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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"

5848 results found.

  1. LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
  2. GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz
  3. GRB 250702B,D,E / EP250702a: ALMA detection
  4. IceCube-250708A: No Candidates from WINTER
  5. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  6. IceCube-250708A: Upper limits from a search for additional neutrino events in IceCube
  7. GRB 250709A: Fermi GBM Final Localization
  8. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 4-Update Localization Volume
  9. GRB 250704B / EP250704a: VLA radio detection
  10. Fermi-LAT Gamma-ray Observations of IceCube-250706A
  11. EP250702a/ GRB 250702B: NuSTAR X-ray Observations
  12. GRB 250703A: EIRSAT-1 GMOD Detection
  13. Konus-Wind detection of GRB 250703A
  14. IPN triangulation of GRB 250703A
  15. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  16. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 3-Initial Localization Volume
  17. GRB 250702A: CALET Gamma-Ray Burst Monitor detection
  18. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  19. Fermi GRB 250703A: Global MASTER-Net observations report
  20. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  21. GRB 250703A: DDOTI Optical Upper Limit
  22. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  23. GRB 250703A: Fermi GBM Final Real-time Localization
  24. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  25. Fermi GRB 250702F: Global MASTER-Net observations report
  26. GRB 250702F: Swift detection of a burst with an optical counterpart
  27. Fermi GBM Triggers 250702B, C, D and E are likely from the same source
  28. GRB 250702A: Fermi GBM Detection
  29. GRB 250702D: Fermi GBM Final Localization Correction
  30. GRB 250702A: BALROG localization (Fermi Trigger 773142852 / GRB 250702413)
  31. GRB 250702A: Fermi GBM Final Real-time Localization
  32. Fermi Gamma-ray Burst Monitor trigger 772981768/250630548 is not a GRB
  33. Fermi GRB 250626A: Global MASTER-Net observations report
  34. GRB 250625A: AbAO and INASAN Kislovodsk Optical Observations
  35. GRB 250625A: GTC/OSIRIS+ spectroscopic observations of the potential host galaxy
  36. GRB 250625A: ABObservatory afterglow detection
  37. GRB 250521A: VZLUSAT-2 detection
  38. Fermi trigger No 772190032: Global MASTER-Net observations report
  39. GRB 250620C: Fermi GBM Final Real-time Localization
  40. Fermi trigger No 772128434: Global MASTER-Net observations report
  41. GRB 250617B: Nickel telescope optical observations
  42. GRB 250617B: COLIBRÍ optical observations
  43. GRB 250617B: NUTTelA-TAO early time optical observations
  44. GRB 250617A: Fermi GBM Final Real-time Localization
  45. EP#01709178975: Swift-XRT counterpart detection
  46. GRB 250615A: DDOTI Optical Upper Limit
  47. Fermi trigger No 771752663: Global MASTER-Net observations report
  48. IceCube alert 141029_8144692 retraction
  49. EP250610a: Global MASTER-Net observations report
  50. EP250610a: REM optical/NIR observations
  51. GRB 250609A: Fermi GBM Observation
  52. Fermi trigger No 771072240: Global MASTER-Net observations report
  53. The EP-WXT trigger 01709178283 is likely a flaring star
  54. Fermi trigger No 770867684: Global MASTER-Net observations report
  55. Fermi GRB 250601A: Global MASTER-Net observations report
  56. EP#01709177494: SVOM/VT optical observations
  57. GRB 250530C: BOOTES-7 optical upper limit
  58. GRB 250521C (short): Zwicky Transient Facility identification of a possible fast optical transient counterpart
  59. Fermi trigger No 770047117: Global MASTER-Net observations report
  60. Fermi trigger No 769611916: Global MASTER-Net observations report
  61. Fermi GRB 250522B: Global MASTER-Net observations report
  62. Fermi GRB 250521D: Global MASTER-Net observations report
  63. GRB 250521D: DDOTI Optical Upper Limit
  64. GRB 250520A: 10 GHz VLA radio source
  65. GRB 250516A: COLIBRÍ optical upper limit
  66. Fermi GRB 250516A: Global MASTER-Net observations report
  67. Fermi GRB 250512A: Global MASTER-Net observations report
  68. GRB 250507B: AstroSat CZTI detection
  69. EP250512a: Global MASTER-Net observations report
  70. GRB 250507B: GRBAlpha detection
  71. EP250511a: COLIBRÍ optical counterpart candidate
  72. EP250511a: BOOTES-5 optical upper limit
  73. Fermi GRB 250510C: Global MASTER-Net observations report
  74. GRB 250509A: Fermi GBM Observation
  75. Fermi GRB 250509A: Global MASTER-Net observations report
  76. Swift GRB 250509A: Global MASTER-Net observations report
  77. GRB 250509A: Swift detection of a burst
  78. Fermi-LAT Gamma-ray Observations of IceCube-250506A
  79. IceCube Alert 250506.59: Global MASTER-Net observations report
  80. GRB 250506A: SVOM improved position and MXT detection of a fading X-ray afterglow
  81. GRB 250504A: REM optical/NIR observations
  82. GRB 250502A: SVOM/COLIBRÍ (FM-GFT) Detection of a Bright Optical Counterpart Candidate
  83. Fermi trigger No 767623859: Global MASTER-Net observations report
  84. EP250427A: COLIBRÍ Continuing Optical Observations
  85. EP250427A: COLIBRÍ Optical Detection
  86. EP 250427a: BOOTES-7 optical afterglow candidate
  87. EP250427a: Global MASTER-Net observations report
  88. GRB 250424A: SVOM/VT optical observation
  89. Fermi-LAT gamma-ray observations of IceCube-250421A
  90. GRB 250424A: BlackGEM optical afterglow detection
  91. IceCube Alert 250421.71: Global MASTER-Net observations report
  92. Fermi-LAT Gamma-ray Observations of IceCube-250416A
  93. EP250225a: SVOM/VT optical brightening
  94. IceCube 250414.324: DDOTI Optical Observations
  95. Fermi trigger No 766148493: Global MASTER-Net observations report
  96. Fermi trigger No 766173972: Global MASTER-Net observations report
  97. GRB 250411A: Fermi GBM Final Real-time Localization
  98. GRB 250407A: Continued KAIT/Nickel optical observations
  99. GRB 250407A: Mondy and AbAO Optical Observations
  100. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-250409A

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