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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').
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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"
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submitter:"Judith Racusin"

32710 results found.

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

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