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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"

5152 results found.

  1. GRB 251201A: MAXI/GSC detection
  2. Fermi GRB 251130B: Global MASTER-Net observations report
  3. IceCube Alert 251130.75: Global MASTER-Net observations report
  4. EP251130a: Global MASTER-Net observations report
  5. GRB 251129A: Swift-XRT afterglow detection
  6. GRB 251129A: SVOM detection of a burst
  7. GRB 251129A: SVOM detection of a burst
  8. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  9. EP251124a: Pan-STARRS ri-band imaging and photometry
  10. GRB 251126A: Swift-XRT refined Analysis
  11. Fermi GRB 251125B: Global MASTER-Net observations report
  12. EP251124a: NOT r- and z-band optical upper limits
  13. EP251124a: Global MASTER-Net observations report
  14. GRB 251124A: Fermi GBM Localization by automated pipeline
  15. EP251124a: Optical upper limit with Kinder observations
  16. Fermi GRB 251124a: Global MASTER-Net observations report
  17. GRB 251124a: Fermi GBM Final Localization
  18. GRB 251122A/EP251122a: FTW optical and NIR observations
  19. Fermi trigger No 785388351: Global MASTER-Net observations report
  20. GRB 251117A: Swift-XRT observations
  21. LAT GRB251118.86: Global MASTER-Net observations report
  22. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  23. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  24. EP251023a: UAFO and AbAO optical observations
  25. GRB 251025B: further Mondy optical observations
  26. SVOM GRB251116C: Global MASTER-Net observations report
  27. Fermi GRB 251115A: Global MASTER-Net observations report
  28. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 4-Update Localization Volume
  29. Fermi GRB 251114A: Global MASTER-Net observations report
  30. GRB 251025B: SVOM/ECLAIRs refined analysis
  31. LIGO/Virgo/KAGRA S251112cm: ATLAS pre-detections of AT2025adgp and AT2025adgq
  32. GRB 251112A: Swift-XRT refined Analysis
  33. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 3-Initial Localization Volume
  34. GRB251111A: 1.3m DFOT optical upper limit
  35. SVOM GRB251108.54: Global MASTER-Net observations report
  36. SVOM GRB251106.83: Global MASTER-Net observations report
  37. GRB 251106A: Swift-XRT afterglow detection
  38. GRB 251106A: MASTER optical observations
  39. Fermi trigger No 784034269: Global MASTER-Net observations report
  40. GRB 251105B: AstroSat CZTI detection of a short burst with extended emission
  41. GRB 251103A: OHP/T193 optical observations
  42. GRB 251103A: Swift/BAT-GUANO arcminute localization of a burst
  43. GRB 251103B: Swift-XRT refined Analysis
  44. GRB 251103B: Prompt enhanced Swift-XRT position
  45. GRB 251103A: Swift-XRT afterglow detection
  46. GRB 251103A: SVOM detection of a bright burst
  47. Fermi GRB 251102A: Global MASTER-Net observations report
  48. LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate
  49. GRB 251028A: Fermi GBM Observation
  50. IceCube-251025A: Upper limits from a search for additional neutrino events in IceCube
  51. GRB 251027A: Swift-XRT observations
  52. Fermi GRB 251025C: Global MASTER-Net observations report
  53. IceCube-251025A: DDOTI Optical Upper Limit
  54. GRB 251025B: MASTER OT detection
  55. GRB 251025B: SVOM detection of a burst
  56. GRB 251023C: Glowbug gamma-ray detection
  57. GRB 251024A: LCOGT Optical Afterglow Detection
  58. Swift GRB 251024A: Global MASTER-Net observations report
  59. GRB 251023B / EP251023b: COLIBRÍ Confirmation of the Fading Nature of the Optical Candidate
  60. GRB 251022A: COLIBRÍ Further Multi-frequency Optical Observations
  61. GRB 251023B: OHP/T193 optical observations
  62. EP251023a: OHP/T193 optical observations
  63. GRB 251023C: AstroSat CZTI detection
  64. EP251023b: Global MASTER-Net observations report
  65. GRB 251023C: CALET Gamma-Ray Burst Monitor detection
  66. GRB 251023C: Swift/BAT-GUANO localization skymap of a burst
  67. EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
  68. Fermi GRB 251023A: Global MASTER-Net observations report
  69. GRB 251018A: Swift-XRT refined Analysis
  70. IceCube-251018A: Global MASTER-Net observations report
  71. GRB 251016A: VLT/FORS2 Optical Observation
  72. GRB 251017A: Swift-XRT refined Analysis
  73. GRB 251018A: MASTER OT detection
  74. Swift GRB 251018A: Global MASTER-Net observations report
  75. Fermi GRB 251016B: Global MASTER-Net observations report
  76. sb25101602: Swift-XRT counterpart detection
  77. Fermi GRB 251016A: Global MASTER-Net observations report
  78. GRB 251014A: Swift-XRT observations
  79. Upper limits from a search for additional neutrino events in IceCube
  80. GRB 251014B: VLT/FORS2 Optical Observation
  81. LIGO/Virgo/KAGRA S251014cn: Identification of a GW compact binary merger candidate
  82. GRB 251014A: Swift detection of a possibly-short burst
  83. GRB 251014A: Fermi GBM Final Real-time Localization
  84. GRB 251013C: NOT spectroscopic redshift z = 0.572
  85. GRB 251013B: SVOM/GRM observation
  86. GRB 251013B: Fermi GBM Final Real-time Localization
  87. GRB 251011B: Swift-XRT refined Analysis
  88. Fermi Gamma-ray Burst Monitor trigger 781824269/251010892 is not a GRB
  89. EP251006a: Global MASTER-Net observations report
  90. GRB 251007A: Swift-XRT refined Analysis
  91. GRB 251007B: Swift-XRT refined Analysis
  92. Swift GRB 251007B: Global MASTER-Net observations report
  93. GRB 251007A: Swift detection of a burst with an optical counterpart
  94. GRB 251006B: SVOM/GRM observation
  95. Fermi GRB 251006B: Global MASTER-Net observations report
  96. GRB 251005C: VLT/X-shooter Imaging
  97. GRB 251005C: Swift-XRT refined Analysis
  98. GRB 251003A: Swift-XRT refined Analysis
  99. GRB 251002A: Swift-XRT afterglow detection
  100. GRB 251002A: FRAM-ORM afterglow detection

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