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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"

44399 results found.

  1. GRB 241029A: TRT optical afterglow candidate detection
  2. GRB 241029A: Swift ToO observations
  3. GRB 241029A: SVOM/GRM observation
  4. GRB 241029A : Detection and localization of a bright long GRB by SVOM/ECLAIRs
  5. Fermi trigger No 751861204: Global MASTER-Net observations report
  6. GRB 241029A: Fermi GBM Final Real-time Localization
  7. GRB 240821A: Keck/LRIS spectroscopic observations
  8. EP241021a: Gemini-South detection of optical rebrightening
  9. GRB 241026A: the 100th GRB detected by GRBAlpha
  10. GRB 241026A: TNOT optical counterpart detection
  11. Konus-Wind detection of GRB 241025A
  12. GRB 241025A (EP241025a): Optical afterglow observations with the Tsinghua-Nanshan Optical Telescope
  13. GRB 241026A: LBT redshift confirmation
  14. GRB 241026A: GECAM detection
  15. GRB 241025A: further SAO RAS optical observations
  16. GRB 241026A: BTA and Zeiss-1000 optical observations
  17. GRB 241026A: SVOM/GRM observation
  18. EP241026B: GROWTH-India Telescope optical upper limit
  19. GRB 241025A: Swift/UVOT Detection
  20. GRB 241026A: GROWTH-India Telescope optical observations
  21. GRB 241026A Fermi GBM Analysis
  22. GRB 241026A: BTA redshift identification of z = 2.79
  23. GRB 241026A: J-band observations with WINTER
  24. GRB 241025A: SAO RAS optical observations
  25. GRB 241026A: Las Cumbres optical detection
  26. GRB 241025A: Mondy optical observations
  27. EP241021a: SOAR observations of the optical counterpart
  28. EP241021a: further SAO RAS optical observations
  29. EP241026a (GRB 241026A): EP on-board trigger and follow-up observation
  30. GRB 241026A: Swift-XRT refined Analysis
  31. EP 241026b: LBT optical observations
  32. EP241021a: e-MERLIN radio observation
  33. EP EP241026b: Global MASTER-Net observations report
  34. GRB 241026A: Enhanced Swift-XRT position
  35. GRB 241026A: KAIT optical observations
  36. EP241026b: EP detection of a fast X-ray transient
  37. Fermi trigger No 751616906: Global MASTER-Net observations report
  38. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  39. GRB 241026A: SAO RAS observations of possible optical afterglow
  40. Fermi GRB 241026A: Global MASTER-Net observations report
  41. GRB 241026A: Prompt enhanced Swift-XRT position
  42. GRB 241026A: Swift detection of a burst
  43. Swift GRB241026.95: Global MASTER-Net observations report
  44. GRB 241026A: Fermi GBM Final Real-time Localization
  45. GRB241025A: 1.3m DFOT optical afterglow detection
  46. EP241021a: optical follow-up observations with Xinglong Observatory
  47. ​GRB 241025A: optical photometry from Konkoly
  48. GRB 241025A: GROWTH-India Telescope optical observations
  49. GRB 241025A: COLIBRÍ Detection of the Afterglow
  50. GRB 241025A: Swift-XRT refined Analysis
  51. GRB 241025C: Fermi GBM Detection
  52. GRB 241025A: Fermi GBM Observation
  53. IPN triangulation of GRB 241022A (short/hard)
  54. LIGO/Virgo/KAGRA S241009l: Upper limits from Swift/BAT-GUANO
  55. GRB 241025C: Fermi GBM Final Localization
  56. GRB 241025A: GRANDMA and Kilonova-Catcher optical afterglow detections and upperlimits
  57. GRB 241025B: Fermi GBM Final Localization
  58. Fermi trigger No 751563375: Global MASTER-Net observations report
  59. Fermi trigger No 751554401: Global MASTER-Net observations report
  60. EP241021a: Optical and NIR observations of counterpart with the Fraunhofer Telescope at Wendelstein Observatory
  61. EP241021a: Optical and NIR observations of counterpart with the Fraunhofer Telescope at Wendelstein Observatory
  62. EP 241021a: Swift-XRT observations
  63. EP241021a: optical follow-up observations with the Liverpool Telescope
  64. Fermi GRB 241025A: Global MASTER-Net observations report
  65. Swift GRB 241025A: Global MASTER-Net observations report
  66. EP241025a (GRB 241025A): EP observations update
  67. GRB 241025A : SVOM/VT optical afterglow observations
  68. EP 241021A: Swift ToO observations
  69. EP241021a: Liverpool Telescope optical follow-up observations
  70. GRB 241025A: Enhanced Swift-XRT position
  71. GRB 241001A: JWST spectroscopic identification of a supernova counterpart
  72. GRB 241025A: NOT spectroscopic redshift of z = 4.20
  73. GRB 241025A: DDOTI Afterglow detection
  74. EP241025a (GRB 241025A): EP on-board trigger and autonomous follow-up observation
  75. GRB 241025A: SVOM/GRM observation
  76. GRB 241025A: TRT optical afterglow observation
  77. Fermi GRB 241024B: Global MASTER-Net observations report
  78. GRB 241025A: Fermi GBM Final Real-time Localization
  79. GRB 241025A: Swift detection of a burst with an optical counterpart
  80. EP241021a: GTC OSIRIS+ spectroscopy of the optical counterpart
  81. GRB 241001A: ATCA radio observations
  82. GRB 241024B: Fermi GBM Final Localization
  83. EP241021a: No Detection in Fermi-GBM Observation
  84. GRB 241010A: VIRT Optical Upper Limit
  85. GRB 241024A: Fermi GBM Final Localisation
  86. EP241021a: VLT/FORS2 redshift z = 0.75
  87. Fermi trigger No 751449953: Global MASTER-Net observations report
  88. EP241021a: SAO RAS optical observations
  89. EP241021a: KAIT optical observations
  90. EP241021a: EP-FXT follow-up observation update
  91. IPN triangulation of GRB 241021A (long)
  92. EP241021a: Optical counterpart observations with the Liverpool Telescope
  93. EP241021a: 1.3m DFOT Optical observations
  94. EP241021a: GSP detects optical candidate counterpart
  95. EP241021a: Optical upper limits with Kinder observations
  96. EP241021a: TRT optical observations
  97. GRB 241018A: SVOM/C-GFT optical observations
  98. EP241021a: NOT likely optical counterpart
  99. EP EP241021a: Global MASTER-Net observations report
  100. GRB241017A: 1.3m DFOT optical upper limit

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