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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"

14824 results found.

  1. GRB 251129A / EP251129a: OSN and CAHA optical follow-up
  2. GRB 251128A: AstroSat CZTI detection
  3. GRB 251128A: GECAM-B detection
  4. GRB 251128A: Insight-HXMT/HE detection
  5. SVOM GRB 251129A : MASTER optical counterpart detection
  6. GRB 251129A: Swift-XRT afterglow detection
  7. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  8. GRB 251129A: SVOM detection of a burst
  9. GRB 251129A: SVOM detection of a burst
  10. GRB 251127A: Glowbug gamma-ray detection
  11. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  12. GRB251126A: MAO/AZT-22 optical observations
  13. GRB 251128A: Fermi GBM Final Real-time Localization
  14. GRB251126A: Continued optical observation from 1.3m DFOT
  15. GRB 251126A: Swift/UVOT Detection
  16. EP251124a: Pan-STARRS ri-band imaging and photometry
  17. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  18. GRB 251126A: 1.3m DFOT optical afterglow detection
  19. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  20. GRB 251125B: GECAM-B detection
  21. GRB 251127A: Fermi GBM Final Real-time Localization
  22. GRB 251126A: Kilonova-Catcher optical afterglow detection
  23. GRB 251126A: Asiago i-band detection
  24. GRB 251126A: Nanshan/HMT optical afterglow detection
  25. GRB 251126A: Swift detection of a burst
  26. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  27. GRB 251125B: Fermi GBM Final Real-time Localization
  28. EP251124b: EP-WXT detection of a fast X-ray transient
  29. GRB 251125A: Fermi GBM Final Real-time Localization
  30. GRB 251124A: Fermi GBM Localization by automated pipeline
  31. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  32. GRB 251122B: Fermi GBM Final Localization
  33. EP251118A: 6 GHz VLA Detection
  34. GRB 251124a: Fermi GBM Final Localization
  35. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  36. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  37. EP251124a: Einstein Probe detection of an X-ray transient
  38. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  39. EP251118A: 3.6m DOT optical afterglow detection
  40. GRB 251122A / EP251122a: EP-FXT counterpart detection
  41. GRB 251122A / EP251122a: WFST optical observations
  42. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  43. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  44. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  45. GRB 251122A / EP251122a: SVOM detection of a long burst
  46. EP251122a: Einstein Probe detection of an X-ray transient
  47. EP251118a: Continued Optical Detection with Kinder observations
  48. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  49. GRB 251121A: Glowbug gamma-ray detection of a likely short burst
  50. EP251118a: Xinglong-2.16m optical observation
  51. GRB 251121A: Fermi GBM Final Real-time Localization
  52. EP251118A: 1.3m DFOT optical afterglow detection
  53. GRB 251118A: Swift/UVOT Detection
  54. GRB 251118A: Glowbug gamma-ray detection
  55. GRB 251118A: Swift-XRT afterglow detection
  56. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  57. EP251118a: Optical detection with Kinder observations
  58. GRB 251118A: GECAM-B detection
  59. GRB 251118A: NuSTAR detection of bright prompt emission
  60. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  61. GRB 251116C: NOT optical observations
  62. GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A
  63. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  64. GRB 251018A: FRAM-Auger optical detection
  65. Konus-Wind detection of GRB 251118C (EP251118a)
  66. GRB 251117A: Insight-HXMT/HE detection
  67. EP251118a: GOTO optical afterglow detection
  68. GRB 251119A: SVOM detection of a possible burst
  69. EP251118a: NOT spectroscopic redshift of z = 1.216
  70. GRB 251118A: Fermi-LAT detection
  71. EP251118a: Einstein Probe detected of a fast X-ray transient
  72. GRB 251118B: Fermi GBM Final Real-time Localization
  73. GRB 251118A: Fermi GBM Final Real-time Localization
  74. GRB 251117A: AstroSat CZTI detection
  75. GRB 251114B: Insight-HXMT/HE detection
  76. GRB 251114B: GECAM-B detection of a short burst
  77. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  78. GRB 251116D: Insight-HXMT/HE detection
  79. GRB 251117A: Fermi-LAT detection
  80. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  81. GRB 251117A: Fermi GBM Final Localization Correction
  82. GRB 251116D: Glowbug gamma-ray detection
  83. GRB 251116D: AstroSat CZTI detection
  84. GRB 251116C: SVOM detection of a burst
  85. GRB 251116B: SVOM detection of a burst
  86. GRB 251116A: Fermi GBM Final Real-time Localization
  87. GRB 251115A: Fermi-LAT detection
  88. GRB 251115A: Fermi GBM Final Real-time Localization
  89. GRB 251113A: Glowbug gamma-ray detection
  90. GRB 251113A: AstroSat CZTI detection
  91. GRB 251114B: Fermi GBM Final Real-time Localization
  92. Konus-Wind detection of GRB 251108C
  93. Konus-Wind detection of GRB 251103A
  94. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  95. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  96. IPN triangulation of GRB 251108C
  97. GRB 251114A: Fermi GBM Final Real-time Localization
  98. LIGO/Virgo/KAGRA S251112cm: TROVE Vetting of TNS Candidates
  99. GRB 251113A: Fermi GBM Final Real-time Localization
  100. LIGO/Virgo/KAGRA S251112cm: ATLAS pre-detections of AT2025adgp and AT2025adgq

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