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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').
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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"

32490 results found.

  1. GRB 241213A: REM optical/NIR upper limits
  2. GRB241212A: OHP/T193 optical observations
  3. GRB 241213A: SAO RAS optical upper limit
  4. LIGO/Virgo/KAGRA S241210fu: Updated Sky localization
  5. Swift GRB 241213A: Global MASTER-Net observations report
  6. GRB 241212A : SVOM/C-GFT optical upper limit at early phase
  7. GRB 241212A : SVOM/VT bright optical afterglow
  8. GRB 241212A: AstroSat CZTI detection
  9. GRB 241209B: GRANDMA/TRT upper limit
  10. GRB 241207A: TSHAO Zeiss-1000 optical observations
  11. GRB 241212A: SVOM detection of a bright long burst
  12. GRB 241209B: Mondy AZT-33IK and AbAO AS-32 optical observations
  13. GRB 241209A: Chandra X-ray Detection
  14. Konus-Wind detection of GRB 241209B
  15. GRB 241207A: EIRSAT-1 GMOD Detection
  16. GRB 241209A: Redshift of the likely host galaxy z = 0.784 from OSIRIS+/GTC
  17. GRB 241209B: GRBAlpha detection
  18. GRB 241206C: GRBAlpha detection
  19. LIGO/Virgo/KAGRA S241210cw: Updated Sky localization
  20. LIGO/Virgo/KAGRA S241210d: Updated Sky localization and EM Bright Classification
  21. GRB 241129A: Fermi GBM Observation
  22. GRB 241209B: Swift/BAT-GUANO localization skymap of a burst
  23. GRB 241209D: REM optical/NIR upper limits
  24. Konus-Wind detection of GRB 241209D
  25. GRB 241209B: Swift-XRT afterglow detection
  26. GRB 241209C: Fermi GBM Observation
  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. GRB 241207B: Fermi GBM Observation
  38. GRB 241209A: BOOTES-7 and 2.2m CAHA early optical upper limits
  39. GRB 241209D: Fermi GBM Observation
  40. GRB 241209A: VLT/HAWK-I near-IR counterpart candidate
  41. GRB 241209D: COLIBRÍ detection of the afterglow
  42. GRB 241209A: COLIBRÍ Optical Upper Limit
  43. Fermi GRB 241209D: Global MASTER-Net observations report
  44. GRB 241209A: Fermi GBM Observation
  45. GRB 241209C: Swift/BAT-GUANO localization skymap of a burst
  46. GRB 241209A: GRANDMA/TAROT upper limit
  47. GRB 241209B: BOOTES-5 optical upper limit
  48. Swift GRB 241209D: Global MASTER-Net observations report
  49. Fermi GRB 241209C: Global MASTER-Net observations report
  50. Fermi GRB 241209E: Global MASTER-Net observations report
  51. GRB 241209B: Swift ToO observations
  52. LIGO/Virgo/KAGRA S241102br: continued GRAWITA observations and detection of an optical transient (AT2024adip)
  53. GRB 241209A: REM optical/NIR observations
  54. GRB 241209C: AstroSat CZTI detection
  55. GRB 241209A: VLT/X-shooter spectroscopy
  56. GRB 241114B: cubesat Avion detection
  57. GRB 241209A: VLT optical observations
  58. Fermi GRB 241209A: Global MASTER-Net observations report
  59. GRB 241209A: GOTO optical upper limits
  60. Fermi GRB 241207B: Global MASTER-Net observations report
  61. GRB 241207B: Swift/BAT-GUANO localization skymap of a short burst
  62. GRB 241201A: AstroSat CZTI detection
  63. GRB 241206A: DDOTI Upper Limit on the Afterglow
  64. AT2024adec: X-ray Upper Limits from EP-FXT Observation
  65. GRB 241207C: MASTER optical observations
  66. GRB 241207C: Tiled Swift observations
  67. Fermi GRB 241207A: Global MASTER-Net observations report
  68. EP241206a: Global MASTER-Net observations report
  69. GRB 241206A: Fermi GBM observation
  70. GRB 241206A: Swift/BAT-GUANO localization skymap of a burst
  71. GRB 241206B: SVOM/MXT observations: a probable flare from the QSO 1ES 1959+650
  72. GRB 241206B: GWAC-F50A optical upper limit
  73. EP241113a: Keck/LRIS spectroscopic observation and tentative redshift
  74. Fermi GRB 241206A: Global MASTER-Net observations report
  75. EP241201a: 1.6m Mephisto Optical Upper Limits
  76. GRB 241204A: COLIBRÍ Optical Upper Limit
  77. EP241202b: KAIT optical upper limit
  78. GRB 241204A: DDOTI Upper Limits on the Afterglow
  79. GRB 241204A: Fermi GBM Observation
  80. Fermi GRB 241204A: Global MASTER-Net observations report
  81. GRB 241130A: CALET Gamma-Ray Burst Monitor detection
  82. GRB 241128A : RAPAS follow-up observations
  83. GRB 241201A: GRBAlpha detection
  84. EP241202b: Upper limits from Fermi-GBM Observations
  85. IceCube-241127A: No transient candidates from the Zwicky Transient Facility
  86. EP241202b: Kinder optical counterpart candidate
  87. Fermi-GBM Sub-Threshold Detection of GRB 241128A
  88. GRB 241113B : RAPAS follow-up observation
  89. EP241201a: EP-FXT follow-up observations
  90. Konus-Wind detection of GRB 241130A
  91. EP241202b: Global MASTER-Net observations report
  92. EP241201a: BOOTES-5 optical upper limit
  93. EP241201a: NOT optical observations
  94. IPN triangulation of GRB 241130A
  95. GRB 241130A: EIRSAT-1 GMOD Detection
  96. GRB 241128A: Swift/UVOT Upper Limits
  97. IceCube-241127A: Upper limits from a search for additional neutrino events in IceCube
  98. GRB 241129A: Swift/BAT-GUANO localization skymap of a burst
  99. EP241201a: Kinder optical counterpart candidate
  100. LIGO/Virgo/KAGRA S241102br: GRAWITA wide-field optical observations

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