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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"

3137 results found.

  1. GRB 250204B: AstroSat CZTI detection of a short burst
  2. GRB 250129A: AbAO AS-32 and Mondy AZT-33IK optical observations
  3. GRB 250202B: AstroSat CZTI detection of a bright long GRB
  4. LIGO/Virgo/KAGRA S250201i: Coverage and upper limits from MAXI/GSC observations
  5. Fermi GRB 250128B: Global MASTER-Net observations report
  6. GRB 250128A: Fermi GBM Final Real-time Localization
  7. EP250125a: Swift/XRT detection of a fading counterpart
  8. EP250125a: Gemini-South optical afterglow discovery and redshift z = 2.89
  9. IPN triangulation of GRB 250119B
  10. EP250108a: MeerKAT radio upper limit
  11. GRB 250113A: INTEGRAL/SPI-ACS detection
  12. GRB 250113A: SVOM/GRM observation of a long burst
  13. EP250109b: optical upper limits with the Liverpool Telescope
  14. EP250111a: Mondy optical observation
  15. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  16. EP250108a: EP-FXT follow-up observation
  17. IPN triangulation of GRB 250107D (short/hard)
  18. EP250108a: Liverpool Telescope likely optical counterpart
  19. EP250109a: GOTO optical upper limits
  20. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  21. Fermi GRB 250107B: Global MASTER-Net observations report
  22. EPWXT01709129925: Xinglong optical observations
  23. GRB 250106A: NOT optical observations
  24. GRB 250106A: Swift-XRT observations
  25. GRB 250106A: SVOM/VT optical candidate
  26. Fermi trigger No 757753930: Global MASTER-Net observations report
  27. Fermi GRB 250102A: Global MASTER-Net observations report
  28. GRB 241228A: Mondy optical afterglow observations
  29. GRB 241229A: GOTO optical upper limits
  30. GRB 241229B: Swift detection of a burst
  31. GRB 241228B: GOTO24jmz optical follow-up observations
  32. GRB 241228B: GOTO possible optical counterpart candidate
  33. Fermi GRB 241226A: Global MASTER-Net observations report
  34. Fermi trigger No 756678579: Global MASTER-Net observations report
  35. GRB 241219A: SVOM/GRM observation
  36. GRB241113A: 7DT Optical upper limits
  37. Fermi trigger No 756447119: Global MASTER-Net observations report
  38. EP241217a: Global MASTER-Net observations report
  39. EP241217A: Non-detection from Fermi-GBM Observations
  40. GRB 241217A : SVOM/ECLAIRs,GRM,MXT detection of a long burst with a bright X-ray afterglow candidate
  41. GRB 241215A: Montarrenti Observatory optical upper limit
  42. GRB 241212A: AstroSat CZTI detection
  43. GRB 241207A: TSHAO Zeiss-1000 optical observations
  44. GRB 241209A: Swift-XRT refined Analysis
  45. GRB 241209D: AstroSat CZTI detection
  46. Fermi GRB 241209C: Global MASTER-Net observations report
  47. GRB 241209C: AstroSat CZTI detection
  48. GRB 241209D: Swift detection of a burst
  49. Fermi GRB 241209A: Global MASTER-Net observations report
  50. GRB 241209A: GOTO optical upper limits
  51. Fermi GRB 241207B: Global MASTER-Net observations report
  52. GRB 241201A: AstroSat CZTI detection
  53. GRB 241207C: MASTER optical observations
  54. Fermi trigger No 755225799: Global MASTER-Net observations report
  55. IPN triangulation of GRB 241130A
  56. EP241201a: Global MASTER-Net observations report
  57. EP241126a: WFST Observations
  58. EP241126a: TRT optical counterpart detection
  59. LIGO/Virgo/KAGRA S241125n: Kinder optical upper limit in the BAT error region
  60. GRB 241113A: Possible ATCA Radio detection
  61. GRB 241120A: Fermi GBM Final Real-time Localization
  62. Fermi GRB 241118A: Global MASTER-Net observations report
  63. Fermi GRB 241117A: Global MASTER-Net observations report
  64. The EP-WXT trigger 01709120856 is likely a flaring star
  65. GRB 241115A: Fermi GBM Final Real-time Localization
  66. Fermi GRB 241114A: Global MASTER-Net observations report
  67. EP241113b: Global MASTER-Net observations report
  68. GRB 241112B: GMG Optical Upper Limit
  69. LIGO/Virgo/KAGRA S241110bk: 1 counterpart neutrino candidate event from an IceCube neutrino search
  70. Fermi trigger No 752878030: Global MASTER-Net observations report
  71. LIGO/Virgo/KAGRA S241109bn: Global MASTER-Net observations report
  72. GRB 241105A: SVOM/GRM observation
  73. GRB 241105A: GOTO tentative optical counterpart candidate
  74. Fermi GRB 241105A: Global MASTER-Net observations report
  75. GRB 241105A: Fermi GBM Final Real-time Localization
  76. Fermi GRB 241104A: Global MASTER-Net observations report
  77. Fermi trigger No 752365806: Global MASTER-Net observations report
  78. Kinder optical follow-up observations of EP241021a, EP241026b, and EP241030a/GRB241030A
  79. GRB 241101A: FRAM-ORM optical limit
  80. GRB 241026A: SAO RAS optical observations
  81. GRB 241030B : GIT optical upper limits
  82. EP EP241030a: Global MASTER-Net observations report
  83. Fermi trigger No 752006065: Global MASTER-Net observations report
  84. GRB 241030B: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.82
  85. GRB 241030A: AKO Optical Afterglow Detection
  86. GRB 241026A: SAO RAS optical observations
  87. EP241021a: SAO RAS observations of rebrightening
  88. GRB 241026A: the 100th GRB detected by GRBAlpha
  89. GRB 241026A: GECAM detection
  90. GRB 241025A: further SAO RAS optical observations
  91. GRB 241026A: SVOM/GRM observation
  92. GRB 241026A Fermi GBM Analysis
  93. GRB 241026A: BTA redshift identification of z = 2.79
  94. GRB 241026A: Swift detection of a burst
  95. GRB 241026A: Fermi GBM Final Real-time Localization
  96. Fermi trigger No 751554401: Global MASTER-Net observations report
  97. EP241021a: Optical and NIR observations of counterpart with the Fraunhofer Telescope at Wendelstein Observatory
  98. EP241021a: Optical and NIR observations of counterpart with the Fraunhofer Telescope at Wendelstein Observatory
  99. Fermi trigger No 750788395: Global MASTER-Net observations report
  100. Fermi GRB 241013B: Global MASTER-Net observations report

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