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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"

3051 results found.

  1. EP250215a / GRB 250215A: AstroSat CZTI detection
  2. EP250215a: Global MASTER-Net observations report
  3. Fermi GRB 250215A: Global MASTER-Net observations report
  4. GRB 250213A：SVOM/VT optical candidate
  5. Fermi GRB 250214A: Global MASTER-Net observations report
  6. EP250212a: Global MASTER-Net observations report
  7. GRB 250210A: AstroSat CZTI detection
  8. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  9. IceCube Alert 250207.09: Global MASTER-Net observations report
  10. GRB 250207A: 1.3m DFOT Optical observations
  11. GRB 250206A: Swift-XRT observations
  12. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  13. EP250205a/GRB 250205A: Einstein Probe observation
  14. GRB 250205A: OHP/T193 optical counterpart candidate
  15. GRB 250204B: AstroSat CZTI detection of a short burst
  16. GRB 250129A: AbAO AS-32 and Mondy AZT-33IK optical observations
  17. GRB 250202B: AstroSat CZTI detection of a bright long GRB
  18. LIGO/Virgo/KAGRA S250201i: Coverage and upper limits from MAXI/GSC observations
  19. Fermi GRB 250128B: Global MASTER-Net observations report
  20. GRB 250128A: Fermi GBM Final Real-time Localization
  21. EP250125a: Swift/XRT detection of a fading counterpart
  22. EP250125a: Gemini-South optical afterglow discovery and redshift z = 2.89
  23. IPN triangulation of GRB 250119B
  24. EP250108a: MeerKAT radio upper limit
  25. GRB 250113A: INTEGRAL/SPI-ACS detection
  26. GRB 250113A: SVOM/GRM observation of a long burst
  27. EP250109b: optical upper limits with the Liverpool Telescope
  28. EP250111a: Mondy optical observation
  29. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  30. EP250108a: EP-FXT follow-up observation
  31. IPN triangulation of GRB 250107D (short/hard)
  32. EP250108a: Liverpool Telescope likely optical counterpart
  33. EP250109a: GOTO optical upper limits
  34. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  35. Fermi GRB 250107B: Global MASTER-Net observations report
  36. EPWXT01709129925: Xinglong optical observations
  37. GRB 250106A: NOT optical observations
  38. GRB 250106A: Swift-XRT observations
  39. GRB 250106A: SVOM/VT optical candidate
  40. Fermi trigger No 757753930: Global MASTER-Net observations report
  41. Fermi GRB 250102A: Global MASTER-Net observations report
  42. GRB 241228A: Mondy optical afterglow observations
  43. GRB 241229A: GOTO optical upper limits
  44. GRB 241229B: Swift detection of a burst
  45. GRB 241228B: GOTO24jmz optical follow-up observations
  46. GRB 241228B: GOTO possible optical counterpart candidate
  47. Fermi GRB 241226A: Global MASTER-Net observations report
  48. Fermi trigger No 756678579: Global MASTER-Net observations report
  49. GRB 241219A: SVOM/GRM observation
  50. GRB241113A: 7DT Optical upper limits
  51. Fermi trigger No 756447119: Global MASTER-Net observations report
  52. EP241217a: Global MASTER-Net observations report
  53. EP241217A: Non-detection from Fermi-GBM Observations
  54. GRB 241217A : SVOM/ECLAIRs,GRM,MXT detection of a long burst with a bright X-ray afterglow candidate
  55. GRB 241215A: Montarrenti Observatory optical upper limit
  56. GRB 241212A: AstroSat CZTI detection
  57. GRB 241207A: TSHAO Zeiss-1000 optical observations
  58. GRB 241209A: Swift-XRT refined Analysis
  59. GRB 241209D: AstroSat CZTI detection
  60. Fermi GRB 241209C: Global MASTER-Net observations report
  61. GRB 241209C: AstroSat CZTI detection
  62. GRB 241209D: Swift detection of a burst
  63. Fermi GRB 241209A: Global MASTER-Net observations report
  64. GRB 241209A: GOTO optical upper limits
  65. Fermi GRB 241207B: Global MASTER-Net observations report
  66. GRB 241201A: AstroSat CZTI detection
  67. GRB 241207C: MASTER optical observations
  68. Fermi trigger No 755225799: Global MASTER-Net observations report
  69. IPN triangulation of GRB 241130A
  70. EP241201a: Global MASTER-Net observations report
  71. EP241126a: WFST Observations
  72. EP241126a: TRT optical counterpart detection
  73. LIGO/Virgo/KAGRA S241125n: Kinder optical upper limit in the BAT error region
  74. GRB 241113A: Possible ATCA Radio detection
  75. GRB 241120A: Fermi GBM Final Real-time Localization
  76. Fermi GRB 241118A: Global MASTER-Net observations report
  77. Fermi GRB 241117A: Global MASTER-Net observations report
  78. The EP-WXT trigger 01709120856 is likely a flaring star
  79. GRB 241115A: Fermi GBM Final Real-time Localization
  80. Fermi GRB 241114A: Global MASTER-Net observations report
  81. EP241113b: Global MASTER-Net observations report
  82. GRB 241112B: GMG Optical Upper Limit
  83. LIGO/Virgo/KAGRA S241110bk: 1 counterpart neutrino candidate event from an IceCube neutrino search
  84. Fermi trigger No 752878030: Global MASTER-Net observations report
  85. LIGO/Virgo/KAGRA S241109bn: Global MASTER-Net observations report
  86. GRB 241105A: SVOM/GRM observation
  87. GRB 241105A: GOTO tentative optical counterpart candidate
  88. Fermi GRB 241105A: Global MASTER-Net observations report
  89. GRB 241105A: Fermi GBM Final Real-time Localization
  90. Fermi GRB 241104A: Global MASTER-Net observations report
  91. Fermi trigger No 752365806: Global MASTER-Net observations report
  92. Kinder optical follow-up observations of EP241021a, EP241026b, and EP241030a/GRB241030A
  93. GRB 241101A: FRAM-ORM optical limit
  94. GRB 241026A: SAO RAS optical observations
  95. GRB 241030B : GIT optical upper limits
  96. EP EP241030a: Global MASTER-Net observations report
  97. Fermi trigger No 752006065: Global MASTER-Net observations report
  98. GRB 241030B: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.82
  99. GRB 241030A: AKO Optical Afterglow Detection
  100. GRB 241026A: SAO RAS optical observations

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