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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"

2900 results found.

  1. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  2. GRB 241229B: SAO RAS optical upper limit
  3. GRB 241229A: SAO RAS optical observations
  4. GRB 240606B: 7DT Optical upper limits
  5. IceCube-241224A: No transient candidates from the Zwicky Transient Facility
  6. Fermi GRB 241228B: Global MASTER-Net observations report
  7. GRB 241228B: GOTO possible optical counterpart candidate
  8. GRB 241212A: VZLUSAT-2 detection
  9. GRB 241223A: Fermi GBM Detection
  10. Fermi trigger No 756678579: Global MASTER-Net observations report
  11. IceCube Alert 241224.30: Global MASTER-Net observations report
  12. GRB241113A: 7DT Optical upper limits
  13. GRB 241105A: JWST photometric observations of the host galaxy
  14. GRB 241223A: Fermi GBM Final Real-time Localization
  15. EP241217a : Leavitt Observatory optical upper limit
  16. EP241119a: 7DT Optical upper limits
  17. GRB 241213B: MAXI/GSC detection
  18. GRB 241209A: Chandra X-ray Detection
  19. Fermi GRB 241209E: Global MASTER-Net observations report
  20. Fermi GRB 241209A: Global MASTER-Net observations report
  21. GRB 241207C: MASTER optical observations
  22. Fermi trigger No 755225799: Global MASTER-Net observations report
  23. GRB 241207C: MAXI/GSC detection
  24. Fermi GRB 241207A: Global MASTER-Net observations report
  25. EP241206a: EP detection of a fast X-ray transient
  26. Fermi GRB 241204A: Global MASTER-Net observations report
  27. IceCube-241127A: No transient candidates from the Zwicky Transient Facility
  28. GRB 241130A: Fermi GBM Detection
  29. Fermi GRB 241201A: Global MASTER-Net observations report
  30. LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
  31. GRB 241128A: AbAO optical upper limit
  32. EP241126a: WFST Observations
  33. Swift GRB241127.91: Global MASTER-Net observations report
  34. Fermi GRB 241118A: Global MASTER-Net observations report
  35. GRB 241117A: Fermi GBM Detection
  36. EP241113a: Swift XRT weak detection
  37. EP241115a: EP detection of a fast X-ray transient
  38. EP 241113a: LBT possible optical counterpart
  39. GRB 241113B: KAIT Optical Afterglow Candidate
  40. EP241113a: Global MASTER-Net observations report
  41. LIGO/Virgo/KAGRA S241114y: Identification of a GW compact binary merger candidate
  42. Fermi trigger No 753166198: Global MASTER-Net observations report
  43. EP241107a: EP-FXT follow-up observations
  44. Fermi trigger No 752990530: Global MASTER-Net observations report
  45. Fermi trigger No 752878030: Global MASTER-Net observations report
  46. LIGO/Virgo/KAGRA S241109bn: Global MASTER-Net observations report
  47. GRB 241108A: COLIBRÍ Upper Limits on the Optical Counterpart
  48. GRB 241030A: optical afterglow detection from the INAF Asiago Observatory
  49. Fermi GRB 241105A: Global MASTER-Net observations report
  50. Fermi GRB 241104A: Global MASTER-Net observations report
  51. EP241101a: Optical upper limits with Kinder observations
  52. S241102cy: Identification of a GW compact binary merger candidate
  53. LIGO/Virgo/KAGRA S241102br: Identification of a GW compact binary merger candidate
  54. GRB 241026A: SAO RAS optical observations
  55. Fermi trigger No 752006065: Global MASTER-Net observations report
  56. GRB 241030A: Keck/LRIS spectroscopic redshift z = 1.411
  57. GRB 241030A: ULL-ASTRO-MASTER detection of a bright optical counterpart with the LCOGT 40-cm telescope at McDonald Observatory
  58. GRB 241030A: Fermi GBM Final Real-time Localization
  59. GRB 241029A: Mephisto observations
  60. GRB 241026A: BTA and Zeiss-1000 optical observations
  61. EP241021a: further SAO RAS optical observations
  62. EP EP241026b: Global MASTER-Net observations report
  63. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  64. GRB 241025A: Fermi GBM Observation
  65. IPN triangulation of GRB 241022A (short/hard)
  66. EP241021a: GTC OSIRIS+ spectroscopy of the optical counterpart
  67. GRB 241018A: EP-FXT afterglow detection
  68. GRB 240727A: VIRT Optical Upper Limit
  69. Fermi trigger No 750788395: Global MASTER-Net observations report
  70. Fermi GRB 241016A: Global MASTER-Net observations report
  71. Fermi trigger No 750211959: Global MASTER-Net observations report
  72. GRB 241010A: LCO optical observations
  73. Fermi GRB 241008A: Global MASTER-Net observations report
  74. IceCube-241006A: No candidates from the Zwicky Transient Facility
  75. IceCube Alert 241006.94: Global MASTER-Net observations report
  76. GRB 241006A: Swift detection of a burst
  77. EP trigger ID 01709065118: the X-ray transient is likely a stellar flare event
  78. Fermi trigger No 749693019: Global MASTER-Net observations report
  79. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  80. GRB 241002A: 1.5m OSN optical upper limit
  81. IceCube-240929A: Upper limits from a search for additional neutrino events in IceCube
  82. Fermi GRB 240930B: Global MASTER-Net observations report
  83. GRB 240930B: Fermi GBM Final Real-time Localization
  84. Fermi GRB 240930A: Global MASTER-Net observations report
  85. Fermi GRB 240929A: Global MASTER-Net observations report
  86. Konus-Wind detection of GRB 240912A
  87. LIGO/Virgo/KAGRA S240921cw: Upper limits from Swift/BAT-GUANO
  88. EP trigger ID 01709059262: correction to the observation start time and source localization
  89. EP trigger ID 01709059262: the X-ray transient is likely a stellar flare event
  90. Fermi GBM Sub-Threshold Detection of GRB240919A / EP240919a
  91. GRB 240919A / EP240919a: SVOM/GRM observation
  92. EP240919a: NOT and Gemini optical observations
  93. EP240919a is likely a GRB event
  94. EP240919a: EP-WXT detection of a fast X-ray transient
  95. EP240918b and EP240918c: EP-WXT detection of two fast X-ray transients
  96. EP EP240918a: Global MASTER-Net observations report
  97. GRB 240914B: AstroSat CZTI detection
  98. EP240913a: Swift/XRT detection of an X-ray source within the EP/WXT error circle
  99. GRB 240914B: BALROG localization (Fermi Trigger 747990592 / GRB 240914298)
  100. GRB 240912A: SVOM/GRM observation

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