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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"

2906 results found.

  1. GRB 241229A: SAO RAS optical observations
  2. GRB 240606B: 7DT Optical upper limits
  3. IceCube-241224A: No transient candidates from the Zwicky Transient Facility
  4. Fermi GRB 241228B: Global MASTER-Net observations report
  5. GRB 241228B: GOTO possible optical counterpart candidate
  6. GRB 241212A: VZLUSAT-2 detection
  7. GRB 241223A: Fermi GBM Detection
  8. Fermi trigger No 756678579: Global MASTER-Net observations report
  9. IceCube Alert 241224.30: Global MASTER-Net observations report
  10. GRB241113A: 7DT Optical upper limits
  11. GRB 241105A: JWST photometric observations of the host galaxy
  12. GRB 241223A: Fermi GBM Final Real-time Localization
  13. EP241217a : Leavitt Observatory optical upper limit
  14. EP241119a: 7DT Optical upper limits
  15. GRB 241213B: MAXI/GSC detection
  16. GRB 241209A: Chandra X-ray Detection
  17. Fermi GRB 241209E: Global MASTER-Net observations report
  18. Fermi GRB 241209A: Global MASTER-Net observations report
  19. GRB 241207C: MASTER optical observations
  20. Fermi trigger No 755225799: Global MASTER-Net observations report
  21. GRB 241207C: MAXI/GSC detection
  22. Fermi GRB 241207A: Global MASTER-Net observations report
  23. EP241206a: EP detection of a fast X-ray transient
  24. Fermi GRB 241204A: Global MASTER-Net observations report
  25. IceCube-241127A: No transient candidates from the Zwicky Transient Facility
  26. GRB 241130A: Fermi GBM Detection
  27. Fermi GRB 241201A: Global MASTER-Net observations report
  28. LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
  29. GRB 241128A: AbAO optical upper limit
  30. EP241126a: WFST Observations
  31. Swift GRB241127.91: Global MASTER-Net observations report
  32. Fermi GRB 241118A: Global MASTER-Net observations report
  33. GRB 241117A: Fermi GBM Detection
  34. EP241113a: Swift XRT weak detection
  35. EP241115a: EP detection of a fast X-ray transient
  36. EP 241113a: LBT possible optical counterpart
  37. GRB 241113B: KAIT Optical Afterglow Candidate
  38. EP241113a: Global MASTER-Net observations report
  39. LIGO/Virgo/KAGRA S241114y: Identification of a GW compact binary merger candidate
  40. Fermi trigger No 753166198: Global MASTER-Net observations report
  41. EP241107a: EP-FXT follow-up observations
  42. Fermi trigger No 752990530: Global MASTER-Net observations report
  43. Fermi trigger No 752878030: Global MASTER-Net observations report
  44. LIGO/Virgo/KAGRA S241109bn: Global MASTER-Net observations report
  45. GRB 241108A: COLIBRÍ Upper Limits on the Optical Counterpart
  46. GRB 241030A: optical afterglow detection from the INAF Asiago Observatory
  47. Fermi GRB 241105A: Global MASTER-Net observations report
  48. Fermi GRB 241104A: Global MASTER-Net observations report
  49. EP241101a: Optical upper limits with Kinder observations
  50. S241102cy: Identification of a GW compact binary merger candidate
  51. LIGO/Virgo/KAGRA S241102br: Identification of a GW compact binary merger candidate
  52. GRB 241026A: SAO RAS optical observations
  53. Fermi trigger No 752006065: Global MASTER-Net observations report
  54. GRB 241030A: Keck/LRIS spectroscopic redshift z = 1.411
  55. GRB 241030A: ULL-ASTRO-MASTER detection of a bright optical counterpart with the LCOGT 40-cm telescope at McDonald Observatory
  56. GRB 241030A: Fermi GBM Final Real-time Localization
  57. GRB 241029A: Mephisto observations
  58. GRB 241026A: BTA and Zeiss-1000 optical observations
  59. EP241021a: further SAO RAS optical observations
  60. EP EP241026b: Global MASTER-Net observations report
  61. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  62. GRB 241025A: Fermi GBM Observation
  63. IPN triangulation of GRB 241022A (short/hard)
  64. EP241021a: GTC OSIRIS+ spectroscopy of the optical counterpart
  65. GRB 241018A: EP-FXT afterglow detection
  66. GRB 240727A: VIRT Optical Upper Limit
  67. Fermi trigger No 750788395: Global MASTER-Net observations report
  68. Fermi GRB 241016A: Global MASTER-Net observations report
  69. Fermi trigger No 750211959: Global MASTER-Net observations report
  70. GRB 241010A: LCO optical observations
  71. Fermi GRB 241008A: Global MASTER-Net observations report
  72. IceCube-241006A: No candidates from the Zwicky Transient Facility
  73. IceCube Alert 241006.94: Global MASTER-Net observations report
  74. GRB 241006A: Swift detection of a burst
  75. EP trigger ID 01709065118: the X-ray transient is likely a stellar flare event
  76. Fermi trigger No 749693019: Global MASTER-Net observations report
  77. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  78. GRB 241002A: 1.5m OSN optical upper limit
  79. IceCube-240929A: Upper limits from a search for additional neutrino events in IceCube
  80. Fermi GRB 240930B: Global MASTER-Net observations report
  81. GRB 240930B: Fermi GBM Final Real-time Localization
  82. Fermi GRB 240930A: Global MASTER-Net observations report
  83. Fermi GRB 240929A: Global MASTER-Net observations report
  84. Konus-Wind detection of GRB 240912A
  85. LIGO/Virgo/KAGRA S240921cw: Upper limits from Swift/BAT-GUANO
  86. EP trigger ID 01709059262: correction to the observation start time and source localization
  87. EP trigger ID 01709059262: the X-ray transient is likely a stellar flare event
  88. Fermi GBM Sub-Threshold Detection of GRB240919A / EP240919a
  89. GRB 240919A / EP240919a: SVOM/GRM observation
  90. EP240919a: NOT and Gemini optical observations
  91. EP240919a is likely a GRB event
  92. EP240919a: EP-WXT detection of a fast X-ray transient
  93. EP240918b and EP240918c: EP-WXT detection of two fast X-ray transients
  94. EP EP240918a: Global MASTER-Net observations report
  95. GRB 240914B: AstroSat CZTI detection
  96. EP240913a: Swift/XRT detection of an X-ray source within the EP/WXT error circle
  97. GRB 240914B: BALROG localization (Fermi Trigger 747990592 / GRB 240914298)
  98. GRB 240912A: SVOM/GRM observation
  99. GRB 240825A: 7DT Optical Upper Limit
  100. GRB 240902B: AstroSat CZTI detection of a long burst

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