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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"

2676 results found.

  1. Fermi trigger No 762963055: Global MASTER-Net observations report
  2. Swift GRB 250306A: Global MASTER-Net observations report
  3. Konus-Wind detection of GRB 250222A
  4. EP250304a: TRT optical counterpart detection
  5. EP250302a: NUTTelA-TAO Early Measurments
  6. EP250302a: Mondy Observations and Optical Light Curve
  7. EP250302a: Xinglong F60B optical observation
  8. EP250302a: Montarrenti Observatory optical detection
  9. Fermi GRB 250302A: Global MASTER-Net observations report
  10. EP250226a/GRB 250226A: 1.6m Mephisto observations
  11. GRB 250225B: Fermi GBM Observation
  12. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  13. Fermi GRB 250226A: Global MASTER-Net observations report
  14. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  15. EP250223a: Kinder optical follow-up observations
  16. EP250223a: LCO detection of the afterglow
  17. Fermi GRB 250223A: Global MASTER-Net observations report
  18. GRB 250219A: NOT optical observations
  19. GRB 250219A: SVOM/VT optical counterpart
  20. GRB 250219A: Swift-XRT observations
  21. IPN triangulation of GRB 250217C (short)
  22. GRB 250216A: AstroSat CZTI detection
  23. GRB 250217C: AstroSat CZTI detection of a short burst
  24. Fermi GRB 250217A: Global MASTER-Net observations report
  25. Fermi GRB 250216A: Global MASTER-Net observations report
  26. EP250215a / GRB 250215A: AstroSat CZTI detection
  27. EP250215a: Global MASTER-Net observations report
  28. Fermi GRB 250215A: Global MASTER-Net observations report
  29. GRB 250213A：SVOM/VT optical candidate
  30. Fermi GRB 250214A: Global MASTER-Net observations report
  31. EP250212a: Global MASTER-Net observations report
  32. GRB 250210A: AstroSat CZTI detection
  33. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  34. IceCube Alert 250207.09: Global MASTER-Net observations report
  35. GRB 250207A: 1.3m DFOT Optical observations
  36. GRB 250206A: Swift-XRT observations
  37. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  38. EP250205a/GRB 250205A: Einstein Probe observation
  39. GRB 250205A: OHP/T193 optical counterpart candidate
  40. GRB 250204B: AstroSat CZTI detection of a short burst
  41. GRB 250129A: AbAO AS-32 and Mondy AZT-33IK optical observations
  42. GRB 250202B: AstroSat CZTI detection of a bright long GRB
  43. LIGO/Virgo/KAGRA S250201i: Coverage and upper limits from MAXI/GSC observations
  44. Fermi GRB 250128B: Global MASTER-Net observations report
  45. GRB 250128A: Fermi GBM Final Real-time Localization
  46. EP250125a: Swift/XRT detection of a fading counterpart
  47. EP250125a: Gemini-South optical afterglow discovery and redshift z = 2.89
  48. IPN triangulation of GRB 250119B
  49. EP250108a: MeerKAT radio upper limit
  50. GRB 250113A: INTEGRAL/SPI-ACS detection
  51. GRB 250113A: SVOM/GRM observation of a long burst
  52. EP250109b: optical upper limits with the Liverpool Telescope
  53. EP250111a: Mondy optical observation
  54. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  55. EP250108a: EP-FXT follow-up observation
  56. IPN triangulation of GRB 250107D (short/hard)
  57. EP250108a: Liverpool Telescope likely optical counterpart
  58. EP250109a: GOTO optical upper limits
  59. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  60. Fermi GRB 250107B: Global MASTER-Net observations report
  61. EPWXT01709129925: Xinglong optical observations
  62. GRB 250106A: NOT optical observations
  63. GRB 250106A: Swift-XRT observations
  64. GRB 250106A: SVOM/VT optical candidate
  65. Fermi trigger No 757753930: Global MASTER-Net observations report
  66. Fermi GRB 250102A: Global MASTER-Net observations report
  67. GRB 241228A: Mondy optical afterglow observations
  68. GRB 241229A: GOTO optical upper limits
  69. GRB 241229B: Swift detection of a burst
  70. GRB 241228B: GOTO24jmz optical follow-up observations
  71. GRB 241228B: GOTO possible optical counterpart candidate
  72. Fermi GRB 241226A: Global MASTER-Net observations report
  73. Fermi trigger No 756678579: Global MASTER-Net observations report
  74. GRB 241219A: SVOM/GRM observation
  75. GRB241113A: 7DT Optical upper limits
  76. Fermi trigger No 756447119: Global MASTER-Net observations report
  77. EP241217a: Global MASTER-Net observations report
  78. EP241217A: Non-detection from Fermi-GBM Observations
  79. GRB 241217A : SVOM/ECLAIRs,GRM,MXT detection of a long burst with a bright X-ray afterglow candidate
  80. GRB 241215A: Montarrenti Observatory optical upper limit
  81. GRB 241212A: AstroSat CZTI detection
  82. GRB 241207A: TSHAO Zeiss-1000 optical observations
  83. GRB 241209A: Swift-XRT refined Analysis
  84. GRB 241209D: AstroSat CZTI detection
  85. Fermi GRB 241209C: Global MASTER-Net observations report
  86. GRB 241209C: AstroSat CZTI detection
  87. GRB 241209D: Swift detection of a burst
  88. Fermi GRB 241209A: Global MASTER-Net observations report
  89. GRB 241209A: GOTO optical upper limits
  90. Fermi GRB 241207B: Global MASTER-Net observations report
  91. GRB 241201A: AstroSat CZTI detection
  92. GRB 241207C: MASTER optical observations
  93. Fermi trigger No 755225799: Global MASTER-Net observations report
  94. IPN triangulation of GRB 241130A
  95. EP241201a: Global MASTER-Net observations report
  96. EP241126a: WFST Observations
  97. EP241126a: TRT optical counterpart detection
  98. LIGO/Virgo/KAGRA S241125n: Kinder optical upper limit in the BAT error region
  99. GRB 241113A: Possible ATCA Radio detection
  100. GRB 241120A: Fermi GBM Final Real-time Localization

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