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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').
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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

32513 results found.

  1. GRB 250912A: SVOM detection of a burst
  2. EP250908c: tentative VLT/FORS2 redshift z = 2.87
  3. EP250911a: Upper limit from Fermi-GBM Observations
  4. LIGO/Virgo/KAGRA S250912f: Updated Sky localization
  5. GRB 250911A: GECAM-B detection
  6. GRB 250911A: Swift-BAT refined analysis
  7. EP250911a: GTC/OSIRIS+ spectroscopic redshift z = 3.84
  8. LIGO/Virgo/KAGRA S250912f: Identification of a GW compact binary merger candidate
  9. EP250911a: refined analysis of the EP-WXT and EP-FXT observations
  10. GRB 250910B: SVOM/GRM observation
  11. EP250911a: SVOM/VT optical observation
  12. GRB 250911A: MASTER optical counterpart observations
  13. EP250911a: SAO RAS optical observations
  14. EP250911a: Swift-XRT observations
  15. EP250911a: Optical detection with Kinder observations
  16. GRB 250911A: Swift/UVOT Detection
  17. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  18. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  19. GRB 250909B: Insight-HXMT detection
  20. GRB 250909B: SVOM/GRM observation
  21. LIGO/Virgo/KAGRA S250911ac: Updated Sky localization and Source Classification
  22. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  23. EP250911a: COLIBRÍ optical observations
  24. LIGO/Virgo/KAGRA S250908y: Updated Sky localization
  25. Fermi GRB 250910B: Global MASTER-Net observations report
  26. EP250911a: LCO optical counterpart discovery
  27. EP250910a: Global MASTER-Net observations report
  28. GRB 250404A / EP250404a: spectroscopic redshift at z = 1.88 (correction to GCN 40084)
  29. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  30. GRB 250903A: SVOM/ECLAIRs refined analysis
  31. GRB 250911A: COLIBRÍ optical counterpart candidate
  32. LIGO/Virgo/KAGRA S250906ca: Updated Sky localization
  33. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  34. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  35. GRB 250910A: SVOM/VT optical upper limit
  36. EP250908C: GROND observation of the fading optical counterpart
  37. GRB 250910A: LCO optical upper limit
  38. GRB 250909A: AstroSat CZTI detection
  39. GRB 250910A: SVOM/MXT possible afterglow detection
  40. GRB 250702B: Late time Chandra observations
  41. EP250908b/EP#01709240653: Swift/UVOT Detection
  42. EP250908c: refined analysis of the EP-WXT and EP-FXT observations
  43. GRB 250907A: CALET Gamma-Ray Burst Monitor detection
  44. EP250908c: SVOM/VT optical observation
  45. EP250908c: VLT/FORS2 optical counterpart identification
  46. EP250908b: SVOM/VT optical candidate (Coordinate supplement for GCN 41758)
  47. EP250908b: SVOM/VT optical candidate
  48. EP250908c: Global MASTER-Net observations report
  49. Fermi GRB 250909A: Global MASTER-Net observations report
  50. LIGO/Virgo/KAGRA S250908y: Identification of a GW compact binary merger candidate
  51. GRB 250905A: Swift-BAT refined analysis
  52. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  53. GRB 250903A: Swift-XRT afterglow detection
  54. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  55. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  56. EP250905a: Liverpool Telescope i-band upper limits
  57. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  58. EP250905b: EP-FXT follow-up observation
  59. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 2 Candidates
  60. EP250905a: Liverpool Telescope observations
  61. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  62. EP250905b: Global MASTER-Net observations report
  63. EP250905a: FTW one optical and multiple NIR counterpart candidates
  64. EP250905a: JinShan likely optical counterpart detection
  65. GRB 250904A: Swift-BAT refined analysis
  66. GRB 250905A: Swift/UVOT Upper Limits
  67. EP250905a: Global MASTER-Net observations report
  68. GRB 250901A - SVOM/ECLAIRs refined analysis
  69. GRB250904A: Liverpool Telescope upper limits
  70. GRB 250904A: Swift/UVOT Detection
  71. GRB 250903A: Swift/UVOT detection
  72. LIGO/Virgo/KAGRA S250904cv: Updated Sky localization
  73. LIGO/Virgo/KAGRA S250904br: Updated Sky localization
  74. GRB 250905A: KAIT optical upper limit
  75. Swift GRB 250904A: Global MASTER-Net observations report
  76. GRB 250904A: TRT optical counterpart detection
  77. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  78. GRB 250902B: CALET Gamma-Ray Burst Monitor detection
  79. EP250827b: Gemini Spectroscopic Confirmation of AT2025wkm as a Ic-BL Supernova
  80. GRB 250902A: CALET Gamma-Ray Burst Monitor detection
  81. LIGO/Virgo/KAGRA S250904ae: Updated Sky localization
  82. GRB 250902A: VZLUSAT-2 detection
  83. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  84. GRB 250903A: Swift-XRT observations
  85. EP250903a: Swift-XRT observations
  86. EP#01709201209: Swift-XRT observations
  87. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  88. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  89. GRB 250830C: VZLUSAT-2 detection
  90. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  91. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  92. GRB 250903A: VLT X-shooter spectroscopic redshift z = 1.590
  93. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  94. GRB 250903A: EP-FXT counterpart detection
  95. GRB 250902A: GECAM-B detection
  96. GRB 250903A: LCO optical observation
  97. GRB 250903A: LCO optical afterglow detection
  98. GRB 250903A: SVOM/VT optical confirmation with VHF data
  99. EP250903a: SVOM/VT optical confirmation
  100. EP250901a: Mondy, Assy and SAO RAS optical limits

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