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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"

32689 results found.

  1. GRB 250916A: FTW optical and NIR observations of the counterpart
  2. GRB 250920C: Swift/UVOT Detection
  3. GRB 250920B: Fermi GBM Observation
  4. GRB 250920A: Fermi GBM Detection
  5. GRB 250920C: Fermi GBM Observation
  6. Swift GRB 250920C: Global MASTER-Net observations report
  7. GRB 250920B: Swift/UVOT Detection
  8. GRB 250920B: FTW optical and NIR observations of the counterpart
  9. GRB 250920C: Optical counterpart detection by LCO
  10. GRB 250920A: SVOM/GRM observation
  11. GRB250920C: LCOGT Optical Detection
  12. GRB 250920B: SVOM/C-GFT optical observations
  13. GRB 250920C: GOTO optical counterpart candidate
  14. GRB 250919A / EP250919a: LCO optical observation
  15. Konus-Wind detection of GRB 250919A
  16. Swift GRB 250920B: Global MASTER-Net observations report
  17. GRB 250919A / EP250919a: Insight-HXMT detection
  18. GRB 250920A: AstroSat CZTI detection
  19. GRB 250919A/EP250919a: SVOM/VT optical observation
  20. GRB 250919A / EP250919a: MASTER bright afterglow detection 24h after GRB time
  21. GRB 250916A: Mondy R-band optical observations
  22. GRB 250919A: Glowbug gamma-ray detection
  23. GRB 250919A: Fermi GBM Observation
  24. Fermi GRB 250918A: Global MASTER-Net observations report
  25. GRB 250919A / EP250919a: NuSTAR detection of bright prompt emission
  26. GRB 250918A: SVOM/GRM observation
  27. GRB 250919A/EP250919A: Swift/UVOT afterglow detection
  28. GRB 250919A: Swift-XRT afterglow detection
  29. GRB 250919A: Fermi-LAT detection
  30. EP250919a/GRB 250919A: Gemini/GMOS-S spectroscopic redshift z = 1.145
  31. GRB 250919A: SVOM/GRM observation of a very bright GRB
  32. EP250919a: Global MASTER-Net observations report
  33. EP250919a: Einstein Probe detection of an X-ray transient
  34. Correction for GCN 41877: EP-WXT ID is 01709243841
  35. GRB 250916A: Fermi GBM Observation
  36. Fermi GRB 250919A: Global MASTER-Net observations report
  37. GRB 250916A: KAIT optical observations
  38. GRB 250917B: VLT/HAWK-I near-infrared observations
  39. GRB 250916A: NuSTAR detection of the prompt emission
  40. GRB 250916A: further SAO RAS optical observations
  41. GRB 250912A: SVOM/ECLAIRs refined analysis
  42. GRB 250917B: Swift-BAT refined analysis
  43. GRB 250917B: Swift/UVOT Upper Limits
  44. GRB 250916A: OSIRIS+/GTC redshift z = 2.015
  45. GRB 250916A: Swift-XRT observations
  46. EP250916a: EP-FXT follow-up observation
  47. GRB 250916A: MAO/AZT-22 optical observations
  48. GRB 250916A: SAO RAS optical observations
  49. GRB 250916A : GIT optical observations
  50. LIGO/Virgo/KAGRA S250917aq: Updated Sky localization
  51. GRB 250916A: Glowbug gamma-ray detection
  52. GRB250917B: WFST optical observations
  53. GRB 250916A: Swift ToO observations
  54. GRB 250917B: Fermi GBM Observation
  55. LIGO/Virgo/KAGRA S250917aq: Identification of a GW compact binary merger candidate
  56. Fermi GRB 250917B: Global MASTER-Net observations report
  57. GRB 250916A: GOTO optical counterpart candidate
  58. GRB 250916A: AstroSat CZTI detection of a bright long burst
  59. GRB 250910A: SVOM/ECLAIRs refined analysis
  60. Fermi GRB 250916A: Global MASTER-Net observations report
  61. EP250827b: VLA Observations
  62. LIGO/Virgo/KAGRA S250818k: HCT optical follow-up
  63. SVOM/sb25091517: Confirmation of a stellar flare by SVOM/VT
  64. SVOM/sb25091517: FRAM-ORM stellar flare - transient observation
  65. GRB 250912A: Swift/BAT-GUANO localization skymap of a possibly short burst
  66. GRB 250912A: SVOM/COLIBRÍ (FM-GFT) optical observations
  67. GRB 250912A: Swift-XRT observations
  68. GRB250912A: VLT/HAWK-I follow-up observations
  69. GRB 250912A: VLT observations
  70. GRB 250912A: Fermi GBM Observation
  71. GRB 250911A: Insight-HXMT detection
  72. GRB 250912A: SVOM/GRM analysis suggests a possible short GRB with extended emission
  73. GRB 250912A:SVOM/VT optical upper limit
  74. GRB 250912A: LCO optical upper limit
  75. Fermi GRB 250912A: Global MASTER-Net observations report
  76. EP250911a: Global MASTER-Net observations report
  77. GRB 250912A: SVOM detection of a burst
  78. EP250908c: tentative VLT/FORS2 redshift z = 2.87
  79. EP250911a: Upper limit from Fermi-GBM Observations
  80. LIGO/Virgo/KAGRA S250912f: Updated Sky localization
  81. GRB 250911A: GECAM-B detection
  82. GRB 250911A: Swift-BAT refined analysis
  83. EP250911a: GTC/OSIRIS+ spectroscopic redshift z = 3.84
  84. LIGO/Virgo/KAGRA S250912f: Identification of a GW compact binary merger candidate
  85. EP250911a: refined analysis of the EP-WXT and EP-FXT observations
  86. GRB 250910B: SVOM/GRM observation
  87. EP250911a: SVOM/VT optical observation
  88. GRB 250911A: MASTER optical counterpart observations
  89. EP250911a: SAO RAS optical observations
  90. EP250911a: Swift-XRT observations
  91. EP250911a: Optical detection with Kinder observations
  92. GRB 250911A: Swift/UVOT Detection
  93. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  94. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  95. GRB 250909B: Insight-HXMT detection
  96. GRB 250909B: SVOM/GRM observation
  97. LIGO/Virgo/KAGRA S250911ac: Updated Sky localization and Source Classification
  98. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  99. EP250911a: COLIBRÍ optical observations
  100. LIGO/Virgo/KAGRA S250908y: Updated Sky localization

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