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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"

3039 results found.

  1. Fermi GRB 250313A: Global MASTER-Net observations report
  2. Fermi GRB 250312B: Global MASTER-Net observations report
  3. GRB 250312B: Fermi GBM Final Localization
  4. GRB 241228A: VIRT Optical Upper Limit
  5. GRB 250311A: Swift-XRT observations
  6. GRB 250311A/MAXI J1457-026: MAXI/GSC detection
  7. IceCube Alert 250309.32: Global MASTER-Net observations report
  8. EP250308a: Global MASTER-Net observations report
  9. EP250308a: Einstein Probe detection of an X-ray transient
  10. GRB 250307A: Fermi GBM Final Real-time Localization
  11. GRB 250306A: Swift-BAT refined analysis
  12. GRB 250305A: AstroSat CZTI detection
  13. Fermi trigger No 762963055: Global MASTER-Net observations report
  14. GRB 250305A: Fermi GBM Final Real-time Localization
  15. LIGO/Virgo/KAGRA S250302av: 2 counterpart neutrino candidate events from an IceCube neutrino search
  16. EP250302a: Montarrenti Observatory optical detection
  17. Fermi GRB 250302A: Global MASTER-Net observations report
  18. EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection
  19. EP250226a / GRB 250226A: VLT/X-shooter redshift of z = 3.315
  20. EP250226a / GRB 250226A: TRT optical counterpart observation
  21. GRB 250226A: Fermi GBM Final Real-time Localization
  22. Fermi GRB 250225A: Global MASTER-Net observations report
  23. GRB 250202B: VZLUSAT-2 detection
  24. EP250220a: EP-FXT follow-up observations
  25. EP250220a: 1.6m Mephisto observations
  26. SVOM trigger sb25022102 is not an astrophysical event
  27. SVOM/sb25022102: SVOM detection of an X-ray transient
  28. GRB 250221A: Swift detection of a burst with an optical counterpart
  29. Swift GRB250221.15: Global MASTER-Net observations report
  30. IceCube-Cascade 250215A: Upper limits from a search for additional neutrino events in IceCube
  31. LIGO/Virgo/KAGRA S250206dm: observation in AbAO, optical transient near NED/GLADE+ galaxy WISEA J021210.14+514821.7
  32. Fermi GRB 250217A: Global MASTER-Net observations report
  33. EP250215a: Global MASTER-Net observations report
  34. Fermi GRB 250212A: Global MASTER-Net observations report
  35. Fermi trigger No 760945500: Global MASTER-Net observations report
  36. LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
  37. LIGO/Virgo/KAGRA S250206dm: continued in SOAR galaxy targeted observations and identification of one possible transient
  38. EP250207b: Global MASTER-Net observations report
  39. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  40. IceCube Alert 250207.09: Global MASTER-Net observations report
  41. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  42. LIGO/Virgo/KAGRA S250206dm: SOAR galaxy targeted observations
  43. LIGO/Virgo/KAGRA S250206dm: Updated-6 NED Galaxies in the Localization Volume
  44. LIGO/Virgo/KAGRA S250206dm: Updated NED Galaxies in the Localization Volume
  45. LIGO/Virgo/KAGRA S250206dm: NED Galaxies in the Localization Volume
  46. Konus-Wind detection of GRB 250202B
  47. IPN triangulation of GRB 250202B
  48. GRB 250202B: NuSTAR detection of the prompt emission
  49. GRB 250202B: Fermi GBM Detection
  50. GRB 250202B: AstroSat CZTI detection of a bright long GRB
  51. GRB 250202B: Fermi GBM Final Real-time Localization
  52. GRB 250129A: 1.3m DFOT Optical observations
  53. GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
  54. Fermi GRB 250128B: Global MASTER-Net observations report
  55. Fermi GRB 250127B: Global MASTER-Net observations report
  56. IPN triangulation of GRB 250119C
  57. GRB 250114A: Swift-BAT refined analysis
  58. GRB 250101A: Terskol Zeiss-2000 optical observations
  59. EP250111a: Mondy optical observation
  60. EP250111a: Global MASTER-Net observations report
  61. GRB 250108B: 1.3m DFOT upper limit
  62. EP250109a: Global MASTER-Net observations report
  63. EP250108a: Global MASTER-Net observations report
  64. Fermi GRB 250107B: Global MASTER-Net observations report
  65. Fermi trigger No 757753930: Global MASTER-Net observations report
  66. GRB 250103A: Fermi GBM Observation
  67. GRB 250103A: SVOM/C-GFT optical upper limit
  68. GRB 250101A NUTTelA-TAO / BSTI Early Measurements
  69. GRB 250101A: OASDG optical observations
  70. GRB 241228B: SAO RAS optical observations
  71. Konus-Wind detection of GRB 241228A
  72. GRB 241229B: Swift-BAT refined analysis
  73. Fermi GRB 241228B: Global MASTER-Net observations report
  74. GRB 241228A: Fermi GBM Observation
  75. GRB 241228B: TRT optical counterpart confirmation
  76. GRB 241228A: Swift detection of a burst
  77. Fermi trigger No 756678579: Global MASTER-Net observations report
  78. GRB 241217A/EP241217b: SOAR afterglow detection
  79. GRB 241217A/EP241217B: Fermi-GBM Sub-Threshold Detection
  80. EP241217a: refined EP-WXT analysis and EP-FXT follow-up observations
  81. GRB 241217A: refined SVOM/MXT data analysis. Long lasting X-ray emission.
  82. EP241217a: Liverpool Telescope optical follow-up
  83. EP241217a: Global MASTER-Net observations report
  84. GRB 241217A: GMG Optical Upper Limit
  85. GRB 241217A : SVOM/ECLAIRs,GRM,MXT detection of a long burst with a bright X-ray afterglow candidate
  86. EP241208a: Global MASTER-Net observations report
  87. Fermi GRB 241209E: Global MASTER-Net observations report
  88. Fermi GRB 241209A: Global MASTER-Net observations report
  89. Fermi GRB 241206A: Global MASTER-Net observations report
  90. Fermi GRB 241204A: Global MASTER-Net observations report
  91. Fermi GRB 241201A: Global MASTER-Net observations report
  92. LIGO/Virgo/KAGRA S241201ac: Identification of a GW compact binary merger candidate
  93. GRB 241127A: Swift-BAT refined analysis
  94. GRB 241026A: radio detection with the VLA
  95. GRB241120A: OHP/T193 optical observations
  96. GRB 241120A: Mondy and AbAO optical observations
  97. Fermi GRB 241118A: Global MASTER-Net observations report
  98. EP241113a: Global MASTER-Net observations report
  99. Fermi trigger No 753166198: Global MASTER-Net observations report
  100. Fermi-GBM Sub-Threshold Detection of GRB 241112B

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