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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"

26672 results found.

  1. GRB 250920B: Swift detection of a burst with a bright optical counterpart.
  2. GRB 250920A: BALROG localization (Fermi Trigger 780029651 / GRB 250920121)
  3. GRB 250919A/EP250919a: SVOM/VT optical observation
  4. GRB 250916A: Mondy R-band optical observations
  5. GRB 250919A: Glowbug gamma-ray detection
  6. GRB 250919A: Fermi GBM Observation
  7. GRB 250918A: SVOM/GRM observation
  8. GRB 250919A: Swift-XRT afterglow detection
  9. GRB 250919A: SVOM/GRM observation of a very bright GRB
  10. GRB 250919A: BALROG localization (Fermi Trigger 779934537 / GRB 250919020)
  11. EP250919a: Einstein Probe detection of an X-ray transient
  12. GRB 250916A: Fermi GBM Observation
  13. GRB 250916A: KAIT optical observations
  14. GRB 250917B: VLT/HAWK-I near-infrared observations
  15. GRB 250916A: further SAO RAS optical observations
  16. GRB 250912A: SVOM/ECLAIRs refined analysis
  17. LIGO/Virgo/KAGRA S250918aw: 1 counterpart neutrino candidate event from an IceCube neutrino search
  18. GRB 250918A: BALROG localization (Fermi Trigger 779891543 / GRB 250918522)
  19. GRB 250917B: Swift/UVOT Upper Limits
  20. GRB 250916A: OSIRIS+/GTC redshift z = 2.015
  21. GRB 250916A: Swift-XRT observations
  22. EP250916a: EP-FXT follow-up observation
  23. GRB 250916A: MAO/AZT-22 optical observations
  24. GRB 250916A: SAO RAS optical observations
  25. GRB 250916A : GIT optical observations
  26. LIGO/Virgo/KAGRA S250917aq: Three counterpart neutrino candidates from IceCube neutrino searches
  27. GRB 250916A: Glowbug gamma-ray detection
  28. GRB250917B: WFST optical observations
  29. GRB 250917B: Fermi GBM Observation
  30. GRB 250917B: Swift-XRT observations
  31. LIGO/Virgo/KAGRA S250917aq: Identification of a GW compact binary merger candidate
  32. GRB 250917B: Swift detection of a short burst
  33. The EP-WXT trigger 01709241037 is likely a flaring star
  34. GRB 250916A: AstroSat CZTI detection of a bright long burst
  35. GRB 250910A: SVOM/ECLAIRs refined analysis
  36. EP250916a: Einstein Probe detection of an X-ray transient
  37. SVOM/sb25091517: SVOM detection of an X-ray transient
  38. GRB 250912A: Swift/BAT-GUANO localization skymap of a possibly short burst
  39. GRB 250912A: SVOM/COLIBRÍ (FM-GFT) optical observations
  40. GRB 250912A: Swift-XRT observations
  41. GRB250912A: VLT/HAWK-I follow-up observations
  42. GRB 250912A: Fermi GBM Observation
  43. GRB 250912A: SVOM/GRM analysis suggests a possible short GRB with extended emission
  44. GRB 250912A:SVOM/VT optical upper limit
  45. GRB 250912A: LCO optical upper limit
  46. The EP-WXT trigger 01709240768 is likely a flaring star
  47. GRB 250912A: SVOM detection of a burst
  48. IceCube-Cascade 250911A: Upper limits from a search for additional neutrino events in IceCube
  49. LIGO/Virgo/KAGRA S250912s: 2 counterpart neutrino candidate events from an IceCube neutrino search
  50. GRB 250911A: GECAM-B detection
  51. LIGO/Virgo/KAGRA S250912f: Identification of a GW compact binary merger candidate
  52. EP250911a: refined analysis of the EP-WXT and EP-FXT observations
  53. GRB 250910B: SVOM/GRM observation
  54. EP250911a: SVOM/VT optical observation
  55. GRB 250911A: MASTER optical counterpart observations
  56. EP250911a: SAO RAS optical observations
  57. GRB 250911A: Swift-XRT refined Analysis
  58. EP250911a: Swift-XRT observations
  59. EP250911a: Optical detection with Kinder observations
  60. GRB 250911A: Swift/UVOT Detection
  61. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  62. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  63. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  64. EP250911a: COLIBRÍ optical observations
  65. EP250911a: Einstein Probe detection of an X-ray transient
  66. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  67. GRB 250903A: SVOM/ECLAIRs refined analysis
  68. GRB 250911A: Enhanced Swift-XRT position
  69. GRB 250911A: Swift-XRT observations
  70. GRB 250911A: COLIBRÍ optical counterpart candidate
  71. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  72. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  73. GRB 250910A: SVOM/VT optical upper limit
  74. GRB 250910A: LCO optical upper limit
  75. GRB 250910A: SVOM detection of a faint burst
  76. GRB 250702B: Late time Chandra observations
  77. EP250908b/EP#01709240653: Swift/UVOT Detection
  78. EP#01709240653: Swift-XRT observations
  79. The EP-WXT trigger 01709240674 is triggered by the known source SS Cyg
  80. EP250908c: refined analysis of the EP-WXT and EP-FXT observations
  81. EP250908c: SVOM/VT optical observation
  82. EP250908c: VLT/FORS2 optical counterpart identification
  83. EP250908b: SVOM/VT optical candidate (Coordinate supplement for GCN 41758)
  84. EP250908b: SVOM/VT optical candidate
  85. EP250908c: Einstein Probe detection of an X-ray transient
  86. EP250908b: EP-WXT detection of a fast X-ray transient and EP-FXT observation
  87. LIGO/Virgo/KAGRA S250908y: Identification of a GW compact binary merger candidate
  88. GRB 250907A: GECAM-B detection
  89. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  90. GRB 250903A: Swift-XRT afterglow detection
  91. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  92. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  93. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  94. EP250905a: Liverpool Telescope i-band upper limits
  95. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  96. EP250905b: EP-FXT follow-up observation
  97. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 2 Candidates
  98. EP250905a: Liverpool Telescope observations
  99. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  100. EP250905b: EP-WXT detection of a fast X-ray transient

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