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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

32557 results found.

  1. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  2. EP250404a: LCO optical counterpart detection
  3. Fermi GRB 250404A: Global MASTER-Net observations report
  4. GRB 250403A: Montarrenti Observatory optical detection
  5. EP250404a: Global MASTER-Net observations report
  6. GRB 250403A: KAIT optical observations
  7. EP250404a: AKO Optical Afterglow Detection
  8. EP250404a: LAST detection of optical counterpart
  9. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  10. EP250404a: Xinglong-2.16m spectroscopic redshift
  11. GRB 250403A: Fermi GBM observations
  12. GRB 250327B: VIRT Optical Upper Limit
  13. EP250404a: Mephisto multi-band optical detection
  14. GRB 250331C Swift-BAT refined analysis
  15. GRB 250331B Swift-BAT refined analysis
  16. GRB 250330A Swift-BAT refined analysis
  17. EP250321A: J band upper limit by SYSU 80cm telescope
  18. EP250404a: BOOTES-4/JGT optical afterglow detection
  19. EP250404a: Nanshan/HMT optical counterpart detection
  20. EP250404a: Einstein Probe detection of an X-ray transient
  21. GRB 250402A: Mondy optical observations
  22. GRB 250403A: Swift/UVOT Detection
  23. GRB 250402A: Swift/UVOT Upper Limits
  24. EP250402a: Optical upper limit with Kinder observations
  25. GRB 250403A: SVOM/VT optical observation
  26. GRB 250403A: REM NIR afterglow detection
  27. GRB 250403A: LCO optical counterpart detection
  28. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  29. GRB 250403A: JinShan optical observations
  30. GRB 250402A: EP-FXT afterglow detection
  31. GRB 250403A: Optical counterpart detection by LCO.
  32. EP250402a: EP-FXT follow-up observations
  33. GRB 250403A: Swift-XRT observations
  34. GRB 250322A: 10 GHz VLA radio upper limits
  35. Fermi GRB 250403A: Global MASTER-Net observations report
  36. GRB 250403A: GOTO optical counterpart follow-up observations
  37. GRB 250402A: NUTTelA-TAO Early Optical Limits
  38. GRB 250403A: GMG Optical Observation
  39. GRB 250403A: 1.6m Mephisto multi-band optical detection
  40. GRB 250402A: Fermi GBM Observation
  41. GRB 250403A: SVOM/C-GFT optical observations
  42. GRB 250403A: GOTO detection of the optical afterglow
  43. GRB 250402A: Swift-XRT observations
  44. GRB 250403A : SVOM detection of a burst
  45. GRB 250225B: VLT host galaxy redshift z = 0.950
  46. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  47. GRB 250402A: VLT/FORS2 spectroscopic redshift z = 2.823
  48. GRB 250402A: REM optical/NIR upper limits
  49. GRB 250402A: LCO optical counterpart detection
  50. GRB 250402A: refined SVOM/MXT data analysis
  51. GRB 250402A: SVOM/VT optical counterpart
  52. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  53. GRB 250314A: ALMA detection
  54. GRB 250329B: Swift/UVOT Upper Limit
  55. GRB 250329A: Swift/UVOT Upper Limit
  56. GRB 250327B: Swift/UVOT Detection
  57. GRB 250327A: Swift/UVOT Upper Limits
  58. GRB 250331E: SVOM/GRM observation
  59. GRB 250327B: Kilonova-Catcher Observations
  60. GRB250331D: AbAO optical observations
  61. GRB 250331D: Fermi GBM observation
  62. GRB 250331C: Swift/UVOT Upper Limits
  63. GRB 250331B: Swift/UVOT Upper Limits
  64. GRB 250328A: AbAO AS-32 Optical Observations
  65. GRB 250219A: NOT candidate host galaxy detection
  66. GRB 250322B: GRBAlpha detection
  67. GRB 250330B: SVOM/GRM observation of a short burst
  68. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 2)
  69. Fermi GRB 250331E: Global MASTER-Net observations report
  70. Fermi GRB 250331D: Global MASTER-Net observations report
  71. GRB 250330B: EIRSAT-1 GMOD Detection
  72. GRB 250327A Swift-BAT refined analysis
  73. LIGO/Virgo/KAGRA S250331o: Updated Sky localization
  74. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  75. GRB 250331D: Swift ToO observations
  76. Swift GRB 250331C: Global MASTER-Net observations report
  77. Swift GRB 250331B: Global MASTER-Net observations report
  78. GRB 250331D: Swift/BAT-GUANO arcminute localization of a burst during slew
  79. Konus-Wind detection of GRB 250327B
  80. IceCube-250330A: Upper limits from a search for additional neutrino events in IceCube
  81. GRB 250329B: Swift-XRT confirmation of fading
  82. GRB 250330A: VLT/FORS2 Afterglow Detection
  83. GRB20250327B: 45th Parallel Observatory upper limit
  84. GRB 250328A: Swift/UVOT Detection
  85. GRB 250328A: Swift-XRT refined Analysis
  86. Fermi-LAT gamma-ray observations of IceCube-250330A
  87. SVOM/sb25033102 is a false trigger
  88. GRB 250330A: Fermi GBM Observation
  89. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  90. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  91. GRB 250330A: SVOM/VT optical upper limit
  92. GRB 250314A: VLA detection
  93. LIGO/Virgo/KAGRA S250331o: Identification of a GW compact binary merger candidate
  94. Fermi GRB 250330B: Global MASTER-Net observations report
  95. Fermi GRB 250330A: Global MASTER-Net observations report
  96. GRB 250330A: BOOTES-7 early optical upper limit
  97. GRB 250330A: Swift/UVOT Upper Limits
  98. GRB 250328A: 1.6m Mephisto optical observations
  99. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  100. GRB 250330A: Fermi GBM Final Localization

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