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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"

3113 results found.

  1. Fermi GRB 250107B: Global MASTER-Net observations report
  2. GRB 250103B: REM optical/NIR upper limits
  3. GRB 250101A: REM optical/NIR counterpart detection
  4. GRB 250106A: Swift-XRT observations
  5. GRB 250101A: Swift-BAT refined analysis
  6. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  7. GRB 241229B: SAO RAS optical upper limit
  8. GRB 241229A: SAO RAS optical observations
  9. GRB 240606B: 7DT Optical upper limits
  10. IceCube-241224A: No transient candidates from the Zwicky Transient Facility
  11. Fermi GRB 241228B: Global MASTER-Net observations report
  12. GRB 241228B: GOTO possible optical counterpart candidate
  13. GRB 241212A: VZLUSAT-2 detection
  14. GRB 241223A: Fermi GBM Detection
  15. Fermi trigger No 756678579: Global MASTER-Net observations report
  16. IceCube Alert 241224.30: Global MASTER-Net observations report
  17. GRB241113A: 7DT Optical upper limits
  18. GRB 241105A: JWST photometric observations of the host galaxy
  19. GRB 241223A: Fermi GBM Final Real-time Localization
  20. EP241217a : Leavitt Observatory optical upper limit
  21. EP241119a: 7DT Optical upper limits
  22. GRB 241213B: MAXI/GSC detection
  23. GRB 241209A: Chandra X-ray Detection
  24. Fermi GRB 241209E: Global MASTER-Net observations report
  25. Fermi GRB 241209A: Global MASTER-Net observations report
  26. GRB 241207C: MASTER optical observations
  27. Fermi trigger No 755225799: Global MASTER-Net observations report
  28. GRB 241207C: MAXI/GSC detection
  29. Fermi GRB 241207A: Global MASTER-Net observations report
  30. EP241206a: EP detection of a fast X-ray transient
  31. Fermi GRB 241204A: Global MASTER-Net observations report
  32. IceCube-241127A: No transient candidates from the Zwicky Transient Facility
  33. GRB 241130A: Fermi GBM Detection
  34. Fermi GRB 241201A: Global MASTER-Net observations report
  35. LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
  36. GRB 241128A: AbAO optical upper limit
  37. EP241126a: WFST Observations
  38. Swift GRB241127.91: Global MASTER-Net observations report
  39. Fermi GRB 241118A: Global MASTER-Net observations report
  40. GRB 241117A: Fermi GBM Detection
  41. EP241113a: Swift XRT weak detection
  42. EP241115a: EP detection of a fast X-ray transient
  43. EP 241113a: LBT possible optical counterpart
  44. GRB 241113B: KAIT Optical Afterglow Candidate
  45. EP241113a: Global MASTER-Net observations report
  46. LIGO/Virgo/KAGRA S241114y: Identification of a GW compact binary merger candidate
  47. Fermi trigger No 753166198: Global MASTER-Net observations report
  48. EP241107a: EP-FXT follow-up observations
  49. Fermi trigger No 752990530: Global MASTER-Net observations report
  50. Fermi trigger No 752878030: Global MASTER-Net observations report
  51. LIGO/Virgo/KAGRA S241109bn: Global MASTER-Net observations report
  52. GRB 241108A: COLIBRÍ Upper Limits on the Optical Counterpart
  53. GRB 241030A: optical afterglow detection from the INAF Asiago Observatory
  54. Fermi GRB 241105A: Global MASTER-Net observations report
  55. Fermi GRB 241104A: Global MASTER-Net observations report
  56. EP241101a: Optical upper limits with Kinder observations
  57. S241102cy: Identification of a GW compact binary merger candidate
  58. LIGO/Virgo/KAGRA S241102br: Identification of a GW compact binary merger candidate
  59. GRB 241026A: SAO RAS optical observations
  60. Fermi trigger No 752006065: Global MASTER-Net observations report
  61. GRB 241030A: Keck/LRIS spectroscopic redshift z = 1.411
  62. GRB 241030A: ULL-ASTRO-MASTER detection of a bright optical counterpart with the LCOGT 40-cm telescope at McDonald Observatory
  63. GRB 241030A: Fermi GBM Final Real-time Localization
  64. GRB 241029A: Mephisto observations
  65. GRB 241026A: BTA and Zeiss-1000 optical observations
  66. EP241021a: further SAO RAS optical observations
  67. EP EP241026b: Global MASTER-Net observations report
  68. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  69. GRB 241025A: Fermi GBM Observation
  70. IPN triangulation of GRB 241022A (short/hard)
  71. EP241021a: GTC OSIRIS+ spectroscopy of the optical counterpart
  72. GRB 241018A: EP-FXT afterglow detection
  73. GRB 240727A: VIRT Optical Upper Limit
  74. Fermi trigger No 750788395: Global MASTER-Net observations report
  75. Fermi GRB 241016A: Global MASTER-Net observations report
  76. Fermi trigger No 750211959: Global MASTER-Net observations report
  77. GRB 241010A: LCO optical observations
  78. Fermi GRB 241008A: Global MASTER-Net observations report
  79. IceCube-241006A: No candidates from the Zwicky Transient Facility
  80. IceCube Alert 241006.94: Global MASTER-Net observations report
  81. GRB 241006A: Swift detection of a burst
  82. EP trigger ID 01709065118: the X-ray transient is likely a stellar flare event
  83. Fermi trigger No 749693019: Global MASTER-Net observations report
  84. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  85. GRB 241002A: 1.5m OSN optical upper limit
  86. IceCube-240929A: Upper limits from a search for additional neutrino events in IceCube
  87. Fermi GRB 240930B: Global MASTER-Net observations report
  88. GRB 240930B: Fermi GBM Final Real-time Localization
  89. Fermi GRB 240930A: Global MASTER-Net observations report
  90. Fermi GRB 240929A: Global MASTER-Net observations report
  91. Konus-Wind detection of GRB 240912A
  92. LIGO/Virgo/KAGRA S240921cw: Upper limits from Swift/BAT-GUANO
  93. EP trigger ID 01709059262: correction to the observation start time and source localization
  94. EP trigger ID 01709059262: the X-ray transient is likely a stellar flare event
  95. Fermi GBM Sub-Threshold Detection of GRB240919A / EP240919a
  96. GRB 240919A / EP240919a: SVOM/GRM observation
  97. EP240919a: NOT and Gemini optical observations
  98. EP240919a is likely a GRB event
  99. EP240919a: EP-WXT detection of a fast X-ray transient
  100. EP240918b and EP240918c: EP-WXT detection of two fast X-ray transients

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