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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"

2857 results found.

  1. GRB 250219A: Swift-XRT observations
  2. IPN triangulation of GRB 250217C (short)
  3. GRB 250216A: AstroSat CZTI detection
  4. GRB 250217C: AstroSat CZTI detection of a short burst
  5. Fermi GRB 250217A: Global MASTER-Net observations report
  6. Fermi GRB 250216A: Global MASTER-Net observations report
  7. EP250215a / GRB 250215A: AstroSat CZTI detection
  8. EP250215a: Global MASTER-Net observations report
  9. Fermi GRB 250215A: Global MASTER-Net observations report
  10. GRB 250213A：SVOM/VT optical candidate
  11. Fermi GRB 250214A: Global MASTER-Net observations report
  12. EP250212a: Global MASTER-Net observations report
  13. GRB 250210A: AstroSat CZTI detection
  14. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  15. IceCube Alert 250207.09: Global MASTER-Net observations report
  16. GRB 250207A: 1.3m DFOT Optical observations
  17. GRB 250206A: Swift-XRT observations
  18. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  19. EP250205a/GRB 250205A: Einstein Probe observation
  20. GRB 250205A: OHP/T193 optical counterpart candidate
  21. GRB 250204B: AstroSat CZTI detection of a short burst
  22. GRB 250129A: AbAO AS-32 and Mondy AZT-33IK optical observations
  23. GRB 250202B: AstroSat CZTI detection of a bright long GRB
  24. LIGO/Virgo/KAGRA S250201i: Coverage and upper limits from MAXI/GSC observations
  25. Fermi GRB 250128B: Global MASTER-Net observations report
  26. GRB 250128A: Fermi GBM Final Real-time Localization
  27. EP250125a: Swift/XRT detection of a fading counterpart
  28. EP250125a: Gemini-South optical afterglow discovery and redshift z = 2.89
  29. IPN triangulation of GRB 250119B
  30. EP250108a: MeerKAT radio upper limit
  31. GRB 250113A: INTEGRAL/SPI-ACS detection
  32. GRB 250113A: SVOM/GRM observation of a long burst
  33. EP250109b: optical upper limits with the Liverpool Telescope
  34. EP250111a: Mondy optical observation
  35. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  36. EP250108a: EP-FXT follow-up observation
  37. IPN triangulation of GRB 250107D (short/hard)
  38. EP250108a: Liverpool Telescope likely optical counterpart
  39. EP250109a: GOTO optical upper limits
  40. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  41. Fermi GRB 250107B: Global MASTER-Net observations report
  42. EPWXT01709129925: Xinglong optical observations
  43. GRB 250106A: NOT optical observations
  44. GRB 250106A: Swift-XRT observations
  45. GRB 250106A: SVOM/VT optical candidate
  46. Fermi trigger No 757753930: Global MASTER-Net observations report
  47. Fermi GRB 250102A: Global MASTER-Net observations report
  48. GRB 241228A: Mondy optical afterglow observations
  49. GRB 241229A: GOTO optical upper limits
  50. GRB 241229B: Swift detection of a burst
  51. GRB 241228B: GOTO24jmz optical follow-up observations
  52. GRB 241228B: GOTO possible optical counterpart candidate
  53. Fermi GRB 241226A: Global MASTER-Net observations report
  54. Fermi trigger No 756678579: Global MASTER-Net observations report
  55. GRB 241219A: SVOM/GRM observation
  56. GRB241113A: 7DT Optical upper limits
  57. Fermi trigger No 756447119: Global MASTER-Net observations report
  58. EP241217a: Global MASTER-Net observations report
  59. EP241217A: Non-detection from Fermi-GBM Observations
  60. GRB 241217A : SVOM/ECLAIRs,GRM,MXT detection of a long burst with a bright X-ray afterglow candidate
  61. GRB 241215A: Montarrenti Observatory optical upper limit
  62. GRB 241212A: AstroSat CZTI detection
  63. GRB 241207A: TSHAO Zeiss-1000 optical observations
  64. GRB 241209A: Swift-XRT refined Analysis
  65. GRB 241209D: AstroSat CZTI detection
  66. Fermi GRB 241209C: Global MASTER-Net observations report
  67. GRB 241209C: AstroSat CZTI detection
  68. GRB 241209D: Swift detection of a burst
  69. Fermi GRB 241209A: Global MASTER-Net observations report
  70. GRB 241209A: GOTO optical upper limits
  71. Fermi GRB 241207B: Global MASTER-Net observations report
  72. GRB 241201A: AstroSat CZTI detection
  73. GRB 241207C: MASTER optical observations
  74. Fermi trigger No 755225799: Global MASTER-Net observations report
  75. IPN triangulation of GRB 241130A
  76. EP241201a: Global MASTER-Net observations report
  77. EP241126a: WFST Observations
  78. EP241126a: TRT optical counterpart detection
  79. LIGO/Virgo/KAGRA S241125n: Kinder optical upper limit in the BAT error region
  80. GRB 241113A: Possible ATCA Radio detection
  81. GRB 241120A: Fermi GBM Final Real-time Localization
  82. Fermi GRB 241118A: Global MASTER-Net observations report
  83. Fermi GRB 241117A: Global MASTER-Net observations report
  84. The EP-WXT trigger 01709120856 is likely a flaring star
  85. GRB 241115A: Fermi GBM Final Real-time Localization
  86. Fermi GRB 241114A: Global MASTER-Net observations report
  87. EP241113b: Global MASTER-Net observations report
  88. GRB 241112B: GMG Optical Upper Limit
  89. LIGO/Virgo/KAGRA S241110bk: 1 counterpart neutrino candidate event from an IceCube neutrino search
  90. Fermi trigger No 752878030: Global MASTER-Net observations report
  91. LIGO/Virgo/KAGRA S241109bn: Global MASTER-Net observations report
  92. GRB 241105A: SVOM/GRM observation
  93. GRB 241105A: GOTO tentative optical counterpart candidate
  94. Fermi GRB 241105A: Global MASTER-Net observations report
  95. GRB 241105A: Fermi GBM Final Real-time Localization
  96. Fermi GRB 241104A: Global MASTER-Net observations report
  97. Fermi trigger No 752365806: Global MASTER-Net observations report
  98. Kinder optical follow-up observations of EP241021a, EP241026b, and EP241030a/GRB241030A
  99. GRB 241101A: FRAM-ORM optical limit
  100. GRB 241026A: SAO RAS optical observations

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