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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.

Lucene Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

4690 results found.

  1. EP250427a: LT optical counterpart detection
  2. GRB 250330B: GRBAlpha detection
  3. IceCube-250421A: DDOTI Detection of the LAST Candidate
  4. EP250421A: COLIBRÍ Optical Upper Limit
  5. GRB 250419A: Mondy Continued Optical Observations
  6. IceCube Alert 250421.71: Global MASTER-Net observations report
  7. GRB 250419A: LCO optical afterglow multi-band observations
  8. GRB 250419A: MASTER optical afterglow observation
  9. GRB 250407A: GTC/OSIRIS+ spectroscopic redshift z = 1.36
  10. GRB 250419A: GOTO optical counterpart detection
  11. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  12. IceCube-250416A: DDOTI Optical Observations
  13. EP250416a: Gemini South-GMOS optical counterpart
  14. EP250225a: SVOM/VT optical brightening
  15. IceCube 250414.324: DDOTI Optical Observations
  16. EP250404a: Nanshan 0.43m Telescope optical observatios
  17. Fermi trigger No 766148493: Global MASTER-Net observations report
  18. Fermi trigger No 766173972: Global MASTER-Net observations report
  19. GRB 250407A: Continued KAIT/Nickel optical observations
  20. GRB 250320B: cubesat Avion detection
  21. IceCube-250406A: Swift-XRT observations
  22. EP250407a: Global MASTER-Net observations report
  23. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  24. IceCube-250406A: No candidates from the Zwicky Transient Facility
  25. Fermi GRB 250407A: Global MASTER-Net observations report
  26. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  27. IPN triangulation of GRB 250406B (short/hard)
  28. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  29. IceCube 250406.951: DDOTI Optical Observations
  30. Fermi GRB 250406A: Global MASTER-Net observations report
  31. Fermi trigger No 765619921: Global MASTER-Net observations report
  32. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  33. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  34. EP250402a: Optical upper limit with PD 1.3m observations
  35. GRB 250403A: AstroSat CZTI detection
  36. Fermi GRB 250404A: Global MASTER-Net observations report
  37. EP250404a: Xinglong decaying optical counterpart
  38. GRB 250403A: Montarrenti Observatory optical detection
  39. EP250404a: Global MASTER-Net observations report
  40. GRB 250403A: Fermi GBM observations
  41. GRB 250327B: VIRT Optical Upper Limit
  42. EP250404a: Mephisto multi-band optical detection
  43. GRB 250402A: Mondy optical observations
  44. GRB 250403A: Swift/UVOT Detection
  45. GRB 250402A: Swift/UVOT Upper Limits
  46. GRB 250403A: REM NIR afterglow detection
  47. GRB 250403A: LCO optical counterpart detection
  48. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  49. GRB 250403A: JinShan optical observations
  50. GRB 250402A: EP-FXT afterglow detection
  51. Fermi GRB 250403A: Global MASTER-Net observations report
  52. GRB 250403A: GOTO optical counterpart follow-up observations
  53. GRB 250403A: GMG Optical Observation
  54. GRB 250403A: 1.6m Mephisto multi-band optical detection
  55. GRB 250403A: GOTO detection of the optical afterglow
  56. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  57. GRB 250402A: REM optical/NIR upper limits
  58. GRB 250402A: LCO optical counterpart detection
  59. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  60. GRB 250331E: SVOM/GRM observation
  61. GRB250331D: AbAO optical observations
  62. GRB 250328A: AbAO AS-32 Optical Observations
  63. GRB 250322B: GRBAlpha detection
  64. GRB 250331D: Swift-XRT observations
  65. GRB 250330B: SVOM/GRM observation of a short burst
  66. Fermi GRB 250331E: Global MASTER-Net observations report
  67. Fermi GRB 250331D: Global MASTER-Net observations report
  68. GRB 250330B: EIRSAT-1 GMOD Detection
  69. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  70. Fermi trigger No 765078057: Global MASTER-Net observations report
  71. Swift GRB 250331C: Global MASTER-Net observations report
  72. Swift GRB 250331B: Global MASTER-Net observations report
  73. GRB 250331D: Swift/BAT-GUANO arcminute localization of a burst during slew
  74. GRB 250331C: Enhanced Swift-XRT position
  75. IceCube-250330A: Upper limits from a search for additional neutrino events in IceCube
  76. GRB 250320C : SVOM detection of a burst through offline search
  77. Fermi-LAT gamma-ray observations of IceCube-250330A
  78. SVOM/sb25033102 is a false trigger
  79. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  80. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  81. GRB 250331C: Prompt enhanced Swift-XRT position
  82. GRB 250331C: Swift detection of a burst
  83. GRB 250330A: SVOM/VT optical upper limit
  84. GRB 250331A: MAXI/GSC detection
  85. SVOM/sb25033102: SVOM detection of an X-ray transient
  86. LIGO/Virgo/KAGRA S250331o: Identification of a GW compact binary merger candidate
  87. Fermi GRB 250330B: Global MASTER-Net observations report
  88. Fermi GRB 250330A: Global MASTER-Net observations report
  89. GRB 250328A: 1.6m Mephisto optical observations
  90. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  91. IceCube-250330A - IceCube observation of a high-energy neutrino candidate track-like event
  92. IceCube Alert 250330.35: Global MASTER-Net observations report
  93. Swift GRB250330.26: Global MASTER-Net observations report
  94. GRB 250329B: SVOM/C-GFT optical upper limit
  95. GRB 250327B: VLA detection
  96. GRB 250329B: SVOM/VT optical upper limit
  97. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  98. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  99. LIGO/Virgo/KAGRA S250329fl: 2 counterpart neutrino candidate events from an IceCube neutrino search
  100. GRB 250329B: GWAC-F50A optical upper limit

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