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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"

35436 results found.

  1. GRB 241228B: Fermi GBM Observation
  2. GRB 241228B: Swift-XRT afterglow detection
  3. GRB 241229B: Fermi GBM Observation
  4. GRB 241229A: Swift ToO observations
  5. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  6. GRB 241228A: Mondy optical afterglow observations
  7. GRB 241229B: Swift-XRT refined Analysis
  8. Swift GRB 241229B: Global MASTER-Net observations report
  9. GRB 241229A: GOTO optical upper limits
  10. GRB 241228B: VLT/X-shooter redshift of z = 2.674
  11. GRB 241228A: NOT optical upper limits
  12. GRB 241228B: LCO optical observation
  13. GRB 241228A: Swift-BAT refined analysis
  14. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
  15. GRB 241229B: Swift detection of a burst
  16. GRB 241229B: Fermi GBM Final Real-time Localization
  17. GRB 241229A: SVOM detection of a long burst
  18. Fermi GRB 241228B: Global MASTER-Net observations report
  19. GRB 241228A: Fermi GBM Observation
  20. GRB241228B: GROWTH-India Telescope optical observations
  21. Swift GRB 241228A: Global MASTER-Net observations report
  22. GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
  23. GRB 241228B: GOTO24jmz optical follow-up observations
  24. GRB 241226A: Swift/BAT-GUANO localization skymap of a burst
  25. GRB 241228A: GROWTH-India telescope optical upper limit
  26. GRB 241228B: Swift ToO observations
  27. GRB 241228B: TRT optical counterpart confirmation
  28. GRB 241228A: Swift-XRT refined Analysis
  29. GRB 241228A: Swift/UVOT Upper Limits
  30. GRB 241228B: GOTO possible optical counterpart candidate
  31. GRB 241228A: Enhanced Swift-XRT position
  32. GRB 241228B: Fermi GBM Final Real-time Localization
  33. GRB 241228A: Swift detection of a burst
  34. IceCube-241224A: Upper limits from a search for additional neutrino events in IceCube
  35. GRB 241223A: GRBAlpha detection
  36. GRB 241212A: VZLUSAT-2 detection
  37. GRB 241217A/EP241217b: continued SOAR observations
  38. Fermi GRB 241226A: Global MASTER-Net observations report
  39. GRB 241226A: Fermi GBM Final Real-time Localization
  40. EP241223a: Mondy AZT-33IK optical observations
  41. GRB 241029A: LCO optical observation
  42. GRB 241223A: Swift-XRT observations
  43. GRB 241029A: AbAO AS-32 optical observations
  44. GRB 241223A: Fermi GBM Detection
  45. GRB 241219A: SVOM/GRM observation
  46. GRB241113A: 7DT Optical upper limits
  47. Fermi Gamma-ray Burst Monitor trigger 756678579 / 241223854 is not a GRB
  48. Fermi GRB 241223A: Global MASTER-Net observations report
  49. GRB 241223A: GOTO optical observations summary
  50. GRB 241105A: JWST photometric observations of the host galaxy
  51. GRB 241223A: Swift ToO observations
  52. GRB 241223A: BALROG localization (Fermi Trigger 756648531 / GRB 241223506)
  53. GRB 241223A: Fermi GBM Final Real-time Localization
  54. GRB 241217A / EP241217b: Non-detection in ATCA Radio Follow-up Observations
  55. GRB 241209B: host galaxy detection and GTC/OSIRIS+ spectroscopy
  56. Fermi Gamma-ray Burst Monitor trigger 756447119/241221175 is not a GRB
  57. Fermi GRB 241221A: Global MASTER-Net observations report
  58. GRB 241221A: Fermi GBM Final Real-time Localization
  59. GRB 241217A/EP241217b: SOAR afterglow detection
  60. GRB 241218A: Mondy AZT-33IK optical upper limit
  61. EP241217a : Leavitt Observatory optical upper limit
  62. GRB 241217A/EP241217b: tentative VLT spectroscopic redshift z=1.879
  63. GRB 241217a/EP241217B: 1.6m Mephisto optical upper limits
  64. GRB 241218A: Swift/UVOT Upper Limits
  65. GRB 241209B: EP-FXT afterglow detection
  66. Konus-Wind detection of GRB 241204A (short/hard)
  67. GRB 241218A: NOT optical upper limits
  68. GRB 241218A: Swift-BAT refined analysis
  69. GRB 241217A / EP241217B: GRANDMA/T1MPicduMidi optical upperlimits
  70. GRB 241217A/EP241217B: Fermi-GBM Sub-Threshold Detection
  71. GRB 241217A / EP241217b: Nanshan/HMT optical upper limit
  72. GRB 241217A: refined SVOM/MXT data analysis. Long lasting X-ray emission.
  73. GRB 241217A / EP241217b: NOT optical upper limits
  74. GRB 241218A: REM optical upper limit
  75. GRB 241217A/EP241217b: REM optical/NIR upper limits
  76. GRB 241218a: Liverpool Telescope optical follow-up
  77. GRB 241217a: Liverpool Telescope optical follow-up
  78. GRB 241218A: Swift-XRT refined Analysis
  79. GRB 241218A: NUTTelA-TAO / BSTI Optical Limits
  80. GRB 241209A: ATCA radio follow-up observations
  81. EP241217b/GRB 241217A: EP detection of the prompt X-ray emssion
  82. GRB 241218A: LCOGT Optical Upper Limit
  83. GRB 241218A: Enhanced Swift-XRT position
  84. GRB 241217A: GMG Optical Upper Limit
  85. GRB 241218A: Swift detection of a burst
  86. GRB 241217A : SVOM/VT optical afterglow detection
  87. GRB 241217A: Swift-XRT afterglow detection
  88. GRB 241217A: LCO optical upper limit
  89. GRB 241217A: GRANDMA/TAROT optical upperlimits
  90. EP241217A: Non-detection from Fermi-GBM Observations
  91. GRB 241217A : SVOM/ECLAIRs,GRM,MXT detection of a long burst with a bright X-ray afterglow candidate
  92. GRB 241214A: GRBAlpha detection
  93. GRB 241213A (EP241213a): GRBAlpha detection
  94. GRB 241209D: GRBAlpha detection
  95. GRB 241213A: Swift-BAT refined analysis
  96. GRB 241214A: Swift/BAT-GUANO localization skymap of a burst
  97. Konus-Wind detection of GRB 241213A (EP 241213a)
  98. GRB 241215A: Mondy AZT-33IK optical observations
  99. GRB 241212A: Swift-XRT observations
  100. GRB 241214A: SVOM/GRM observation

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