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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"

32495 results found.

  1. GRB 241228A: Fermi GBM Observation
  2. GRB241228B: GROWTH-India Telescope optical observations
  3. Swift GRB 241228A: Global MASTER-Net observations report
  4. GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
  5. GRB 241228B: GOTO24jmz optical follow-up observations
  6. GRB 241226A: Swift/BAT-GUANO localization skymap of a burst
  7. GRB 241228A: GROWTH-India telescope optical upper limit
  8. GRB 241228B: Swift ToO observations
  9. GRB 241228B: TRT optical counterpart confirmation
  10. GRB 241228A: Swift/UVOT Upper Limits
  11. GRB 241228B: GOTO possible optical counterpart candidate
  12. IceCube-241224A: Upper limits from a search for additional neutrino events in IceCube
  13. GRB 241223A: GRBAlpha detection
  14. GRB 241212A: VZLUSAT-2 detection
  15. GRB 241217A/EP241217b: continued SOAR observations
  16. Fermi GRB 241226A: Global MASTER-Net observations report
  17. EP241223a: Mondy AZT-33IK optical observations
  18. GRB 241029A: LCO optical observation
  19. GRB 241223A: Swift-XRT observations
  20. LIGO/Virgo/KAGRA S241225v: Identification of a GW compact binary merger candidate
  21. GRB 241029A: AbAO AS-32 optical observations
  22. LIGO/Virgo/KAGRA S241225c: Identification of a GW compact binary merger candidate
  23. EP241223a
  24. EP241223a: Global MASTER-Net observations report
  25. EP241113a: Non-detection in Radio Follow-up Observations with eMERLIN
  26. GRB241113A: 7DT Optical upper limits
  27. Fermi GRB 241223A: Global MASTER-Net observations report
  28. GRB 241223A: GOTO optical observations summary
  29. GRB 241105A: JWST photometric observations of the host galaxy
  30. GRB 241223A: Swift ToO observations
  31. EP241217a: e-MERLIN radio observations
  32. GRB 241217A / EP241217b: Non-detection in ATCA Radio Follow-up Observations
  33. GRB 241209B: host galaxy detection and GTC/OSIRIS+ spectroscopy
  34. Fermi GRB 241221A: Global MASTER-Net observations report
  35. GRB 241217A/EP241217b: SOAR afterglow detection
  36. EP241217a: Liverpool Telescope optical upper limit
  37. EP241021a: VLA radio detection
  38. GRB 241218A: Mondy AZT-33IK optical upper limit
  39. EP241217a : Leavitt Observatory optical upper limit
  40. GRB 241217A/EP241217b: tentative VLT spectroscopic redshift z=1.879
  41. EP241217a: 1.6m Mephisto multi-band optical observations
  42. GRB 241217a/EP241217B: 1.6m Mephisto optical upper limits
  43. GRB 241218A: Swift/UVOT Upper Limits
  44. EP241217a: optical upper limit with the Liverpool Telescope
  45. GRB 241209B: EP-FXT afterglow detection
  46. Konus-Wind detection of GRB 241204A (short/hard)
  47. GRB 241218A: NOT optical upper limits
  48. GRB 241218A: Swift-BAT refined analysis
  49. GRB 241217A / EP241217B: GRANDMA/T1MPicduMidi optical upperlimits
  50. EP 241217a: NIR detection with P200/WIRC
  51. EP 241217a: Possible J-band detection with WINTER
  52. GRB 241217A/EP241217B: Fermi-GBM Sub-Threshold Detection
  53. EP241217a: refined EP-WXT analysis and EP-FXT follow-up observations
  54. GRB 241217A / EP241217b: Nanshan/HMT optical upper limit
  55. GRB 241217A: refined SVOM/MXT data analysis. Long lasting X-ray emission.
  56. GRB 241217A / EP241217b: NOT optical upper limits
  57. GRB 241218A: REM optical upper limit
  58. GRB 241217A/EP241217b: REM optical/NIR upper limits
  59. EP241217a: REM optical/NIR upper limits
  60. GRB 241218a: Liverpool Telescope optical follow-up
  61. GRB 241217a: Liverpool Telescope optical follow-up
  62. EP241217a: Liverpool Telescope optical follow-up
  63. EP241217a: NOT optical observations
  64. EP241217a: GROWTH-India Telescope optical observations
  65. GRB 241218A: NUTTelA-TAO / BSTI Optical Limits
  66. EP241119a: 7DT Optical upper limits
  67. EP241217b: Global MASTER-Net observations report
  68. GRB 241209A: ATCA radio follow-up observations
  69. EP241217a: Xinglong optical follow-up observations
  70. EP241217b/GRB 241217A: EP detection of the prompt X-ray emssion
  71. GRB 241218A: LCOGT Optical Upper Limit
  72. EP241217a: Global MASTER-Net observations report
  73. GRB 241217A: GMG Optical Upper Limit
  74. GRB 241217A : SVOM/VT optical afterglow detection
  75. GRB 241217A: LCO optical upper limit
  76. GRB 241217A: GRANDMA/TAROT optical upperlimits
  77. EP241217a: Swift-XRT Detection
  78. EP241217A: Non-detection from Fermi-GBM Observations
  79. EP241217a: Gemini-North spectroscopic redshift z = 4.59
  80. EP241217a: Kinder optical follow-up observations
  81. GRB 241214A: GRBAlpha detection
  82. GRB 241213A (EP241213a): GRBAlpha detection
  83. GRB 241209D: GRBAlpha detection
  84. EP241217A: LCO optical observations
  85. EP241217a: Gemini-North detection of the likely optical counterpart
  86. EP241107a: VLA Radio Observation
  87. GRB 241213A: Swift-BAT refined analysis
  88. GRB 241214A: Swift/BAT-GUANO localization skymap of a burst
  89. Konus-Wind detection of GRB 241213A (EP 241213a)
  90. GRB 241215A: Mondy AZT-33IK optical observations
  91. GRB 241215A: Nanshan/HMT optical upper limit
  92. GRB 241215A: Montarrenti Observatory optical upper limit
  93. GRB 241215A: GROWTH-India telescope optical upper limit
  94. GRB 241209D: CALET Gamma-Ray Burst Monitor detection
  95. GRB 241209B: SVOM/VT optical continuous fading
  96. GRB 241213A: SVOM/VT optical candidate
  97. GRB 241213B: Tiled Swift observations
  98. GRB 241213A: Swift/UVOT Upper Limits
  99. GRB 241213B: CALET Gamma-Ray Burst Monitor detection
  100. GRB 241212A: Fermi GBM detection

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