  51. GRB 241025A: Swift detection of a burst with an optical counterpart
  52. GRB 241001A: ATCA radio observations
  53. GRB 241024B: Fermi GBM Final Localization
  54. EP241021a: No Detection in Fermi-GBM Observation
  55. GRB 241010A: VIRT Optical Upper Limit
  56. GRB 241024A: Fermi GBM Final Localisation
  57. EP241021a: VLT/FORS2 redshift z = 0.75
  58. Fermi trigger No 751449953: Global MASTER-Net observations report
  59. EP241021a: SAO RAS optical observations
  60. EP241021a: KAIT optical observations
  61. IPN triangulation of GRB 241021A (long)
  62. EP241021a: 1.3m DFOT Optical observations
  63. EP241021a: GSP detects optical candidate counterpart
  64. EP241021a: TRT optical observations
  65. GRB 241018A: SVOM/C-GFT optical observations
  66. EP EP241021a: Global MASTER-Net observations report
  67. GRB241017A: 1.3m DFOT optical upper limit
  68. GRB 241018A: 1.3m DFOT Optical upper limit
  69. GRB 241018A: EP-FXT afterglow detection
  70. Konus-Wind detection of GRB 241018A
  71. GRB 241018A: SVOM/GRM observation
  72. GRB 241018A/sb24101802: Mephisto optical upper limit
  73. GRB 241017A/sb24101702: Mephisto optical upper limit
  74. GRB 241018A: BOOTES-4/MET optical upper limit
  75. GRB 241018A: Mondy optical upper limit
  76. GRB 241018A: SVOM/VT further analysis and counterpart confirmed
  77. GRB 241018A: GROWTH-India telescope optical upper limit
  78. GRB 241018A: Swift-XRT observations
  79. GRB 241018A: REM optical/NIR upper limits
  80. GRB 241018A: NOT optical observations
  81. GRB 241017A: SVOM/VT follow-up and optical upper limit
  82. GRB 241018A: SVOM/VT follow-up and optical candidate
  83. GRB 241018A: LCO/0.4m optical upper limits
  84. GRB 241018A: Swift ToO observations
  85. GRB 241006A: VIRT Optical Upper Limit
  86. GRB 240727A: VIRT Optical Upper Limit
  87. GRB 241018A: X-ray afterglow candidate observed by MXT
  88. GRB 241016B: Fermi GBM Observations
  89. GRB 241018A: Detection of a bright long GRB by SVOM
  90. GRB 241017A: Swift-XRT observations
  91. GRB 241001A: EP-FXT afterglow detection
  92. GRB 241017A: GROWTH-India Telescope optical upper limit
  93. GRB 241016B: Swift/BAT-GUANO localization skymap of a short burst
  94. GRB 241017A: J-band upper limit from WINTER
  95. Fermi trigger No 750788395: Global MASTER-Net observations report
  96. GRB 241016B: SVOM/GRM observation
  97. GRB241016C: Fermi GBM Final Localization
  98. Fermi Gamma-ray Burst Monitor trigger 750792698/241016730 is not a GRB
  99. GRB 241017A: Swift ToO observations
  100. GRB 241017A : Detection of a weak and soft long duration GRB by SVOM/ECLAIRs

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