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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. GRB 241223A: Fermi GBM Final Real-time Localization
  2. GRB 241217A / EP241217b: Non-detection in ATCA Radio Follow-up Observations
  3. The EP-WXT trigger 01709129287 is likely a flaring star
  4. Fermi trigger No 756447119: Global MASTER-Net observations report
  5. GRB 241209B: host galaxy detection and GTC/OSIRIS+ spectroscopy
  6. Fermi Gamma-ray Burst Monitor trigger 756447119/241221175 is not a GRB
  7. Fermi GRB 241221A: Global MASTER-Net observations report
  8. GRB 241221A: Fermi GBM Final Real-time Localization
  9. GRB 241217A/EP241217b: SOAR afterglow detection
  10. EP241217a: Liverpool Telescope optical upper limit
  11. EP241021a: VLA radio detection
  12. GRB 241218A: Mondy AZT-33IK optical upper limit
  13. EP241217a : Leavitt Observatory optical upper limit
  14. GRB 241217A/EP241217b: tentative VLT spectroscopic redshift z=1.879
  15. EP241217a: 1.6m Mephisto multi-band optical observations
  16. GRB 241217a/EP241217B: 1.6m Mephisto optical upper limits
  17. GRB 241218A: Swift/UVOT Upper Limits
  18. EP241217a: optical upper limit with the Liverpool Telescope
  19. GRB 241209B: EP-FXT afterglow detection
  20. Konus-Wind detection of GRB 241204A (short/hard)
  21. GRB 241218A: NOT optical upper limits
  22. GRB 241218A: Swift-BAT refined analysis
  23. GRB 241217A / EP241217B: GRANDMA/T1MPicduMidi optical upperlimits
  24. EP 241217a: NIR detection with P200/WIRC
  25. EP 241217a: Possible J-band detection with WINTER
  26. GRB 241217A/EP241217B: Fermi-GBM Sub-Threshold Detection
  27. EP241217a: refined EP-WXT analysis and EP-FXT follow-up observations
  28. GRB 241217A / EP241217b: Nanshan/HMT optical upper limit
  29. GRB 241217A: refined SVOM/MXT data analysis. Long lasting X-ray emission.
  30. GRB 241217A / EP241217b: NOT optical upper limits
  31. GRB 241218A: REM optical upper limit
  32. GRB 241217A/EP241217b: REM optical/NIR upper limits
  33. EP241217a: REM optical/NIR upper limits
  34. GRB 241218a: Liverpool Telescope optical follow-up
  35. GRB 241217a: Liverpool Telescope optical follow-up
  36. EP241217a: Liverpool Telescope optical follow-up
  37. GRB 241218A: Swift-XRT refined Analysis
  38. EP241217a: NOT optical observations
  39. EP241217a: GROWTH-India Telescope optical observations
  40. GRB 241218A: NUTTelA-TAO / BSTI Optical Limits
  41. EP241119a: 7DT Optical upper limits
  42. EP241217b: Global MASTER-Net observations report
  43. GRB 241209A: ATCA radio follow-up observations
  44. EP241217a: Xinglong optical follow-up observations
  45. EP241217b/GRB 241217A: EP detection of the prompt X-ray emssion
  46. GRB 241218A: LCOGT Optical Upper Limit
  47. GRB 241218A: Enhanced Swift-XRT position
  48. EP241217a: Global MASTER-Net observations report
  49. GRB 241217A: GMG Optical Upper Limit
  50. GRB 241218A: Swift detection of a burst
  51. GRB 241217A : SVOM/VT optical afterglow detection
  52. GRB 241217A: Swift-XRT afterglow detection
  53. GRB 241217A: LCO optical upper limit
  54. GRB 241217A: GRANDMA/TAROT optical upperlimits
  55. EP241217a: Swift-XRT Detection
  56. EP241217A: Non-detection from Fermi-GBM Observations
  57. GRB 241217A : SVOM/ECLAIRs,GRM,MXT detection of a long burst with a bright X-ray afterglow candidate
  58. EP241217a: Gemini-North spectroscopic redshift z = 4.59
  59. EP241217a: Kinder optical follow-up observations
  60. GRB 241214A: GRBAlpha detection
  61. GRB 241213A (EP241213a): GRBAlpha detection
  62. GRB 241209D: GRBAlpha detection
  63. EP241217A: LCO optical observations
  64. EP241217a: Gemini-North detection of the likely optical counterpart
  65. EP241217a: EP detection of an X-ray transient
  66. The EP-WXT trigger 01709129023 is likely a flaring star
  67. EP241107a: VLA Radio Observation
  68. GRB 241213A: Swift-BAT refined analysis
  69. GRB 241214A: Swift/BAT-GUANO localization skymap of a burst
  70. Konus-Wind detection of GRB 241213A (EP 241213a)
  71. GRB 241215A: Mondy AZT-33IK optical observations
  72. GRB 241212A: Swift-XRT observations
  73. GRB 241214A: SVOM/GRM observation
  74. The EP-WXT trigger 01709128948 is likely a flaring star
  75. GRB 241215A: Nanshan/HMT optical upper limit
  76. GRB 241215A: Montarrenti Observatory optical upper limit
  77. GRB 241215A: GROWTH-India telescope optical upper limit
  78. GRB 241215A: A long GRB detected by INTEGRAL
  79. Integral GRB241215.58: Global MASTER-Net observations report
  80. The EP-WXT trigger 01709128921 is likely a flaring star
  81. GRB 241213B: Swift-XRT observations
  82. GRB 241209D: CALET Gamma-Ray Burst Monitor detection
  83. GRB 241209B: SVOM/VT optical continuous fading
  84. EP trigger ID 01709128824 is not a real source
  85. GRB 241213A: SVOM/VT optical candidate
  86. GRB 241213B: Tiled Swift observations
  87. GRB 241213A: Swift/UVOT Upper Limits
  88. GRB 241213B: CALET Gamma-Ray Burst Monitor detection
  89. GRB 241213A: Swift-XRT refined Analysis
  90. GRB 241212A: Fermi GBM detection
  91. EP241208a: NOT optical upper limits
  92. GRB 241212A: Swift ToO observations
  93. GRB 241213A: LCOGT Optical Upper Limits
  94. EP 241208A : Detection of a long soft transient by SVOM/ECLAIRs
  95. EP241213a/GRB241213a: Likely joint detection and INTEGRAL/SPI-ACS counterpart
  96. GRB 241213B: MAXI/GSC detection
  97. EP241213a: EP detection of An X-ray Transient
  98. GRB 241213A: REM optical/NIR upper limits
  99. GRB 241213A: Enhanced Swift-XRT position
  100. GRB241212A: OHP/T193 optical observations

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