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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"

3138 results found.

  1. GRB 250205A: OHP/T193 optical counterpart candidate
  2. GRB 250204B: AstroSat CZTI detection of a short burst
  3. GRB 250129A: AbAO AS-32 and Mondy AZT-33IK optical observations
  4. GRB 250202B: AstroSat CZTI detection of a bright long GRB
  5. LIGO/Virgo/KAGRA S250201i: Coverage and upper limits from MAXI/GSC observations
  6. Fermi GRB 250128B: Global MASTER-Net observations report
  7. GRB 250128A: Fermi GBM Final Real-time Localization
  8. EP250125a: Swift/XRT detection of a fading counterpart
  9. EP250125a: Gemini-South optical afterglow discovery and redshift z = 2.89
  10. IPN triangulation of GRB 250119B
  11. EP250108a: MeerKAT radio upper limit
  12. GRB 250113A: INTEGRAL/SPI-ACS detection
  13. GRB 250113A: SVOM/GRM observation of a long burst
  14. EP250109b: optical upper limits with the Liverpool Telescope
  15. EP250111a: Mondy optical observation
  16. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  17. EP250108a: EP-FXT follow-up observation
  18. IPN triangulation of GRB 250107D (short/hard)
  19. EP250108a: Liverpool Telescope likely optical counterpart
  20. EP250109a: GOTO optical upper limits
  21. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  22. Fermi GRB 250107B: Global MASTER-Net observations report
  23. EPWXT01709129925: Xinglong optical observations
  24. GRB 250106A: NOT optical observations
  25. GRB 250106A: Swift-XRT observations
  26. GRB 250106A: SVOM/VT optical candidate
  27. Fermi trigger No 757753930: Global MASTER-Net observations report
  28. Fermi GRB 250102A: Global MASTER-Net observations report
  29. GRB 241228A: Mondy optical afterglow observations
  30. GRB 241229A: GOTO optical upper limits
  31. GRB 241229B: Swift detection of a burst
  32. GRB 241228B: GOTO24jmz optical follow-up observations
  33. GRB 241228B: GOTO possible optical counterpart candidate
  34. Fermi GRB 241226A: Global MASTER-Net observations report
  35. Fermi trigger No 756678579: Global MASTER-Net observations report
  36. GRB 241219A: SVOM/GRM observation
  37. GRB241113A: 7DT Optical upper limits
  38. Fermi trigger No 756447119: Global MASTER-Net observations report
  39. EP241217a: Global MASTER-Net observations report
  40. EP241217A: Non-detection from Fermi-GBM Observations
  41. GRB 241217A : SVOM/ECLAIRs,GRM,MXT detection of a long burst with a bright X-ray afterglow candidate
  42. GRB 241215A: Montarrenti Observatory optical upper limit
  43. GRB 241212A: AstroSat CZTI detection
  44. GRB 241207A: TSHAO Zeiss-1000 optical observations
  45. GRB 241209A: Swift-XRT refined Analysis
  46. GRB 241209D: AstroSat CZTI detection
  47. Fermi GRB 241209C: Global MASTER-Net observations report
  48. GRB 241209C: AstroSat CZTI detection
  49. GRB 241209D: Swift detection of a burst
  50. Fermi GRB 241209A: Global MASTER-Net observations report
  51. GRB 241209A: GOTO optical upper limits
  52. Fermi GRB 241207B: Global MASTER-Net observations report
  53. GRB 241201A: AstroSat CZTI detection
  54. GRB 241207C: MASTER optical observations
  55. Fermi trigger No 755225799: Global MASTER-Net observations report
  56. IPN triangulation of GRB 241130A
  57. EP241201a: Global MASTER-Net observations report
  58. EP241126a: WFST Observations
  59. EP241126a: TRT optical counterpart detection
  60. LIGO/Virgo/KAGRA S241125n: Kinder optical upper limit in the BAT error region
  61. GRB 241113A: Possible ATCA Radio detection
  62. GRB 241120A: Fermi GBM Final Real-time Localization
  63. Fermi GRB 241118A: Global MASTER-Net observations report
  64. Fermi GRB 241117A: Global MASTER-Net observations report
  65. The EP-WXT trigger 01709120856 is likely a flaring star
  66. GRB 241115A: Fermi GBM Final Real-time Localization
  67. Fermi GRB 241114A: Global MASTER-Net observations report
  68. EP241113b: Global MASTER-Net observations report
  69. GRB 241112B: GMG Optical Upper Limit
  70. LIGO/Virgo/KAGRA S241110bk: 1 counterpart neutrino candidate event from an IceCube neutrino search
  71. Fermi trigger No 752878030: Global MASTER-Net observations report
  72. LIGO/Virgo/KAGRA S241109bn: Global MASTER-Net observations report
  73. GRB 241105A: SVOM/GRM observation
  74. GRB 241105A: GOTO tentative optical counterpart candidate
  75. Fermi GRB 241105A: Global MASTER-Net observations report
  76. GRB 241105A: Fermi GBM Final Real-time Localization
  77. Fermi GRB 241104A: Global MASTER-Net observations report
  78. Fermi trigger No 752365806: Global MASTER-Net observations report
  79. Kinder optical follow-up observations of EP241021a, EP241026b, and EP241030a/GRB241030A
  80. GRB 241101A: FRAM-ORM optical limit
  81. GRB 241026A: SAO RAS optical observations
  82. GRB 241030B : GIT optical upper limits
  83. EP EP241030a: Global MASTER-Net observations report
  84. Fermi trigger No 752006065: Global MASTER-Net observations report
  85. GRB 241030B: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.82
  86. GRB 241030A: AKO Optical Afterglow Detection
  87. GRB 241026A: SAO RAS optical observations
  88. EP241021a: SAO RAS observations of rebrightening
  89. GRB 241026A: the 100th GRB detected by GRBAlpha
  90. GRB 241026A: GECAM detection
  91. GRB 241025A: further SAO RAS optical observations
  92. GRB 241026A: SVOM/GRM observation
  93. GRB 241026A Fermi GBM Analysis
  94. GRB 241026A: BTA redshift identification of z = 2.79
  95. GRB 241026A: Swift detection of a burst
  96. GRB 241026A: Fermi GBM Final Real-time Localization
  97. Fermi trigger No 751554401: Global MASTER-Net observations report
  98. EP241021a: Optical and NIR observations of counterpart with the Fraunhofer Telescope at Wendelstein Observatory
  99. EP241021a: Optical and NIR observations of counterpart with the Fraunhofer Telescope at Wendelstein Observatory
  100. Fermi trigger No 750788395: Global MASTER-Net observations report

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