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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"

45930 results found.

  1. GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
  2. EP250704a / GRB250704B: Swift-XRT counterpart detection
  3. GRB 250704A: Swift-XRT afterglow detection
  4. GRB 250702B / EP2050702a: FTW optical and NIR observations
  5. Konus-Wind detection of GRB 250702F
  6. EP250704a / GRB 250704B - REM observations
  7. GRB 250702F: GROWTH-India Telescope optical observations
  8. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  9. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  10. EP250702a: WFST optical observations
  11. EP250704a: COLIBRÍ optical counterpart candidate
  12. EP250704a: Einstein Probe detection of an X-ray transient
  13. GRB 250704B: SVOM/GRM observation of a short burst
  14. GRB 250702F: optical photometry from Konkoly
  15. GRB 250704A: REM detection of the optical afterglow
  16. LIGO/Virgo/KAGRA S250704ab: Coverage and upper limits from MAXI/GSC observations
  17. GRB 250702F: SVOM/VT optical observation
  18. LIGO/Virgo/KAGRA S250704ab: Identification of a GW compact binary merger candidate
  19. GRB 250704A: SVOM detection of a burst
  20. GRB 250702F: Swift/UVOT Detection
  21. GRB 250702A: CALET Gamma-Ray Burst Monitor detection
  22. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  23. Fermi GRB 250703A: Global MASTER-Net observations report
  24. GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit
  25. GRB 250702F: Swift-XRT refined Analysis
  26. GRB 250702F: Fermi GBM Observation
  27. GRB 250702F: Leavitt Observatory optical observations
  28. GRB 250702F: AKO Optical Afterglow Detection
  29. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  30. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  31. GRB 250702A: GECAM-B detection
  32. GRB 250702F: Skynet Optical Observations
  33. GRB 250424A: VIRT Optical Upper Limit
  34. GRBs 250702B/C/D/E / EP250702a: Swift XRT localization
  35. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  36. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  37. GRB 250702F: TRT Optical Observation
  38. GRB 250703A: DDOTI Optical Upper Limit
  39. GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
  40. GRB 250702F: REM optical afterglow detection
  41. EP250702a: Global MASTER-Net observations report
  42. GRB 250702F: DDOTI Optical Observation
  43. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  44. GRB 250703A: Fermi GBM Final Real-time Localization
  45. EP250702a/GRB 250702B,C,D,E: GOTO optical upper limits
  46. GRB 250702F: COLIBRÍ Observations of the Afterglow
  47. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  48. Fermi GRB 250702E: Global MASTER-Net observations report
  49. Fermi GRB 250702B: Global MASTER-Net observations report
  50. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  51. GRB 250702F: Enhanced Swift-XRT position
  52. GRB 250702F: GTC/OSIRIS+ spectroscopic redshift z = 1.520
  53. GRB 250702F: NOT observations of the optical afterglow
  54. GRB 250702F: MASTER optical afterglow observation
  55. Fermi GRB 250702F: Global MASTER-Net observations report
  56. Fermi GRB 250702C: Global MASTER-Net observations report
  57. GRB 250702F: GOTO optical counterpart detection
  58. GRB 250702F: Ondrejov D50 optical afterglow detection
  59. GRB 250702F: Swift detection of a burst with an optical counterpart
  60. Swift GRB 250702F: Global MASTER-Net observations report
  61. GRB 250702F: Fermi GBM Final Real-time Localization
  62. Fermi GBM Triggers 250702B, C, D and E are likely from the same source
  63. GRB 250702E: Fermi GBM Final Real-time Localization
  64. Konus-Wind detection of GRB 250627A
  65. IPN triangulation of GRB 250627A (short)
  66. GRB 250702A: Fermi GBM Detection
  67. GRB 250702D: Fermi GBM Final Localization Correction
  68. GRB 250702C: Fermi GBM Final Real-time Localization
  69. LIGO/Virgo/KAGRA S250702n: Identification of a GW compact binary merger candidate
  70. GRB 250702B: Fermi GBM Final Real-time Localization
  71. GRB 250702A: BALROG localization (Fermi Trigger 773142852 / GRB 250702413)
  72. GRB 250702A: Fermi GBM Final Real-time Localization
  73. LIGO/Virgo/KAGRA S250701bq: Identification of a GW compact binary merger candidate
  74. LIGO/Virgo/KAGRA S250701bp: Identification of a GW compact binary merger candidate
  75. Fermi Gamma-ray Burst Monitor trigger 772838080/250628885 is not a GRB
  76. GRB 250628B: Swift-XRT observations
  77. Fermi Gamma-ray Burst Monitor trigger 772981768/250630548 is not a GRB
  78. GRB 250628B: SVOM/VT optical upper limit
  79. GRB 250628B: EP-FXT counterpart detection
  80. LIGO/Virgo/KAGRA S250629bs: Updated Sky localization
  81. GRB 250627A: Insight-HXMT detection
  82. GRB 250627A: SVOM/GRM detection of a short burst
  83. LIGO/Virgo/KAGRA S250629ae: Updated Sky localization
  84. LIGO/Virgo/KAGRA S250629bs: Identification of a GW compact binary merger candidate
  85. LIGO/Virgo/KAGRA S250628am: Identification of a GW compact binary merger candidate (duplicate submission)
  86. LIGO/Virgo/KAGRA S250629ae: Identification of a GW compact binary merger candidate
  87. LIGO/Virgo/KAGRA S250628am: Updated Sky localization
  88. GRB 250628A: REM optical/NIR upper limits
  89. GRB 250628C: Fermi GBM Final Real-time Localization
  90. LIGO/Virgo/KAGRA S250628am: Identification of a GW compact binary merger candidate
  91. GRB 250628B: SVOM detection of a long burst
  92. Fermi Gamma-ray Burst Monitor trigger 772811638/250628579 is not a GRB
  93. GRB 250625A: VLT/X-shooter spectroscopic observations at the afterglow position
  94. GRB 250628A: VLT/X-shooter upper limits
  95. GRB 250628A: Swift/UVOT Upper Limits
  96. GRB 250628A: Swift-XRT refined Analysis
  97. Fermi GRB 250626A: Global MASTER-Net observations report
  98. Swift GRB 250628A: Global MASTER-Net observations report
  99. GRB 250628A: Enhanced Swift-XRT position
  100. GRB 250628A: Swift detection of a burst

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