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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"

2902 results found.

  1. GRB 250106A: Swift-XRT observations
  2. GRB 250101A: Swift-BAT refined analysis
  3. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  4. GRB 241229B: SAO RAS optical upper limit
  5. GRB 241229A: SAO RAS optical observations
  6. GRB 240606B: 7DT Optical upper limits
  7. IceCube-241224A: No transient candidates from the Zwicky Transient Facility
  8. Fermi GRB 241228B: Global MASTER-Net observations report
  9. GRB 241228B: GOTO possible optical counterpart candidate
  10. GRB 241212A: VZLUSAT-2 detection
  11. GRB 241223A: Fermi GBM Detection
  12. Fermi trigger No 756678579: Global MASTER-Net observations report
  13. IceCube Alert 241224.30: Global MASTER-Net observations report
  14. GRB241113A: 7DT Optical upper limits
  15. GRB 241105A: JWST photometric observations of the host galaxy
  16. GRB 241223A: Fermi GBM Final Real-time Localization
  17. EP241217a : Leavitt Observatory optical upper limit
  18. EP241119a: 7DT Optical upper limits
  19. GRB 241213B: MAXI/GSC detection
  20. GRB 241209A: Chandra X-ray Detection
  21. Fermi GRB 241209E: Global MASTER-Net observations report
  22. Fermi GRB 241209A: Global MASTER-Net observations report
  23. GRB 241207C: MASTER optical observations
  24. Fermi trigger No 755225799: Global MASTER-Net observations report
  25. GRB 241207C: MAXI/GSC detection
  26. Fermi GRB 241207A: Global MASTER-Net observations report
  27. EP241206a: EP detection of a fast X-ray transient
  28. Fermi GRB 241204A: Global MASTER-Net observations report
  29. IceCube-241127A: No transient candidates from the Zwicky Transient Facility
  30. GRB 241130A: Fermi GBM Detection
  31. Fermi GRB 241201A: Global MASTER-Net observations report
  32. LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
  33. GRB 241128A: AbAO optical upper limit
  34. EP241126a: WFST Observations
  35. Swift GRB241127.91: Global MASTER-Net observations report
  36. Fermi GRB 241118A: Global MASTER-Net observations report
  37. GRB 241117A: Fermi GBM Detection
  38. EP241113a: Swift XRT weak detection
  39. EP241115a: EP detection of a fast X-ray transient
  40. EP 241113a: LBT possible optical counterpart
  41. GRB 241113B: KAIT Optical Afterglow Candidate
  42. EP241113a: Global MASTER-Net observations report
  43. LIGO/Virgo/KAGRA S241114y: Identification of a GW compact binary merger candidate
  44. Fermi trigger No 753166198: Global MASTER-Net observations report
  45. EP241107a: EP-FXT follow-up observations
  46. Fermi trigger No 752990530: Global MASTER-Net observations report
  47. Fermi trigger No 752878030: Global MASTER-Net observations report
  48. LIGO/Virgo/KAGRA S241109bn: Global MASTER-Net observations report
  49. GRB 241108A: COLIBRÍ Upper Limits on the Optical Counterpart
  50. GRB 241030A: optical afterglow detection from the INAF Asiago Observatory
  51. Fermi GRB 241105A: Global MASTER-Net observations report
  52. Fermi GRB 241104A: Global MASTER-Net observations report
  53. EP241101a: Optical upper limits with Kinder observations
  54. S241102cy: Identification of a GW compact binary merger candidate
  55. LIGO/Virgo/KAGRA S241102br: Identification of a GW compact binary merger candidate
  56. GRB 241026A: SAO RAS optical observations
  57. Fermi trigger No 752006065: Global MASTER-Net observations report
  58. GRB 241030A: Keck/LRIS spectroscopic redshift z = 1.411
  59. GRB 241030A: ULL-ASTRO-MASTER detection of a bright optical counterpart with the LCOGT 40-cm telescope at McDonald Observatory
  60. GRB 241030A: Fermi GBM Final Real-time Localization
  61. GRB 241029A: Mephisto observations
  62. GRB 241026A: BTA and Zeiss-1000 optical observations
  63. EP241021a: further SAO RAS optical observations
  64. EP EP241026b: Global MASTER-Net observations report
  65. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  66. GRB 241025A: Fermi GBM Observation
  67. IPN triangulation of GRB 241022A (short/hard)
  68. EP241021a: GTC OSIRIS+ spectroscopy of the optical counterpart
  69. GRB 241018A: EP-FXT afterglow detection
  70. GRB 240727A: VIRT Optical Upper Limit
  71. Fermi trigger No 750788395: Global MASTER-Net observations report
  72. Fermi GRB 241016A: Global MASTER-Net observations report
  73. Fermi trigger No 750211959: Global MASTER-Net observations report
  74. GRB 241010A: LCO optical observations
  75. Fermi GRB 241008A: Global MASTER-Net observations report
  76. IceCube-241006A: No candidates from the Zwicky Transient Facility
  77. IceCube Alert 241006.94: Global MASTER-Net observations report
  78. GRB 241006A: Swift detection of a burst
  79. EP trigger ID 01709065118: the X-ray transient is likely a stellar flare event
  80. Fermi trigger No 749693019: Global MASTER-Net observations report
  81. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  82. GRB 241002A: 1.5m OSN optical upper limit
  83. IceCube-240929A: Upper limits from a search for additional neutrino events in IceCube
  84. Fermi GRB 240930B: Global MASTER-Net observations report
  85. GRB 240930B: Fermi GBM Final Real-time Localization
  86. Fermi GRB 240930A: Global MASTER-Net observations report
  87. Fermi GRB 240929A: Global MASTER-Net observations report
  88. Konus-Wind detection of GRB 240912A
  89. LIGO/Virgo/KAGRA S240921cw: Upper limits from Swift/BAT-GUANO
  90. EP trigger ID 01709059262: correction to the observation start time and source localization
  91. EP trigger ID 01709059262: the X-ray transient is likely a stellar flare event
  92. Fermi GBM Sub-Threshold Detection of GRB240919A / EP240919a
  93. GRB 240919A / EP240919a: SVOM/GRM observation
  94. EP240919a: NOT and Gemini optical observations
  95. EP240919a is likely a GRB event
  96. EP240919a: EP-WXT detection of a fast X-ray transient
  97. EP240918b and EP240918c: EP-WXT detection of two fast X-ray transients
  98. EP EP240918a: Global MASTER-Net observations report
  99. GRB 240914B: AstroSat CZTI detection
  100. EP240913a: Swift/XRT detection of an X-ray source within the EP/WXT error circle

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