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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"

45409 results found.

  1. GRB 241213A: Swift detection of a burst
  2. GRB 241212A : SVOM/C-GFT optical upper limit at early phase
  3. GRB 241212A : SVOM/VT bright optical afterglow
  4. GRB 241212A: AstroSat CZTI detection
  5. GRB 241209B: GRANDMA/TRT upper limit
  6. GRB 241207A: TSHAO Zeiss-1000 optical observations
  7. GRB 241212A: SVOM detection of a bright long burst
  8. GRB 241212A: Fermi GBM Final Real-time Localization
  9. GRB 241209B: Mondy AZT-33IK and AbAO AS-32 optical observations
  10. GRB 241209A: Chandra X-ray Detection
  11. Konus-Wind detection of GRB 241209B
  12. GRB 241207A: EIRSAT-1 GMOD Detection
  13. GRB 241209A: Redshift of the likely host galaxy z = 0.784 from OSIRIS+/GTC
  14. GRB 241209B: GRBAlpha detection
  15. GRB 241206C: GRBAlpha detection
  16. LIGO/Virgo/KAGRA S241210cw: Updated Sky localization
  17. LIGO/Virgo/KAGRA S241210d: Updated Sky localization and EM Bright Classification
  18. GRB 241211A: Fermi GBM Final Real-time Localization
  19. GRB 241129A: Fermi GBM Observation
  20. GRB 241209B: Swift/BAT-GUANO localization skymap of a burst
  21. GRB 241209D: REM optical/NIR upper limits
  22. Konus-Wind detection of GRB 241209D
  23. GRB 241209B: Swift-XRT afterglow detection
  24. GRB 241209C: Fermi GBM Observation
  25. GRB 241209A: Swift-XRT refined Analysis
  26. Fermi Gamma-ray Burst Monitor trigger 755485387 / 241210044 is not a GRB
  27. LIGO/Virgo/KAGRA S241210fu: Identification of a GW compact binary merger candidate
  28. EP241208a: Optical upper limit with Kinder observations
  29. GRB 241128A: CrAO ZTSh and Mondy AZT-33IK optical observations
  30. GRB 241209D: AstroSat CZTI detection
  31. GRB 241209A: EP-FXT follow-up observations
  32. GRB 241209B: SVOM/VT afterglow detection
  33. LIGO/Virgo/KAGRA S241210cw: Identification of a GW compact binary merger candidate
  34. EP241208a: Global MASTER-Net observations report
  35. EP241208a: EP-FXT follow-up observations
  36. LIGO/Virgo/KAGRA S241210d: Identification of a GW compact binary merger candidate
  37. Fermi trigger No 755485387: Global MASTER-Net observations report
  38. GRB 241207B: Fermi GBM Observation
  39. GRB 241209A: BOOTES-7 and 2.2m CAHA early optical upper limits
  40. GRB 241209D: Swift-XRT refined Analysis
  41. GRB 241209D: Fermi GBM Observation
  42. GRB 241209A: VLT/HAWK-I near-IR counterpart candidate
  43. GRB 241209D: COLIBRÍ detection of the afterglow
  44. GRB 241209A: COLIBRÍ Optical Upper Limit
  45. Fermi GRB 241209D: Global MASTER-Net observations report
  46. GRB 241209A: Fermi GBM Observation
  47. GRB 241209C: Swift/BAT-GUANO localization skymap of a burst
  48. GRB 241209A: GRANDMA/TAROT upper limit
  49. GRB 241209B: BOOTES-5 optical upper limit
  50. Swift GRB 241209D: Global MASTER-Net observations report
  51. Fermi GRB 241209C: Global MASTER-Net observations report
  52. Fermi GRB 241209E: Global MASTER-Net observations report
  53. GRB 241209E: Fermi GBM Final Real-time Localization
  54. GRB 241209B: Swift ToO observations
  55. LIGO/Virgo/KAGRA S241102br: continued GRAWITA observations and detection of an optical transient (AT2024adip)
  56. GRB 241209A: REM optical/NIR observations
  57. GRB 241209D: Enhanced Swift-XRT position
  58. GRB 241209C: AstroSat CZTI detection
  59. GRB 241209D: Swift detection of a burst
  60. GRB 241209D: Fermi GBM Final Real-time Localization
  61. GRB 241209A: VLT/X-shooter spectroscopy
  62. GRB 241209A: Enhanced Swift-XRT position
  63. GRB 241114B: cubesat Avion detection
  64. GRB 241209A: VLT optical observations
  65. Fermi GRB 241209A: Global MASTER-Net observations report
  66. GRB 241209C: Fermi GBM Final Real-time Localization
  67. GRB 241209A: GOTO optical upper limits
  68. EP241206a: 1.5m OSN optical limit
  69. GRB 241209A: Prompt enhanced Swift-XRT position
  70. GRB 241209B: SVOM/ECLAIRs and GRM detection of a long burst
  71. EP241208a: EP detection of a fast X-ray transient
  72. GRB 241209A: Swift detection of a short burst
  73. Swift GRB241209.23: Global MASTER-Net observations report
  74. GRB 241209A: Fermi GBM Final Real-time Localization
  75. Fermi GRB 241207B: Global MASTER-Net observations report
  76. GRB 241207B: Swift/BAT-GUANO localization skymap of a short burst
  77. Fermi Gamma-ray Burst Monitor trigger 755277791/241207641 is not a GRB
  78. GRB 241201A: AstroSat CZTI detection
  79. GRB 241206A: DDOTI Upper Limit on the Afterglow
  80. AT2024adec: X-ray Upper Limits from EP-FXT Observation
  81. AT2024adec: X-ray Upper Limits from EP-FXT Observation
  82. EP241206a: BOOTES Global Network optical limits
  83. GRB 241207C: MASTER optical observations
  84. Fermi trigger No 755225799: Global MASTER-Net observations report
  85. GRB 241207C: Tiled Swift observations
  86. GRB 241207C: MAXI/GSC detection
  87. GRB 241207B: Fermi GBM Final Real-time Localization
  88. Fermi trigger No 755277791: Global MASTER-Net observations report
  89. Fermi GRB 241207A: Global MASTER-Net observations report
  90. EP241206a: Global MASTER-Net observations report
  91. EP241206a: EP detection of a fast X-ray transient
  92. GRB 241206A: Fermi GBM observation
  93. GRB 241206C: SVOM/GRM observation of a likely short burst
  94. GRB 241207A: Fermi GBM Final Real-time Localization
  95. GRB 241206A: Swift/BAT-GUANO localization skymap of a burst
  96. GRB 241206B: SVOM/MXT observations: a probable flare from the QSO 1ES 1959+650
  97. GRB 241206B: GWAC-F50A optical upper limit
  98. GRB 241206B: SVOM/ECLAIRs detection of a long soft transient
  99. EP241113a: Keck/LRIS spectroscopic observation and tentative redshift
  100. Fermi GRB 241206A: Global MASTER-Net observations report

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