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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

18467 results found.

  1. EP260119a: SVOM/VT optical observation
  2. EP260119a: update of EP-FXT follow-up observation
  3. EP260119a: NOT optical observations
  4. EP260119a: SAO RAS optical observations
  5. EP260116a: COLIBRÍ detection of a fading optical source
  6. GRB 260117A: Swift-XRT afterglow detection
  7. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  8. GRB 260115A: AstroSat CZTI detection
  9. EP260119a: LCO optical observations
  10. GRB 260117A: ZTSh optical upper limit
  11. EP260119a: COLIBRÍ optical counterpart candidate
  12. EP260119a: preliminary result from the EP-FXT observation
  13. EP260119a: EP-WXT detection of a fast X-ray transient
  14. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  15. Swift trigger on the HMXB 1A 1118-61
  16. GRB 260117A: SVOM/C-GFT upper limit
  17. EP 260116a: COLIBRÍ optical upper limit
  18. Swift triggered on the HMXB 1A 1118-61
  19. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  20. EP260116a: Liverpool Telescope upper limits
  21. EP260116A: 1.3m DFOT optical upper limit
  22. GRB 260114A: VLT/MUSE spectroscopic observations
  23. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  24. EP260116a: Xinglong optical upper limit
  25. EP260116a: Einstein Probe detection of an X-ray transient
  26. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  27. Fermi GRB 260115A: Global MASTER-Net observations report
  28. GRB 251222A: radio detection with the VLA
  29. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  30. GRB 260114A: Swift-XRT refined Analysis
  31. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  32. GRB 260114A : MITSuME Akeno optical upper limits
  33. GRB 260114A: COLIBRÍ optical upper limits
  34. GRB 260114A: TNG NIR upper limit
  35. GRB 260114A: NOT optical observations
  36. GRB 260114A: SVOM/GRM observation of a short burst
  37. GRB 260114A: Mondy optical observations
  38. GRB 260114A: GMG Optical Observation
  39. GRB 260114A: Swift detection of a short burst
  40. EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
  41. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  42. EP260110a: TRT optical upper limits
  43. Swift Trigger 1439093: is probably not GRB 260113A
  44. GRB 260111A: COLIBRÍ optical afterglow candidate
  45. The EP-WXT trigger 01709251266 is likely a flaring star
  46. GRB 260111A: GOTO optical upper limits
  47. GRB 251230A: Mondy Optical Observations
  48. Swift trigger 1436759 is not an astrophysical event
  49. EP260110a: KAIT optical upper limit
  50. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  51. EP 260110a: COLIBRÍ optical observations
  52. EP260110a: SVOM/C-GFT upper limit
  53. EP260110a: Einstein Probe detection of an X-ray transient
  54. GRB 260109C: LCO optical upper limits
  55. GRB 260109C: Kilonova-Catcher optical upper limit
  56. Swift Trigger 1434591: possible GRB 260109C
  57. GRB 260109B: Fermi GBM Final Real-time Localization
  58. GRB 260102A: Swift-XRT afterglow detection
  59. GRB 260109A: Fermi GBM Final Real-time Localization
  60. GRB 260102A: AbAO optical observations
  61. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  62. The EP-WXT trigger 01709251112 is likely a flaring star
  63. GRB 260105A: SVOM/GRM observation
  64. GRB 260105B: SVOM/GRM observation
  65. The EP-WXT trigger 01709251028 is likely a flaring star
  66. FRB 20251229A: COLIBRÍ optical upper limits
  67. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  68. EP260105a: LCO Optical Upper limit
  69. EP260104a: Einstein Probe detection of a fast X-ray transient
  70. GRB 260101A: COLIBRÍ optical upper limits
  71. EP260105a: Einstein Probe detection of an X-ray transient
  72. GRB 260104A: COLIBRÍ optical upper limits
  73. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  74. GRB 260104A: Enhanced Swift-XRT position
  75. GRB 260101A: Swift/UVOT Detection
  76. GRB 260104A: Swift detection of a burst
  77. GRB 260101A: COLIBRÍ optical observations
  78. SVOM GRB260103.08: Global MASTER-Net observations report
  79. GRB 260102A: EP-FXT follow-up observation
  80. GRB 260102A: LCO optical upper limits
  81. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  82. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  83. GRB 260102A: SVOM detection of a burst
  84. GRB 260101A: SVOM/GRM observation
  85. GRB 260101A: Enhanced Swift-XRT position
  86. EP260101a: Einstein Probe detection of an X-ray transient
  87. GRB 260101A: LCO detection of the optical counterpart
  88. GRB 260101A: Swift detection of a burst with an optical counterpart
  89. GRB 251230A: GRANDMA/TAROT Early Detection
  90. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  91. EP251229a: Optical upper limit with Kinder observations
  92. GRB 251230A: 1.3m DFOT optical upper limit
  93. GRB 251222A: Mondy Optical Observations
  94. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  95. GRB 251230A: Swift/UVOT detection
  96. GRB251230A: 7DT optical upper limits
  97. GRB 251230A: GOTO optical upper limit
  98. EP251229a: NOT optical upper limits
  99. GRB 251230A / EP251230a: SVOM/VT optical observation
  100. EP251229a: refined analysis of the EP-WXT and EP-FXT observations

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