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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. The EP-WXT trigger 01709129287 is likely a flaring star
  2. Fermi trigger No 756447119: Global MASTER-Net observations report
  3. GRB 241209B: host galaxy detection and GTC/OSIRIS+ spectroscopy
  4. Fermi Gamma-ray Burst Monitor trigger 756447119/241221175 is not a GRB
  5. Fermi GRB 241221A: Global MASTER-Net observations report
  6. GRB 241221A: Fermi GBM Final Real-time Localization
  7. GRB 241217A/EP241217b: SOAR afterglow detection
  8. EP241217a: Liverpool Telescope optical upper limit
  9. EP241021a: VLA radio detection
  10. GRB 241218A: Mondy AZT-33IK optical upper limit
  11. EP241217a : Leavitt Observatory optical upper limit
  12. GRB 241217A/EP241217b: tentative VLT spectroscopic redshift z=1.879
  13. EP241217a: 1.6m Mephisto multi-band optical observations
  14. GRB 241217a/EP241217B: 1.6m Mephisto optical upper limits
  15. GRB 241218A: Swift/UVOT Upper Limits
  16. EP241217a: optical upper limit with the Liverpool Telescope
  17. GRB 241209B: EP-FXT afterglow detection
  18. Konus-Wind detection of GRB 241204A (short/hard)
  19. GRB 241218A: NOT optical upper limits
  20. GRB 241218A: Swift-BAT refined analysis
  21. GRB 241217A / EP241217B: GRANDMA/T1MPicduMidi optical upperlimits
  22. EP 241217a: NIR detection with P200/WIRC
  23. EP 241217a: Possible J-band detection with WINTER
  24. GRB 241217A/EP241217B: Fermi-GBM Sub-Threshold Detection
  25. EP241217a: refined EP-WXT analysis and EP-FXT follow-up observations
  26. GRB 241217A / EP241217b: Nanshan/HMT optical upper limit
  27. GRB 241217A: refined SVOM/MXT data analysis. Long lasting X-ray emission.
  28. GRB 241217A / EP241217b: NOT optical upper limits
  29. GRB 241218A: REM optical upper limit
  30. GRB 241217A/EP241217b: REM optical/NIR upper limits
  31. EP241217a: REM optical/NIR upper limits
  32. GRB 241218a: Liverpool Telescope optical follow-up
  33. GRB 241217a: Liverpool Telescope optical follow-up
  34. EP241217a: Liverpool Telescope optical follow-up
  35. GRB 241218A: Swift-XRT refined Analysis
  36. EP241217a: NOT optical observations
  37. EP241217a: GROWTH-India Telescope optical observations
  38. GRB 241218A: NUTTelA-TAO / BSTI Optical Limits
  39. EP241119a: 7DT Optical upper limits
  40. EP241217b: Global MASTER-Net observations report
  41. GRB 241209A: ATCA radio follow-up observations
  42. EP241217a: Xinglong optical follow-up observations
  43. EP241217b/GRB 241217A: EP detection of the prompt X-ray emssion
  44. GRB 241218A: LCOGT Optical Upper Limit
  45. GRB 241218A: Enhanced Swift-XRT position
  46. EP241217a: Global MASTER-Net observations report
  47. GRB 241217A: GMG Optical Upper Limit
  48. GRB 241218A: Swift detection of a burst
  49. GRB 241217A : SVOM/VT optical afterglow detection
  50. GRB 241217A: Swift-XRT afterglow detection
  51. GRB 241217A: LCO optical upper limit
  52. GRB 241217A: GRANDMA/TAROT optical upperlimits
  53. EP241217a: Swift-XRT Detection
  54. EP241217A: Non-detection from Fermi-GBM Observations
  55. GRB 241217A : SVOM/ECLAIRs,GRM,MXT detection of a long burst with a bright X-ray afterglow candidate
  56. EP241217a: Gemini-North spectroscopic redshift z = 4.59
  57. EP241217a: Kinder optical follow-up observations
  58. GRB 241214A: GRBAlpha detection
  59. GRB 241213A (EP241213a): GRBAlpha detection
  60. GRB 241209D: GRBAlpha detection
  61. EP241217A: LCO optical observations
  62. EP241217a: Gemini-North detection of the likely optical counterpart
  63. EP241217a: EP detection of an X-ray transient
  64. The EP-WXT trigger 01709129023 is likely a flaring star
  65. EP241107a: VLA Radio Observation
  66. GRB 241213A: Swift-BAT refined analysis
  67. GRB 241214A: Swift/BAT-GUANO localization skymap of a burst
  68. Konus-Wind detection of GRB 241213A (EP 241213a)
  69. GRB 241215A: Mondy AZT-33IK optical observations
  70. GRB 241212A: Swift-XRT observations
  71. GRB 241214A: SVOM/GRM observation
  72. The EP-WXT trigger 01709128948 is likely a flaring star
  73. GRB 241215A: Nanshan/HMT optical upper limit
  74. GRB 241215A: Montarrenti Observatory optical upper limit
  75. GRB 241215A: GROWTH-India telescope optical upper limit
  76. GRB 241215A: A long GRB detected by INTEGRAL
  77. Integral GRB241215.58: Global MASTER-Net observations report
  78. The EP-WXT trigger 01709128921 is likely a flaring star
  79. GRB 241213B: Swift-XRT observations
  80. GRB 241209D: CALET Gamma-Ray Burst Monitor detection
  81. GRB 241209B: SVOM/VT optical continuous fading
  82. EP trigger ID 01709128824 is not a real source
  83. GRB 241213A: SVOM/VT optical candidate
  84. GRB 241213B: Tiled Swift observations
  85. GRB 241213A: Swift/UVOT Upper Limits
  86. GRB 241213B: CALET Gamma-Ray Burst Monitor detection
  87. GRB 241213A: Swift-XRT refined Analysis
  88. GRB 241212A: Fermi GBM detection
  89. EP241208a: NOT optical upper limits
  90. GRB 241212A: Swift ToO observations
  91. GRB 241213A: LCOGT Optical Upper Limits
  92. EP 241208A : Detection of a long soft transient by SVOM/ECLAIRs
  93. EP241213a/GRB241213a: Likely joint detection and INTEGRAL/SPI-ACS counterpart
  94. GRB 241213B: MAXI/GSC detection
  95. EP241213a: EP detection of An X-ray Transient
  96. GRB 241213A: REM optical/NIR upper limits
  97. GRB 241213A: Enhanced Swift-XRT position
  98. GRB241212A: OHP/T193 optical observations
  99. GRB 241213A: SAO RAS optical upper limit
  100. LIGO/Virgo/KAGRA S241210fu: Updated Sky localization

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