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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"
  1. Fermi GRB 241223A: Global MASTER-Net observations report
  2. GRB 241223A: GOTO optical observations summary
  3. GRB 241105A: JWST photometric observations of the host galaxy
  4. GRB 241223A: Swift ToO observations
  5. EP241217a: e-MERLIN radio observations
  6. GRB 241223A: BALROG localization (Fermi Trigger 756648531 / GRB 241223506)
  7. GRB 241223A: Fermi GBM Final Real-time Localization
  8. GRB 241217A / EP241217b: Non-detection in ATCA Radio Follow-up Observations
  9. The EP-WXT trigger 01709129287 is likely a flaring star
  10. Fermi trigger No 756447119: Global MASTER-Net observations report
  11. GRB 241209B: host galaxy detection and GTC/OSIRIS+ spectroscopy
  12. Fermi Gamma-ray Burst Monitor trigger 756447119/241221175 is not a GRB
  13. Fermi GRB 241221A: Global MASTER-Net observations report
  14. GRB 241221A: Fermi GBM Final Real-time Localization
  15. GRB 241217A/EP241217b: SOAR afterglow detection
  16. EP241217a: Liverpool Telescope optical upper limit
  17. EP241021a: VLA radio detection
  18. GRB 241218A: Mondy AZT-33IK optical upper limit
  19. EP241217a : Leavitt Observatory optical upper limit
  20. GRB 241217A/EP241217b: tentative VLT spectroscopic redshift z=1.879
  21. EP241217a: 1.6m Mephisto multi-band optical observations
  22. GRB 241217a/EP241217B: 1.6m Mephisto optical upper limits
  23. GRB 241218A: Swift/UVOT Upper Limits
  24. EP241217a: optical upper limit with the Liverpool Telescope
  25. GRB 241209B: EP-FXT afterglow detection
  26. Konus-Wind detection of GRB 241204A (short/hard)
  27. GRB 241218A: NOT optical upper limits
  28. GRB 241218A: Swift-BAT refined analysis
  29. GRB 241217A / EP241217B: GRANDMA/T1MPicduMidi optical upperlimits
  30. EP 241217a: NIR detection with P200/WIRC
  31. EP 241217a: Possible J-band detection with WINTER
  32. GRB 241217A/EP241217B: Fermi-GBM Sub-Threshold Detection
  33. EP241217a: refined EP-WXT analysis and EP-FXT follow-up observations
  34. GRB 241217A / EP241217b: Nanshan/HMT optical upper limit
  35. GRB 241217A: refined SVOM/MXT data analysis. Long lasting X-ray emission.
  36. GRB 241217A / EP241217b: NOT optical upper limits
  37. GRB 241218A: REM optical upper limit
  38. GRB 241217A/EP241217b: REM optical/NIR upper limits
  39. EP241217a: REM optical/NIR upper limits
  40. GRB 241218a: Liverpool Telescope optical follow-up
  41. GRB 241217a: Liverpool Telescope optical follow-up
  42. EP241217a: Liverpool Telescope optical follow-up
  43. GRB 241218A: Swift-XRT refined Analysis
  44. EP241217a: NOT optical observations
  45. EP241217a: GROWTH-India Telescope optical observations
  46. GRB 241218A: NUTTelA-TAO / BSTI Optical Limits
  47. EP241119a: 7DT Optical upper limits
  48. EP241217b: Global MASTER-Net observations report
  49. GRB 241209A: ATCA radio follow-up observations
  50. EP241217a: Xinglong optical follow-up observations
  51. EP241217b/GRB 241217A: EP detection of the prompt X-ray emssion
  52. GRB 241218A: LCOGT Optical Upper Limit
  53. GRB 241218A: Enhanced Swift-XRT position
  54. EP241217a: Global MASTER-Net observations report
  55. GRB 241217A: GMG Optical Upper Limit
  56. GRB 241218A: Swift detection of a burst
  57. GRB 241217A : SVOM/VT optical afterglow detection
  58. GRB 241217A: Swift-XRT afterglow detection
  59. GRB 241217A: LCO optical upper limit
  60. GRB 241217A: GRANDMA/TAROT optical upperlimits
  61. EP241217a: Swift-XRT Detection
  62. EP241217A: Non-detection from Fermi-GBM Observations
  63. GRB 241217A : SVOM/ECLAIRs,GRM,MXT detection of a long burst with a bright X-ray afterglow candidate
  64. EP241217a: Gemini-North spectroscopic redshift z = 4.59
  65. EP241217a: Kinder optical follow-up observations
  66. GRB 241214A: GRBAlpha detection
  67. GRB 241213A (EP241213a): GRBAlpha detection
  68. GRB 241209D: GRBAlpha detection
  69. EP241217A: LCO optical observations
  70. EP241217a: Gemini-North detection of the likely optical counterpart
  71. EP241217a: EP detection of an X-ray transient
  72. The EP-WXT trigger 01709129023 is likely a flaring star
  73. EP241107a: VLA Radio Observation
  74. GRB 241213A: Swift-BAT refined analysis
  75. GRB 241214A: Swift/BAT-GUANO localization skymap of a burst
  76. Konus-Wind detection of GRB 241213A (EP 241213a)
  77. GRB 241215A: Mondy AZT-33IK optical observations
  78. GRB 241212A: Swift-XRT observations
  79. GRB 241214A: SVOM/GRM observation
  80. The EP-WXT trigger 01709128948 is likely a flaring star
  81. GRB 241215A: Nanshan/HMT optical upper limit
  82. GRB 241215A: Montarrenti Observatory optical upper limit
  83. GRB 241215A: GROWTH-India telescope optical upper limit
  84. GRB 241215A: A long GRB detected by INTEGRAL
  85. Integral GRB241215.58: Global MASTER-Net observations report
  86. The EP-WXT trigger 01709128921 is likely a flaring star
  87. GRB 241213B: Swift-XRT observations
  88. GRB 241209D: CALET Gamma-Ray Burst Monitor detection
  89. GRB 241209B: SVOM/VT optical continuous fading
  90. EP trigger ID 01709128824 is not a real source
  91. GRB 241213A: SVOM/VT optical candidate
  92. GRB 241213B: Tiled Swift observations
  93. GRB 241213A: Swift/UVOT Upper Limits
  94. GRB 241213B: CALET Gamma-Ray Burst Monitor detection
  95. GRB 241213A: Swift-XRT refined Analysis
  96. GRB 241212A: Fermi GBM detection
  97. EP241208a: NOT optical upper limits
  98. GRB 241212A: Swift ToO observations
  99. GRB 241213A: LCOGT Optical Upper Limits
  100. EP 241208A : Detection of a long soft transient by SVOM/ECLAIRs

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