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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"

28089 results found.

  1. GRB 250912A: SVOM/COLIBRÍ (FM-GFT) optical observations
  2. GRB 250912A: Swift-XRT observations
  3. GRB250912A: VLT/HAWK-I follow-up observations
  4. GRB 250912A: Fermi GBM Observation
  5. GRB 250912A: SVOM/GRM analysis suggests a possible short GRB with extended emission
  6. GRB 250912A:SVOM/VT optical upper limit
  7. GRB 250912A: LCO optical upper limit
  8. EP250911a: Global MASTER-Net observations report
  9. GRB 250912A: SVOM detection of a burst
  10. IceCube-Cascade 250911A: Upper limits from a search for additional neutrino events in IceCube
  11. LIGO/Virgo/KAGRA S250912s: 2 counterpart neutrino candidate events from an IceCube neutrino search
  12. EP250911a: Upper limit from Fermi-GBM Observations
  13. LIGO/Virgo/KAGRA S250912f: Updated Sky localization
  14. GRB 250911A: GECAM-B detection
  15. GRB 250911A: Swift-BAT refined analysis
  16. LIGO/Virgo/KAGRA S250912f: Identification of a GW compact binary merger candidate
  17. EP250911a: refined analysis of the EP-WXT and EP-FXT observations
  18. GRB 250910B: SVOM/GRM observation
  19. EP250911a: SVOM/VT optical observation
  20. GRB 250911A: MASTER optical counterpart observations
  21. EP250911a: SAO RAS optical observations
  22. GRB 250911A: Swift-XRT refined Analysis
  23. EP250911a: Swift-XRT observations
  24. EP250911a: Optical detection with Kinder observations
  25. GRB 250911A: Swift/UVOT Detection
  26. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  27. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  28. LIGO/Virgo/KAGRA S250911ac: Updated Sky localization and Source Classification
  29. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  30. EP250911a: COLIBRÍ optical observations
  31. LIGO/Virgo/KAGRA S250908y: Updated Sky localization
  32. EP250911a: LCO optical counterpart discovery
  33. EP250911a: Einstein Probe detection of an X-ray transient
  34. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  35. GRB 250903A: SVOM/ECLAIRs refined analysis
  36. GRB 250911A: Enhanced Swift-XRT position
  37. GRB 250911A: Swift-XRT observations
  38. GRB 250911A: COLIBRÍ optical counterpart candidate
  39. LIGO/Virgo/KAGRA S250906ca: Updated Sky localization
  40. GRB 250910B: BALROG localization (Fermi Trigger 779223130 / GRB 250910786)
  41. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  42. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  43. GRB 250910A: SVOM/VT optical upper limit
  44. GRB 250910A: LCO optical upper limit
  45. EP250908b/EP#01709240653: Swift/UVOT Detection
  46. EP#01709240653: Swift-XRT observations
  47. EP250908c: refined analysis of the EP-WXT and EP-FXT observations
  48. EP250908c: SVOM/VT optical observation
  49. EP250908c: VLT/FORS2 optical counterpart identification
  50. EP250908b: SVOM/VT optical candidate (Coordinate supplement for GCN 41758)
  51. EP250908b: SVOM/VT optical candidate
  52. Fermi GRB 250909A: Global MASTER-Net observations report
  53. EP250908c: Einstein Probe detection of an X-ray transient
  54. EP250908b: EP-WXT detection of a fast X-ray transient and EP-FXT observation
  55. LIGO/Virgo/KAGRA S250908y: Identification of a GW compact binary merger candidate
  56. GRB 250907A: GECAM-B detection
  57. GRB 250905A: Swift-BAT refined analysis
  58. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  59. GRB 250903A: Swift-XRT afterglow detection
  60. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  61. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  62. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  63. EP250905a: Liverpool Telescope i-band upper limits
  64. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  65. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 2 Candidates
  66. EP250905a: Liverpool Telescope observations
  67. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  68. EP250905b: EP-WXT detection of a fast X-ray transient
  69. GRB 250905A: Swift-XRT refined Analysis
  70. EP250905a: JinShan likely optical counterpart detection
  71. GRB 250904A: Swift-BAT refined analysis
  72. GRB 250905A: Swift/UVOT Upper Limits
  73. GRB 250901A - SVOM/ECLAIRs refined analysis
  74. EP250905a: Einstein Probe detection of an X-ray transient
  75. GRB250904A: Liverpool Telescope upper limits
  76. GRB 250905A: Enhanced Swift-XRT position
  77. GRB 250904A: Swift/UVOT Detection
  78. GRB 250903A: Swift/UVOT detection
  79. GRB 250904A: Swift-XRT refined Analysis
  80. LIGO/Virgo/KAGRA S250904cv: Updated Sky localization
  81. LIGO/Virgo/KAGRA S250904br: Updated Sky localization
  82. EP detected a brightening of LMXB 1ES 1735-26.9
  83. GRB 250905A: KAIT optical upper limit
  84. GRB 250905A: Swift detection of a burst
  85. GRB 250904A: Enhanced Swift-XRT position
  86. IceCube-Cascade 250903A: Upper limits from a search for additional neutrino events in IceCube
  87. GRB 250904A: TRT optical counterpart detection
  88. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  89. GRB 250904A: Swift detection of a burst
  90. LIGO/Virgo/KAGRA S250904ae: Updated Sky localization
  91. GRB 250902A: VZLUSAT-2 detection
  92. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  93. GRB 250903A: Swift-XRT observations
  94. EP250903a: Swift-XRT observations
  95. EP#01709201209: Swift-XRT observations
  96. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  97. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  98. GRB 250830C: VZLUSAT-2 detection
  99. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  100. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate

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