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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"

34082 results found.

  1. GRB 251129A / EP251129a: SAO RAS optical observations
  2. GRB 251126A: SAO RAS optical observations
  3. GRB 251128A: GECAM-B detection
  4. GRB 251128A: SVOM/GRM observation of a long burst
  5. GRB 251128A: Insight-HXMT/HE detection
  6. SVOM GRB 251129A : MASTER optical counterpart detection
  7. GRB 251129A: Swift-XRT afterglow detection
  8. GRB 251129A: Swift ToO observations
  9. GRB 251129A / EP251129a: SVOM/VT optical fading
  10. GRB 251129A: Optical Observations via Virtual Telescope Project, Italy
  11. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  12. GRB 251129A: Correction to the position of the optical counterpar
  13. GRB 251129A: SVOM/VT optical counterpart confirmation with VHF data
  14. GRB 251128A: Fermi GBM Observation
  15. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  16. GRB 251129A: SVOM detection of a burst
  17. GRB 251129A: SVOM detection of a burst
  18. GRB 251126A: Swift-BAT refined analysis
  19. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  20. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  21. Fermi GRB 251128A: Global MASTER-Net observations report
  22. GRB 251127A: Glowbug gamma-ray detection
  23. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  24. GRB 251126A: further SAO RAS optical observations
  25. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  26. GRB 251126A NUTTelA-TAO Early Measurements
  27. GRB251126A: MAO/AZT-22 optical observations
  28. GRB 251128A: Fermi GBM Final Real-time Localization
  29. GRB251126A: Continued optical observation from 1.3m DFOT
  30. GRB 251126A: Swift/UVOT Detection
  31. GRB 251126A: Mondy and SAO RAS optical observations
  32. GRB 251126A: Swift-XRT refined Analysis
  33. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  34. GRB 251126A: NOT optical observations
  35. GRB 251126A: 1.3m DFOT optical afterglow detection
  36. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  37. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  38. GRB 251125B: GECAM-B detection
  39. Fermi GRB 251127A: Global MASTER-Net observations report
  40. GRB 251127A: Fermi GBM Final Real-time Localization
  41. GRB 251126A: Enhanced Swift-XRT position
  42. GRB 251126A: Kilonova-Catcher optical afterglow detection
  43. GRB 251126A: Asiago i-band detection
  44. GRB 251126A: Nanshan/HMT optical afterglow detection
  45. Swift GRB 251126A: Global MASTER-Net observations report
  46. GRB 251121A: Fermi GBM Observation
  47. GRB 251126A: Prompt enhanced Swift-XRT position
  48. GRB 251126A: GIT discovery of the likely optical afterglow
  49. GRB 251126A: Swift detection of a burst
  50. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  51. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  52. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  53. Fermi GRB 251125B: Global MASTER-Net observations report
  54. GRB 251125B: Fermi GBM Final Real-time Localization
  55. Fermi GRB 251125A: Global MASTER-Net observations report
  56. GRB 251125A: Fermi GBM Final Real-time Localization
  57. GRB 251124A: Fermi GBM Localization by automated pipeline
  58. GRB 251122B: Fermi GBM Final Localization
  59. Fermi GRB 251124a: Global MASTER-Net observations report
  60. GRB 251124a: Fermi GBM Final Localization
  61. GRB 251116C: Swift-XRT confirmation of fading
  62. GRB 251122A/EP251122a: FTW optical and NIR observations
  63. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  64. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  65. GRB 251122A / EP251122a: EP-FXT counterpart detection
  66. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  67. GRB 251122A / EP251122a: WFST optical observations
  68. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  69. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  70. GRB 251122A / EP251122a: LCO optical upper limits
  71. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  72. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  73. GRB 251122A / EP251122a: SVOM detection of a long burst
  74. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  75. GRB 251121A: Glowbug gamma-ray detection of a likely short burst
  76. EP251118a: Xinglong-2.16m optical observation
  77. GRB 251115A: Fermi GBM Observation
  78. GRB 251121A: Fermi GBM Final Real-time Localization
  79. Fermi Gamma-ray Burst Monitor trigger 785388351 / 251121143 is not a GRB
  80. GRB 251118A: Swift/UVOT Detection
  81. EP251118a / GRB 251118C: SAO RAS optical observations
  82. GRB 251118A: Glowbug gamma-ray detection
  83. GRB 251118A: Fermi GBM Observation
  84. GRB 251118A: Swift-XRT afterglow detection
  85. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  86. GRB 251118A: GECAM-B detection
  87. EP251118a / GRB 251118C: SVOM/VT optical observation
  88. GRB 251118A: NuSTAR detection of bright prompt emission
  89. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  90. GRB 251116C: NOT optical observations
  91. GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A
  92. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  93. GRB 251018A: FRAM-Auger optical detection
  94. GRB 251117A: Swift-XRT observations
  95. EP251118A / GRB 251118C : MASTER optical counterpart observations
  96. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  97. Konus-Wind detection of GRB 251118C (EP251118a)
  98. GRB 251117A: Insight-HXMT/HE detection
  99. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  100. GRB 251116D: SVOM/GRM observation of a long GRB

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