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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"

26037 results found.

  1. GRB 250101A: SAO RAS observations of optical brightening
  2. GRB 250101A: BOOTES-4/MET optical afterglow detection
  3. GRB 250101A: AKO Optical Afterglow Detection
  4. GRB 250101A: SAO RAS optical observations
  5. GRB 250101A: Enhanced Swift-XRT position
  6. GRB 250101A: Xinglong-2.16m spectroscopic redshift
  7. GRB 250101A: SVOM/C-GFT early optical observations
  8. GRB 250101A: MASTER earlier OT observations with SOSS emission features
  9. GRB 250101A: Nanshan/HMT optical observations
  10. GRB 250101A : GIT optical detection
  11. GRB 250101A: Swift detection of a burst with an optical counterpart
  12. Swift GRB250101.56: Global MASTER-Net observations report
  13. EP241217a: VLA Radio Detection

  14. GRB 241229A: EP-FXT X-ray afterglow confirmation
  15. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  16. GRB 241229B: SVOM/GRM observation
  17. EP241217A: J band upper limit by SYSU 80cm telescope
  18. GRB 241228B: SAO RAS optical observations
  19. GRB 241229A: SAO RAS optical observations
  20. GRB 241229B: SVOM/VT optical candidate
  21. GRB 241229A: Swift-XRT observations
  22. Konus-Wind detection of GRB 241228A
  23. GRB 241229A: EP-FXT afterglow candidates
  24. GRB 240606B: 7DT Optical upper limits
  25. GRB 241229B: Swift-BAT refined analysis
  26. GRB241229B: UVOT upper limits
  27. GRB 241228B: D50 optical detection
  28. GRB 241228B: Fermi GBM Observation
  29. GRB 241228B: Swift-XRT afterglow detection
  30. GRB 241229B: Fermi GBM Observation
  31. GRB 241229A: Swift ToO observations
  32. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  33. GRB 241228A: Mondy optical afterglow observations
  34. GRB 241229B: Swift-XRT refined Analysis
  35. Swift GRB 241229B: Global MASTER-Net observations report
  36. GRB 241228B: VLT/X-shooter redshift of z = 2.674
  37. GRB 241228A: NOT optical upper limits
  38. GRB 241228A: Swift-BAT refined analysis
  39. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
  40. GRB 241229B: Swift detection of a burst
  41. GRB 241228A: Fermi GBM Observation
  42. GRB241228B: GROWTH-India Telescope optical observations
  43. Swift GRB 241228A: Global MASTER-Net observations report
  44. GRB 241226A: Swift/BAT-GUANO localization skymap of a burst
  45. GRB 241228A: GROWTH-India telescope optical upper limit
  46. GRB 241228B: Swift ToO observations
  47. GRB 241228A: Swift-XRT refined Analysis
  48. GRB 241228A: Swift/UVOT Upper Limits
  49. GRB 241228A: Enhanced Swift-XRT position
  50. GRB 241228A: Swift detection of a burst
  51. GRB 241223A: Swift-XRT observations
  52. GRB241113A: 7DT Optical upper limits
  53. GRB 241223A: GOTO optical observations summary
  54. GRB 241105A: JWST photometric observations of the host galaxy
  55. GRB 241223A: Swift ToO observations
  56. GRB 241209B: host galaxy detection and GTC/OSIRIS+ spectroscopy
  57. GRB 241217A/EP241217b: SOAR afterglow detection
  58. GRB 241218A: Mondy AZT-33IK optical upper limit
  59. EP241217a : Leavitt Observatory optical upper limit
  60. GRB 241217A/EP241217b: tentative VLT spectroscopic redshift z=1.879
  61. GRB 241218A: Swift/UVOT Upper Limits
  62. EP241217a: optical upper limit with the Liverpool Telescope
  63. GRB 241209B: EP-FXT afterglow detection
  64. GRB 241218A: NOT optical upper limits
  65. GRB 241218A: Swift-BAT refined analysis
  66. EP241217a: refined EP-WXT analysis and EP-FXT follow-up observations
  67. GRB 241217A / EP241217b: Nanshan/HMT optical upper limit
  68. GRB 241217A: refined SVOM/MXT data analysis. Long lasting X-ray emission.
  69. GRB 241217A / EP241217b: NOT optical upper limits
  70. GRB 241218A: REM optical upper limit
  71. GRB 241217A/EP241217b: REM optical/NIR upper limits
  72. EP241217a: REM optical/NIR upper limits
  73. GRB 241218a: Liverpool Telescope optical follow-up
  74. GRB 241217a: Liverpool Telescope optical follow-up
  75. GRB 241218A: Swift-XRT refined Analysis
  76. GRB 241209A: ATCA radio follow-up observations
  77. EP241217b/GRB 241217A: EP detection of the prompt X-ray emssion
  78. GRB 241218A: LCOGT Optical Upper Limit
  79. GRB 241218A: Enhanced Swift-XRT position
  80. GRB 241218A: Swift detection of a burst
  81. GRB 241217A : SVOM/VT optical afterglow detection
  82. GRB 241217A: Swift-XRT afterglow detection
  83. GRB 241217A: LCO optical upper limit
  84. GRB 241217A: GRANDMA/TAROT optical upperlimits
  85. EP241217a: Swift-XRT Detection
  86. GRB 241217A : SVOM/ECLAIRs,GRM,MXT detection of a long burst with a bright X-ray afterglow candidate
  87. GRB 241214A: GRBAlpha detection
  88. GRB 241213A (EP241213a): GRBAlpha detection
  89. GRB 241209D: GRBAlpha detection
  90. GRB 241213A: Swift-BAT refined analysis
  91. GRB 241214A: Swift/BAT-GUANO localization skymap of a burst
  92. Konus-Wind detection of GRB 241213A (EP 241213a)
  93. GRB 241212A: Swift-XRT observations
  94. GRB 241213B: Swift-XRT observations
  95. GRB 241209D: CALET Gamma-Ray Burst Monitor detection
  96. GRB 241213A: SVOM/VT optical candidate
  97. GRB 241213B: Tiled Swift observations
  98. GRB 241213A: Swift/UVOT Upper Limits
  99. GRB 241213A: Swift-XRT refined Analysis
  100. GRB 241212A: Swift ToO observations

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